ISO CLNS Commands

The International Organization for Standardization (ISO) Connectionless Network Service (CLNS) protocol is a standard for the network layer of the OSI model.

Use the commands in this chapter to configure and monitor ISO CLNS networks. For ISO CLNS protocol configuration information and examples, refer to the "Configuring ISO CLNS" chapter of the Cisco IOS Apollo Domain, Banyan VINES, DECnet, ISO CLNS, and XNS Configuration Guide.

Note Cisco access servers currently support End System-to-Intermediate System (ES-IS), but not Intermediate System-to-Intermediate System (IS-IS).

clear clns cache

To clear and reinitialize the CLNS routing cach, use the clear clns cache command in EXEC mode.

clear clns cache

Syntax Description

This command has no arguments or keywords.

Command Modes

EXEC

Command History

Release Modification

10.0

This command was introduced.

Release	Modification
10.0	This command was introduced.

Examples

The following example clears the CLNS routing cache:

clear clns cache

Related Commands

Command Description

show clns cache

Displays the CLNS routing cache.

Command	Description
show clns cache	Displays the CLNS routing cache.

clear clns es-neighbors

To remove end system (ES) neighbor information from the adjacency database, use the clear clns es-neighbors command in EXEC mode.

clear clns es-neighbors

Syntax Description

This command has no arguments or keywords.

Command Modes

EXEC

Command History

Release Modification

10.0

This command was introduced.

Release	Modification
10.0	This command was introduced.

Examples

The following example removes the ES neighbor information from the adjacency database:

clear clns es-neighbors

Related Commands

Command Description

clear clns is-neighbors

Removes IS neighbor information from the adjacency database.

clear clns neighbors

Removes CLNS neighbor information from the adjacency database.

clear clns es-neighbors

Lists the ES neighbors that this router knows.

Command	Description
clear clns is-neighbors	Removes IS neighbor information from the adjacency database.
clear clns neighbors	Removes CLNS neighbor information from the adjacency database.
clear clns es-neighbors	Lists the ES neighbors that this router knows.

clear clns is-neighbors

To remove intermediate system (IS) neighbor information from the adjacency database, use the clear clns is-neighbors command in EXEC mode.

clear clns is-neighbors

Syntax Description

This command has no arguments or keywords.

Command Modes

EXEC

Command History

Release Modification

10.0

This command was introduced.

Release	Modification
10.0	This command was introduced.

Examples

The following example removes the IS neighbor information from the adjacency database:

clear clns is-neighbors

Related Commands

Command Description

clear clns es-neighbors

Removes ES neighbor information from the adjacency database.

clear clns neighbors

Removes CLNS neighbor information from the adjacency database.

show clns is-neighbors

Displays IS-IS related information for IS-IS router adjacencies.

Command	Description
clear clns es-neighbors	Removes ES neighbor information from the adjacency database.
clear clns neighbors	Removes CLNS neighbor information from the adjacency database.
show clns is-neighbors	Displays IS-IS related information for IS-IS router adjacencies.

clear clns neighbors

To remove CLNS neighbor information from the adjacency database, use the clear clns neighbors command in EXEC mode.

clear clns neighbors

Syntax Description

This command has no arguments or keywords.

Command Modes

EXEC

Command History

Release Modification

10.0

This command was introduced.

Release	Modification
10.0	This command was introduced.

Examples

The following example removes the CLNS neighbor information from the adjacency database:

clear clns neighbors

Related Commands

Command Description

clear clns es-neighbors

Removes ES neighbor information from the adjacency database.

clear clns is-neighbors

Removes IS neighbor information from the adjacency database.

show clns neighbors

Displays both ES and IS neighbors.

Command	Description
clear clns es-neighbors	Removes ES neighbor information from the adjacency database.
clear clns is-neighbors	Removes IS neighbor information from the adjacency database.
show clns neighbors	Displays both ES and IS neighbors.

clear clns route

To remove all of the dynamically derived CLNS routing information, use the clear clns route command in EXEC mode.

clear clns route

Syntax Description

This command has no arguments or keywords.

Command Modes

EXEC

Command History

Release Modification

10.0

This command was introduced.

Release	Modification
10.0	This command was introduced.

Examples

The following example removes all of the dynamically derived CLNS routing information:

clear clns route

Related Commands

Command Description

show clns route

Displays all of the destinations to which this router knows how to route packets.

Command	Description
show clns route	Displays all of the destinations to which this router knows how to route packets.

clear tarp counters

To clear all Target Identifier Address Resolution Protocol (TARP) counters that are shown with the show tarp traffic command, use the clear tarp counters command in EXEC mode.

clear tarp counters

Syntax Description

This command has no arguments or keywords.

Command Modes

EXEC

Command History

Release Modification

11.1

This command was introduced.

Release	Modification
11.1	This command was introduced.

Usage Guidelines

Clearing the counters can assist you with troubleshooting. For example, you may want to clear the counter and then check to see how many PDUs the router is originating.

Examples

The following example clears the TARP counters:

clear tarp counters

Related Commands

Command Description

show tarp traffic

Displays statistics about TARP PDUs since the last time the counters were cleared.

Command	Description
show tarp traffic	Displays statistics about TARP PDUs since the last time the counters were cleared.

clear tarp ldb-table

To clear the system ID-to-sequence number mapping entries stored in the TARP loop-detection buffer table, use the clear tarp ldb-table command in EXEC mode.

clear tarp ldb-table

Syntax Description

This command has no arguments or keywords.

Command Modes

EXEC

Command History

Release Modification

11.1

This command was introduced.

Release	Modification
11.1	This command was introduced.

Usage Guidelines

The loop-detection buffer table prevents TARP packets from looping.

Clearing the counters assists you with troubleshooting. For example, clear the loop-detection buffer table and assign a new sequence number (using the tarp sequence-number command) to ensure that other hosts update their entries.

Examples

The following example clears the TARP loop-detection buffer table:

clear tarp ldb-table

Related Commands

Command Description

show tarp ldb

Displays the contents of the loop-detection buffer table.

tarp ldb-timer

Specifies the length of time that a system ID-to-sequence number mapping entry remains in the loop-detection buffer table.

Command	Description
show tarp ldb	Displays the contents of the loop-detection buffer table.
tarp ldb-timer	Specifies the length of time that a system ID-to-sequence number mapping entry remains in the loop-detection buffer table.

clear tarp tid-table

To clear the dynamically created TARP target identifier (TID)-to-NSAP address mapping entries stored in TID cache, use the clear tarp tid-table command in EXEC mode.

clear tarp tid-table

Syntax Description

This command has no arguments or keywords.

Command Modes

EXEC

Command History

Release Modification

11.1

This command was introduced.

Release	Modification
11.1	This command was introduced.

Usage Guidelines

Clearing the TID cache is one method to remove old entries. Another method is to set the length of time a dynamically created TARP entry remains in the TID cache using the tarp cache-timer command.

The clear tarp tid-table command does not delete the cache entry for its own TID or the cache entries explicitly configured with the tarp map command.

Examples

The following example clears the TARP TID table:

clear tarp tid-table

Related Commands

Command Description

show tarp map

Lists all static entries in the TID cache that were configured with the tarp map command.

show tarp tid-cache

Displays information about the entries in the TID cache.

tarp allow-caching

Reenables the storage of TID-to-NSAP address mapping in the TID cache.

tarp cache-timer

Specifies the length of time that a dynamically created TARP entry remains in the TID cache.

tarp map

Enters a TID-to-NSAP static route in the TID cache.

