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The Layer 2 Local Switching feature allows you to switch Layer 2 data in two ways:
- Between two interfaces on the same router
- Between two circuits on the same interface port, which is called same-port switching
The following interface-to-interface switching combinations are supported by this feature:
- ATM to ATM
- ATM to Ethernet
- Ethernet/Ethernet VLAN to Ethernet/Ethernet VLAN
- Frame Relay to Frame Relay
The following same-port switching features are supported:
- ATM Permanent Virtual Circuit (PVC) and Permanent Virtual Path (PVP)
- Ethernet VLAN
- Frame Relay
- Finding Feature Information, page 2
- Prerequisites for Layer 2 Local Switching, page 2
- Restrictions for Layer 2 Local Switching, page 2
- Information About Layer 2 Local Switching, page 2
- How to Configure Layer 2 Local Switching, page 3
- Configuration Examples for Layer 2 Local Switching, page 14
- Additional References, page 17
- Feature Information for Layer 2 Local Switching, page 19
Wide-Area Networking Configuration Guide: Layer 2 Services, Cisco IOS XE Release 3S
Finding Feature Information
Your software release may not support all the features documented in this module. For the latest caveats and feature information, see Bug Search Tool and the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the feature information table at the end of this module. Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.
Prerequisites for Layer 2 Local Switching
You must enable Cisco Express Forwarding for the Cisco ASR 1000 Series Aggregation Services Router.
Restrictions for Layer 2 Local Switching
- For Ethernet/Ethernet VLAN circuits, the Cisco ASR 1000 Series Aggregation Services Router must have Ethernet Adapters.
- For Frame Relay local switching, you must globally issue the frame-relay switching command.
Information About Layer 2 Local Switching
Layer 2 Local Switching Overview
Local switching allows you to switch Layer 2 data between two interfaces of the same type (for example, Ethernet to Ethernet or Frame Relay to Frame Relay) or between interfaces of different types (for example, Ethernet VLAN to Ethernet VLAN or Ethernet to Ethernet VLAN) on the same router. The interfaces can be on the same line card or on two different cards. During these kinds of switching, the Layer 2 address is used, not the Layer 3 address. Additionally, same-port local switching allows you to switch Layer 2 data between two circuits on the same interface.
NSF SSO—Local Switching Overview
Nonstop forwarding (NSF) and stateful switchover (SSO) improve the availability of the network by providing redundant Route Processors and checkpointing of data to ensure minimal packet loss when the primary Route Processor goes down. NSF/SSO support is available for the following locally switched attachment circuits:
- Ethernet/Ethernet VLAN to Ethernet/Ethernet VLAN
- Frame Relay to Frame Relay
Wide-Area Networking Configuration Guide: Layer 2 Services, Cisco IOS XE Release 3S
Finding Feature Information
SUMMARY STEPS
- enable
- configure terminal
- interface fastethernet slot / port. subinterface-number
- encapsulation dot1q^ vlan-id
- exit
- interface fastethernet slot / port. subinterface-number
- encapsulation dot1q vlan-id
- exit
- connect connection-name type number type number
DETAILED STEPS
Command or Action Purpose Step 1 enable Enables privileged EXEC mode.
Example: Router> enable
- Enter your password if prompted.
configure terminal Enters global configuration mode.
Example: Router# configure terminal
Step 2
Specifies the first Fast Ethernet line card, subslot (if available), port, and subinterface, and enters subinterface configuration mode.
interface fastethernet slot / port. subinterface-number
Example: Router(config)# interface fastethernet6/0.
Step 3
Enables the subinterface to accept 802.1Q VLAN packets and specifies the first VLAN.
encapsulation dot1q vlan-id
Example: Router(config-subif)# encapsulation dot1q 10
Step 4
Exits subinterface configuration mode and returns to global configuration mode.
exit
Example: Router(config-subif)# exit
Step 5
Wide-Area Networking Configuration Guide: Layer 2 Services, Cisco IOS XE Release 3S
Configuring Ethernet VLAN Same-Port Switching
Command or Action Purpose
Specifies the second Fast Ethernet line card, subslot (if available), port, and subinterface, and enters subinterface configuration mode.
interface fastethernet slot / port. subinterface-number
Example: Router(config)# interface fastethernet6/0.
