Configuring Token Ring Modules

This chapter describes how to configure the Catalyst 5000 series Token Ring modules. The Token Ring modules have 16 shielded (or Volition) RJ-45 connectors for Token Ring connections. These ports allow full- or half-duplex connections to other switches, hubs, or end nodes.

The Catalyst 5000 series Token Ring modules provide these features:

16 shielded RJ-45 Token Ring ports, individually programmable and capable of running in 4- or 16- Mbps, full- or half duplex, and behaving as either a concentrator or end station
Frame forwarding between ports and modules
Concentrator and bridge relay functions that enable switching between ports.
Switching features
- Source-route bridging (SRB), source-route switching, or source-route transparent (SRT) bridging
- Store-and-forward frame-forwarding mode
- 4-Mbps, 16-Mbps, and automatic speed adaption
- Dedicated Token Ring (DTR) support
- Priority queues for multimedia traffic
- Address and protocol filters
- All-Routes Explorer reduction
- Spanning-Tree Protocol support: IBM, IEEE 802.1d, Cisco
VLAN support
Management Utilities and Support
- SNMP-based management
- CiscoView graphical monitoring
- TrafficDirector for Remote Monitoring (RMON)

In addition to the standard MIB objects supported the Catalyst 5000 series switch, the Token Ring modules support these additional MIBs:

Token Ring Extensions to the Managed Objects for Bridges (RFC 1525)
IEEE 802.5 Token Ring MIB (RFC 1748)
RMON MIB/Token Ring Extensions (RFC 1513) partial support

The proprietary MIBs supported are:

Cisco Workgroup MIB (CISCO-STACK-MIB)
VLAN Trunk Protocol (VTP) pruning (CISCO-VTP-MIB)
Cisco VLAN Bridging (CISCO-VLAN-BRIDGING-MIB)

Most user-configurable variables are supported in either the standard MIBs or private MIBs.

Default Configuration

The default values of the Token Ring module features are:

All ports are enabled
All ports are assigned to the default Token Ring Concentrator Relay Function (TrCRF)
No port name is configured for any port
Priority level for all ports is set to normal
Transmission speeds for the ports is set to auto-detect
Transmission modes for the ports is set to auto
Transmission threshold is 3
Minimum transmit setting is 4
Spanning-Tree Protocol is enabled for all ports
All-Routes Explorer Reduction is enabled

This section describes how to use the CLI to configure the ports on the Token Ring switching modules. For additional information on the CLI, refer to the Catalyst 5000 Series Command Reference publication.

Note If you change certain configuration parameters of a connected port, the port will close and reopen and you will lose all address information and statistics for that port.

Setting the Port Name

To assign a name to a port on the Token Ring module, enter this command in privileged mode:

Task	Command
Assign a name to a port.	set port name mod_num/port_num name

After entering the set port name command, you see a display similar to the following:

Console> (enable) set port name 4/1 Print-1st Floor
Port 4/1 name set.
Console> (enable) set port name 4/2 Server 1
Port 4/2 name set.

Setting Frame Priority Levels

To address the needs of delay-sensitive data, each port on a Token Ring module has two data queues: high-priority and low-priority.

The queue is determined by the value of the priority field in the frame control (FC) byte of the frame. If the FC priority is above the user-defined priority level, the frame is put in the high-priority queue and is transmitted using the frame priority. If the FC priority is at or below the user-defined priority level, then the frame is sent to the low-priority queue.

You can set two types of frame priorities for a port.

Priority threshold--Highest Token Ring frame priority in the Frame Control Field of the frame that the switch should place in the low-priority transmit queue. The default priority queue threshold is 3.
Minimum transmit priority--Minimum reservation priority used when requesting a token on a busy ring. The default minimum frame priority is 4.

Note The defaults for the priority queue are compatible with current source-route bridges and provide a high-priority queue for Token Ring multimedia traffic (priorities 5 and 6).