Command	Description
show tarp map	Lists all static entries in the TID cache that were configured with the tarp map command.
show tarp tid-cache	Displays information about the entries in the TID cache.
tarp allow-caching	Reenables the storage of TID-to-NSAP address mapping in the TID cache.
tarp cache-timer	Specifies the length of time that a dynamically created TARP entry remains in the TID cache.
tarp map	Enters a TID-to-NSAP static route in the TID cache.

clns access-group

To filter transit CLNS traffic going either into or out of the router or both on a per-interface basis, use the clns access-group command in interface configuration mode. To disable filtering of transit CLNS packets, use the no form of this command.

clns access-group name [in | out]

no clns access-group name [in | out]

Syntax Description

name

Name of the filter set or expression to apply.

in

(Optional) Filter should be applied to CLNS packets entering the router.

out

(Optional) Filter should be applied to CLNS packets leaving the router. If you do not specify an in or out keyword, out is assumed.

name	Name of the filter set or expression to apply.
in	(Optional) Filter should be applied to CLNS packets entering the router.
out	(Optional) Filter should be applied to CLNS packets leaving the router. If you do not specify an in or out keyword, out is assumed.

Defaults

Disabled

Command Modes

Interface configuration

Command History

Release Modification

10.0

This command was introduced.

Release	Modification
10.0	This command was introduced.

Usage Guidelines

This command has no effect on any CLNS packets sourced by the Cisco IOS software. It applies only to packets forwarded by the software. Fast switching is still supported with access groups in place, but its performance will be impacted based on the complexity of the filters.

For descriptions of filter sets and expressions, refer to the clns filter-expr, clns filter-set, and clns template-alias global configuration commands in this chapter.

Examples

The following example enables forwarding of frames received on Ethernet 0 that had a source address of anything other than 38.840F, and a destination address that started with 47.0005 or 47.0023, but nothing else:

clns filter-set US-OR-NORDUNET permit 47.0005...
clns filter-set US-OR-NORDUNET permit 47.0023...
clns filter-set NO-ANSI deny 38.840F...
clns filter-set NO-ANSI permit default
clns filter-expr STRANGE source NO-ANSI and destination US-OR-NORDUNET
 
interface ethernet 0
 clns access-group STRANGE in

Related Commands

Command Description

clns filter-expr

Combines CLNS filter sets and CLNS address templates to create complex logical NSAP pattern-matching expressions.

clns filter-set

Builds a list of CLNS address templates with associated permit and deny conditions for use in CLNS filter expressions.

clns template-alias

Builds a list of alphanumeric aliases of CLNS address templates for use in the definition of CLNS filter sets.

Command	Description
clns filter-expr	Combines CLNS filter sets and CLNS address templates to create complex logical NSAP pattern-matching expressions.
clns filter-set	Builds a list of CLNS address templates with associated permit and deny conditions for use in CLNS filter expressions.
clns template-alias	Builds a list of alphanumeric aliases of CLNS address templates for use in the definition of CLNS filter sets.

clns adjacency-filter

To filter the establishment of CLNS ES and IS adjacencies, use the clns adjacency-filter command in interface configuration mode. To disable this filtering, use the no form of this command.

clns adjacency-filter {es | is} name

no clns adjacency-filter {es | is} name

Syntax Description

es

ES adjacencies are to be filtered.

is

IS adjacencies are to be filtered.

name

Name of the filter set or expression to apply.

es	ES adjacencies are to be filtered.
is	IS adjacencies are to be filtered.
name	Name of the filter set or expression to apply.

Defaults

Disabled

Command Modes

Interface configuration

Command History

Release Modification

10.0

This command was introduced.

Release	Modification
10.0	This command was introduced.

Usage Guidelines

Filtering is performed on full NSAP addresses. If filtering should only be performed on system IDs or any other substring of the full NSAP address, the wildcard-matching capabilities of filter sets should be used to ignore the insignificant portions of the NSAP addresses.

For descriptions of filter sets and expressions, refer to the clns filter-expr, clns filter-set, and clns template-alias global configuration commands in this chapter.

Examples

The following example builds a filter that accepts end system adjacencies with only two systems, based only on their system IDs:

clns filter-set ourfriends...0000.0c00.1234.**
clns filter-set ourfriends...0000.0c00.125a.**
 
interface ethernet 0
 clns adjacency-filter es ourfriends

Command	Description
clns filter-expr	Combines CLNS filter sets and CLNS address templates to create complex logical NSAP pattern-matching expressions.
clns filter-set	Builds a list of CLNS address templates with associated permit and deny conditions for use in CLNS filter expressions.
clns template-alias	Builds a list of alphanumeric aliases of CLNS address templates for use in the definition of CLNS filter sets.

clns checksum

To enable checksum generation when ISO CLNS routing software sources a CLNS packet, use the clns checksum command in interface configuration mode. To disable checksum generation, use the no form of this command.

clns checksum

no clns checksum

Syntax Description

This command has no arguments or keywords.

Defaults

Enabled

Command Modes

Interface configuration

Command History

Release Modification

10.0

This command was introduced.

Release	Modification
10.0	This command was introduced.

Usage Guidelines

This command has no effect on routing packets, such as ES-IS, ISO-Interior Gateway Routing Protocol (IGRP) and IS-IS, sourced by the system. It applies to pings and trace route packets.

Examples

The following example enables checksum generation:

interface ethernet 0
 clns checksum

clns cluster-alias

To advertise the same system ID as other systems in ES hello messages, use the clns cluster-alias command in interface configuration mode to allow multiple systems. To disable cluster aliasing, use the no form of this command.

clns cluster-alias

no clns cluster-alias

Syntax Description

This command has no arguments or keywords.

Defaults

Disabled

Command Modes

Interface configuration

Command History

Release Modification

10.0

This command was introduced.

Release	Modification
10.0	This command was introduced.

Usage Guidelines

This feature caches multiple ES adjacencies with the same NSAP, but with different SNPA addresses. When a packet is destined to the common NSAP address, the Cisco IOS software load-splits the packets among the different SNPA addresses. A router that supports this capability forwards traffic to each system.

If DECnet Phase V cluster aliases are disabled on an interface, ES hello packet information is used to replace any existing adjacency information for the NSAP. Otherwise, an additional adjacency (with a different SNPA) is created for the same NSAP.

Examples

The following example enables cluster aliasing on specified interfaces:

clns nsap 47.0004.004d.0001.0000.0c00.1111.00
clns routing
 
interface ethernet 0
 clns cluster-alias
 
interface ethernet 1
 clns cluster-alias

clns configuration-time

To specify the rate at which ES hellos and IS hellos are sent, use the clns configuration-time command in global configuration mode. To restore the default value, use the no form of this command.

clns configuration-time seconds

no clns configuration-time

Syntax Description

seconds

Rate in seconds at which ES and IS hello packets are sent.

Defaults

60 seconds

Command Modes

Global configuration

Command History

Release Modification

10.0

This command was introduced.

Usage Guidelines

The clns configuration-time command controls how frequently a router will send hello messages to its adjacent routers. A hello message sent by the router contains the clns-holding time that tells the receiver for how long it should consider the hello message valid. By default, the clns configuration-time is 60 seconds and the clns holding-time is 300 seconds.

