Cisco Nexus 5000 Series Switch CLI Software Configuration Guide, NX-OS 4.0(1a)N1 (OL-16597-01, January 2009)

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36-12
Cisco Nexus 5000 Series Switch CLI Software Configuration Guide
OL-16597-01
Chapter 36 Configuring SAN Port Channels
Port Channel Protocol
• Autocreation Guidelines, page 36-13
• Enabling and Configuring Autocreation, page 36-14
• About Manually Configured Channel Groups, page 36-14
• Converting to Manually Configured Channel Groups, page 36-14
About Channel Group Creation
If channel group autocreation is enabled, ISLs can be configured automatically into channel groups
without manual intervention. Figure 36-7 shows an example of channel group autocreation.
The first ISL comes up as an individual link. In the example shown in Figure 36-7, this is link A1-B1.
When the next link comes up (A2-B2 in the example), the port channel protocol determines if this link
is compatible with link A1-B1 and automatically creates channel groups 10 and 20 in the respective
switches. Link A3-B3 can join the channel groups (and the port channels) if the respective ports have
compatible configurations. Link A4-B4 operates as an individual link, because it is not compatible with
the existing member ports in the channel group.
Figure 36-7 Autocreating Channel Groups
The channel group numbers are assigned dynamically (when the channel group is formed).
The channel group number may change across reboots for the same set of port channels depending on
the initialization order of the ports.
Table 36-2 identifies the differences between user-configured and auto-configured channel groups.
1
po10 po20
2
3
4
1
2
3
4
Switch A Switch B
Channel Group 10 Channel Group 20
187288
Table 36-2 Channel Group Configuration Differences
User-Configured Channel Group Autocreated Channel Group
Manually configured by the user. Created automatically when compatible links come
up between two compatible switches, if channel
group autocreation is enabled in all ports at both
ends.
Member ports cannot participate in autocreation
of channel groups. The autocreation feature
cannot be configured.
None of these ports are members of a
user-configured channel group.