Chapter 21: Extreme Standby Router Protocol; Overview Of Esrp - Extreme Networks ExtremeWare XOS Guide Manual

21 Extreme Standby Router Protocol
This chapter covers the following topics:
Overview of ESRP on page 455
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ESRP Concepts on page 456
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Determining the ESRP Master on page 462
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Configuring an ESRP Domain on a Switch on page 466
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Advanced ESRP Features on page 469
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Displaying ESRP Information on page 476
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Using ELRP with ESRP on page 476
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ESRP Examples on page 479
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ESRP Cautions on page 484
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Overview of ESRP

The Extreme Standby Router Protocol (ESRP) is a feature of ExtremeWare XOS that allows multiple
switches to provide redundant routing services to users. From the workstation's perspective, there is
only one default router (that has one IP address and one MAC address), so address resolution protocol
(ARP) cache entries in client workstations do not need to be refreshed or aged out. ESRP is available
only on Extreme Networks switches.
In addition to providing Layer 3 routing redundancy for IP and IPX, ESRP also provides Layer 2
redundancy. You can use these "layered" redundancy features in combination or independently.
You do not have to configure the switch for routing to make valuable use of ESRP. The Layer 2
redundancy features of ESRP offer fast failure recovery and provide for dual-homed system design. In
some instances, depending on network system design, ESRP can provide better resiliency than using
Spanning Tree Protocol (STP) or Virtual Router Redundancy Protocol (VRRP).
Extreme Networks recommends that all switches participating in ESRP run the same version of
ExtremeWare XOS.
This section provides an overview of the following topics:
"ESRP Modes of Operation" on page 456
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"ESRP and ELRP" on page 456
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"Reasons to Use ESRP" on page 456
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ExtremeWare XOS 11.3 Concepts Guide
455