Caution Warning: Do not set the clns configuration-time and the clns holding-time so that the clns configuration-time is more than half of the clns holding-time. Doing so can lead to adjacencies being reformed. When adjacenies are being reformed, the routers at either end of the adjacency will flood their new link-state packet (LSP) routing packets throughout the network, forcing all routers to recompute the network topology. If this situation occurs repeatedly, it can have a detrimental effect on networkperformance.

Examples

The following example specifies that ES hellos and IS hellos are to be sent every 100 seconds:

clns configuration-time 100

Related Commands

Command Description

clns esct-time

Supplies an ES configuration timer option in a sent IS hello packet that tells the ES how often it should send ES hello packet PDUs.

clns holding-time

Allows the sender of an ES hello or IS hello packet to specify the length of time you consider the information in the hello packets to be valid.

clns congestion-threshold

To set the congestion experienced bit if the output queue has more than the specified number of packets in it, use the clns congestion-threshold command in interface configuration mode. A number value of zero or the no form of this command prevents this bit from being set. To remove the parameter setting and set it to 0, use the no form of this command.

clns congestion-threshold number

no clns congestion-threshold

Syntax Description

number

Number of packets that are allowed in the output queue before the system sets the congestion-experienced bit. The value zero (0) prevents this bit from being set.

Defaults

4 packets

Command Modes

Interface configuration

Command History

Release Modification

10.0

This command was introduced.

Usage Guidelines

If a router configured for CLNS experiences congestion, it sets the congestion experienced bit. The congestion threshold is a per-interface parameter set by this interface configuration command. An error PDU (ERPDU) is sent to the sending router and the packet is dropped if the number of packets exceeds the threshold.

Examples

The following example sets the congestion threshold to 10:

interface ethernet 0
 clns congestion-threshold 10

clns dec-compatible

To allow IS hellos sent and received to ignore the N-selector byte, use the clns dec-compatible command in interface configuration mode. To disable this feature, use the no form of this command.

clns dec-compatible

no clns dec-compatible

Syntax Description

This command has no arguments or keywords.

Defaults

Disabled

Command Modes

Interface configuration

Command History

Release Modification

10.0

This command was introduced.

Examples

The following example enables DEC-compatible mode:

interface ethernet 0
 clns dec-compatible

clns enable

If you do not intend to perform any static or dynamic routing on an interface, but intend to pass ISO CLNS packet traffic to end systems, use the clns enable command in interface configuration mode. To disable ISO CLNS on a particular interface, use the no form of this command.

clns enable

no clns enable

Syntax Description

This command has no arguments or keywords.

Defaults

Disabled

Command Modes

Interface configuration

Command History

Release Modification

10.0

This command was introduced.

Examples

The following example enables ISO CLNS on Ethernet interface 0:

interface ethernet 0
 clns enable

clns erpdu-interval

To determine the minimum interval time, in milliseconds, between error ERPDUs, use the clns erpdu-interval command in interface configuration mode. A milliseconds value of zero or the no form of this command turns off the interval and effectively sets no limit between ERPDUs.

clns erpdu-interval milliseconds

no clns erpdu-interval milliseconds

Syntax Description

milliseconds

Minimum interval time (in milliseconds) between ERPDUs.

Defaults

10 ms

Command Modes

Interface configuration

Command History

Release Modification

10.0

This command was introduced.

Usage Guidelines

This command prevents the router from sending ERPDUs more frequently than 1 per interface per 10 ms. It is wise not to send an ERPDU frequently if bandwidth is precious (such as over slow serial lines).

Examples

The following example sets the ERPDU interval to 30 ms:

interface ethernet 0
 clns erpdu-interval 30

Related Commands

Command Description

clns send-erpdu

Allows CLNS to send an error PDU when the routing software detects an error in a data PU.

clns esct-time

To supply an ES configuration timer option in a transmitted IS hello packet that tells the ES how often it should transmit ES hello packet PDUs, use the clns esct-time command in interface configuration mode. To restore the default value and disable this function, use the no form of this command.

clns esct-time seconds

no clns esct-time seconds

Syntax Description

seconds

Time, in seconds, between ES hello PDUs. Range is from 0 to 65535.

Defaults

0 seconds (disabled)

Command Modes

Interface configuration

Command History

Release Modification

10.0

This command was introduced.

Examples

The following example sets the ES configuration time to 10 seconds:

interface ethernet 0
 clns esct-time 10

Related Commands

Command Description

clns configuration-time

Specifies the rate at which ES hello mesages and IS hello messages are sent.

clns holding-time

Allows the sender of an ES hello or IS hello packet to specify the length of time you consider the information in the hello packets to be valid.

clns es-neighbor

To list all systems that will be used when you manually specify the NSAP-to-SNPA mapping, use the clns es-neighbor command in interface configuration mode. The SNPAs are the MAC addresses. To delete the ES neighbor, use the no form of this command.

clns es-neighbor nsap snpa

no clns es-neighbor nsap

Syntax Description

nsap

Specific NSAP to map to a specific MAC address.

snpa

Data link (MAC) address.

Defaults

No end systems are listed.

Command Modes

Interface configuration

Command History

Release Modification

10.0

This command was introduced.

Usage Guidelines

If you have configured either the clns router iso-igrp or clns router isis interface configuration commands for a particular interface, the ES-IS routing software automatically turns ES-IS on for that interface.

It is only necessary to use static mapping for those end systems that do not support ES-IS. The Cisco IOS software will continue to discover dynamically those end systems that do support ES-IS.

Examples

The following example defines an ES neighbor on Ethernet interface 0:

interface ethernet 0
 clns es-neighbor 47.0004.004D.0055.0000.0C00.A45B.00 0000.0C00.A45B

In this case, the end system with the following NSAP, or network entity title (NET), is configured with an Ethernet MAC address of 0000.0C00.A45B:

47.0004.004D.0055.0000.0C00.A45B.00

Related Commands

Command Description

clns host

Defines a name-to-NSAP mapping that can then be used with commands requiring NSAPs.

clns is-neighbor

Lists all intermediate systems that will be used when you manually specify the NSAP-to-SNPA mapping.

clns filter-expr

To combine CLNS filter sets and CLNS address templates to create complex logical NSAP pattern-matching expressions, use one or more clns filter-expr commands in global configuration mode. To delete the expression, use the no form of this command.

clns filter-expr ename [term | not term | term [and | or | xor] term]

no clns filter-expr ename

Syntax Description

ename

Alphanumeric name to apply to this filter expression.

not

(Optional) Defines a filter expression that is pattern matched only if the pattern given by term is not matched.

or

(Optional) Defines a filter expression that is pattern matched if either of the patterns given by the two terms is matched.

and

(Optional) Defines a filter expression that is pattern matched only if both of the patterns given by the two terms are matched.

xor

(Optional) Defines a filter expression that is pattern matched only if one of the patterns, but not both, given by the two terms are matched.

term

Filter expression term. A term can be any of the following:

ename---Another, previously defined, filter expression.

sname (or destination sname)---A previously defined filter set name, with the filter set applied to the destination NSAP address.

source sname---A previously defined filter set name, with the filter set applied to the source NSAP address.

Defaults

No filter expression is defined.

