Extreme Networks ExtremeWare XOS 11.3, Manual

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Extreme Standby Router Protocol
ExtremeWare XOS 11.3 Concepts Guide
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In extended mode, the active port count considers the number of active ports and the port weight
configuration also considers the bandwidth of those ports. You enable port weight only on the load-
shared master port.
●
Domain ID
In standard mode, ESRP packets do not contain domain information; therefore, the only information
about the packet comes from the receiving port.
The concept of domain ID is applicable only to extended mode. A domain ID in the packet clearly
classifies the packet, associates a received ESRP PDU to a specific ESRP domain, and tells the
receiving port where the packet came from. In extended mode, you must have a domain ID for each
ESRP domain. Each switch participating in ESRP for a particular domain must have the same
domain ID configured.
The ESRP domain ID is determined from one of the following user-configured parameters:
■
ESRP domain number created with the
configure esrp <esrpDomain> domain-id <number>
command
■
802.1Q tag (VLANid) of the tagged master VLAN
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Hello messages
In standard mode, both the master switch and slave switch send periodic ESRP hello messages. This
causes an increase in packet processing by both the master and slave.
In extended mode, the master switch sends periodic ESRP hello messages. This reduces the amount
of packet processing, increases the amount of available link bandwidth, and does not impact
communicating state changes between switches.
In addition to the modes of operation, ESRP has an auto toggle feature. Depending on the mode of
operation configured on the neighbor switch, the mode of operation at this end will toggle to the same
mode of operation as the neighbor. For example, if you use the default mode—extended—and your
ESRP domain contains a switch running ExtremeWare XOS that detects a neighbor switch running
ExtremeWare, the mode automatically changes to standard for that domain. This action causes the
switch to enter the neutral state and re-elect the ESRP master. Since you are using the default mode of
operation, and the switch running ExtremeWare XOS detected a neighbor switch running ExtremeWare,
the ExtremeWare XOS switch toggles to standard mode although the configured mode of operation
remains as extended.
ESRP Domains
ESRP domains allow you to configure multiple VLANs under the control of a single instance of the
ESRP protocol. By grouping multiple VLANs under one ESRP domain, the ESRP protocol can scale to
provide protection to large numbers of VLANs. All VLANs within an ESRP domain simultaneously
share the same active and standby router and failover router, as long as one port of each member VLAN
belongs to the domain master.
Depending on the election policy used, when a port in a member VLAN belongs to the domain master,
the member VLAN ports are considered when determining the ESRP master. You can configure a
maximum of 64 ESRP domains in a network.
If you disable an ESRP domain, the switch notifies its neighbor that the ESRP domain is going down,
and the neighbor clears its neighbor table. If the master switch receives this information, it enters the
neutral state to prevent a network loop. If the slave switch receives this information, it enters the
neutral state.