Cisco Cisco Aironet 340 Ethernet Bridges ユーザーガイド
Using the Spanning-Tree Protocol 8 - 3
Understanding Loops
If there is more than one path from one LAN to another, the infrastruc-
ture contains a loop.
ture contains a loop.
If Node A transmits a multicast packet, both Bridge 1 and Bridge 2 will
try and forward the packet to LAN 2. Each bridge, on seeing the other’s
transmission on LAN 2, will forward the packet back to LAN 1. The
cycle will continue and the packet will loop forever taking up all of the
bandwidth of the bridges.
try and forward the packet to LAN 2. Each bridge, on seeing the other’s
transmission on LAN 2, will forward the packet back to LAN 1. The
cycle will continue and the packet will loop forever taking up all of the
bandwidth of the bridges.
Topologies containing loops may be more complicated. For example, if
Bridge 2 was replaced by two bridges with a LAN between them, the
effect would still be the same.
Bridge 2 was replaced by two bridges with a LAN between them, the
effect would still be the same.
Figure 8.1 - Example Loop on a Bridge Infrastructure
Node A
LAN 1
LAN 2
Bridge 1
Bridge 2