Step 6
Enables the subinterface to accept 802.1Q VLAN packets and specifies the second VLAN.
encapsulation dot1q vlan-id
Example: Router(config-subif)# encapsulation dot1q 20
Step 7
Exits subinterface configuration mode and returns to global configuration mode.
exit
Example: Router(config-subif)# exit
Step 8
Creates a local connection between the two subinterfaces (and hence their previously specified VLANs) on the same Fast Ethernet port.
connect connection-name type number type number
Example: Router(config)# connect conn fastethernet 6/0.1 fastethernet 6/0.
Step 9
Configuring Ethernet Port Mode to Ethernet VLAN Local Switching
Perform this task to configure local switching for Ethernet (port mode) to Ethernet VLAN.
SUMMARY STEPS
- enable
- configure terminal
- interface fastethernet slot / subslot / port
- interface fastethernet slot / port / subinterface-number
- encapsulation dot1q vlan-id
- exit
- connect connection-name type number type number
Wide-Area Networking Configuration Guide: Layer 2 Services, Cisco IOS XE Release 3S
Configuring Ethernet Port Mode to Ethernet VLAN Local Switching
Configuring ATM-to-ATM PVC Local Switching and Same-Port Switching
You can configure local switching for both ATM AAL5 and ATM AAL0 encapsulation types. Creating the ATM PVC is not required. If you do not create a PVC, one is created for you. For ATM-to-ATM local switching, the autoprovisioned PVC is given the default encapsulation type AAL0 cell relay.
SUMMARY STEPS
- enable
- configure terminal
- interface atm slot / port
- pvc vpi / vci l2transport
- encapsulation layer-type
- exit
- exit
- connect connection-name interface pvc interface pvc
DETAILED STEPS
Command or Action Purpose Step 1 enable Enables privileged EXEC mode.
Example: Router> enable
- Enter your password if prompted.
configure terminal Enters global configuration mode.
Example: Router# configure terminal
Step 2
Specifies an ATM line card, subslot (if available), and port, and enters interface configuration mode.
interface atm slot / port
Example: Router(config)# interface atm1/0/
Step 3
Assigns a VPI and VCI and enters ATM PVC l2transport configuration mode.
pvc vpi / vci l2transport
Example: Router(config-if)# pvc 1/100 l2transport
Step 4
- The^ l2transport^ keyword indicates that the PVC is a switched PVC instead of a terminated PVC.
Specifies the encapsulation type for the ATM PVC. Both AAL and AAL5 are supported.
encapsulation layer-type
Example: Router(cfg-if-atm-l2trans-pvc)# encapsulation aal
Step 5
- Repeat Steps 3 through 5 for another ATM PVC on the same router.
Wide-Area Networking Configuration Guide: Layer 2 Services, Cisco IOS XE Release 3S
Configuring ATM-to-ATM PVC Local Switching and Same-Port Switching
Command or Action Purpose
Exits PVC l2transport configuration mode and returns to interface configuration mode.
exit
Example: Router(cfg-if-atm-l2trans-pvc)# exit
Step 6
Exits interface configuration mode and returns to global configuration mode.
exit
Example: Router(config-if)# exit
Step 7
Creates a local connection between the two specified permanent virtual circuits.
connect connection-name interface pvc interface pvc
Example: Router(config)# connect atm-con atm1/0/ 1/100 atm2/0/0 1/
Step 8
Configuring ATM-to-ATM PVP Local Switching
Perform this task to configure ATM-to-ATM PVP local switching. Starting with Cisco IOS Release 12.0(30)S, you can configure same-port switching, as detailed in the Configuring ATM PVP Same-Port Switching, on page 9.
SUMMARY STEPS
- enable
- configure terminal
- interface atm slot / port
- atm pvp vpi l2transport
- exit
- exit
- connect connection-name interface pvp interface pvp
DETAILED STEPS
Command or Action Purpose
Step 1 enable Enables privileged EXEC mode.
Example: Router> enable
- Enter your password if prompted.
Wide-Area Networking Configuration Guide: Layer 2 Services, Cisco IOS XE Release 3S
Configuring ATM-to-ATM PVP Local Switching
SUMMARY STEPS
- enable
- configure terminal
- interface atm slot / subslot / port
- atm pvp^ vpi^ l2transport
- exit
- exit
- connect connection-name interface pvp interface pvp
DETAILED STEPS
Command or Action Purpose
Step 1 enable Enables privileged EXEC mode.
Example: Router> enable
- Enter your password if prompted.
configure terminal Enters global configuration mode.
