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Cisco ONS 15310-CL and Cisco ONS 15310-MA Ethernet Card Software Feature and Configuration Guide R8.5
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Chapter 8 Configuring IEEE 802.1Q Tunneling and Layer 2 Protocol Tunneling on the ML-Series Card
Understanding Layer 2 Protocol Tunneling
no ip address
no ip route-cache
mode dot1q-tunnel
bridge-group 10
bridge-group 10 spanning-disabled
!
interface POS0.1
encapsulation dot1Q 10
no ip route-cache
bridge-group 10
Understanding 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 w ell as the local sites. Spanning Tree
Protocol (STP) must run properly, and every VLAN should build a proper spanning tree that in cludes the
local site and all remote sites across the service-provider infrastructure. Cisco Discovery Protocol (CDP)
must discover neighboring Cisco devices from local and remote sites. VLAN Trunking Protocol ( VTP)
must provide consistent VLAN configuration throughout all sites in the customer network.
When protocol tunneling is enabled, edge switches on the inbound side of the service-provider
infrastructure encapsulate Layer 2 protocol packets with a special MAC address and send them across
the service-provider network. Core switches in the network do not process these packets, but forward
them as normal packets. CDP, STP, or VTP Layer 2 protocol data units (PDUs) cross the
service-provider infrastructure and are delivered to customer switches on the outbound side of the
service-provider network. Identical packets are received by all customer ports on the same VLANs with
the following results:
• Users on each of a customer’s sites are able to properly run STP and every VLAN can build a correct
spanning tree based on parameters from all sites and not just from the local site.
• CDP discovers and shows information about the other Cisco devices connected through the
service-provider network.
• VTP provides consistent VLAN configuration throughout the customer network, propagating
through the service provider to all switches.
Layer 2 protocol tunneling can be used independently or to enhance IEE E 802.1Q tunneling. If protocol
tunneling is not enabled on IEEE 802.1Q tunneling ports or on speci fic VLANs, remote switches at the
receiving end of the service-provider network do not receive the PDUs and cannot properly run STP,
CDP, and VTP. When protocol tunneling is enabled, Layer 2 protocols within each customer’s network
are totally separate from those running within the service-provider network. Customer switches on
different sites that send traffic through the service-provider network with IEEE 802.1Q tunneling
achieve complete knowledge of the customer’s VLAN. If IEEE 802.1Q tunneling is not used, you can
still enable Layer 2 protocol tunneling by connecting to the customer switch through access ports and
enabling tunneling on the service-provider access port.
Configuring Layer 2 Protocol Tunneling
Layer 2 protocol tunneling (by protocol) is enabled on the tunn el ports or on specific tunnel VLANs that
are connected to the customer by the edge switches of the service-provider network. ML-Series card
tunnel ports are connected to customer IEEE 802.1Q trunk ports. Th e ML-Series card supports Layer 2