Cisco ASR 920 series Configuration Guide Ethernet Router

the encapsulations don’t match (filtering criteria). However, you can use the rewrite command to allow
communication between these two.
Router (config)# interface gigabitethernet0/1
Router (config-if)# service instance 1 Ethernet
Router (config-if-srv)# encapsulation dot1q 10
Router (config-if-srv)# bridge-domain 3000
Router (config)# interface gigabitethernet0/2
Router (config-if)# service instance 1 Ethernet
Router (config-if-srv)# encapsulation dot1q 99
Router (config-if-srv)# bridge-domain 3000
Example for Rewrite
In this example, a packet that matches the encapsulation will have one tag removed (popped off). The symmetric
keyword allows the reverse direction to have the inverse action: a packet that egresses out this service instance
will have the encapsulation (VLAN 10) added (pushed on).
Router (config)# interface gigabitethernet0/1
Router (config-if)# service instance 1 Ethernet
Router (config-if-srv)# encapsulation dot1q 10
Router (config-if-srv)# rewrite ingress tag pop 1 symmetric
Router (config-if-srv)# bridge-domain 3000
Example for Split Horizon
In this example, service instances 1 and 2 cannot forward and receive packets from each other. Service instance
3 can forward traffic to any service instance in bridge domain 3000 since no other service instance in bridge
domain 3000 is in split-horizon group 2. Service instance 4 can forward traffic to any service instance in
bridge domain 3000 since it has not joined any split-horizon groups.
Router (config)# interface gigabitethernet0/1
Router (config-if)# service instance 1 Ethernet
Router (config-if-srv)# encapsulation dot1q 10
Router (config-if-srv)# rewrite ingress pop 1 symmetric
Router (config-if-srv)# bridge-domain 3000 split-horizon group 1
Router (config-if-srv)# exit
Router (config-if)# service instance 2 Ethernet
Router (config-if-srv)# encapsulation dot1q 99
Router (config-if-srv)# rewrite ingress pop 1 symmetric
Router (config-if-srv)# bridge-domain 3000 split-horizon group 1
Router (config)# interface gigabitethernet0/2
Router (config-if)# service instance 3 Ethernet
Router (config-if-srv)# encapsulation dot1q 10
Router (config-if-srv)# rewrite ingress pop 1 symmetric
Router (config-if-srv)# bridge-domain 3000 split-horizon group 2
Router (config-if-srv)# exit
Router (config-if)# service instance 4 Ethernet
Router (config-if-srv)# encapsulation dot1q 99
Router (config-if-srv)# rewrite ingress pop 1 symmetric
Router (config-if-srv)# bridge-domain 3000
Example for Hairpinning
The switch supports hairpinning, which refers to traffic ingressing and egressing same interface. To achieve
haripinning, configure two EFPs in the same bridge domain on the same physical interface, as in this example.
Router (config)# interface gigabitethernet0/2
Carrier Ethernet Configuration Guide (Cisco ASR 920 Series)
27
Ethernet Virtual Connections Configuration
Configuration Examples

Cisco ASR 920 series Specifications

General

Brand	Cisco
Model	ASR 920 series
Category	Network Router
Language	English