Specifications

ExtremeWare XOS 11.0 Concepts Guide 227
13 Extreme Standby Router Protocol
This chapter covers the following topics:
• Overview of ESRP on page 227
• ESRP Concepts on page 230
• Determining the ESRP Master on page 234
• Advanced ESRP Features on page 238
• Displaying ESRP Information on page 244
• ESRP Examples on page 244
• ESRP Cautions on page 248
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.
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.
ExtremeWare XOS has two modes of ESRP operation: standard and extended. Select standard ESRP if
your network contains some switches running ExtremeWare, others running ExtremeWare XOS, and a
combination of those switches participating in ESRP. Standard ESRP is backward compatible with and
supports the ESRP functionality of ExtremeWare.
Select extended ESRP if your network contains switches running only ExtremeWare XOS. Extended
mode ESRP supports and is compatible with switches running ExtremeWare XOS. By default,
ExtremeWare XOS operates in extended mode.