Bridge Spoofing; Bpdu Spoofing - Intel ER8100STUS - Express 8100 Router Reference Manual

Bridge Spoofing
BPDU Spoofing
Configuration BPDU
packets over WAN links
Bridge Spoofing
114
Configuration BPDU packets used by the Spanning tree Algorithm take up valu-
able bandwidth on any type of WAN link. An example of this occurs when com-
municating over dial-up (switched) WAN links. Configuration BPDU packets
are sent from Designated Ports to Root Ports at intervals defined by the Hello
Time in the Root Bridge (2 seconds as the default). These configuration BPDU
packets can prevent dial-up (switched) WAN links from becoming timecut (in-
active)—the operating costs are then excessive.
Designated Port
Root Port
Bridge
Hello
Packets
When the bridging topology is stable (when no bridges are being added or re-
moved from the bridged network), the contents of Configuration BPDU packets
sent between the bridges is the same. The contents of these packets only changes
when the bridged network topology changes.
To counteract the problem of Configuration BPDU packets taking up excessive
WAN link bandwidth the Intel Express 8100 Router implements Bridge Spoof-
ing. When Bridge Spoofing is set up at the bridges at either side of a WAN link,
the WAN link is not used to send Configuration BPDU packets from a Designat-
ed Port to a non-designated port unless the contents of the Configuration BPDU
packet changes.
Designated Port
Root Port
Bridge
Hello
Packets
WAN with a
Root Port
dial-up (switched)
connection
Bridge
Designated Port
Bridge
WAN with a
Root Port
dial-up (switched)
connection in timecut mode
Bridge
Designated Port
Bridge
WAN Bridging Services

Bridge Spoofing

Bridge
Bridge
1061
Hello Packets
Bridge
Bridge
1059