To set the frame priority levels for a port, enter this command in privileged mode:

Task	Command
Set the frame priority levels for a port.	set tokenring priority mod_num/port_num {threshold 0-7 \| minxmit 0-6}

After entering the set tokenring priority command, you see a display similar to the following:

Console> (enable) set tokenring priority 4/2 threshold 6
Port 2 priority threshold set to 6.
Console> (enable) set tokenring priority 4/2 minxmit 5
Port 2 priority minxmit set to 5.

Setting the Port Speed

The Token Ring modules support 4- and 16-Mbps Token Ring transmission speeds. You can configure ports on the Token Ring modules to operate at one of these speeds or to automatically sense the speed of the ring to which it is connected (the default setting). However, with Token Ring technology, you cannot change a transmission speed without closing and reopening the port. These rules apply:

If the port is open and running at a transmission speed that is the same as the speed you specify when entering the set port speed command, no action is performed.
If the port is open and running at a speed different from a speed you specify when entering the set port speed command, the port closes and reopens at the new transmission speed.
If the port is closed, you can change the speed without any restrictions.

Note If the ports on the Token Ring modules are configured to automatically sense the speed of the ring, the first port inserted on the ring does not set the speed, because it cannot detect the speed.

Note Closing and opening the port on an existing ring at a different transmission speed from which the ring is currently operating causes the port to issue a beacon on that ring.

To set the transmission speed for a port on the Token Ring module, enter this command in privileged mode:

Task	Command
Set the transmission speed for a Token Ring module port.	set port speed mod_num/port_num {4 \| 16 \| auto}

After entering the set port speed command, you see a display similar to the following:

Console> (enable) set port speed 4/1 4
Port 4/1 speed set to 4Mbps.
Console> (enable) set port speed 4/2 16
Port 4/2 speed set to 16Mbps.
Console> (enable) set port speed 4/3 auto
Port 4/3 speed set to auto detect.
Console> (enable)

Setting the Port Transmission Mode

Each port on the Token Ring module can operate in one of the following modes:

Half-duplex concentrator port--Port is connected to a port on an MAU. In this case, the port behaves like a station connected to a classic Token Ring segment that contains multiple stations.
Half-duplex station emulation--Port is connected to a single station in half-duplex (HDX) mode.
Full-duplex concentrator port--Port is connected to another Token Ring switch in FDX mode.
Full-duplex station emulation--Port is connected to a single station in full-duplex (FDX) mode.

The default mode, auto, enables the port to detect the transmission mode it needs to use. However, you can configure the mode if necessary.

To set the transmission mode for a port, enter this command in privileged mode:

Task	Command
Set the transmission mode for a port.	set tokenring portmode mod_num/port_num {auto \| fdxcport \| hdxcport \| fdxstation \| hdxstation \| riro}

After entering the set tokenring portmode command, you see a display similar to the following:

Console> (enable) set tokenring portmode 4/2 fdxcport
Port 3/2 mode set to fdxcport
Console> (enable)

Note The Ring in (RI)/Ring out (RO) parameter applies to the ports on a fiber Token Ring module only.

Setting Early Token Release

The interface ports on the Token Ring modules support early token release. Early token release allows a station to release a new token onto the ring immediately after transmitting, instead of waiting for the first frame to return. Early token release increases the total bandwidth on the ring. All ports, by default, are enabled to use early token release.

To enable or disable the early token release feature on a Token Ring module port, enter this command in privileged mode:

Task	Command
Enable or disable the early token release feature on a Token Ring module port.	set tokenring etr mod_num/port_num {enable \| disable}

After entering the set tokenring etr command, you see a display similar to the following:

Console> (enable) set tokenring etr 4/1 enable
Port 4/1 Early Token Release enabled.
Console> (enable) set tokenring etr 4/2 disable
Port 4/2 Early Token Release disabled.

Note Early token release is valid for 16-Mbps media only. If early token release is enabled and the media speed is 4 Mbps, the switch disables this feature.

Setting Address-Recognized/Frame-Copied Bits

You can specify whether the address-recognized (A) bit and the frame-copied (C) bit should be set unconditionally on repeated source-routed Logical Link Control (LLC) frames. These include source-routed frames with a Routing Information Field (RIF) length greater than 2 and all Spanning-Tree Explorer and All-Routes Explorer frames. The default is disable. If this parameter is disable, the setting of these bits is based on whether the frame was actually forwarded.

