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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
The following same-port switching features are supported:
•ATM Permanent Virtual Circuit (PVC) and Permanent Virtual Path (PVP)
•Ethernet VLAN
Your software release may not support all the features documented in this module. For the latest feature information and caveats, see 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 for Layer 2 Local Switching" section.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.
•Prerequisites for Layer 2 Local Switching
•Restrictions for Layer 2 Local Switching
•Information About Layer 2 Local Switching
•How to Configure Layer 2 Local Switching
•Configuration Examples for Layer 2 Local Switching
•Feature Information for Layer 2 Local Switching
You must enable Cisco Express Forwarding for the Cisco ASR 1000 Series Aggregation Services Router.
For Ethernet/Ethernet VLAN circuits, the Cisco ASR 1000 Series Aggregation Services Router must have Ethernet Adapters.
•Layer 2 Local Switching Overview
•NSF SSO - Local Switching Overview
•Layer 2 Local Switching Applications
Local switching allows you to switch Layer 2 data between two interfaces (for example, Ethernet to Ethernet, 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.
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
Incumbent local exchange carriers (ILECs) that use an interexchange carrier (IXC) to carry traffic between two local exchange carriers can use the Layer 2 Local Switching feature. Telecom regulations require the ILECs to pay the IXCs to carry that traffic. At times, the ILECs cannot terminate customer connections that are in different local access and transport areas (LATAs). In other cases, customer connections terminate in the same LATA, which may also be on the same router.
For example, company A has more than 50 LATAs across the country and uses three routers for each LATA. Company A uses companies B and C to carry traffic between local exchange carriers. Local switching of Layer 2 frames on the same router might be required.
Similarly, if a router is using, for example, a channelized interface, it might need to switch incoming and outgoing traffic across two logical interfaces that reside on a single physical port. The same-port local switching feature addresses that implementation.
•Configuring Ethernet VLAN Same-Port Switching (optional)
•Configuring Ethernet Port Mode to Ethernet VLAN Local Switching (optional)
•Configuring ATM-to-ATM PVC Local Switching and Same-Port Switching (optional)
•Configuring ATM-to-ATM PVP Local Switching (optional)
•Configuring ATM PVP Same-Port Switching (optional)
•Verifying Layer 2 Local Switching (optional)
Perform this task to configure Ethernet VLAN same-port switching.
1. enable
2. configure terminal
3. interface fastethernetslot/port.subinterface-number
4. encapsulation dot1q vlan-id
5. exit
6. interface fastethernetslot/port.subinterface-number
7. encapsulation dot1q vlan-id
8. exit
9. connect connection-name type number type number
Perform this task to configure local switching for Ethernet (port mode) to Ethernet VLAN.
1. enable
2. configure terminal
3. interface fastethernetslot/subslot/port
4. interface fastethernetslot/port/subinterface-number
5. encapsulation dot1q vlan-id
6. exit
7. connect connection-name type number type number
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.
Perform this task to configure ATM-to-ATM PVC local switching and same-port switching.
1. enable
2. configure terminal
3. interface atmslot/port
4. pvc vpi/vci l2transport
5. encapsulation layer-type
6. exit
7. exit
8. connect connection-name interface pvc interface pvc
Perform this task to configure ATM-to-ATM PVP local switching.
1. enable
2. configure terminal
3. interface atmslot/port
4. atm pvp vpi l2transport
5. exit
6. exit
7. connect connection-name interface pvp interface pvp
Perform this task to configure ATM PVP switching on an ATM interface.
1. enable
2. configure terminal
3. interface atmslot/subslot/port
4. atm pvp vpi l2transport
5. exit
6. exit
7. connect connection-name interface pvp interface pvp
•Verifying Layer 2 Local Switching Configuration
•Verifying the NSF SSO Local Switching Configuration
To verify configuration of the Layer 2 local switching feature, use the show connection command on the provider edge (PE) router.
