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Provider Backbone Bridging
IEEE 802.1ad—Provider Bridges amends 802.1Q—Virtual Bridged Local Area Networks so that service providers can use 802.1Q
architecture to offer separate VLANs to customers with no coordination between customers, and minimal coordination between
customers and the provider.
802.1ad specifies that provider bridges operating spanning tree use a reserved destination MAC address called the Provider
Bridge Group Address, 01-80-C2-00-00-08, to exchange BPDUs instead of the Bridge Group Address, 01-80-C2-00-00-00,
originally specified in 802.1Q. Only bridges in the service provider network use this destination MAC address so these bridges
treat BPDUs originating from the customer network as normal data frames, rather than consuming them.
The same is true for GARP VLAN registration protocol (GVRP). 802.1ad specifies that provider bridges participating in GVRP
use a reserved destination MAC address called the Provider Bridge GVRP Address, 01-80-C2-00-00-0D, to exchange GARP
PDUs instead of the GVRP Address, 01-80-C2-00-00-21, specified in 802.1Q. Only bridges in the service provider network use
this destination MAC address so these bridges treat GARP PDUs originating from the customer network as normal data frames,
rather than consuming them.
Provider backbone bridging through IEEE 802.1ad eliminates the need for tunneling BPDUs with L2PT and increases the
reliability of provider bridge networks as the network core need only learn the MAC addresses of core switches, as opposed to
all MAC addresses received from attached customer devices.
● Use the Provider Bridge Group address as the destination MAC address in BPDUs. The xstp keyword applies this
functionality to STP, RSTP, and MSTP; this functionality is not available for PVST+.
CONFIGURATION Mode
bpdu-destination-mac-address [xstp | gvrp] provider-bridge-group
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Service Provider Bridging