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Cisco ME 3800X and 3600X Switch Software Configuration Guide
OL-23400-01
Chapter 11 Configuring Ethernet Virtual Connections (EVCs)
Configuring Other Features on EFPs
Figure 11-9
Single-tagged Traffic Between a Switchport and an EFP with no Rewrite
On ingress at the switchport, a VLAN tag is popped at the switchport trunk, and an untagged packet is
bridged over bridge-domain 10. On egress at the EFP with no rewrite, there is an encapsulation mismatch
because the bridged packet is untagged, and the encapsulation is 802.1q VLAN 10. Therefore, the packet
is dropped.
Figure 11-10
Single-tagged and Double-tagged Traffic Between a Switchport and an EFP with no
Rewrite
On ingress at the switchport, the outer most VLAN tag (VLAN 10) is popped at the switchport trunk and
singled-tagged packet (VLAN 20) is bridged over bridge-domain 10. On egress at the EFP with no
rewrite, the bridged packet tag (VLAN 20) matches the encapsulation, and a single-tagged packet
(VLAN 20) is sent out on the EFP.
On ingress at the EFP with no rewrite, a single- tagged packet (VLAN 20) is bridged over bridge-domain
10. On egress at the switchport, a VLAN tag corresponding to the bridge-domain (VLAN 10) is pushed,
and a double-tagged packet (VLAN 10 and VLAN 20) is sent out on the switchport.
Figure 11-11
Untagged Traffic From a Switchport (with Native or Access VLAN) to an EFP with No
Rewrite
After ingress at the switchport, the untagged packet is bridged over bridge-domain 10. On egress at the
EFP with no rewrite, there is an encapsulation mismatch because the bridged packet is untagged and the
encapsulation is dot1q 10. Therefore, the packet is dropped.
The same scenario applies when the switchport trunk is configured with the access VLAN ID or native
VLAN ID.
Switchport trunk
VLAN tag
Service instance 1 ethernet
encapsulation dot1q10
bridge-domain 10
10
10
Bridge domain
254608
Packet is dropped
due to encapsulation
mismatch
Outer
VLAN tag
10
20
254609
20
Service instance 1 ethernet
encapsulation dot1q10
bridge-domain 10
Bridge domain
10
Switchport trunk
Untagged
10
Bridge domain
254610
Switchport trunk
native vlan 10
or
Switchport access
access vlan 10
Packet is dropped
due to encapsulation
mismatch
Service instance 1 ethernet
encapsulation dot1q10
bridge-domain 10