Cisco 3845 Software Guide - Page 252

Configuring Other Features on EFPs Chapter 11 Configuring Ethernet Virtual Connections (EVCs) Switch (config)# interface gigabitethernet0/2 Switch (config-if)# switchport mode trunk Switch (config-if)# switchport allowed vlan none Switch (config-if)# service instance 1 Ethernet Switch (config-if-srv)# encapsulation dot1q 3000 Switch (config-if-srv)# rewrite ingress tag pop 1 symmetric Switch (config-if-srv)# bridge-domain 20 Switch (config-if-srv)# exit Switch (config-if)# service instance 2 Ethernet Switch (config-if-srv)# encapsulation dot1q 3001 Switch (config-if-srv)# rewrite ingress tag pop 1 symmetric Switch (config-if-srv)# bridge-domain 30 EVCs and switchports can exist simultaneously on the same switch. When an EFP joins a bridge domain 1 through 4095, it is part of the same flood domain as VLANs 1 through 4095. If an EFP uses a bridge domain greater than or equal to 4096, it belongs to the EFP-only flood domain. This example shows VLANs and EFPs sharing the same flooding domain. Switch (config)# interface gigabitethernet0/1 Switch (config-if)# switchport mode trunk Switch (config-if)# switchport allowed vlan 1000 Switch (config)# interface gigabitethernet0/2 Switch (config-if)# service instance 1 Ethernet Switch (config-if-srv)# encapsulation dot1q 1000 Switch (config-if-srv)# bridge-domain 1000 When data packets are forwarded between EFPs and switchports, the EFP and switchport configurations are applied to the packet. This removes the ambiguity of the tagging behavior between them. The following illustrations show tagging behavior between an EFP and a switchport. A switchport trunk has an implicit outer VLAN pop at ingress and an implicit outer VLAN push at egress. When rewrite is enabled, a VLAN tag is popped at ingress and a VLAN tag corresponding to the bridge domain that bridged the packet is pushed at egress on the switchport trunk without any explicit configuration. When a VLAN tag is pushed on a packet egressing at the switchport, the VLAN ID corresponds to the bridge-domain ID over which the packet is bridged. Figure 11-6 to Figure 11-8 show traffic between a switchport and an EFP when rewrite symmetric is enabled on the EFP. Figure 11-6 Single-tagged Traffic Between a Switchport and an EFP with Rewrite VLAN tag 10 Switchport trunk Bridge domain 10 Service instance 1 ethernet encapsulation dot1q10 rewrite ingress tag pop 1 symmetric bridge-domain 10 VLAN tag 10 254605 In this example, for traffic entering the switchport trunk port, the VLAN tag is popped on ingress at the switchport trunk port and the untagged packet is bridged over bridge domain 10. On egress, the rewrite operation results in a VLAN tag (encapsulation dot1q 10) to be pushed (added), and the packet egresses on the EFP with a single tag (VLAN l0). 11-26 Cisco ME 3800X and 3600X Switch Software Configuration Guide OL-23400-01