Specifications

234 ExtremeWare XOS 11.0 Concepts Guide
Extreme Standby Router Protocol
control from the primary MSM to the backup MSM and maintains the state of ESRP. The ESRP extended
version supports hitless failover.
For ESRP support of hitless failover, both ESRP switches and the primary and backup MSMs must be
running ExtremeWare XOS 11.0 or later operating in ESRP extended mode.
NOTE
You must run ExtremeWare XOS 11.0 or later for ESRP support of hitless failover.
The ESRP domain on the primary MSM is active and participates in the ESRP protocol. The ESRP
domain on the backup MSM is in the neutral state listening for configuration changes, tracking failures,
and checkpointing messages and link state events. When you initiate MSM failover, the master ESRP
switch notifies its neighbor ESRP switch about the failover. After the neighbor receives information
from the master switch, the neighbor remains in its current state and waits for the failover to occur.
After the failover from the primary MSM to the backup MSM is complete, the master ESRP switch
notifies the neighbor so the neighbor can relinquish its current state.
To initiate hitless MSM failover on a network that uses ESRP:
1 Confirm that the MSMs are synchronized and have identical software and switch configurations
using the
show switch {detail} command. The output displays the status of the MSMs, with the
primary MSM showing
MASTER and the backup MSM showing BACKUP (InSync).
If the MSMs are not synchronized, proceed to step 2.
If the MSMs are synchronized, proceed to step 3.
2 If the MSMs are not in sync, replicate all saved images and configurations from the primary to the
backup using the
synchronize command.
3 Initiate failover using the run msm-failover command.
For more detailed information about verifying the status of the MSMs and system redundancy, see
“System Redundancy” on page 47.
Determining the ESRP Master
The system determines the ESRP master switch (providing Layer 3 routing and/or Layer 2 switching
services for a VLAN) using the following default factors:
• Stickiness—The switch with the higher sticky value has higher priority. When an ESRP domain
claims master, its sticky value is set to 1 (available only in extended mode).
• Active ports—The switch that has the greatest number of active ports takes highest precedence.
•Tracking information—Various types of tracking are used to determine if the switch performing the
master ESRP function has connectivity to the outside world. ExtremeWare XOS supports the
following types of tracking:
— VLAN—Tracks any active port connectivity to one designated VLANs. An ESRP domain can
track one VLAN, and the tracked VLAN should not be a member of any other ESRP domain in
the system.
— IP route table entry—Tracks specific learned routes from the IP route table.