Configuring Tag Switching

Note   This chapter provides advanced configuration instructions for the Catalyst 8540 MSR, Catalyst 8510 MSR, and LightStream 1010 ATM switch routers. For an overview of tag switching, refer to the Guide to ATM Technology . For complete descriptions of the commands mentioned in this chapter, refer to the ATM  Switch Router Command Reference publication.

This chapter includes the following sections:

To configure the loopback interface, perform the following steps, beginning in global configuration mode:

	Command	Purpose
Step 1	Switch(config)# interface loopback number Switch(config-if)#	Enters interface configuration mode and assigns a number to the loopback interface.
Step 2	Switch(config-if)# ip address ip-address mask	Assigns an IP address and subnet mask to the loopback interface. Note   We recommend a 32-bit subnet mask (255.255.255.255) for the loopback interface. If you do not use a 32-bit subnet mask, two TVCs1 terminate for the same address—one for a 32-bit subnet mask and the other for the mask you entered. Entering a 32-bit subnet mask reduces the number of TVCs to one.

1TVCs = tag virtual channels.

Example

In the following example, loopback interface 0 is created with an IP address of 1.0.1.11 and a subnet mask of 255.255.255.255:

Switch(config)# interface loopback 0
Switch(config-if)# ip address 1.0.1.11 255.255.255.255
Switch(config-if)# exit

Switch(config-if)# interface atm 1/0/1
Switch(config-if)# ip unnumbered loopback 0
Switch(config-if)# tag-switching ip
Switch(config-if)# exit
 

In the following example, ATM interface 0/0/3 is configured with a specific IP address and subnet mask (1.3.11.3 255.255.0.0):

Switch(config)# interface atm 0/0/3
Switch(config-if)# ip address 1.3.11.3 255.255.0.0
Switch(config-if)# tag-switching ip
Switch(config-if)# exit

Switch# show tag-switching interfaces
Interface              IP    Tunnel   Operational
ATM0/0/3               Yes   No       Yes         (ATM tagging)
ATM1/0/1               Yes   No       Yes         (ATM tagging)

	Command	Purpose
Step 1	Switch(config)# router ospf process_number Switch(config-router)#	Enables OSPF and assigns it a process number. The process number can be any positive integer.
Step 2	Switch(config-router)# network address wildcard-mask area area-id	Defines the network prefix, a wildcard subnet mask, and the associated area number on which to run OSPF. An area number is an identification number for an OSPF address range. Repeat this command for each additional area you want to add to the OSPF process. Caution  Ethernet0 is used for system management only. Do not add this interface to the routing protocol process.

Note   Since the 12.0(1a)W5(5b) release of the system software, addressing the interface on the route processor (CPU) has changed. The ATM interface is now called atm0, and the Ethernet interface is now called ethernet0. Old formats (atm 2/0/0 and ethernet 2/0/0) are still supported.

Example

Note   An IP address of 1.1.1.1 with a subnet mask of 255.255.255.0 is entered as an IP network prefix of 1.1.1.0 with a subnet mask of 0.0.0.255. Likewise, an IP address of 1.2.1.1 with a subnet mask of 255.255.255.0 is entered as an IP network prefix of 1.2.1.0 with a subnet mask of 0.0.0.255.

Switch(config)# router ospf 10000
Switch(config-router)# network 1.1.1.0 0.0.0.255 area 0
Switch(config-router)# network 1.2.1.0 0.0.0.255 area 0
Switch(config-router)# network 1.3.0.0 0.0.255.255 area 0
Switch(config-router)# network 200.2.2.0 0.0.0.255 area 0
Switch(config-router)# network 1.0.1.0 0.0.0.255 area 0
Switch(config-router)# network 1.18.0.0 0.0.255.255 area 0

	Command	Purpose
Step 1	Switch(config)# interface atm card/subcard/port Switch(config-if)#	Enters interface configuration mode on the specified ATM interface.
Step 2	Switch(config-if)# tag-switching atm vpi vpi [- vpi]	Enters the VPI range. Note   If the TDP neighbor is a router, the VPI range can be no larger than two. For example, from 5 to 6 (a range of two), not 5 to 7 (a range of three). If the TDP neighbor is a switch, the maximum VPI range is 0 to 255.