Command Modes

Global configuration

Command History

Release Modification

10.0

This command was introduced.

Usage Guidelines

Filter expressions can reference previously defined filter expressions, so you can build arbitrarily complex expressions.

If none of the optional keywords is used, then the command defines a simple filter expression that is pattern matched only if the pattern given by term is matched.

Use this command to define complex filter expressions. See the description of the clns filter-set global configuration command to learn how to define filter sets.

Examples

The following example defines a filter expression that matches addresses with a source address of anything besides 39.840F, and a destination address that started with 47.0005 or 47.0023, but nothing else:

clns filter-set US-OR-NORDUNET permit 47.0005...
clns filter-set US-OR-NORDUNET permit 47.0023
clns filter-set NO-ANSI deny 38.840F...
clns filter-set NO-ANSI permit default
!
clns filter-expr STRANGE source NO-ANSI and destination US-OR-NORDUNET

Related Commands

Command Description

clns filter-set

Builds a list of CLNS address templates with associated permit and deny conditions for use in CLNS filter expressions.

clns template-alias

Builds a list of alphanumeric aliases of CLNS address templates for use in the definition of CLNS filter sets.

show clns filter-expr

Displays one or all currently defined CLNS filter expressions.

clns filter-set

To build a list of CLNS address templates with associated permit and deny conditions for use in CLNS filter expressions, use the clns filter-set command in global configuration mode. CLNS filter expressions are used in the creation and use of CLNS access lists. To delete the entire filter set, use the no form of this command.

clns filter-set name [permit | deny] template

no clns filter-set name

Syntax Description

name

Alphanumeric name to apply to this filter set.

permit | deny

(Optional) Addresses matching the pattern specified by template are to be permitted or denied. If neither permit nor deny is specified, permit is assumed.

template

Address template, template alias name, or the keyword default. Address templates and alias names are described under the description of the clns template-alias global configuration command. The default keyword denotes a zero-length prefix and matches any address.

Defaults

No address templates are defined.

Command Modes

Global configuration

Command History

Release Modification

10.0

This command was introduced.

Usage Guidelines

Use this command to define a list of pattern matches and permit/deny conditions for use in CLNS filter expressions. Filter expressions are used in the creation and use of CLNS access lists. See the description of the clns filter-expr global configuration command to learn how to define filter expressions and the clns template-alias global configuration command to learn how to define address templates and address template aliases.

Each address that must be matched against a filter set is first compared against all the entries in the filter set, in order, for an exact match with the address. If the exact match search fails to find a match, then the entries in the filter set containing wildcard matches are scanned for a match, again, in order. The first template that matches is used. If an address does not match any of the filter set entries, an implicit "deny" is returned as the permit/deny action of the filter set.

Examples

The following example returns a permit action if an address starts with either 47.0005 or 47.0023. It returns an implicit deny action on any other address.

clns filter-set US-OR-NORDUNET permit 47.0005...
clns filter-set US-OR-NORDUNET permit 47.0023...

The following example returns a deny action if an address starts with 39.840F, but returns a permit action for any other address:

clns filter-set NO-ANSI deny 38.840F...
clns filter-set NO-ANSI permit default

Related Commands

Command Description

clns filter-expr

Combines CLNS filter sets and CLNS address templates to create complex logical NSAP pattern-matching expressions.

clns template-alias

Builds a list of alphanumeric aliases of CLNS address templates for use in the definition of CLNS filter sets.

show clns filter-set

Displays one or all currently defined CLNS filter sets.

clns holding-time

To allow the sender of an ES hello or IS hello to specify the length of time you consider the information in the hello packets to be valid, use the clns holding-time command in global configuration mode. To restore the default value (300 seconds, or 5 minutes), use the no form of this command.

clns holding-time seconds

no clns holding-time

Syntax Description

seconds

Length of time in seconds during which the information in the hello packets is considered valid.

Defaults

300 seconds (5 minutes)

Command Modes

Global configuration

Command History

Release Modification

10.0

This command was introduced.

Usage Guidelines

Setting this value too high puts extra traffic on a line and adds time to process hellos. However, you want to avoid setting it too low if your topology changes more often than the Cisco IOS software sends updates.

Examples

The following example sets the holding time at 150 seconds:

clns holding-time 150

Related Commands

Command Description

clns configuration-time

Specifies the rate at which ES hello mesages and IS hello messages are sent.

clns esct-time

Supplies an ES configuration timer option in a sent IS hello packet that tells the ES how often it should send ES hello packet PDUs.

clns host

To define a name-to-NSAP mapping that can then be used with commands requiring NSAPs, use the clns host command in global configuration mode.

clns host name nsap

Syntax Description

name

Desired name for the NSAP. The first character can be either a letter or a number, but if you use a number, the operations you can perform are limited.

nsap

NSAP to which that the name maps.

Defaults

No mapping is defined.

Command Modes

Global configuration

Command History

Release Modification

10.0

This command was introduced.

Usage Guidelines

The assigned NSAP name is displayed, where applicable, in show and debug EXEC commands. There are some effects and requirements associated with using names to represent network entity titles (NETs) and NSAPs, however. Although using names as proxies for addresses is allowed with CLNS commands, they are never written out to nonvolatile random-access memory (NVRAM).

The first character can be either a letter or a number, but if you use a number, the operations you can perform (such as ping) are limited.

The clns host command is generated after all other CLNS commands when the configuration file is parsed. As a result, the NVRAM version of the configuration cannot be edited to specifically change the address defined in the original clns host command. You must specifically change any commands that refer to the original address. This affects all commands that accept names.

The commands that are affected by these requirements include the following:

net (router configuration command)
clns is-neighbor (interface configuration command)
clns es-neighbor (interface configuration command)
clns route (global configuration command)

Examples

The following example defines names to NSAPs:

clns host cisco1 39.0001.0000.0c00.1111.00
clns host cisco2 39.0002.0000.0c00.1111.00
router iso-igrp
 net cisco1
!
interface ethernet 0
 clns net cisco2

Related Commands

Command Description

clns es-neighbor

Lists all systems that will be used when you manually specify the NSAP-to-SNPA mapping.

clns is-neighbor

Lists all intermediate systems that will be used when you manually specify the NSAP-to-SNPA mapping.

net

Configures an IS-IS NET for the routing process.

clns is-neighbor

To list all intermediate systems that will be used when you manually specify the NSAP-to-SNPA mapping, use the clns is-neighbor command in interface configuration mode. The SNPAs are the MAC addresses. To delete the specified IS neighbor, use the no form of this command.

clns is-neighbor nsap snpa

no clns is-neighbor nsap

Syntax Description

nsap

NSAP of a specific intermediate system to enter as neighbor to a specific MAC address.

snpa

Data link (MAC) address.

Defaults

No intermediate systems are listed.

Command Modes

Interface configuration

Command History

Release Modification

10.0

This command was introduced.

Usage Guidelines

It is sometimes preferable for a router to have a neighbor entry statically configured rather than learned through ES-IS, ISO IGRP, or IS-IS. This interface configuration command enters an IS neighbor.