Example: Router# configure terminal
Step 2
Specifies an ATM line card, subslot (if available), and port, and enters interface configuration mode.
interface atm slot / subslot / port
Example: Router(config)# interface atm1/0/
Step 3
Specifies one VPI and enters PVP l2transport configuration mode. Repeat this step for the other ATM permanent virtual path on this same port.
atm pvp vpi l2transport
Example: Router(config-if)# atm pvp 100 l2transport
Step 4
- The^ l2transport keyword indicates that the indicated PVP is a switched PVP instead of a terminated PVP.
Exits PVP l2transport configuration mode and returns to interface configuration mode.
exit
Example: Router(config-if-atm-l2trans-pvp)# exit
Step 5
Exits interface configuration mode and returns to global configuration mode.
exit
Example: Router(config-if)# exit
Step 6
Wide-Area Networking Configuration Guide: Layer 2 Services, Cisco IOS XE Release 3S
Configuring ATM PVP Same-Port Switching
Command or Action Purpose
In global configuration mode, creates the local connection between the two specified permanent virtual paths.
connect connection-name interface pvp interface pvp
Example: Router(config)# connect atm-con atm1/0/ 100 atm1/0/0 200
Step 7
Configuring Frame Relay-to-Frame Relay Local Switching
For information about Frame Relay-to-Frame Relay local switching, see the Distributed Frame Relay Switching feature module.
SUMMARY STEPS
- enable
- configure^ terminal
- ip cef distributed
- frame-relay switching
- interface type number
- encapsulation frame-relay [ cisco | ietf ]
- frame-relay interface-dlci dlci switched
- exit
- exit
- connect connection-name interface dlci interface dlci
DETAILED STEPS
Command or Action Purpose Step 1 enable Enables privileged EXEC mode.
Example: Router> enable
- Enter your password if prompted.
configure terminal Enters global configuration mode.
Example: Router# configure terminal
Step 2
Wide-Area Networking Configuration Guide: Layer 2 Services, Cisco IOS XE Release 3S
Configuring Frame Relay-to-Frame Relay Local Switching
Verifying Layer 2 Local Switching
Verifying Layer 2 Local Switching Configuration To verify configuration of the Layer 2 local switching feature, use the show connection command on the provider edge (PE) router.
SUMMARY STEPS
- show connection [ all | element | id id | name name | port port ]
DETAILED STEPS
show connection [ all | element | id id | name name | port port ] The show connection command displays the local connection between a Gigabit Ethernet interface and another local Gigabit Ethernet interface:
Example: Router# show connection name ethconn Connection: 1 - ethconn Current State: UP Segment 1: GigabitEthernet0/0/0.1 up Segment 2: GigabitEthernet0/0/0.2 up
Verifying the NSF SSO Local Switching Configuration Layer 2 local switching provides NSF/SSO support for Local Switching of the following attachment circuits on the same router:
- Ethernet/Ethernet VLAN to Ethernet/Ethernet VLAN
For information about configuring NSF/SSO on the Route Processors, see the " Stateful Switchover " module in the Cisco IOS XE High Availability Configuration Guide. Perform this task to verify that the NSF/SSO: Layer 2 Local Switching feature is working correctly.
SUMMARY STEPS
- ping
- redundancy force-switchover
- show connection all
- ping
Wide-Area Networking Configuration Guide: Layer 2 Services, Cisco IOS XE Release 3S
Verifying Layer 2 Local Switching
DETAILED STEPS
Step 1 ping Issue the ping command or initiate traffic between the two CE routers.
Step 2 redundancy force-switchover Force the switchover from the active RP to the standby RP by using the redundancy force-switchover command. This manual procedure allows for a "graceful" or controlled shutdown of the active RP and switchover to the standby RP. This graceful shutdown allows critical cleanup to occur.
Step 3 show connection all Issue the show connection all command to ensure that the Layer 2 local switching connection on the dual RP is operating:
Example: Router# show connection all D Name Segment 1 Segment 2 State ================================================================================ 1 conn Gi0/0/0.1 Gi0/0/0.2 UP
Step 4 ping Issue the ping command from the CE router to verify that the contiguous packet outage was minimal during the switchover.
Troubleshooting Tips You can troubleshoot Layer 2 local switching using the following commands on the PE router:
- debug conn
- show connection
Configuration Examples for Layer 2 Local Switching
Example: Configuring Ethernet VLAN Same-Port Switching
The following example shows same-port switching between two VLANs on one Ethernet interface: interface fastethernet 0/0. encapsulation dot1q 1 interface fastethernet 0/0. encapsulation dot1q 2 connect conn FastEthernet 0/0.1 FastEthernet 0/0.