Examples

Switch(config)# interface atm 3/0/1 
Switch(config-if)# tag-switching ip
Switch(config-if)# tag-switching atm vpi 5 - 6
 

Switch(config)# interface atm 3/0/1 
Switch(config-if)# tag-switching ip
Switch(config-if)# tag-switching atm vpi 5 - 7

Note   Although the example shows a VPI range of three, you are not limited to a range of three if the TDP neighbor is a switch. The maximum VPI range is 0 to 255 if the TDP neighbor is a switch.

Switch# show tag-switching interfaces detail
Interface ATM0/0/3:
        IP tagging enabled
        TSP Tunnel tagging not enabled
        Tagging operational
        MTU = 4470
        ATM tagging: Tag VPI = 1, Control VC = 0/32
Interface ATM1/0/1:
        IP tagging enabled
        TSP Tunnel tagging not enabled
        Tagging operational
        MTU = 4470
                ATM tagging: Tag VPI range = 5 - 6, Control VC = 6/32
<information deleted>

To change the TDP control channel, perform the following steps, beginning in global configuration mode:

	Command	Purpose
Step 1	Switch(config)# interface atm card/subcard/port Switch(config-if)#	Enters interface configuration mode on the specified ATM interface.
Step 2	Switch(config-if)# ip address ip-address mask	Assigns an IP address and subnet mask to the ATM interface.
Step 3	Switch(config-if)# tag-switching ip	Enables tag switching of IPv4 packets.
Step 4	Switch(config-if)# tag-switching atm control-vc vpi vci	Changes the TDP control channel.

Examples

Switch(config)# interface atm 0/0/1
Switch(config-if)# ip address 1.2.0.11 255.255.255.0
Switch(config-if)# tag-switching ip
Switch(config-if)# tag-switching atm control-vc 6 32
Switch(config-if)# exit
 

In the following example, a TDP control channel is configured on the destination switch:

Switch(config)# interface atm 0/0/1
Switch(config-if)# ip address 1.2.0.12 255.255.255.0
Switch(config-if)# tag-switching ip
Switch(config-if)# tag-switching atm control-vc 6 32
Switch(config-if)# exit
 

Examples

Switch(config-if)# interface atm 0/1/1
Switch(config-if)# atm pvp 51
Switch(config-if)# exit
Switch(config-if)# interface atm 0/1/1.51
Switch(config-subif)# ip unnumbered loopback 0
Switch(config-subif)# tag-switching ip
Switch(config-subif)# exit
 

In the following example, ATM interface 0/1/3 on the destination switch has no IP address and PVP 101 is configured for IP unnumbered to loopback interface 0:

Switch(config)# interface atm 0/1/3
Switch(config-if)# atm pvp 101
Switch(config-if)# exit
Switch(config)# interface atm 0/1/3.101
Switch(config-subif)# ip unnumbered loopback 0
Switch(config-subif)# tag-switching ip
Switch(config-subif)# exit
 

Switch# show atm vp
Interface    VPI    Type  X-Interface     X-VPI     Status
ATM0/1/1     51      PVP     TUNNEL

	Command	Purpose
Step 1	Switch(config)# interface atm card/subcard/port Switch(config-if)#	Enters interface configuration mode on the specified ATM interface.
Step 2	Switch(config-if)# atm pvp vpi interface atm card/subcard/port vpi-B	Connects the PVP from the source switch to the destination switch.

Example

Switch(config)# interface atm 0/1/1
Switch(config-if)# atm pvp 51 interface atm 0/1/3 101
Switch(config-if)# exit

Command	Purpose
no tag-switching atm vc-merge	Enables VC merge.

TBR classes support only best-effort VCs (similar to the ATM Forum service category UBR); therefore, there is no bandwidth guarantee from the RS, which is not used for TVCs. All of the TVCs fall into one of the four TBR classes, each carrying a different default relative weight. The default values of the relative weights for the four TBR classes are configurable, so you can change the priority of the default values.

