Article Detail

Description

SRX software allows users to add more than 32 destinations using backup router config. However, only 32 entries are added in forwarding table and remaining backup-router destinations are ignored. This article explains that backup router destinations are limited to 32 in a forwarding-table, even though Junos OS allows adding more than 32 destinations from the CLI. This behavior is as per current design and is an expected behavior.

Symptoms

SRX software allows users to add more than 32 destinations using backup router config; this is successfully committed.

 root@SRX1400-6> show configuration groups node1 system backup-router | display set 
 
 set groups node1 system backup-router 20.20.20.254 
 set groups node1 system backup-router destination 10.0.0.1/32 
 set groups node1 system backup-router destination 10.0.0.2/32 
 set groups node1 system backup-router destination 10.0.0.3/32 
 set groups node1 system backup-router destination 10.0.0.4/32 
 set groups node1 system backup-router destination 10.0.0.5/32 
 set groups node1 system backup-router destination 10.0.0.6/32 
 set groups node1 system backup-router destination 10.0.0.7/32 
 set groups node1 system backup-router destination 10.0.0.8/32 
 set groups node1 system backup-router destination 10.0.0.9/32 
 set groups node1 system backup-router destination 10.0.0.10/32 
 set groups node1 system backup-router destination 10.0.0.11/32 
 set groups node1 system backup-router destination 10.0.0.12/32 
 set groups node1 system backup-router destination 10.0.0.13/32 
 set groups node1 system backup-router destination 10.0.0.14/32 
 set groups node1 system backup-router destination 10.0.0.15/32 
 set groups node1 system backup-router destination 10.0.0.16/32 
 set groups node1 system backup-router destination 10.0.0.17/32 
 set groups node1 system backup-router destination 10.0.0.18/32 
 set groups node1 system backup-router destination 10.0.0.19/32 
 set groups node1 system backup-router destination 10.0.0.20/32 
 set groups node1 system backup-router destination 10.0.0.21/32 
 set groups node1 system backup-router destination 10.0.0.22/32 
 set groups node1 system backup-router destination 10.0.0.23/32 
 set groups node1 system backup-router destination 10.0.0.24/32 
 set groups node1 system backup-router destination 10.0.0.25/32 
 set groups node1 system backup-router destination 10.0.0.26/32 
 set groups node1 system backup-router destination 10.0.0.27/32 
 set groups node1 system backup-router destination 10.0.0.28/32 
 set groups node1 system backup-router destination 10.0.0.29/32 
 set groups node1 system backup-router destination 10.0.0.30/32 
 set groups node1 system backup-router destination 10.0.0.31/32 
 set groups node1 system backup-router destination 10.0.0.32/32 
  set groups node1 system backup-router destination 10.0.0.33/32 
 set groups node1 system backup-router destination 10.0.0.34/32

However, only 32 entries are added in the forwarding table; remaining backup-router destinations are ignored.

 root@SRX1400-6> show route forwarding-table | match 10.0.0 
 
 10.0.0.1/32 user 0 20.20.20.254 ucst 340 33 fxp0.0 
 10.0.0.2/32 user 0 20.20.20.254 ucst 340 33 fxp0.0 
 10.0.0.3/32 user 0 20.20.20.254 ucst 340 33 fxp0.0 
 10.0.0.4/32 user 0 20.20.20.254 ucst 340 33 fxp0.0 
 10.0.0.5/32 user 0 20.20.20.254 ucst 340 33 fxp0.0 
 10.0.0.6/32 user 0 20.20.20.254 ucst 340 33 fxp0.0 
 10.0.0.7/32 user 0 20.20.20.254 ucst 340 33 fxp0.0 
 10.0.0.8/32 user 0 20.20.20.254 ucst 340 33 fxp0.0 
 10.0.0.9/32 user 0 20.20.20.254 ucst 340 33 fxp0.0 
 10.0.0.10/32 user 0 20.20.20.254 ucst 340 33 fxp0.0 
 10.0.0.11/32 user 0 20.20.20.254 ucst 340 33 fxp0.0 
 10.0.0.12/32 user 0 20.20.20.254 ucst 340 33 fxp0.0 
 10.0.0.13/32 user 0 20.20.20.254 ucst 340 33 fxp0.0 
 10.0.0.14/32 user 0 20.20.20.254 ucst 340 33 fxp0.0 
 10.0.0.15/32 user 0 20.20.20.254 ucst 340 33 fxp0.0 
 10.0.0.16/32 user 0 20.20.20.254 ucst 340 33 fxp0.0 
 10.0.0.17/32 user 0 20.20.20.254 ucst 340 33 fxp0.0 
 10.0.0.18/32 user 0 20.20.20.254 ucst 340 33 fxp0.0 
 10.0.0.19/32 user 0 20.20.20.254 ucst 340 33 fxp0.0 
 10.0.0.20/32 user 0 20.20.20.254 ucst 340 33 fxp0.0 
 10.0.0.21/32 user 0 20.20.20.254 ucst 340 33 fxp0.0 
 10.0.0.22/32 user 0 20.20.20.254 ucst 340 33 fxp0.0 
 10.0.0.23/32 user 0 20.20.20.254 ucst 340 33 fxp0.0 
 10.0.0.24/32 user 0 20.20.20.254 ucst 340 33 fxp0.0 
 10.0.0.25/32 user 0 20.20.20.254 ucst 340 33 fxp0.0 
 10.0.0.26/32 user 0 20.20.20.254 ucst 340 33 fxp0.0 
 10.0.0.27/32 user 0 20.20.20.254 ucst 340 33 fxp0.0 
 10.0.0.28/32 user 0 20.20.20.254 ucst 340 33 fxp0.0 
 10.0.0.29/32 user 0 20.20.20.254 ucst 340 33 fxp0.0 
 10.0.0.30/32 user 0 20.20.20.254 ucst 340 33 fxp0.0 
 10.0.0.31/32 user 0 20.20.20.254 ucst 340 33 fxp0.0 
 10.0.0.32/32 user 0 20.20.20.254 ucst 340 33 fxp0.0

Solution

In an SRX cluster environment, backup router destinations are limited to 32 in forwarding-table, even though Junos OS allows users to add more than 32 destinations from the CLI.

This behavior is as per current design and is an expected behavior.