Cisco Cisco 1700 2600 3600 3700 Series VPN Module Weißbuch
© 2012 Cisco and/or its affiliates. All rights reserved. This document is Cisco Public Information.
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Virtual Switch Link Initialization
The system must bring the VSL online before activating the Cisco Virtual Switching System. The initialization
sequence consists of the following steps:
Figure 5. VSL Initialization
●
VSL initialization
The supervisor CPU determines which ports local to its chassis form members of the VSL, the configuration
file is preparsed to extract the appropriate VSL commands and their associated interfaces. This way, the
modules containing these interfaces can be powered up, and VSL interfaces brought online.
The Link Management Protocol (LMP) operates on each link of the VSL and is part of the Virtual Switch
Link Protocol (VSLP). The LMP performs the following functions:
◦
Verifies link integrity by establishing bidirection traffic forwarding, and rejects any unidirectional links
◦
Exchanges switch IDs between the two chassis
◦
Exchanges other information required to establish communication between the two chassis
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VSS role resolution
The redundancy role of each supervisor engine is resolved by VSLP. The Role Resolution Protocol (RRP),
performs the following functions:
◦
Determines whether the hardware and software versions allow a Cisco Virtual Switching System to be
formed
◦
Determines which chassis will become the active virtual switch and which will become the standby virtual
switch chassis from a control-plane perspective.
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High-availability role determination
After the role resolution, the active and standby image versions and configurations are checked for compatibility.
This helps ensure that the hardware and software versions are the same on both chassis supervisor engines. The
configuration check makes sure that the VSL-related configurations on the two switches are compatible. If either of
the two checks fails, then the standby chassis comes up in route-processor redundancy (RPR) mode, where all
modules are powered down, as opposed to Nonstop Forwarding/Stateful Switchover (NSF/SSO) mode, where the
standby chassis is fully initialized and can forward traffic.