Examples

The following example defines an IS neighbor on Ethernet interface 0:

interface ethernet 0
 clns is-neighbor 47.0004.004D.0055.0000.0C00.A45B.00 0000.0C00.A45B

Related Commands

Command Description

clns es-neighbor

Lists all systems that will be used when you manually specify the NSAP-to-SNPA mapping.

clns host

Defines a name-to-NSAP mapping that can then be used with commands requiring NSAPs.

clns mtu

To set the maximum transmission unit (MTU) packet size for the interface, use the clns mtu command in interface configuration mode. To restore the default and maximum packet size, use the no form of this command.

clns mtu bytes

no clns mtu

Syntax Description

bytes

Maximum packet size in bytes. The minimum value is 512; the default and maximum packet size depend on the interface type.

Defaults

Depends on interface type

Command Modes

Interface configuration

Command History

Release Modification

10.0

This command was introduced.

Usage Guidelines

All interfaces have a default maximum packet size. You can set the MTU size of the packets sent on the interface with the mtu interface configuration command.

All routers on a physical medium must have the same protocol MTU in order to operate.

The CTR card does not support the switching of frames larger than 4472 bytes. Interoperability problems can occur if CTR cards are intermixed with other Token Ring cards on the same network. These problems can be minimized by lowering the CLNS MTUs to be the same on all routers on the network with the clns mtu command.

Note Changing the MTU value with the mtu interface configuration command can affect the CLNS MTU value. If the CLNS MTU is at its maximum given the interface MTU, the CLNS MTU will change with the interface MTU. However, the reverse is not true; changing the CLNS MTU value has no effect on the value for the mtu interface configuration command.

Examples

The following example sets the MTU packet size to 1000 bytes:

interface ethernet 0
 clns mtu 1000

Related Commands

Command Description

mtu

Adjusts the maximum packet size or MTU size.

clns net (global)

To assign a static address for a router, use the clns net command in global configuration mode. If the Cisco IOS software is configured to support ISO CLNS, but is not configured to dynamically route CLNS packets using ISO IGRP or IS-IS, use this command to assign an address to the router. To remove any previously configured NET or NSAP address, use the no form of this command.

clns net {net-address | name}

no clns net {net-address | name}

Syntax Description

net-address

NET address. Refer to the "Usage Guidelines" section.

name

CLNS host name to be associated with this interface.

Defaults

No static address is assigned.

Command Modes

Global configuration

Command History

Release Modification

10.0

This command was introduced.

Usage Guidelines

A CLNS packet sent to any of the defined NSAPs or NETs will be received by the router. The Cisco IOS software chooses the NET to use when it sends a packet with the following algorithm:

If no dynamic routing protocol is running, use the NET defined for the outgoing interface if it exists; otherwise, use the NET defined for the router.
If ISO IGRP is running, use the NET of the routing process that is running on this interface.
If IS-IS is running, use the NET of the IS-IS routing process that is running on this interface.

Examples

The following example assigns a static address:

clns net 49.0001.aa00.0400.9105.00

clns net (interface)

To assign an NSAP address or name to a router interface, use the clns net command in interface configuration mode. If the Cisco IOS software is configured to support ISO CLNS, but is not configured to dynamically route CLNS packets using an ISO IGRP or IS-IS, use this command to assign an address to the router. To remove any previously configured NSAP address, use the no form of this command.

clns net {nsap-address | name}

no clns net {nsap-address | name}

Syntax Description

nsap-address

Specific NSAP address.

name

Name to be associated with this interface.

Defaults

No address or name is assigned.

Command Modes

Interface configuration

Command History

Release Modification

10.0

This command was introduced.

Usage Guidelines

This command is useful if you are doing static routing and need to control the source NET used by the router on each interface.

Examples

The following example assigns an NSAP address to a router interface:

interface ethernet 0
 clns net 49.0001.0000.0c00.1111.00

The following example assigns a name to a router interface:

interface ethernet 0
 clns net cisco

clns packet-lifetime

To specify the initial lifetime for locally generated packets, use the clns packet-lifetime command in global configuration mode. To remove the parameter's settings, use the no form of this command.

clns packet-lifetime seconds

no clns packet-lifetime

Syntax Description

seconds

Packet lifetime in seconds.

Defaults

32 seconds

Command Modes

Global configuration

Command History

Release Modification

10.0

This command was introduced.

Examples

The following example sets a packet lifetime of 120 seconds:

clns packet-lifetime 120

Related Commands

Command Description

clns want-erpdu

Specifies whether to request ERPDUs on packets sourced by the router.

clns rdpdu-interval

To determine the minimum interval time between redirect PDUs (RDPDUs), use the clns rdpdu-interval command in interface configuration mode. A milliseconds value of zero or the no form of this command turns off the interval rate and effectively sets no limit between RDPDUs.

clns rdpdu-interval milliseconds

no clns rdpdu-interval milliseconds

Syntax Description

milliseconds

Minimum interval time (in milliseconds) between RDPDUs.

Defaults

100 ms

Command Modes

Interface configuration

Command History

Release Modification

10.0

This command was introduced.

Usage Guidelines

RDPDUs are rate-limited and are not sent more frequently than one per interface per 100 ms. There is no need to change the default. This setting will work fine for most networks.

Examples

The following example sets an interval of 50 ms:

interface ethernet 0
 clns rdpdu-interval 50

Related Commands

Command Description

clns send-rdpdu

Allows CLNS to send RPDUs when a better route for a given host is known.

clns route (create)

To create an interface static route, use this form of the clns route command in global configuration mode. To remove this route, use the no form of this command.

clns route nsap-prefix type number [snpa-address]

no clns route nsap-prefix

Syntax Description

nsap-prefix

Network service access point prefix. This value is entered into a static routing table and used to match the beginning of a destination NSAP. The longest NSAP-prefix entry that matches is used.

type

Interface type.

number

Interface number.

snpa-address

(Optional) Specific SNPA address. Optional for serial links; required for multiaccess networks.

Defaults

No interface static routes are created.

Command Modes

Global configuration

Command History

Release Modification

10.0

This command was introduced.

Usage Guidelines

If you do not specify an SNPA address when you have a multiaccess network, you will receive an error message indicating a bad SNPA.

Examples

The following example creates a static route for an Ethernet interface:

clns route 39.0002 ethernet 3 aa00.0400.1111

The following example creates a static route for a serial interface:

clns route 39.0002 serial 0

Related Commands

Command Description

clns route (enter)

Enters a specific static route.

clns route default

Configures a default zero-length prefix rather than typing an NSAP prefix.

clns route discard

Explicitly tells a router to discard packets with NSAP addresses that match the specified nsap-prefix.

clns route (enter)

To enter a specific static route, use this form of the clns route command in global configuration mode. NSAPs that start with nsap-prefix are forwarded to next-hop-net or the name of the next hop. To remove this route, use the no form of this command.

clns route nsap-prefix {next-hop-net | name}

no clns route nsap-prefix

Syntax Description

nsap-prefix

Network service access point prefix. This value is entered into a static routing table and used to match the beginning of a destination NSAP. The longest NSAP-prefix entry that matches is used.

next-hop-net

Next-hop NET. This value is used to establish the next hop of the route for forwarding packets.

name

Name of the next hop node. This value can be used instead of the next-hop NET to establish the next hop of the route for forwarding packets.

Defaults

No static route is entered.

Command Modes

Global configuration

Command History

Release Modification

10.0

This command was introduced.

