Cisco 3845 - Security Bundle Router Software Manual page 253

Chapter 11 Configuring Ethernet Virtual Connections (EVCs)
For traffic entering the EFP, a VLAN tag is popped at the EFP with a rewrite and the untagged packet is
bridged over bridge domain 10. At egress on the switchport trunk port, the VLAN tag corresponding to
the bridge domain (VLAN 10) is pushed, and the packet egresses on the switchport with a single tag
(VLAN l0).
Figure 11-7
Outer
VLAN tag
10
At ingress on the switchport, the outer most VLAN tag (VLAN 10) is popped at the switchport and the
packet is bridged over bridge-domain 10 with a single tag (VLAN 20). On egress at the EFP with a
rewrite, a VLAN tag equal to the encapsulation dot1q VLAN ID (10) is pushed, and the double-tagged
packet (tagged with VLAN 10 and VLAN 20) goes out on the EFP.
For packets ingressing at the EFP, the outer most VLAN tag is popped at the EFP and the single-tagged
packet (VLAN 10) is bridged over bridge-domain 10. On egress at the switchport, a VLAN tag equal to
the bridge domain (VLAN 10) is pushed, and the double-tagged packet (VLAN 10 and 20) goes out the
switchport.
Figure 11-8
Untagged
At ingress on the switchport, an untagged packet is bridged over bridge-domain 10. On egress at the EFP
after a rewrite, a VLAN tag equal to the encapsulation dot1qVLAN (10) is pushed, and a single-tagged
packet (VLAN 10) is sent out on the EFP.
For packets ingressing the EFP with a rewrite, a VLAN tag (VLAN 10) is popped at the EFP, and the
untagged packet is bridged over bridge-domain 10. At egress on the switchport, the native VLAN or
access VLAN matches the bridge-domain, and the packet is sent out as untagged.
Figure 11-9
OL-23400-01
Double-tagged Traffic Between a Switchport and an EFP with Rewrite
Bridge domain
20
Switchport trunk
Untagged Traffic Between a Switchport (with Native or Access VLAN) and an EFP
with Rewrite
Switchport trunk
native vlan 10
or
Switchport access
access vlan 10
to Figure 11-12 show traffic between a switchport and an EFP with no rewrite.
Service instance 1 ethernet
encapsulation dot1q10
10
rewrite ingress tag pop 1 symmetric
bridge-domain 10
Service instance 1 ethernet
Bridge domain
encapsulation dot1q10
10
rewrite ingress tag pop 1 symmetric
Cisco ME 3800X and 3600X Switch Software Configuration Guide
Configuring Other Features on EFPs
bridge-domain 10
Outer
VLAN tag
10 20
VLAN tag
10
11-27