Table 15-1: Service Class to Weight Mapping for Physical Ports

TBR Class	Service Class	Relative Weight
TBR_1 (WRR_1)	1	1
TBR_2 (WRR_2)	6	2
TBR_3 (WRR_3)	7	3
TBR_4 (WRR_4)	8	4

ATM Forum Service Category	Service Class	Relative Weight
CBR1	2	8
VBR-RT	2	8
VBR-NRT	3	1
ABR	4	1
UBR	5	1

1Even though the CBR service category is mapped to service class 2, all of the CBR VCs are rate scheduled only, and therefore they are not WRR scheduled.

When tag switching is enabled on a hierarchical VP tunnel, the tunnel can only be used for tag switching. Because hierarchical VP tunnels support only four service classes, both TVCs and ATM Forum VCs map to the same service classes. Therefore, both ATM Forum VCs and TVCs cannot coexist in a hierarchical VP tunnel. The relative weights assigned to the service classes depend on which is active (either tag switching or ATM Forum). The class weights change whenever a hierarchical VP tunnel is toggled between ATM Forum and tag switching. By default, a hierarchical VP tunnel comes up as an ATM Forum port.

Table 15-2: Service Class to Weight Mapping for Hierarchical VP Tunnels

TBR Class	Service Class	Relative Weight
TBR_1 (WRR_1)	1	1
TBR_2 (WRR_2)	2	2
TBR_3 (WRR_3)	3	3
TBR_4 (WRR_4)	4	4

ATM Forum Service Category	Service Class	Relative Weight
VBR-RT	1	8
VBR-NRT	2	1
ABR	3	1
UBR	4	1

	Command	Purpose
Step 1	Switch(config)# interface atm card/subcard/port[.vpt#] Switch(config-if)#	Specifies an ATM interface and enters interface configuration mode.
Step 2	Switch(config-if)# atm service-class {1 | 6 | 7 | 8} wrr-weight weight or Switch(config-if)# atm service-class {1 | 2 | 3 | 4} wrr-weight weight	Enters the service class and relative weight for a physical interface. or Enters the service class and relative weight for a hierarchical interface.

Example

Switch(config)# interface atm 0/0/3
Switch(config-if)# atm service-class 1 wrr-weight 3

Command	Purpose
show atm vc interface atm card/subcard/port [vpi vci]	Displays the ATM layer connection information about the virtual connection.

The following example shows the service category of the TVC:

Each ATM Forum service category is mapped into a distinct threshold group. All the connections in a particular service category map into one threshold group. Similarly, all the Tag Bit Rate (TBR) classes have best effort traffic and the service differentiation comes mainly by giving different weights. Each of the TBR classes map into four different threshold groups whose parameters are the same as the unspecified bit rate (UBR) threshold group.

Table 15-3: Threshold Group Parameters for TVCs (Catalyst 8540 MSR)

Group	Maximum Cells	Maximum Queue Limit	Minimum Queue Limit	Mark Threshold	Discard Threshold	Use
7	131,071	511	31	25%	87%	TBR_1
8	131,071	511	31	25%	87%	TBR_2
9	131,071	511	31	25%	87%	TBR_3
10	131,071	511	31	25%	87%	TBR_3

Table 15-4: Threshold Group Parameters for TVCs (Catalyst 8510 MSR and LightStream 1010)

Group	Maximum Cells	Maximum Queue Limit	Minimum Queue Limit	Mark Threshold	Discard Threshold	Use
7	65,535	511	31	25%	87%	TBR_1
8	65,535	511	31	25%	87%	TBR_2
9	65,535	511	31	25%	87%	TBR_3
10	65,535	511	31	25%	87%	TBR_3

Router 5-1 Configuration

The configuration of router R5-1, interface e0/1, follows:

router_R5-1# configure terminal
router_R5-2(config)# ip cef switch
router_R5-1(config)# tag-switching advertise-tags
router_R5-1(config)# interface e0/1
router_R5-1(config-if)# tag-switching ip
router_R5-1(config-if)# exit
router_R5-1(config)#