To set the AC bits for a port, enter this command in privileged mode:

Task	Command
Set the AC bits for a port.	set tokenring acbits mod_num/port_num {enable \| disable}

After entering the set tokenring acbits command, you see a display similar to the following:

Console> (enable) set tokenring acbits 4/4 enable
Port 4/4 acbits enabled.
Console> (enable) set tokenring acbits 4/4 disable
Port 4/4 acbits disabled.

Setting Configuration Loss Thresholds

Configuration loss occurs when a port completes a connection, allows data traffic to flow, and subsequently closes. The configuration loss threshold controls the number of configuration losses that can occur within a specified time. When the threshold is exceeded, the port is disabled and you must enable it by entering the set port enable command or an SNMP manager. The valid range for the configuration loss threshold is 1 through 100. The default is 8.

To set and verify the configuration loss threshold for a port, enter this command in privileged mode:

Task	Command
Set and verify the configuration loss threshold for a port.	set tokenring configloss mod_num/port_num {threshold <1..100> \| interval <1..9999>}

After entering the set tokenring configloss command, you see a display similar to the following:

Console> (enable) set tokenring configloss 4/2 threshold 50
Port 4/2 configloss threshold set to 50.
Console> (enable) set tokenring configloss 4/2 interval 20
Port 4/2 configloss interval set to 20.

Note To view reason codes and a counter of the current number of configuration loss events, enter the show tokenring command.

Enabling and Disabling All-Routes Explorer Reduction

For parallel SRB or SRT backbones, All-Routes Explorer reduction ensures that the number of All-Routes Explorer frames generated by the switch does not overwhelm the network.

In accordance with the IEEE 802.1d SRT standard, the Token Ring module discards any All-Routes Explorer frames that have already been on a ring that is attached to the switch. This ensures that only one All-Routes Explorer frame is received on each ring within each VLAN (TrBRF and TrCRF). The number of frames is equal to the number of external parallel paths between the rings. If a port on the switch fails or is disabled, the switch no longer checks for this ring number in the RIF. This bypass allows frames to travel on alternate paths.

By default, All-Routes Explorer reduction is enabled.

To enable All-Routes Explorer reduction, enter this command in privileged mode:

Task	Command
Enable All-Routes Explorer reduction.	set tokenring reduction enable

To disable All-Routes Explorer reduction, enter this command in privileged mode:

Task	Command
Disable All-Routes Explorer reduction.	set tokenring reduction disable

Verifying the Token Ring Port Configuration

After configuring the Token Ring ports, you can verify the configuration using these commands:

To display general port configuration, such as the port name, status, and type, enter the show port mod_num/port_num command.
To display Token Ring specific configuration information, enter the show tokenring mod_num/port_num command.

Note You can verify the ports individually or as a group. To view the configuration parameters for a specific port, specify the module number and port number.

After entering the show port command and specifying the module and port number, you see a display similar to the following:

Console> (enable) show port 3/2
Port  Name               Status     Vlan       Level  Duplex Speed Type
----- ------------------ ---------- ---------- ------ ------ ----- ------------
 3/2                     inactive   1003       normal    fdx  auto TokenRing
 
Last-Time-Cleared
--------------------------
Wed May 6 1998, 18:09:47
Console> (enable)

After entering the show tokenring command and specifying a module and port number, you see a display similar to the following:

Console> (enable) show tokenring 3/2
Ports   Crf/Brf      Ring#    Port-Mode        Early-Token    AC-bits
-----   ---------    -----    -------------    -----------    --------
 3/2    1003/1005    3276     fdx-cport        enabled        disabled
 
Ports   Prior-Thresh    Min-Xmit    MAC-Address
-----   ------------    --------    -----------------
 3/2    6               5           00:40:0b:01:bc:65
 
Ports   Cfg-Loss-Thresh  Cfg-Loss-Intvl  Cfg-Loss-Count  Cfg-Loss-Reason
-----   ---------------  --------------  --------------  ---------------
 3/2    50               20              0               none
Console> (enable)

Configuring Filters

Catalyst 5000 series Token Ring modules provide filtering capabilities to reduce broadcast traffic, block protocols, and provide basic security.

