CHAPTER
Send documentation comments to mdsfeedback-doc@cisco.com
10-1
Cisco MDS 9000 Family Troubleshooting Guide, Release 3.x
OL-9285-05
10
Troubleshooting PortChannels and Trunking
PortChannels refer to the aggregation of multiple physical interfaces into one logical interface to provide
higher aggregated bandwidth, load balancing, and link redundancy.
This chapter includes the following topics:
• PortChannel Overview, page 10-1
• Initial Troubleshooting Checklist, page 10-2
• PortChannel Issues, page 10-3
• Trunking Issues, page 10-4
PortChannel Overview
A PortChannel has the following functionality:
• Provides a point-to-point connection over ISL (E ports) or EISL (TE ports). Multiple links can be
combined into a PortChannel.
• Increases the aggregate bandwidth on an ISL by distributing traffic among all functional links in the
channel.
• Load balances across multiple links and maintains optimum bandwidth utilization. Load balancing
is based on the source ID, destination ID, and exchange ID (OX ID).
• Provides high availability on an ISL. If one link fails, traffic previously carried on this link is switched
to the remaining links. If a link goes down in a PortChannel, the upper protocol is not aware of it. To
the upper protocol, the link is still there, although the bandwidth is diminished. The routing tables
are not affected by link failure. PortChannels may contain up to 16 physical links and may span
multiple modules for added high availability.
On switches with Generation 1 switching modules, or a combination of Generation 1 and Generation 2
switching modules, you can configure a maximum of 128 PortChannels. On switches with Generation 2
switching modules only, you can configure a maximum of 265 PortChannels.
A PortChannel number refers to the unique (to each switch) identifier associated with each channel
group. This number ranges from of 1 to 256.
To Next Page
Loading...
Need help?
General