Examples

The following example forwards all packets toward the specified route:

clns route 39.840F 47.0005.80FF.FF00.0123.4567.89AB.00

Related Commands

Command Description

clns route (create)

Creates an interface static route.

clns route default

Configures a default zero-length prefix rather than typing an NSAP prefix.

clns route discard

Explicitly tells a router to discard packets with NSAP addresses that match the specified nsap-prefix.

clns route-cache

To allow fast switching through the cache, use the clns route-cache command in interface configuration mode. To disable fast switching, use the no form of this command.

clns route-cache

no clns route-cache

Syntax Description

This command has no arguments or keywords.

Defaults

Enabled

Command Modes

Interface configuration

Command History

Release Modification

10.0

This command was introduced.

Usage Guidelines

The cache still exists and is used after the no clns route-cache command is used; the software just does not do fast switching through the cache.

Examples

The following example allows fast switching through the cache:

interface ethernet 0
 clns route-cache

clns route default

To configure a default zero-length prefix rather than type an NSAP prefix, use the clns route default command in global configuration mode. To remove this route, use the no form of this command.

clns route default nsap-prefix type number

no clns route default

Syntax Description

nsap-prefix

Network service access point prefix that is a default zero-length prefix.

type

Interface type. Specify the interface type immediately followed by the interface number; there is no space between the two.

number

Interface number.

Defaults

No default prefix is configured.

Command Modes

Global configuration

Command History

Release Modification

10.0

This command was introduced.

Examples

The following example configures a default zero-length prefix:

clns route default 39.840F ethernet0

Related Commands

Command Description

clns route (interface static route)

Creates an interface static route.

clns route (enter)

Enters a specific static route.

clns route discard

Explicitly tells a router to discard packets with NSAP addresses that match the specified nsap-prefix.

clns route discard

To explicitly tell a router to discard packets with NSAP addresses that match the specified nsap-prefix, use the clns route discard command in global configuration mode. To remove this route, use the no form of this command.

clns route nsap-prefix discard

no clns route nsap-prefix

Syntax Description

nsap-prefix

Network service access point prefix. This value is entered into a static routing table and used to match the beginning of a destination NSAP. The longest NSAP-prefix entry that matches is used.

discard

The router discards packets with NSAPs that match the specified value for the nsap-prefix argument.

Defaults

No NSAP addresses are identified.

Command Modes

Global configuration

Command History

Release Modification

10.0

This command was introduced.

Usage Guidelines

The decnet advertise command and the clns route discard command work together when DECnet Phase IV/V conversion is enabled. Any packet with the specified CLNS NSAP prefix causes CLNS to behave as if no route were found. Because DECnet Phase IV/V conversion is enabled, the route is then looked up in the Phase IV routing table. The router that is advertising the DECnet Phase IV route converts the packet to OSI and sends it to the router that is advertising the CLNS discard static route. Once it gets there, the packet is converted back to Phase IV.

Examples

The following example discards packets with a destination NSAP address that matches the prefix 47.0005:

clns route 47.0005 discard

Related Commands

Command Description

clns route (interface static route)

Creates an interface static route.

clns route (enter)

Enters a specific static route.

clns route default

Configures a default zero-length prefix rather than typing an NSAP prefix.

decnet advertise

Configures border routers to propagate Phase IV areas through an OSI backbone.

clns router isis

To configure an Intermediate System-to-Intermediate System (IS-IS) routing process for International Standards Organization (ISO) Connectionless Network Service Protocol (CLNS) on a specified interface and to attach an area designator to the routing process, use the clns router isis command in interface configuration mode. To disable IS-IS for ISO, use the no form of the command.

clns router isis area-tag

no clns router isis area-tag

Syntax Description

area-tag

Required for multiarea IS-IS configuration. Optional for conventional IS-IS configuration.

Defines a meaningful name for an area routing process. If not specified, a null tag is assumed. It must be unique among all CLNS router processes for a given router. The area-tag argument is used later as a reference to this area routing process.

Each area in a multiarea configuration should have a non-null area tag to facilitate identification of the area.

Defaults

No routing processes are specified.

Command Modes

Interface configuration

Command History

Release Modification

10.0

This command was introduced.

12.0(5)T

Multiarea functionality was added, changing the way the tag argument (now area-tag) is used.

Usage Guidelines

Before the IS-IS router process is useful, a network entity title (NET) must be assigned with the net command and some interfaces must be enabled with IS-IS.

If you have IS-IS running and at least one ISO-IGRP process, the IS-IS process and the ISO-IGRP process cannot both be configured without an area tag. The null tag can be used by only one process. If you run ISO-IGRP and IS-IS, a null tag can be used for IS-IS, but not for ISO-Interior Gateway Routing Protocol (IGRP) at the same time. However, each area in an IS-IS multiarea configuration should have a non-null area tag to facilitate identification of the area.

You can configure only one process to perform Level 2 (interarea) routing. If Level 2 routing is configured on any process, all additional processes are automatically configured as Level 1. You can configure this process to perform intra-area (Level 1) routing at the same time. You can configure up to 29 additional processes as Level 1-only processes. Use the is-type command to remove Level 2 routing from a router instance. You can then use the is-type command to enable Level 2 routing on some other IS-IS router instance.

An interface cannot be part of more than one area, except in the case where the associated routing process is performing both Level 1 and Level 2 routing. On media (such as WAN media, for example) where subinterfaces are supported, different subinterfaces could be configured for different areas.

Examples

The following example enables IS-IS routing for ISO CLNS on Ethernet interface 0:

router isis cisco
 net 39.0001.0000.0c00.1111.00
interface ethernet 0
 clns router isis cisco

The following example shows an IS-IS configuration with two Level 1 areas and one Level 1-2 area:

clns routing
 
...
 
interface Tunnel529
 ip address 10.0.0.5 255.255.255.0
 ip router isis BB
 clns router isis BB
 
interface Ethernet1
 ip address 10.1.1.5 255.255.255.0
 ip router isis A3253-01
 clns router isis A3253-01
!
interface Ethernet2
 ip address 10.2.2.5 255.255.255.0
 ip router isis A3253-02
 clns router isis A3253-02
 
...
 
router isis BB                          ! Defaults to "is-type level-1-2"
 net 49.2222.0000.0000.0005.00
!
router isis A3253-01
 net 49.0553.0001.0000.0000.0005.00
 is-type level-1
!
router isis A3253-02
 net 49.0553.0002.0000.0000.0005.00
 is-type level-1

Related Commands

Command Description

router isis

Enables the IS-IS routing protocol and specifies an IS-IS process for IP.

clns router iso-igrp

To specify ISO IGRP routing on a specified interface, use the clns router iso-igrp command in interface configuration mode. To disable ISO IGRP routing for the system, use the no form of the global configuration command with the appropriate tag.

clns router iso-igrp tag [level 2]

no clns router iso-igrp tag

Syntax Description

tag

Meaningful name for routing process. It must be unique among all CLNS router processes for a given router. This tag should be the same as defined for the routing process in the router iso-igrp global configuration command.

level 2

(Optional) Allows the interface to advertise Level 2 information.

Defaults

ISO IGRP routing is not specified on any interface.

Command Modes

Interface configuration
Global configuration

Command History

Release Modification

10.0

This command was introduced.