1. show connection [all | element | id id | name name | port port]
Step 1 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:
Router# show connection name ethconn1
Connection: 1 - ethconn1
Current State: UP
Segment 1: GigabitEthernet0/0/0.1 up
Segment 2: GigabitEthernet0/0/0.2 up
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.
1. ping
2. redundancy force-switchover
3. show connection all
4. ping
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:
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.
You can troubleshoot Layer 2 local switching using the following commands on the PE router:
•debug conn
•show connection
•Example: Ethernet VLAN Same-Port Switching
•Example: NSF SSO: Ethernet Port Mode to Ethernet VLAN Local Switching
•Example: ATM-to-ATM Local Switching
•Example: ATM PVC Same-Port Switching
•Example: ATM PVP Same-Port Switching
The following example shows same-port switching between two VLANs on one Ethernet interface:
interface fastethernet 0/0.1
encapsulation dot1q 1
interface fastethernet 0/0.2
encapsulation dot1q 2
connect conn FastEthernet 0/0.1 FastEthernet 0/0.2
The following configuration uses the network topology shown in Figure 1.
Figure 1 NSF/SSO: Layer 2 Local Switching: Ethernet to Ethernet VLAN
The following example shows the configuration of the CE interfaces to connect to the PE1 router:
The following example shows the configuration of the PE1 router with NSF/SSO and the PE interfaces to the CE routers:
redundancy
no keepalive-enable
mode sso
!
!
ip routing
ip cef distributed
!
interface fa1/1/1
description - connection to CE1 fa3/1/0
no shutdown
no ip address
!
!
interface fa6/0/0
no shutdown
no ip address
!
interface fa6/0/0.1
description - connection to CE2 fa4/0.1
encapsulation dot1Q 10
no ip address
!
interface fa6/0/0.2
description - connection to CE2 fa4/0.2
encapsulation dot1Q 20
no ip address
The following example shows local switching on ATM interfaces configured for AAL5:
interface atm1/0/0
pvc 0/100 l2transport
encapsulation aal5
interface atm2/0/0
pvc 0/100 l2transport
encapsulation aal5
connect aal5-conn atm1/0/0 0/100 atm2/0/0 0/100
The following example shows same-port switching between two PVCs on one ATM interface:
interface atm1/0/0
pvc 0/100 l2transport
encapsulation aal5
pvc 0/200 l2transport
encapsulation aal5
connect conn atm1/0/0 0/100 atm1/0/0 0/200
The following example shows same-port switching between two PVPs on one ATM interface:
interface atm1/0/0
atm pvp 100 l2transport
atm pvp 200 l2transport
connect conn atm1/0/0 100 atm1/0/0 200
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Cisco IOS commands |
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WAN Commands |
|
Stateful switchover configuration information |
"Stateful Switchover" module in the Cisco IOS XE High Availability Configuration Guide |
|
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None |
To locate and download MIBs for selected platforms, Cisco IOS XE software releases, and feature sets, use Cisco MIB Locator found at the following URL: |
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None |
— |
Table 1 lists the features in this module and provides links to specific configuration information.
Use Cisco Feature Navigator to find information about platform support and software image support. Cisco Feature Navigator enables you to determine which software images support a specific software release, feature set, or platform. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.
Note Table 1 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.
|
|
|
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Layer 2 Local Switching |
Cisco IOS XE Release 2.5 |
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. The following commands were introduced or modified: connect (L2VPN local switching), show connection. |
Layer 2 Local Switching - ATM to ATM |
Cisco IOS XE Release 3.3S |
In Cisco IOS XE Release 3.3S, this feature was introduced on the Cisco ASR 1000 Series Aggregation Services Routers. The following sections provide information about this feature: •Configuring ATM-to-ATM PVC Local Switching and Same-Port Switching •Configuring ATM-to-ATM PVP Local Switching •Configuring ATM PVP Same-Port Switching The following commands were introduced or modified: connect (L2VPN local switching), show connection. |