Enabling Tag Switching on the ATM Interface

Note:Configure all parallel interfaces between ATM switch routers for either IP unnumbered or with a specific IP address. Unnumbering some parallel interfaces and assigning specific IP addresses to others might cause TDP sessions to restart on some parallel interfaces when another parallel interface is shut down. Therefore, we highly recommend that you unnumber all parallel interfaces to loopback.

To enable tag switching on the ATM interface, perform the following steps, beginning in global configuration mode:

1. interface atm card/subcard/port
2. ip unnumbered type number or
ip address ip-address mask
3. tag-switching ip

Examples
In the following example, ATM interface 1/0/1 is configured for IP unnumbered to loopback interface 0:

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


The following example shows that tag switching is configured on ATM interfaces 0/0/3 and 1/0/1:

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)


Configuring OSPF
Enable OSPF on the ATM switch router so that it can create routing tables, which identify routes through the network. Then add the addresses and associated routing areas to the OSPF process so that it can propagate the addresses to other ATM switch routers:

1. router ospf process_number
2. network address wildcard-mask {area area-id}
Note:With this release of the 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
The following is an example of OSPF enabled and assigned process number 10000. All addresses are in area 0:

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


Displaying the OSPF Configuration
To display the OSPF configuration, use the following privileged EXEC command:
The following example shows the OSPF configuration using the show ip ospf privileged EXEC command:

Switch# show ip ospf
Routing Process "ospf 10000" with ID 1.0.1.11
Supports only single TOS(TOS0) routes
SPF schedule delay 5 secs, Hold time between two SPFs 10 secs
Number of DCbitless external LSA 0
Number of DoNotAge external LSA 0
Number of areas in this router is 1. 1 normal 0 stub 0 nssa
Area BACKBONE(0) (Inactive)
Number of interfaces in this area is 4
Area has no authentication
SPF algorithm executed 2 times
Area ranges are
Link State Update Interval is 00:30:00 and due in 00:14:42
Link State Age Interval is 00:20:00 and due in 00:14:10
Number of DCbitless LSA 0
Number of indication LSA 0
Number of DoNotAge LSA 0


Configuring a VPI Range (Optional)
Although not necessary for most configurations, you might need to change the default tag virtual path identifier (VPI) range on the switch if:

  • It is an administrative policy to use a VPI value other than 1, the default VPI.
  • There is a large number of TVCs on an interface.

Note:You cannot enter a VPI range on a VP tunnel. On VP tunnels, the VPI is the permanent virtual path (PVP) number of the tunnel.

To change the default tag VPI range, perform the following steps, beginning in global configuration mode:



1. interface atm card/subcard/port
2. tag-switching atm vpi vpi [- vpi]
Example
The following example shows how to select a VPI range from 5 to 6 (a range of two), an acceptable range if the TDP neighbor is a router:

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


The following example shows how to select a VPI range from 5 to 7 (a range of three), an acceptable range if the TDP neighbor is a switch:

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.

Displaying the Tag Switching VPI Range
To display the tag switching VPI range, use the following EXEC command:

show tag-switching interfaces detail

Example
The following example shows the tag switching VPI range on interface ATM 1/0/1:

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


Configuring TDP Control Channels (Optional)
Although not necessary for most configurations, you can change the default TDP control channel VPI and virtual channel identifier (VCI) if you want to use a nondefault value. The default TDP control channel is on VPI 0 and VCI 32. TDP control channels exchange TDP HELLOs and Protocol Information Elements (PIEs) to establish two-way TDP sessions. Tag virtual channels (TVCs) are created by the exchange of PIEs through TDP control channels.

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

1. interface atm card/subcard/port
2. ip address ip-address mask
3. tag-switching ip
4. tag-switching atm control-vc vpi vci
shows an example TDP control channel configuration between a source switch and destination switch on ATM interface 0/0/1. Note that the VPI and VCI values match on the source switch and destination switch.



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

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


If you are having trouble establishing a TDP session, verify that the VPI and VCI values match on the TDP control channels of the source switch and destination switch.

Displaying the TDP Control Channels
To display the TDP control channel configuration, use the following EXEC command:

show tag-switching interfaces detail
The following example shows the TDP control channel configuration on interface ATM 0/0/3:

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

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