Cisco WS-X6708-10G-3CXL= - 10 Gigabit Ethernet Module Manual de usuario descargar pdf (Pagina 46)

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Figure 34.

In this case, each virtual switch assumes the role as the active virtual switch and each virtual switch controls only its

local ports. However, there will most likely also be some global Layer 2 and Layer 3 configuration, and the interface

configuration for the multichassis Cisco EtherChannel links will be applied on both chassis . Duplication of this

configuration can possibly have adverse effects to the network topology and traffic.

At Layer 3, any virtual interfaces (for example, port channels, SVIs, loopbacks, and so on) are duplicated on both

chassis, causing duplicate IP addresses on the network. Any secure communications such as SSH and the

cryptography feature set have the same set of keys on both chassis. At Layer 2, the spanning tree has the same

bridge ID in both switches, possibly causing conflict. In general, this condition causes the same effect as when two

routers or switches within a network contain the same configuration file.

To avoid this disruptive scenario, you should configure the VSL as a multiple-link port channel and spread it across all

the available supervisor engines and modules within the chassis. You should also run the individual members of the

VSL across separate physical paths when possible.

In some circumstances this configuration may not be possible; Cisco Virtual Switching System has different

mechanisms to address this dual-active scenario:

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Configuration of the VSL failure-detection feature

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Detection of a dual-active scenario

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Action taken to resolve the situation

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Recovery behavior upon restoring the VSL

Detection Mechanisms and Configuration

Because of the challenges to distinguish a remote chassis power failure and a VSL failure, each chassis attempts to

detect its peer chassis in order to avoid the dual-active scenario. In a dual-active scenario, we must assume that the

VSL links cannot be used in any way to detect the failure. The only remaining options are to use alternative paths that

may or may not exist between the two chassis.

Currently, there are currently three mechanisms for detecting a dual-active scenario.

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Enhanced PAgP

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Layer 3 BFD

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Cisco WS-X6708-10G-3CXL= - 10 Gigabit Ethernet Module Manual de usuario Pagina 46