Information About Layer 2 Protocol Tunneling - Cisco 7604-RSP720C-R Configuration Manual

Information About Layer 2 Protocol Tunneling

S e n d d o c u m e n t c o m m e n t s t o n e x u s 7 k - d o c f e e d b a c k @ c i s c o . c o m
that are received from the tunnel port. The packet carries only the VLAN 30 tag through the
service-provider network to the trunk port of the egress-edge switch (Switch C) and is misdirected
through the egress switch tunnel port to Customer Y.
Figure 9-3
Switch A
Customer X
These are a couple ways to solve the native VLAN problem:
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Information About Layer 2 Protocol Tunneling
Customers at different sites connected across a service-provider network need to run various Layer 2
protocols to scale their topology to include all remote sites, as well as the local sites. The spanning Tree
Protocol (STP) must run properly, and every VLAN should build a proper spanning tree that includes the
Cisco Nexus 7000 Series NX-OS Interfaces Configuration Guide, Release 5.x
9-4
Native VLAN Hazard
Switch B
Packet tagged
for VLAN 30
Tunnel port
Access VLAN 40
802.1Q
trunk port
VLANs 30-40
Native VLAN 40
Configure the edge switch so that all packets going out an 802.1Q trunk, including the native VLAN,
are tagged by using the vlan dot1q tag native command. If the switch is configured to tag native
VLAN packets on all 802.1Q trunks, the switch accepts untagged packets but sends only tagged
packets.
The vlan dot1q tag native command is a global command that affects the tagging behavior
Note
on all trunk ports.
Ensure that the native VLAN ID on the edge switch trunk port is not within the customer VLAN
range. For example, if the trunk port carries traffic of VLANs 100 to 200, assign the native VLAN
a number outside that range.
Tag not added
for VLAN 40
Service
provider
VLANs 5-50
Native
Q
VLAN 40
Trunk
Asymmetric link
Correct path for traffic
Incorrect path for traffic due to
misconfiguration of native VLAN
by sending port on Switch B
Q = 802.1Q trunk ports
Chapter 9 Configuring Q-in-Q VLAN Tunnels
Switch D
Customer X
Tag
VLANs 30-40
removed
Native VLAN 40
Tunnel port
Switch C
VLAN 40
Q
Tunnel port
Access VLAN 30
Switch E
Customer Y
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