Белая книга для Cisco Cisco 1700 2600 3600 3700 Series VPN Module
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Figure 23. Link Fail Convergence
This link failure causes the RBH values to be redistributed among the remaining multichassis Cisco EtherChannel
link ports in the local chassis, which is the same as a link failure in a standard Cisco EtherChannel link using a
standalone Cisco Catalyst 6500. The endpoint (host, switch, router, etc.) on the other end of the multichassis Cisco
EtherChannel link detects the link failure, and adjusts its load-balancing algorithms to avoid the failed link.
Availability is not affected for those data flows that do not use the failed link. For those traffic flows that use the
failed link, the effect consists of the time it takes to detect the link failure and reprogram the indices within the
system, estimated to be approximately 50 to 200 ms. You can achieve faster convergence time by using the
adaptive Cisco EtherChannel load-balancing algorithm.
All Links to a Single Chassis Within the Multichassis Cisco EtherChannel Link Fail
When all of the links connecting to a single chassis that is part of the same multichassis Cisco EtherChannel link
fail, the port bundle is converted from a multichassis Cisco EtherChannel link to a standard Cisco EtherChannel
link, and is treated as a single-homed port. The links connecting to the peer chassis remain functional. From this
point onward, all traffic from the failed link chassis destined for the Cisco EtherChannel link are sent to the remote
chassis through the VSL (Figure 24).
Figure 24. Multi-link Failure Scenario