You can filter frames based on the following:

MAC address (source address [SA] or destination address [DA])--Defines a filter that explicitly allows data from the select group of users (based on MAC address) to be sent to that port using MAC filters.
Protocol (Destination Service Access Point [DSAP]/Subnetwork Access Protocol [SNAP])--Creates a filter that blocks all data to a port except data that is explicitly allowed.

You can configure MAC address filters for input ports only, and configure DSAP/SNAP filters for both input and output ports. You can configure up to 16 MAC address or DSAP/SNAP filters for each port on the Token Ring modules.

To filter data based on the MAC address, you must specify an address and indicate whether you want to block or allow frames that contain the address as a source or destination address. To filter data based on a protocol, specify either a DSAP or SNAP, and specify whether to permit or deny frames with that protocol.

Adding a MAC Address Filter

When configuring a MAC address filter, you can enter the MAC address in canonical or noncanonical form. Frames that contain the MAC address as a source or destination address are dropped or passed, depending on whether you specify that the filter permits or denies the frames.

To add a filter based on MAC addresses, enter this command in privileged mode:

Task	Command
Add a filter based on the MAC addresses.	set port filter mod_num/port_num mac_addr {permit \| deny}

After entering the set port filter command, you see a display similar to the following:

Console> (enable) set port filter 3/2 00:40:0b:01:bc:65 permit
Port 3/2 filter Mac Address 00:40:0b:01:bc:65 set to permit.
Console> (enable)

Note You can define up to 16 MAC address filters per port to be filtered at the port of entry into the Token Ring modules. MAC addresses can be unicast, multicast (group), or broadcast.

Adding a Protocol Filter

To add a filter based on the protocols, enter this command in privileged mode:

Task	Command
Add a filter based on the protocols.	set port filter mod_num/port_num protocol_type {permit \| deny}

After entering the set port filter command, you see a display similar to the following:

Console> (enable) set port filter 3/2 ip permit
Port 3/2 filter Protocol ip set to permit.
Console> (enable)

Note You can define up to 16 protocol filters (eight SAP and eight DSAP classes) per port to be filtered at the port of entry into the Token Ring modules.

Clearing Filters

With the clear port filter command, you can clear MAC address or protocol filters configured for a specific port, or clear all the filters configured for each port on the Token Ring modules.

To clear a MAC address filter, protocol filter, or all configured filters, enter this command in privileged mode:

Task	Command
Clear a MAC address filter, protocol filter, or all configured filters.	clear port filter [mod_num/port_num] [mac_addr \| protocol_type \| all]

After entering the clear port filter command to clear a specific MAC address filter on a port, you see a display similar to the following:

Console> (enable) clear port filter 3/2 00:40:0b:01:bc:65
Port 3/2 filter Mac Address 00:40:0b:01:bc:65 cleared.
Console> (enable)

After entering the clear port filter command to clear all configured filters, you see a display similar to the following:

Console> (enable) clear port filter all
All filter MAC addresses and Protocols cleared
Console> (enable)

Verifying Filters

To verify the filters you have configured for the Token Ring modules or for a specific port on the modules, use the show port filter command.

To verify the filters configured on port 2 of module 3, enter this command in privileged mode:

Task	Command
Verify the filters configured on port 2 of module 3.	show port filter 3/2

After entering the show port filter command, you see a display similar to the following:

Console> show port filter 3/2
Port  Mac-Addr          Type
----- ----------------- ------
 3/2  00:00:00:00:00:00 deny
      00:00:00:00:00:00 deny
      00:00:00:00:00:00 deny
      00:00:00:00:00:00 deny
      00:00:00:00:00:00 deny
      00:00:00:00:00:00 deny
      00:00:00:00:00:00 deny
      00:00:00:00:00:00 deny
      00:00:00:00:00:00 deny
      00:00:00:00:00:00 deny
      00:00:00:00:00:00 deny
      00:00:00:00:00:00 deny
      00:00:00:00:00:00 deny
      00:00:00:00:00:00 deny
      00:00:00:00:00:00 deny
      00:00:00:00:00:00 deny
Port  Protocol          Type
----- ----------------- ------
 3/2  0x8035(ip)        deny
      0xffff            deny
      0xfefe            deny
      0xffff            deny
      0xfefe            deny
      0xffff            deny
      0xfefe            deny
      0xffff            deny

Understanding Token Ring Switching

Catalyst 5000 series Token Ring modules support three bridging modes:

Source-Route Bridging

A source-route bridge makes all forwarding decisions based on data in the RIF. It does not learn or look up MAC addresses; SRB frames without a RIF are not forwarded.

Typically, clients or servers that support source routing send an explorer frame to determine the path to a given destination. There are two types of explorer frames: All-Routes Explorer and Spanning-Tree Explorer. All SRB bridges copy All-Routes Explorer frames and add their own routing information. For frames that are received from or sent to ports that are in the spanning-tree forwarding state, bridges copy Spanning-Tree Explorer frames and add their own routing information. Because All-Routes Explorer frames will traverse all paths between two devices, they are used in path determination. Spanning-Tree Explorer frames are used to send datagrams because the spanning tree ensures that only one copy of a Spanning-Tree Explorer frame is sent to each ring.

Note The spanning tree used with source-routing is different from the IEEE spanning tree used in transparent bridges. The Catalyst 5000 series Token Ring modules support both types of spanning-tree algorithms.

Source-Route Transparent Bridging

SRT bridging is an IEEE standard that combines source-route bridging and transparent bridging. An SRT bridge forwards frames that do not contain a RIF based on the destination MAC address. Frames that contain a RIF are forwarded based upon source-routing. The SRT bridge only runs the IEEE Spanning-Tree Protocol. SRT does not support the IBM Spanning-Tree Protocol.

Source-Route Switching

The Token Ring modules can forward broadcast, multicast, and unicast frames based on MAC addresses. If you have source-route bridges in your network, the Token Ring modules can forward frames based on the RIF. This dual frame-forwarding technology is called source-route switching.

In source-route switching, the switch learns and forwards frames based on source-route descriptors for stations that are one or more source-route bridge hops away. A route descriptor is a portion of a RIF that indicates a single hop. It is defined as a ring number and a bridge number. When a source-routed frame enters the switch, the switch learns the route descriptor for the hop closest to the switch. Frames received from other ports with the same next-hop route descriptor as their destination are forwarded to that port.

The key difference between SRB and source-route switching is that while a source-route switch looks at the RIF, it never updates the RIF. Therefore, all ports in a source-route switch group have the same ring number.

Source-route switching provides the following benefits:

The switch does not need to learn the MAC addresses of the devices on the other side of a source-route bridge. Therefore, the number of MAC addresses that the switch must learn and maintain is significantly reduced.
The switch can support parallel source-routing paths.
An existing ring can be partitioned into several segments without requiring a change in the existing ring numbers or the source-route bridges.
The switch can support duplicate MAC addresses if the stations reside on LAN segments with different LAN IDs (ring numbers).

To set the bridging mode of a TrCRF, enter this command in privileged mode:

Task	Command
Set the bridging mode.	set vlan vlan_num [mode {srt \| srb}]

Dedicated Token Ring Support

The Token Ring modules support a new token passing standard called Dedicated Token Ring (DTR). DTR is the IEEE 802.5R standard that:

Enables a switch port to act as a concentrator port, which allows you to connect the port of the switch directly to an end station.
Transmits in Transmit Immediate (TXI) mode (also referred to as full-duplex mode), increasing the aggregate bandwidth to 32 Mbps.

DTR provides improved access to central resources, such as network servers. This allows the server to use the full 16 Mbps available for sending and receiving, which results in an aggregate bandwidth of 32 Mbps.

Table of Contents