27-22
Catalyst 4500 Series Switch, Cisco IOS Software Configuration Guide - Cisco IOS XE 3.9.xE and IOS 15.2(5)Ex
Chapter 27 Configuring EtherChannel and Link State Tracking
Displaying EtherChannel to a Virtual Switch System
Figure 27-1 Enhanced PAgP in VSS Normal Operation
Figure 27-2 Enhanced PAgP in VSS Dual-active Scenario
As a remote switch, the Catalyst 4500 series switch supports stateful VSS client. In particular, the ID of
the current active virtual switch is synchronized from the active supervisor engine to the redundant
supervisor engine of the Catalyst 4500 series switch. This ensures that dual-active detection is not
disrupted even when the active supervisor engine switches over to the redundant supervisor engine.
Virtual
Switch A
(active)
Virtual
Switch B
(standby)
Remote switch
(Catalyst 4500 series switch)
Active_ID = A’s MAC
Virtual switch TLV
Active_ID = A’s MAC
Virtual switch TLV
Active_ID = A’s MAC
Remote switch TLV
Active_ID = A’s MAC
Remote switch TLV
Active_ID = A’s MAC
VSL
EtherChannel
204283
Remote switch
(Catalyst 4500 series switch)
Active_ID = B’s MAC
Virtual switch TLV
Active_ID = B’s MAC
Remote switch TLV
Active_ID = B’s MAC
Dual-active detected by A
Remote switch TLV
Active_ID = B’s MAC
VSL
204284
Virtual
Switch A
(active)
Virtual
Switch B
(standby)
EtherChannel