Cisco 6500 - Manual (Page 14)

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Cisco IOS Software Configuration Guide, Release 12.2SX
OL-13013-06
Chapter 4 Configuring Virtual Switching Systems
Understanding Virtual Switching Systems
User Actions
From the VSS active chassis command console, you can initiate a VSS switchover or a reload.
If you enter the reload command from the command console, the entire VSS performs a reload.
To reload only the VSS standby chassis, use redundancy reload peer command.
To force a switchover from the VSS active to the VSS standby supervisor engine, use the redundancy
force-switchover command.
To reset the VSS standby supervisor engine or to reset both the VSS active and VSS standby supervisor
engines, use the redundancy reload shelf command.
Multichassis EtherChannels
These sections describe multichassis EtherChannels (MECs):
• Overview, page 4-14
• MEC Failure Scenarios, page 4-15
Overview
A multichassis EtherChannel is an EtherChannel with ports that terminate on both chassis of the VSS
(see
Figure 4-8 ). A VSS MEC can connect to any network element that supports EtherChannel (such as
a host, server, router, or switch).
At the VSS, an MEC is an EtherChannel with additional capability: the VSS balances the load across
ports in each chassis independently. For example, if traffic enters the VSS active chassis, the VSS will
select an MEC link from the VSS active chassis. This MEC capability ensures that data traffic does not
unnecessarily traverse the VSL.
Each MEC can optionally be configured to support either PAgP or LACP. These protocols run only on
the VSS active chassis. PAgP or LACP control packets destined for an MEC link on the VSS standby
chassis are sent across VSL.
An MEC can support up to eight VSS active physical links, which can be distributed in any proportion
between the VSS active and VSS standby chassis.