Extreme Networks ExtremeWare 7.2e, Installation And User Manual

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ExtremeWare 7.2e Installation and User Guide 181
10
Ethernet Automatic Protection Switching
This chapter describes the use of the Ethernet Automatic Protection Switching (EAPS
™
) protocol, and
includes information on the following topics:
• Overview of the EAPS Protocol on page 181
• Fault Detection and Recovery on page 184
•
Configuring EAPS on a Switch on page 186
Overview of the EAPS Protocol
The EAPS protocol provides fast protection switching to layer 2 switches interconnected in an Ethernet
ring topology, such as a Metropolitan Area Network (MAN) or large campuses (see Figure 28).
EAPS protection switching is similar to what can be achieved with the Spanning Tree Protocol (STP),
but offers the advantage of converging in less than a second when a link in the ring breaks.
An Ethernet ring built using EAPS can have resilience comparable to that provided by SONET rings, at
a lower cost and with fewer restraints (e.g., ring size). The EAPS technology developed by Extreme
Networks to increase the availability and robustness of Ethernet rings is described in RFC 3619: Extreme
Networks’ Ethernet Automatic Protection Switching (EAPS) Version 1.
In order to use EAPS, you must enable EDP on the switch and EAPS ring ports. For more information
on EDP, see “Extreme Discovery Protocol” on page 89.
EAPS operates by declaring an EAPS domain on a single ring. Any VLAN that warrants fault protection
is configured on all ring ports in the ring, and is then assigned to an EAPS domain. On that ring
domain, one switch, or node, is designated the master node (see Figure 29), while all other nodes are
designated as transit nodes.