Extreme Networks ExtremeWare XOS 11.1, Manual

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Extreme Standby Router Protocol
ExtremeWare XOS 11.1 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.
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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.
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.
ESRP Domain IDs
ESRP packets do not identify themselves to which domain they belong; you either configure a domain
ID or the ESRP domain uses the 802.1Q tag (VLANid) of the master VLAN. 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.