Router 5-2 Configuration

The configuration between router R5-1, interface e0/1, and R5-2, interface e0/1, follows:

router_R5-2# configure terminal
router_R5-2(config)# ip cef switch
router_R5-2(config)# tag-switching advertise-tags
router_R5-2(config)# interface e0/1
router_R5-2(config-if)# tag-switching ip
router_R5-2(config-if)# exit
router_R5-2(config)#
 

The configuration between router R5-2, interface e0/2, and R5-3, interface e0/2, follows:

route_R5-2(config)# interface e0/2
route_R5-2(config-if)# tag-switching ip
route_R5-2(config-if)# exit
 

The configuration of router R5-2, interface a2/0.1, follows:

router_R5-2(config-if)# interface a2/0.1 
router_R5-2(config-subif)# ip address 189.26.11.15 255.255.0.0
router_R5-2(config-subif)# tag-switching ip
router_R5-2(config-subif)# no shutdown
router_R5-2(config-subif)# exit
router_R5-2(config)# interface a2/0
router_R5-2(config)# no shutdown

Router 5-3 Configuration

The configuration of router R5-3, interface e0/2, follows:

router_R5-3# configure terminal
router_R5-3(config)# ip cef switch
router_R5-3(config)# tag-switching advertise-tags
router_R5-3(config)# interface e0/2
router_R5-3(config-if)# tag-switching ip
router_R5-3(config-if)# exit
 

The configuration of router R5-3, interface e0/5 follows:

router_R5-3(config)# interface e0/5
router_R5-3(config-if)# tag-switching ip
router_R5-3(config-if)# exit
 

The configuration of router R5-3, interface atm 2/0.1, follows:

router_R5-3# configure terminal
router_R5-3(config)# interface atm 2/0.1 
router_R5-3(config-if)# ip address 189.25.12.13 255.255.0.0
router_R5-3(config-if)# tag-switching ip
router_R5-3(config-if)# no shutdown
router_R5-3(config-if)# exit
router_R5-3(config)# interface a2/0
router_R5-3(config-if)# no shutdown

ATM Switch Router A5-4 Configuration

The configuration of ATM switch router A5-4, interfaces atm 0/1/1 and atm 0/0/3, follows:

atm_A5-4# configure terminal
atm_A5-4(config)# interface atm 0/1/1
atm_A5-4(config-if)# no shutdown
atm_A5-4(config-if)# ip address 189.24.15.12 255.255.0.0
atm_A5-4(config-if)# tag-switching ip
atm_A5-4(config-if)# exit
atm_A5-4(config)# tag-switching ip
atm_A5-4(config)# interface atm 0/0/3
atm_A5-4(config-if)# no shutdown
atm_A5-4(config-if)# ip address 189.25.15.11 255.255.0.0
atm_A5-4(config-if)# tag-switching ip
atm_A5-4(config-if)# exit
atm_A5-4(config)# tag-switching ip

Router 5-5 Configuration

The configuration of router R5-5, interface e0/2, follows:

router_R5-5# configure terminal
router_R5-5(config)# ip cef switch
router_R5-5(config)# tag-switching advertise-tags
router_R5-5(config)# interface e0/2
router_R5-5(config-if)# tag-switching ip
router_R5-5(config-if)# exit

ATM Switch Router A6-4 Configuration

The configuration of ATM switch router A6-4, interface atm 0/1/1, follows:

atm_A6-4# configure terminal
atm_A6-4(config)# interface atm 0/1/1
atm_A6-4(config-if)# no shutdown
atm_A6-4(config-if)# ip address 189.24.14.12 255.255.0.0
atm_A6-4(config-if)# tag-switching ip
atm_A6-4(config-if)# exit
 

The configuration of ATM switch router A6-4, interface atm 0/0/3, follows:

atm_A6-4# configure terminal
atm_A6-4(config)# interface atm 0/0/3
atm_A6-4(config-if)# no shutdown
atm_A6-4(config-if)# ip address 189.26.14.11 255.255.0.0
atm_A6-4(config-if)# tag-switching ip
atm_A6-4(config-if)# exit