User guide

10-6 E
XTREME
W
ARE
S
OFTWARE
U
SER
G
UIDE
E
XTREME
S
TANDBY
R
OUTER
P
ROTOCOL
S
TANDBY
S
WITCH
B
EHAVIOR
If a switch is in standby mode, it exchanges ESRP packets with other switches on that
same VLAN. When a switch is in standby, it does not perform layer 3 routing or layer 2
switching services for the VLAN. From a layer 3 routing protocol perspective (for
example, RIP or OSPF), when in standby for the VLAN, the switch marks the router
interface associated with the VLAN as down. From a layer 2 switching perspective, no
forwarding occurs between the member ports of the VLAN; this prevents loops and
maintains redundancy.
E
LECTING THE
M
ASTER
S
WITCH
A new master can be elected in one of the following ways:
• A communicated parameter change
• Loss of communication between master and slave(s).
If a parameter that determines the master changes (for example, link loss or priority
change), the election of the new master typically occurs within one timer cycle (2
seconds by default). If a switch in standby mode loses its connection with the master, a
new election (using the same precedence order indicated previously) occurs. The new
election typically takes place in three times the defined timer cycle (6 seconds by
default).
F
AILOVER
T
IME
Failover time is largely determined by the following factors:
• The ESRP timer setting.
• The routing protocol being used for inter-router connectivity if layer 3 redundancy is
used. OSPF fail-over time is faster than RIP fail-over time.
The failover time associated with the ESRP protocol is dependent on the timer setting
and the nature of the failure. The default timer setting is 2 seconds; the range is 1 to 255
seconds.
If routing is configured, the failover of the particular routing protocol (such as RIP V1,
RIP V2, or OSPF) is added to the failover time associated with ESRP.