Configuring SVCs, PVCs, Soft PVCs, PVPs, and VP Tunnels
This chapter describes how to configure switched virtual circuits (SVCs), permanent virtual circuits (PVCs), soft PVCs, permanent virtual paths (PVPs), and VP tunnels, and includes the following sections:
Note For more software configuration information, refer to the ATM Switch Router
Software Configuration Guide. Refer to the ATM Switch Router Command Reference
publication for command syntax.
Configuring SVCs
An SVC is a logical connection established using signaling messages, which reduces the amount of manual configuration required. SVCs are established on demand and torn down when a release message is generated either by signaling messages or by the application.
On the ATM switch router, no configuration is necessary to set up a transit SVC (an SVC that does not terminate on the ATM switch router). The signaling channels are set up by default and do not require manual configuration.
If the SVC terminates on a router, however, configuration is required on the router where the SVC terminates. For your convenience, the router configuration is described in this section.
Figure 3-1 shows an example network that illustrates how to set up SVCs. This example network is used throughout this section.
Figure 3-1 Example Network for Configuring SVCs
Configuring the Router
Perform the following tasks on both routers that terminate the SVC:
Configure PVCs for QSAAL and ILMI signaling
Configure IP and ESI addresses and subnet masks
Determine the NSAP address
Configure a map group and map list
The following subsections describe these procedures in detail.
Tip
Open two Telnet windows for both the source and destination routers.
Configuring Signaling on the Routers
Configure PVCs for QSAAL and ILMI signaling on the main ATM interfaces of both the source and destination routers that terminate the SVC.
Note On the ATM switch router, the signaling and ILMI channels are set up by default and
do not require manual configuration.
Take these steps:
Step
Command
Purpose
1
Router> enable
Router#
Enter privileged EXEC mode.
2
Router# configure terminal
Router(config)#
Enter global configuration mode.
3
Router(config)# interface atmport[/slot]
Router(config-if)#
Enter interface configuration mode on the ATM interface.
4
Router(config-if)# atm pvcnumber0 5 qsaal
Configure a PVC for QSAAL1 signaling.
5
Router(config-if)# atm pvcnumber0 16 ilmi
Configure a PVC for ILMI signaling.
6
Router(config-if)# end
Router#
Return to privileged EXEC mode.
7
(No command.)
Repeat this procedure on the other router.
1QSAAL = Q.2931 protocol over signaling ATM adaptation layer
Example
Router> enable
Router# configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
Router(config)# interface atm 0
Router(config-if)# atm pvc 1 0 5 qsaal
Router(config-if)# atm pvc 2 0 16 ilmi
Router(config-if)# end
Router#
Verify
Switch# show atm vc interface atm 0
VCD / Peak Avg/Min Burst
Interface Name VPI VCI Type Encaps Kbps Kbps Cells Sts
0 1 0 5 PVC SAAL 155000 155000 UP
0 2 0 16 PVC ILMI 155000 155000 UP
Switch#
Configuring the IP Address and ESI Address
On an ATM subinterface, configure the IP address and an ESI address.
Determine the ATM network service access point (NSAP) address for both the source and destination routers. The NSAP addresses is required to complete the SVC.
Step
Command
Purpose
1
Router# show interface atmport[/slot][.subinterface]
Display the 20-byte NSAP address of the router port on which the SVC terminates. Enter the address in Table 3-1.
The NSAP address does not display in certain modes. In this case, you must enter an NSAP address that meets the following criteria:
It must be unique in the network.
It must not be a broadcast or multicast MAC address.
2
(No command.)
Repeat this procedure to display the NSAP address of the other router.
Enter the 20-byte NSAP address of each router in the space provided below in Table 3-1.
Enter the map group name on the ATM subinterface. The map group name is used to associate a map list to the subinterface.
5
Router(config-subif)# no shutdown
Enable the interface. Enter this command even if the interface is already up. This command enables the SAR1 process to use the newly configured parameters.
6
Router(config-subif)# exit
Router(config)#
Return to global configuration mode.
7
Router(config)# map-listname
Create a map list to define an ATM map statement for the SVC. The name you enter here must match the map group name you specified in Step 4.
Add the destination router IP address and ATM NSAP address to the map list. Enter the addresses you noted in Table 3-1 in the section "Determining the NSAP Address."
Router(config-map-list)# ip 192.153.185.65 atm-nsap 47.0091810000000061E5B5C01.555555555555.00
Router(config-map-list)# end
Router#
Verify
Router# ping 192.153.185.65
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echoes to 192.153.185.65, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/2/4 ms
Configuring PVCs
A PVC is a permanent logical connection that you must configure manually, from source to destination, through the ATM network. Once configured, the ATM network maintains the connection at all times, regardless of traffic flow. That is, the connection is always up whether there is traffic to send or not.
Figure 3-2 shows an example PVC between ATM-capable router A and router D. This example network is used throughout this section to describe how to set up PVCs.
Figure 3-2 Example Network for Configuring PVCs
When configuring a PVC, the virtual path identifiers/virtual channel identifiers (VPIs/VCIs) must match between devices, as shown in Figure 3-2 between:
Source router A and ATM switch router B, which both use VPI=0, VCI=50
ATM switch routers B and C, which both use VPI=2, VCI=100
ATM switch router C and destination router D, which both use VPI=50, VCI=255
The VPI/VCIs that create an internal crossconnect within a switch can differ, as shown in:
ATM switch router B between interfaces 3/0/1 (VPI=0, VCI=50) and 3/0/2 (VPI=2, VCI=100)
ATM switch router C between interfaces 0/1/1 (VPI=2, VCI=100) and 0/0/1 (VPI=50, VCI=255)
Table 3-2 describes the in and out interfaces and associated VPIs/VCIs for the PVC shown in Figure 3-2.
