Cisco Cisco 1700 2600 3600 3700 Series VPN Module Weißbuch
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Upon detecting that the interface connected to the standby virtual switch has failed, traffic resorts to using the link
to the active supervisor engine. Those data flows passing through the active virtual switch are not affected. The
control plane is not affected because the control-plane functions remain on the active supervisor engine on the
active virtual switch. The control plane experiences a removal of all of the standby virtual switch interfaces.
If the standby Virtual Switch contains an in-chassis standby supervisor, or, in the case of a single supervisor
configuration, the hot-standby supervisor engine can reinitialize, it will reload. Upon bootup, the chassis proceeds
with VSL initialization, and enters into standby chassis role with all its interfaces becoming operational again.
VSL Single-Link Failure
The failure of a single VSL link is discovered by the active supervisor engine, either through a link-down event or
through the failure of periodic VSLP messages sent across the link to check the VSL link state (Figure 22).
Figure 22. VSL Link Failure
The index values, Result Bundle Hash, and fabric programming for selecting the VSL link will need to be
automatically updated to reflect the removal of a link from the VSL. The active supervisor engine sends all of these
messages.
Availability is not affected for those data flows that do not use the VSL. For those traffic flows that use the VSL,
traffic outage is estimated to be approximately 50 to 100 ms. Notice that the duration of time is slightly faster than
that for other multichassis Cisco EtherChannel links, since VSL always takes advantage of the adaptive Cisco
EtherChannel load-balancing algorithm.
Single Link Failure Within a Multichassis Cisco EtherChannel Link
The failure of a single link within the multichassis Cisco EtherChannel link that is not the last link connecting to a
chassis is recognized by either the multichassis Cisco EtherChannel link control protocol (PAgP or LACP) or the
link-down event (Figure 23).