Wide-Area Networking Configuration Guide: Layer 2 Services, Cisco IOS XE Release 3S
Configuration Examples for Layer 2 Local Switching
PE
redundancy no keepalive-enable mode sso ! ! ip routing ip cef distributed ! interface fa1/1/ description - connection to CE1 fa3/1/ no shutdown no ip address ! ! interface fa6/0/ no shutdown no ip address ! interface fa6/0/0. description - connection to CE2 fa4/0. encapsulation dot1Q 10 no ip address ! interface fa6/0/0. description - connection to CE2 fa4/0. encapsulation dot1Q 20 no ip address
Example: Configuring ATM-to-ATM Local Switching
The following example shows local switching on ATM interfaces configured for AAL5: interface atm1/0/ pvc 0/100 l2transport encapsulation aal interface atm2/0/ pvc 0/100 l2transport encapsulation aal connect aal5-conn atm1/0/0 0/100 atm2/0/0 0/
Wide-Area Networking Configuration Guide: Layer 2 Services, Cisco IOS XE Release 3S
Example: Configuring ATM-to-ATM Local Switching
Example: Configuring ATM PVC Same-Port Switching
The following example shows same-port switching between two PVCs on one ATM interface: interface atm1/0/ pvc 0/100 l2transport encapsulation aal pvc 0/200 l2transport encapsulation aal connect conn atm1/0/0 0/100 atm1/0/0 0/
Example: Configuring ATM PVP Same-Port Switching
The following example shows same-port switching between two PVPs on one ATM interface: interface atm1/0/ atm pvp 100 l2transport atm pvp 200 l2transport connect conn atm1/0/0 100 atm1/0/0 200
Example: Configuring Frame Relay-to-Frame Relay Local Switching
The following example shows serial interfaces configured for Frame Relay. The connect command allows local switching between these two interfaces. frame-relay switching ip cef distributed interface serial3/0/ encapsulation frame-relay frame-relay interface-dlci 100 switched frame-relay intf-type dce interface serial3/1/ encapsulation frame-relay ietf frame-relay interface-dlci 200 switched frame-relay intf-type dce connect fr-con serial3/0/0 100 serial3/1/0 200
Additional References
Related Documents
Related Topic Document Title
Cisco IOS commands Cisco IOS Master Command List, All Releases
Cisco IOS Wide-Area Networking Command Reference
WAN Commands
"Stateful Switchover " module in the Cisco IOS XE High Availability Configuration Guide
Stateful switchover configuration information
Wide-Area Networking Configuration Guide: Layer 2 Services, Cisco IOS XE Release 3S
Example: Configuring ATM PVC Same-Port Switching
Feature Information for Layer 2 Local Switching
The following table provides release information about the feature or features described in this module. This table lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature. Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.
Table 1: Feature Information for Layer 2 Local Switching
Feature Name Releases Feature Information
The Layer 2 Local Switching feature allows you to switch Layer 2 data between two interfaces on the same router, and in some cases to switch Layer 2 data between two circuits on the same interface port. In Cisco IOS XE Release 2.5, this feature was introduced on the Cisco ASR 1000 Series Aggregation Services Routers. Support was added for the following local switching types:
- Ethernet to Ethernet VLAN
- Same-port switching for Ethernet VLAN
The following commands were introduced or modified: connect (L2VPN local switching), show connection.
Layer 2 Local Switching Cisco IOS XE Release 2.
In Cisco IOS XE Release 3.3S, this feature was introduced on the Cisco ASR 1000 Series Aggregation Services Routers. The following commands were introduced or modified: connect (L2VPN local switching), show connection.
Layer 2 Local Switching - ATM to Cisco IOS XE Release 3.3S ATM
In Cisco IOS XE Release 3.9S, this feature was introduced on the Cisco ISR 4400 Series Routers.
Layer 2 Local Switching - Frame Cisco IOS XE Release 3.9S Relay to Frame Relay
Wide-Area Networking Configuration Guide: Layer 2 Services, Cisco IOS XE Release 3S
Feature Information for Layer 2 Local Switching
Wide-Area Networking Configuration Guide: Layer 2 Services, Cisco IOS XE Release 3S
Feature Information for Layer 2 Local Switching