Configure the PVC. When configuring PVCs, configure the lowest available VPI and VCI numbers first.
Note VCIs 0 to 31 on all VPIs are reserved.
5
Switch(config-if)# end
Switch#
Return to privileged EXEC mode.
Note If the PVC terminates on an ATM switch router, you must terminate the connection
on the route processor interface ATM 0. The atm pvc 0 any-vci command allocates the next
available VCI value on the route processor interface ATM 0, although you can specify the
VCI value if you choose. An example follows:
The following example shows how to configure the internal crossconnect (within the switch) PVC on ATM switch router B between interface 3/0/1, VPI = 0, VCI = 50, and interface 3/0/2, VPI = 2, VCI = 100 (see Figure 3-2):
Add the destination router IP address. The VCD1 number must match the VCD number you assigned in Step 5. This configuration allows the VC to receive routing updates.
Sending 5, 100-byte ICMP Echoes to 192.153.185.65, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/1/1 ms
Configuring Soft PVCs
Soft PVCs are a combination of SVCs and PVCs. SVCs are set up on the inside of the path among ATM switch routers, and PVCs are set up between an edge ATM switch router and the terminating device (such as a router).
Soft PVCs require less manual configuration than PVCs. With soft PVCs, you need to configure only the destination ATM switch router in the path and PVCs on the devices that terminate the soft PVC (such as a router).
Figure 3-3 illustrates how to set up soft PVCs. This example network is used throughout this section.
Figure 3-3 Example Network for Configuring Soft PVCs
Configuring the ATM Switch Router
Perform the following tasks on the ATM switch router to set up a soft PVC:
Determine the destination ATM switch router NSAP address
Configure the source ATM switch router
The subsections that follow describe these procedures in detail.
Determining the Destination ATM Switch Router NSAP Address
Determine the destination ATM switch router NSAP address for the interface. See the ATM switch router C in Figure 3-3.
Take these steps:
Step
Command
Purpose
1
Switch# show atm addresses
On the destination ATM switch router, display the destination ATM address. You need this address to complete the soft PVC. Write the address in the space provided below (or copy it to memory):
Sending 5, 100-byte ICMP Echoes to 192.153.185.65, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/1/1 ms
Configuring PVPs
A VP connection is like a bundle of VCs, transporting all cells with a common VPI, rather than a specific VPI and VCI. A PVP is a provisioned VP (like a PVC).
Figure 3-4 illustrates how to set up PVPs. This example network is used throughout this section.
Figure 3-4 Example Network for Configuring PVPs
Table 3-3 describes the in and out interfaces and associated VPIs for the PVP shown in Figure 3-4. Between ATM switch routers, the VPIs for the out port and the in port must match. For example, in Figure 3-4, the VPIs match between ATM switch routers A and B (VPI=3).
Note The VPIs for the internal crossconnects do not have to match. For example, in
Figure 3-4, the VPIs do not
match in ATM switch router A for the internal crossconnect between ports 3/0/1 (VPI=2)
and 3/0/2 (VPI=3).
Table 3-3 VPIs for the Example PVP
Switch A
Switch B
Switch B
Switch C
Switch C
Switch D
Out
In
Out
In
Out
In
Interface
3/0/2
0/0/0
1/1/1
3/1/1
1/0/0
0/1/1
VPI
3
3
5
5
8
8
Take these steps:
Step
Command
Purpose
1
Switch> enable
Switch#
Enter privileged EXEC mode.
2
Switch# configure terminal
Switch(config)#
Enter global configuration mode.
3
Switch(config)# interface atmcard/subcard/port
Router(config-if)#
Enter interface configuration mode on the ATM interface.
Note When configuring PVP connections, use the lowest available VPI numbers first.
5
Switch(config-subif)# end
Switch#
Return to privileged EXEC mode.
Example
The following example shows how to configure the internal crossconnect (within the switch) PVP on ATM switch router B between interface 3/0/1, VPI = 2 and interface 3/0/2, VPI = 3:
Switch# configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
A VP tunnel is a method of linking two private ATM networks across a public network that does not support SVCs. The VP tunnel provides a permanent path through the public network. The public network transparently trunks the entire collection of virtual channels in the virtual path between the two private networks. Signaling traffic is mapped into the PVP and the switches allocate a virtual channel connection (VCC) on that VP, instead of the default VP 0. This mapping allows the signaling traffic to pass transparently through the public network.
Figure 3-5 illustrates how to set up VP tunnels. This example network is used throughout this section.
Figure 3-5 Example Network for Configuring VP Tunnels
Table 3-4 describes the interfaces and associated VPIs and VPTs for the VP tunnel shown in Figure 3-5. Between the source and destination ATM switch routers, the VPIs and VPTs must match. For example, in Figure 3-5, the VPIs and VPTs (99) match between ATM switch routers A and B.
Table 3-4 VPIs and VPTs for the Example VP Tunnel
Switch A
Switch B
Interface
3/0/2.99
0/0/0.99
VPI
99
99
VPT
99
99
Take these steps:
Step
Command
Purpose
1
Switch> enable
Switch#
Enter privileged EXEC mode.
2
Switch# configure terminal
Switch(config)#
Enter global configuration mode.
3
Switch(config)# interface atmcard/subcard/port
Switch(config-if)#
Enter interface configuration mode on the ATM interface.
