Specifications

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Cisco IGX 8400 Series Provisioning Guide, Release 9.3.3 and Later Releases
OL-1166-04
Chapter 3 Cisco IGX 8400 Series Nodes
IGX Network Management
For an example of how this feature works, refer to Figure 3-5. If a trunk is established between switches
A and B with a bandwidth of 1000 load units, it can support connection 1 (Conn. 1) with a bandwidth of
800. However, if we add a second connection (Conn. 2) with a bandwidth of 500, the trunk can no longer
support both connections.
connection 1 (800) + connection 2 (500) = total bandwidth of 1300
When priority bumping is enabled the least important connection is bumped.
connection 1 has CoS of 5
connection 2 has a CoS of 0
The lower CoS connection has the higher priority. Connection 1 with a CoS of 5 is failed in order for
connection 2 traffic (with a CoS of 0) to flow without interruption.
Figure 3-5 Priority Bumping Between Two Nodes
An example with three nodes is illustrated in Figure 3-6. Three trunks are established:
Two connections are established:
A B
Trunk bandwidth = 1000
Conn. 1 = COS 5 (band 2), bandwidth = 800
A B
Trunk bandwidth = 1000
Conn. 2 = COS 0 (band 0), bandwidth = 500
Conn. 1 Fails, Conn. 2 has higher priority
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Table 3-4 Trunks Illustrated in Figure 3-6
Trunk Bandwidth
AB 1000
AC 500
BC 600
Table 3-5 Connections Illustrated in Figure 3-6
Connection Nodes CoS Band Bandwidth
1 AB 10 5 400
2 BC 14 7 300