ExtremeXOS Command Reference Guide

Description

Configures the election algorithm on the switch.

Syntax Description

`esrpDomain`	Specifies an ESRP (Extreme Standby Router Protocol) domain name.
ports > track > priority	Specifies that this ESRP domain should consider election factors in the following order: Active ports, tracking information, ESRP priority.
ports > track > priority > mac	Specifies that this ESRP domain should consider election factors in the following order: Active ports, tracking information, ESRP priority, MAC address. Note: This is the default election algorithm for standard mode.
priority > mac	Specifies that this ESRP domain should consider election factors in the following order: ESRP priority, MAC address.
priority > ports > track > mac	Specifies that this ESRP domain should consider election factors in the following order: ESRP priority, active ports, tracking information, MAC address.
priority > track > ports > mac	Specifies that this ESRP domain should consider election factors in the following order: ESRP priority, tracking information, active ports, MAC address.
sticky > ports > track > priority	Specifies that this ESRP domain should consider election factors in the following order: Stickiness, active ports, tracking information, ESRP priority.
sticky > ports > track > priority > mac	Specifies that this ESRP domain should consider election factors in the following order: Stickiness, active ports, tracking information, ESRP priority, MAC address.
sticky > ports > weight > track > priority > mac	Specifies that this ESRP domain should consider election factors in the following order: Stickiness, active ports, port weight, tracking information, ESRP priority, MAC address. Note: Beginning with ExtremeXOS 11.1 and later, this is the default election algorithm for extended mode.
sticky > priority > mac	Specifies that this ESRP domain should consider election factors in the following order: Stickiness, ESRP priority, MAC address.
sticky > priority > ports > track > mac	Specifies that this ESRP domain should consider election factors in the following order: Stickiness, ESRP priority, active ports, tracking information, MAC address.
sticky > priority > track > ports > mac	Specifies that this ESRP domain should consider election factors in the following order: Stickiness, ESRP priority, tracking information, active ports, MAC address.
sticky > track > ports > priority	Specifies that this ESRP domain should consider election factors in the following order: Stickiness, tracking information, active ports, ESRP priority.
sticky > track > ports > priority > mac	Specifies that this ESRP domain should consider election factors in the following order: Stickiness, tracking information, active ports, ESRP priority, MAC address.
track > ports > priority	Specifies that this ESRP domain should consider election factors in the following order: Tracking information, active ports, ESRP priority.
track > ports > priority > mac	Specifies that this ESRP domain should consider election factors in the following order: Tracking information, active ports, ESRP priority, MAC address.

Default

In extended mode, the default election algorithm is sticky > ports > weight > track > priority > mac.

In standard mode, the default election algorithm is ports > track > priority > mac.

Usage Guidelines

The election algorithm determines the order of precedence of the election factors used to determine the ESRP Master. The election factors are:

Stickiness (sticky): the switch with the higher sticky value has higher priority. When an ESRP domain claims master, its sticky value is set to 1 (available in extended mode only).
Active Ports (ports): the number of active ports (the switch with the highest number takes priority)
Tracking Information (track): whether the switch is using ESRP tracking. A switch using tracking has priority.
ESRP Priority (priority): a user-defined priority number between 0 and 254. A higher number has higher priority. The default priority setting is 0. A priority setting of 255 makes an ESRP switch a standby switch that remains in slave mode until you change the priority setting. We recommend this setting for system maintenance. A switch with a priority setting of 255 never becomes the master.
MAC address (mac): the switch MAC address. A higher-number address has priority.
Active port weight (weight)—The switch that has the highest port weight takes precedence. The bandwidth of the port automatically determines the port weight (available only in extended mode). ESRP does not count ports with a weight of 0 (known as don‘t count ports) regardless of ESRP running in extended or standard mode.

The election algorithm must be the same on all switches for a particular ESRP domain. The election algorithms that use sticky are and weight are available in extended mode only.

In ExtremeXOS 11.0, the extended mode default election algorithm is: sticky > ports > track > priority > mac > weight. This election algorithm is not supported in ExtremeXOS 11.1.

Factors to Consider

The ports-track-priority or track-ports-priority options can be used to ensure that there is no failback if the original Master recovers (the Master has the same ports, tracks and priority, but a higher MAC).

Any of the options with sticky can also be used to ensure that there is no failback if the original master recovers. With sticky, if an event causes the ESRP master to failover, ESRP assigns the new master with the sticky count of 1. After sticky is set on the master, regardless of changes to its neighbor‘s election algorithm, the new master retains its position. For example, adding active ports to the slave does not cause the new master to failback to the original master, even if the slave has more active ports than the master. Sticky algorithms provide for fewer network interruptions than non-sticky algorithms. Sticky is set on the master switch only.

ESRP re-election can occur if sticky is set on the master and a local event occurs. During this time, if the current master has lower election parameters, the backup can become the new master.

Switch Behavior

If a switch is master, it actively provides Layer 3 routing services to other VLAN (Virtual LAN)s, 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.

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.

Updating the Election Algorithm

ESRP uses the default election policy for extended mode. If you have an ESRP domain operating in standard mode, the domain ignores the sticky and weight algorithms. To change the election algorithm, you must first disable the ESRP domain and then configure the new election algorithm. If you attempt to change the election algorithm without disabling the domain first, an error message appears.

To disable the ESRP domain, use the following command:

disable esrp {esrpDomain}

To modify the election algorithm, use the following command:

If you attempt to use an election algorithm not supported by the switch, an error message similar to the following appears:

ERROR: Specified election-policy is not supported!
Supported Policies:
1. sticky > ports > weight > track > priority > mac
2. ports > track > priority
3. sticky > ports > track > priority
4. ports > track > priority > mac
5. sticky > ports > track > priority > mac
6. priority > mac
7. sticky > priority > mac
8. priority > ports > track > mac
9. sticky > priority > ports > track > mac
10. priority > track > ports > mac
11. sticky > priority > track > ports > mac
12. track > ports > priority
13. sticky > track > ports > priority
14. track > ports > priority > mac
15. sticky > track > ports > priority > mac

History

This command was first available in ExtremeXOS 11.0.

The default election algorithm for extended mode was updated to sticky > ports > weight > track > priority > mac, and the weight election factor was used in ExtremeXOS 11.1. The sticky > ports > track > priority > mac > weight election algorithm is not supported in ExtremeXOS 11.1.

Platform Availability

This command is available on the Summit X450-G2, X460-G2, X670-G2, X770, and ExtremeSwitching X440-G2, X620, X690, X870 series switches.

configure esrp election-policy