Example For Egress Filtering; Configuring Examples For Asymmetric Efps - Cisco ASR 920 Series Configuration Manual Ethernet Router

Configuration Examples
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 4000
Router (config-if-srv)# exit
Router (config-if)# service instance 2 Ethernet
Router (config-if-srv)# encapsulation dot1q 20
Router (config-if-srv)# rewrite ingress tag pop 1 symmetric
Router (config-if-srv)# bridge-domain 4000

Example for Egress Filtering

In EVC switching, egress filtering is performed before the frame is sent on the egress EFP. Egress filtering
ensures that when a frame is sent, it conforms to the matching criteria of the service instance applied on the
ingress direction. EFP does not require egress filtering if the number of pops is the same as the number of
VLANs specified in the encapsulation command.
Specifying the cos keyword in the encapsulation command is relevant only in the ingress direction. For
Note
egress filtering, cos is ignored.
For example, consider the following configuration.
Router (config)# interface gigabitethernet0/1
Router (config-if)# service instance 1 Ethernet
Router (config-if-srv)# encapsulation dot1q 20
Router (config-if-srv)# bridge-domain 19
Router (config)# interface gigabitethernet0/2
Router (config-if)# service instance 2 Ethernet
Router (config-if-srv)# encapsulation dot1q 30
Router (config-if-srv)# bridge-domain 19
Router (config)# interface gigabitethernet0/3
Router (config-if)# service instance 3 Ethernet
Router (config-if-srv)# encapsulation dot1q 10 second-dot1q 20
Router (config-if-srv)# rewrite ingress pop 1 symmetric
Router (config-if-srv)# bridge-domain 19
If a packet with VLAN tag 10 or 20 is received on Gigabit Ethernet 0/0/3, the ingress logical port would be
service instance 3. For the frame to be forwarded on a service instance, the egress frame must match the
encapsulation defined on that service instance after the rewrite is done. Service instance 1 checks for outermost
VLAN 20; service instance 2 checks for VLAN 30. In this example, the frame with VLAN tags 10 and 20
can be sent to service instance 1 but not to service instance 2.

Configuring Examples for Asymmetric EFPs

Configuring Asymmetric EFP with POP
enable
configure terminal
interface TenGigabitEthernet0/0/26
no ip address
service instance 1 ethernet
encapsulation untagged
rewrite egress tag pop 1
bridge-domain 30
end
Carrier Ethernet Configuration Guide (Cisco ASR 920 Series)
28
Ethernet Virtual Connections Configuration