Usage Guidelines

If you want this interface to advertise Level 2 information only, use the level 2 keyword. This option reduces the amount of router-to-router traffic by telling the Cisco IOS software to send out only Level 2 routing updates on certain interfaces. Level 1 information is not passed on the interfaces for which the Level 2 option is set.

Examples

In the following example, the interface advertises Level 2 information only on serial interface 0:

router iso-igrp marketing
 net 49.0001.0000.0c00.1111.00
interface serial 0
 clns router iso-igrp marketing level 2

Related Commands

Command Description

router iso-igrp

Identifies the area the router will work in and informs it that it will route dynamically using the ISO IGRP protocol.

clns routing

To enable routing of CLNS packets, use the clns routing command in global configuration mode. To disable CLNS routing, use the no form of this command.

clns routing

no clns routing

Syntax Description

This command has no arguments or keywords.

Defaults

Disabled

Command Modes

Global configuration

Command History

Release Modification

10.0

This command was introduced.

Examples

The following example enables routing of CLNS packets:

clns routing

Related Commands

Command Description

clns security pass-through

Allows the Cisco IOS software to pass packets that have security options set.

clns security pass-through

To allow the Cisco IOS software to pass packets that have security options set, use the clns security pass-through command in global configuration mode. To disable this function, use the no form of this command.

clns security pass-through

no clns security pass-through

Syntax Description

This command has no arguments or keywords.

Defaults

The software discards any packets it sees as set with security options.

Command Modes

Global configuration

Command History

Release Modification

10.0

This command was introduced.

Examples

The following example allows the Cisco IOS software to pass packets that have security options set:

clns routing
router iso-igrp
 net 47.0004.004d.0001.0000.0c11.1111.00
clns security pass-through

Related Commands

Command Description

clns routing

Enables routing of CLNS packets.

clns send-erpdu

To allow CLNS to send an error PDU when the routing software detects an error in a data PDU, use the clns send-erpdu command in interface configuration mode. To disable this function, use the no form of this command.

clns send-erpdu

no clns send-erpdu

Syntax Description

This command has no arguments or keywords.

Defaults

Enabled

Command Modes

Interface configuration

Command History

Release Modification

10.0

This command was introduced.

Usage Guidelines

When a CLNS packet comes in, the routing software looks in the routing table for the next hop. If it does not find the next hop, the packet is discarded and an ERPDU can be sent to the original source/sender of the packet that was discarded.

Examples

The following example allows CLNS to send an error PDU when it detects an error in a data PDU:

interface ethernet 0
 clns send-erpdu

Related Commands

Command Description

clns erpdu-interval

Determines the minimum interval time, in milliseconds, between error ERPDUs.

clns send-rdpdu

To allow CLNS to redirect PDUs (RDPDUs) when a better route for a given host is known, use the clns send-rdpdu command in interface configuration mode. To disable this function, use the no form of this command.

clns send-rdpdu

no clns send-rdpdu

Syntax Description

This command has no arguments or keywords.

Defaults

Enabled

Command Modes

Interface configuration

Command History

Release Modification

10.0

This command was introduced.

Usage Guidelines

If a packet is sent out on the same interface it came in on, an RDPDU can also be sent to the sender of the packet.

Examples

The following example allows CLNS to send RDPDUs:

interface ethernet 0
 clns send-rdpdu

Related Commands

Command Description

clns erpdu-interval

Determines the minimum interval time (in milliseconds) between RDPDUs.

clns split-horizon

To implement split horizon for ISO IGRP updates, use the clns split-horizon command in interface configuration mode. To disable this function, use the no form of this command.

clns split-horizon

no clns split-horizon

Syntax Description

This command has no arguments or keywords.

Defaults

For all LAN interfaces---enabled
For WAN interfaces on X.25, Frame Relay, or SMDS networks---disabled

Command Modes

Interface configuration

Command History

Release Modification

10.0

This command was introduced.

Usage Guidelines

Normally, routers that are connected to broadcast-type OSI networks and that use distance vector routing protocols employ the split-horizon mechanism to prevent routing loops. Split-horizon blocks information about routes from being advertised by a router out any interface from which that information originated. This behavior usually optimizes communications among multiple routers, particularly when links are broken. However, with nonbroadcast networks, such as Frame Relay and SMDS, situations can arise for which this behavior is less than ideal. For all interfaces except those for which either Frame Relay or SMDS encapsulation is enabled, the default condition for this command is for split horizon to be enabled.

If your configuration includes either the encapsulation frame-relay or encapsulation smds interface configuration commands, the default is for split horizon to be disabled. Split horizon is not disabled by default for interfaces using any of the X.25 encapsulations.

For networks that include links over X.25 PSNs, the neighbor interface configuration command can be used to defeat the split horizon feature. You can as an alternative explicitly specify the no clns split-horizon command in your configuration. However, if you do so, you must similarly disable split horizon for all routers in any relevant multicast groups on that network.

Split horizon for ISO IGRP defaults to off for X.25, SMDS, and Frame Relay. Thereby, destinations are advertised out the interface for which the router has a destination.

In general, changing the state of the default for this interface configuration command is not recommended, unless you are certain that your application requires making a change in order to properly advertise routes. Remember that if split horizon is disabled on a serial interface (and that interface is attached to a packet-switched network), you must disable split horizon for all routers in any relevant multicast groups on that network.

Examples

The following example disables split horizon on a serial link connected to an X.25 network:

interface serial 0
 encapsulation x25
 no clns split-horizon

clns template-alias

To build a list of alphanumeric aliases of CLNS address templates for use in the definition of CLNS filter sets, use one or more clns template-alias commands in global configuration mode. To delete the alias, use the no form of this command.

clns template-alias name template

no clns template-alias name

Syntax Description

name

Alphanumeric name to apply as an alias for the template.

template

Address template, as defined in the "Usage Guidelines" section.

Defaults

No alias list is defined.

Command Modes

Global configuration

Command History

Release Modification

10.0

This command was introduced.

Usage Guidelines

Address templates are "pattern forms" that match one or more CLNS addresses. They can be simple single CLNS addresses, which match just themselves, or contain wildcards, prefixes, and suffixes, allowing a single template to match many addresses.

The simplest address template matches just a single address, as shown in this example:

47.0005.1234.5678.9abc.def0.00

Wildcard digits, which can match any value, are indicated with asterisks (*). The following template matches the above address and any other 12-byte long address that starts with 47.0005.1234.5678:

47.0005.1234.5678.****.****.**

Because OSI addresses are variable in length, it is often useful to build templates that match addresses that share a common prefix. The following template matches any address of any length that begins with the prefix 47.0005.1234.5678:

47.0005.1234.5678...

In other instances, matching a suffix of the address is also important, such as when matching system IDs. The following template matches any address that ends with the suffix 0000.0c01.2345.00:

...0000.0c01.2345.00

In other cases, you might want to match addresses on a single-bit granularity, rather than half-byte (four-bit, or nibble) granularity. This pattern matching is supported by allowing the hex digits that represent four bits to be replaced by groups of four binary bits, represented by 0s and 1s. These four binary digits are enclosed within parentheses. The following template matches any address that starts with 47.0005 followed by the binary bits 10. The final two binary bits in the nibble can be either 0 or 1, and are represented with asterisks.

47.0005.(10**)...

Use this command to define aliases for commonly referenced address templates. The use of these aliases reduces the chances for typographical error in the creation of CLNS filter sets.

