Specifications

Determining the ESRP Master
ExtremeWare XOS 11.0 Concepts Guide 235
— Ping—Tracks ICMP ping connectivity to specified devices.
— Environment (health checks)—Tracks the environment of the switch, including power supply and
chassis temperature.
If any of the configured tracking mechanisms fail, the master ESRP switch relinquishes status as
master, and remains in slave mode for as long as the tracking mechanism continues to fail.
• ESRP priority—This is a user-defined field. The range of the priority value is 0 to 255; a higher
number has higher priority, except for 255. The default priority setting is 0. A priority setting of 255
makes an ESRP switch remain in slave mode and is the recommended setting for system
maintenance. A switch with a priority setting of 255 will never become the master.
• System MAC address—The switch with the higher MAC address has higher priority.
You can configure the precedence order of the factors used by the system to determine the master ESRP
switch. For more information about configuring the ESRP election metrics, see “ESRP Election
Algorithms” on page 237.
Master Switch Behavior
If a switch is master, it actively provides Layer 3 routing services to other VLANs, and Layer 2
switching between all the ports of that VLAN. Additionally, the switch exchanges ESRP packets with
other switches that are in slave mode.
Pre-Master Switch Behavior
A pre-master switch is ready to transition to master. Upon entering the pre-master state, the switch
sends ESRP packets to other switches on that same VLAN. If the switch finds itself superior to its
neighbor, the switch transitions to master. This temporary state avoids the possibility of having
simultaneous masters.
Slave Switch Behavior
If a switch is in slave mode, it exchanges ESRP packets with other switches on that same VLAN. When
a switch is in slave mode, 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 slave mode
for the VLAN, the switch marks the router interface associated with that 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.
If you configure the switch to use the optional ESRP HA configuration, the switch continues Layer 2
forwarding to the master. For more information, see “ESRP Host Attach” on page 242.
Neutral Switch Behavior
The neutral state is the initial state entered into by the switch. In a neutral state, the switch waits for
ESRP to initialize and run. A neutral switch does not participate in ESRP elections. If the switch leaves
the neutral state, it enters the slave state.