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PortChannel Protocol
S e n d d o c u m e n t a t i o n c o m m e n t s t o m d s f e e d b a c k - d o c @ c i s c o . c o m .
About PortChannel Protocols
The PortChannel protocol expands the PortChannel functional model in Cisco MDS switches. It uses the
exchange peer parameters (EPP) services to communicate across peer ports in an ISL. Each switch uses
the information received from the peer ports along with its local configuration and operational values to
decide if it should be part of a PortChannel. The protocol ensures that a set of ports are eligible to be
part of the same PortChannel. They are only eligible to be part of the same port channel if all the ports
have a compatible partner.
The PortChannel protocol uses two sub-protocols:
•
•
Channel Group Creation
Assuming link A1-B1 comes up first in
the next link, say A2-B2 comes up, the PortChannel protocol identifies if this link is compatible with
link A1-B1 and automatically creates channel groups 10 and 20 in the respective switches. If link A3-B3
can join the channel groups (and hence, the PortChannels), the respective ports have compatible
configurations. If link A4-B4 operates as an individual link, it is due to the incompatible configuration
of the two end ports with the other member ports in this channel group.
Figure 13-8
Channel Group 10
Cisco MDS
Switch A
The channel group numbers are selected dynamically, and as such, the administrative configuration of
the ports forming the channel group at either end are applicable to the newly created channel group. The
channel group number being chosen dynamically may be different across reboots for the same set of
PortChannels based on the order of ports that are initialized in the switch.
Table 13-2
Cisco MDS 9000 Family Configuration Guide
13-14
Bringup protocol—automatically detects misconfigurations so you can correct them. This protocol
synchronizes the PortChannel at both ends so that all frames for a given flow (as identified by the
source FCID, destination FCID and OX_ID) are carried over the same physical link in both
directions. This helps make applications like write acceleration work for PortChannels over FCIP
links.
Autocreation protocol—automatically aggregates compatible ports into a PortChannel.
Auto-Creating Channel Groups
Channel Group 20
po10
po20
1
2
3
4
identifies the differences between user-configured and auto-configured channel groups.
Figure
13-8, that link is operational as an individual link.When
1
2
Cisco MDS
Switch B
3
4
Chapter 13
Configuring PortChannels
OL-6973-03, Cisco MDS SAN-OS Release 2.x
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