Specifications

230 ExtremeWare XOS 11.0 Concepts Guide
Extreme Standby Router Protocol
ESRP Concepts
You configure ESRP on a per domain basis on each switch. A maximum of two switches can participate
in providing redundant Layer 3 or Layer 2 services to a single VLAN. If you configure and use ESRP
groups, more than two switches can provide redundant Layer 2 or Layer 3 services to a single VLAN.
The switches exchange keep-alive packets for each VLAN independently. Only one switch (the master)
can actively provide Layer 3 routing and/or Layer 2 switching for each VLAN. This switch handles the
forwarding, ARP requests, and routing for this particular VLAN. Other participating switches for the
VLAN are in slave mode waiting for an ESRP state change.
For a VLAN within an ESRP domain, each participating switch uses the same MAC address and must
be configured with the same IP address or IPX NetID. It is possible for one switch to be a master switch
for one or more VLANs while being a slave switch for other VLANs, thus allowing the load to be split
across participating switches.
Figure 34 displays a basic ESRP topology.
Figure 34: Example of a basic ESRP topology
NOTE
If you configure the Open Shortest Path First (OSPF) routing protocol and ESRP, you must manually
configure an OSPF router identifier (ID). Be sure that you configure a unique OSPF router ID on each
switch running ESRP. For more information on configuring OSPF, see Chapter 16.
EX_099
Domain
corpnet1
corpnet2
corpnet3
ESRP Core Switch #1
State
Master
Master
Slave
Group
0
0
0
Domain
corpnet1
corpnet2
corpnet3
ESRP Core Switch #2
State
Slave
Slave
Master
Group
0
0
0
ESRP-aware ESRP-aware ESRP-aware
Corpnet1, Corpnet2
advertised ESRP
virtual mac:
00:E0:2B:00:00:80
Corpnet3
advertised virtual mac:
00:E0:2B:00:00:80