OS6860(E)_AOS_8.1.1.R01_Switch_Management_Guide
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Virtual Chassis Split Protection (VCSP)<br />
Configuring Virtual Chassis<br />
Virtual Chassis Split Protection (VCSP)<br />
In the case of a VC split due to a VFL link failure or the failure of one of the VC elements, both of the<br />
resulting VCs could end up having the same system MAC and IP addresses. Since there is no communication<br />
between these individual VCs due to the VFL link failure they end up communicating with the rest of<br />
the network devices using the same MAC and IP addresses. This split scenario is disruptive to the network<br />
as the conflicting MAC and IP addresses can lead to layer 2 loops and L3 traffic disruption.<br />
VCSP provides the following benefits:<br />
• Avoid network disruptions by preventing duplicate MAC and IP addresses on the network when MAC<br />
retention is enabled and a VC split occurs.<br />
• The sub-VC that forms out of the split is able to detect that a split has occurred.<br />
• Once the VC split condition has been determined, the sub-VC will put its front-panel ports into an<br />
operationally down state preventing traffic forwarding and avoiding loops and possible traffic disruption.<br />
The VCSP link aggregate ports will remain up.<br />
• A trap can be sent by the active-VC indicating the split state. The trap indicates that the split has<br />
occurred and which elements are in the operationally down sub-VC.<br />
• A mechanism is available to recover the non-operational sub-VC.<br />
• A method of detecting a VC split in a remote VC topology where the VC may consist of elements<br />
located in different physical locations such as a remote site, or multiple floors of a building.<br />
VCSP Key Components and Terms<br />
• VCSP PDU - A proprietary packet forwarded between VC elements to help determine that state of the<br />
VC.<br />
• VCSP Helper - A neighboring Omni<strong>Switch</strong>, not an element of the VC, responsible for forwarding<br />
VCSP PDUs between the VC elements. The VCSP feature and the VCSP Helper functionality cannot<br />
be enabled on the same switch. The VCSP helper and the VC cannot have the same Group ID.<br />
• VCSP Link Aggregate - A dedicated link aggregate configured between all elements of a VC and a<br />
helper switch to be used for forwarding VCSP PDUs.<br />
• Active-VC - An element, or multiple elements, that results when a VC split occurs. The active-VC will<br />
keep its front panel ports enabled and continue to forward traffic on the network.<br />
• Sub-VC - An element, or multiple elements, that results when a VC split occurs. The sub-VC will<br />
disable its front panel ports to prevent traffic disruption caused by duplicate MAC/IP addresses with<br />
the active VC.<br />
• Protection State - A state an element will transition to after determining a VC split has occurred. Its<br />
ports will be operationally disabled to prevent duplicate MAC and IP addresses and network disruption.<br />
• Guard Timer - A configurable timer determining how long a unit will wait before beginning to send<br />
VCSP PDUs after a VC recovery.<br />
page 13-12 Omni<strong>Switch</strong> <strong>AOS</strong> Release 8 <strong>Switch</strong> <strong>Management</strong> <strong>Guide</strong> May 2014