Examples

The following command defines a filter set called COMPLEX-PREFIX for the last example given in the "Usage Guidelines" section:

clns template-alias COMPLEX-PREFIX 47.0005.(10**)...

clns want-erpdu

To specify whether to request ERPDUs on packets sourced by the router, use the clns want-erpdu command in global configuration mode. To remove the parameter's settings, use the no form of this command.

clns want-erpdu

no clns want-erpdu

Syntax Description

This command has no arguments or keywords.

Defaults

To request ERPDUs

Command Modes

Global configuration

Command History

Release Modification

10.0

This command was introduced.

Usage Guidelines

This command has no effect on routing packets (ES-IS, ISO IGRP, and IS-IS) sourced by the system. It applies to pings and trace route packets.

Examples

The following example requests ERPDUs on packets sourced by the router:

clns want-erpdu

Related Commands

Command Description

clns packet-lifetime

Specifies the initial lifetime for locally generated packets.

distance (ISO CLNS)

To configure the administrative distance for CLNS routes learned, use the distance command in router configuration mode. To restore the administrative distance to the default, use the no form of this command.

distance value [clns]

no distance value [clns]

Syntax Description

value

Administrative distance, indicating the trustworthiness of a routing information source. This argument has a numerical value between 0 and 255. A higher relative value indicates a lower trustworthiness rating. Preference is given to routes with smaller values. The default, if unspecified, is 110.

clns

(Optional) CLNS-derived routes for IS-IS.

Defaults

Static routes---10
ISO IGRP routes---100
IS-IS routes---110

Command Modes

Router configuration

Command History

Release Modification

10.0

This command was introduced.

Usage Guidelines

When multiple routing processes are running in the same router for CLNS, it is possible for the same route to be advertised by more than one routing process. The Cisco IOS software always picks the route whose routing protocol has the lowest administrative distance.

The show clns protocol EXEC command displays the default administrative distance for a specified routing process.

Examples

In the following example, the distance value for CLNS routes learned is 90. Preference is given to these CLNS routes rather than routes with the default administrative distance value of 110.

router isis
 distance 90 clns

Command	Description
clns esct-time	Supplies an ES configuration timer option in a sent IS hello packet that tells the ES how often it should send ES hello packet PDUs.
clns holding-time	Allows the sender of an ES hello or IS hello packet to specify the length of time you consider the information in the hello packets to be valid.

Command	Description
clns configuration-time	Specifies the rate at which ES hello mesages and IS hello messages are sent.
clns holding-time	Allows the sender of an ES hello or IS hello packet to specify the length of time you consider the information in the hello packets to be valid.

nsap	Specific NSAP to map to a specific MAC address.
snpa	Data link (MAC) address.

Command	Description
clns host	Defines a name-to-NSAP mapping that can then be used with commands requiring NSAPs.
clns is-neighbor	Lists all intermediate systems that will be used when you manually specify the NSAP-to-SNPA mapping.

ename	Alphanumeric name to apply to this filter expression.
not	(Optional) Defines a filter expression that is pattern matched only if the pattern given by term is not matched.
or	(Optional) Defines a filter expression that is pattern matched if either of the patterns given by the two terms is matched.
and	(Optional) Defines a filter expression that is pattern matched only if both of the patterns given by the two terms are matched.
xor	(Optional) Defines a filter expression that is pattern matched only if one of the patterns, but not both, given by the two terms are matched.
term	Filter expression term. A term can be any of the following: ename---Another, previously defined, filter expression. sname (or destination sname)---A previously defined filter set name, with the filter set applied to the destination NSAP address. source sname---A previously defined filter set name, with the filter set applied to the source NSAP address.

name	Alphanumeric name to apply to this filter set.
permit \| deny	(Optional) Addresses matching the pattern specified by template are to be permitted or denied. If neither permit nor deny is specified, permit is assumed.
template	Address template, template alias name, or the keyword default. Address templates and alias names are described under the description of the clns template-alias global configuration command. The default keyword denotes a zero-length prefix and matches any address.

name	Desired name for the NSAP. The first character can be either a letter or a number, but if you use a number, the operations you can perform are limited.
nsap	NSAP to which that the name maps.

Command	Description
clns es-neighbor	Lists all systems that will be used when you manually specify the NSAP-to-SNPA mapping.
clns is-neighbor	Lists all intermediate systems that will be used when you manually specify the NSAP-to-SNPA mapping.
net	Configures an IS-IS NET for the routing process.

nsap	NSAP of a specific intermediate system to enter as neighbor to a specific MAC address.
snpa	Data link (MAC) address.

net-address	NET address. Refer to the "Usage Guidelines" section.
name	CLNS host name to be associated with this interface.

nsap-address	Specific NSAP address.
name	Name to be associated with this interface.

nsap-prefix	Network service access point prefix. This value is entered into a static routing table and used to match the beginning of a destination NSAP. The longest NSAP-prefix entry that matches is used.
type	Interface type.
number	Interface number.
snpa-address	(Optional) Specific SNPA address. Optional for serial links; required for multiaccess networks.

Command	Description
clns route (enter)	Enters a specific static route.
clns route default	Configures a default zero-length prefix rather than typing an NSAP prefix.
clns route discard	Explicitly tells a router to discard packets with NSAP addresses that match the specified nsap-prefix.

nsap-prefix	Network service access point prefix. This value is entered into a static routing table and used to match the beginning of a destination NSAP. The longest NSAP-prefix entry that matches is used.
next-hop-net	Next-hop NET. This value is used to establish the next hop of the route for forwarding packets.
name	Name of the next hop node. This value can be used instead of the next-hop NET to establish the next hop of the route for forwarding packets.

Command	Description
clns route (create)	Creates an interface static route.
clns route default	Configures a default zero-length prefix rather than typing an NSAP prefix.
clns route discard	Explicitly tells a router to discard packets with NSAP addresses that match the specified nsap-prefix.

nsap-prefix	Network service access point prefix that is a default zero-length prefix.
type	Interface type. Specify the interface type immediately followed by the interface number; there is no space between the two.
number	Interface number.

Command	Description
clns route (interface static route)	Creates an interface static route.
clns route (enter)	Enters a specific static route.
clns route discard	Explicitly tells a router to discard packets with NSAP addresses that match the specified nsap-prefix.

nsap-prefix	Network service access point prefix. This value is entered into a static routing table and used to match the beginning of a destination NSAP. The longest NSAP-prefix entry that matches is used.
discard	The router discards packets with NSAPs that match the specified value for the nsap-prefix argument.

Release	Modification
10.0	This command was introduced.
12.0(5)T	Multiarea functionality was added, changing the way the tag argument (now area-tag) is used.

tag	Meaningful name for routing process. It must be unique among all CLNS router processes for a given router. This tag should be the same as defined for the routing process in the router iso-igrp global configuration command.
level 2	(Optional) Allows the interface to advertise Level 2 information.

Table of Contents

ISO CLNS Commands

name	Alphanumeric name to apply as an alias for the template.
template	Address template, as defined in the "Usage Guidelines" section.

value	Administrative distance, indicating the trustworthiness of a routing information source. This argument has a numerical value between 0 and 255. A higher relative value indicates a lower trustworthiness rating. Preference is given to routes with smaller values. The default, if unspecified, is 110.
clns	(Optional) CLNS-derived routes for IS-IS.