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dual master when using VRRP and VRRPv3 and multiple VRIDs

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Titledual master when using VRRP and VRRPv3 and multiple VRIDs
Symptoms
dual-mastership on some VRRP or VRRPv3 instances when a lot of VRIDs are being used
Environment
  • EXOS
  • All EXOS platforms
  • VRRPv3
  • mixed IPv4, IPv6 addressing
Cause
EXOS has the limitation of 7 virtual MAC addresses for VRRP until 16.1. After 16.2 the limit is 31 addresses.
The VRRP MAC address for an IPv6 VRRP router instance is an IEEE 802 MAC address in the following hexadecimal format (in Internet-standard bit-order): 00-00-5E-00-02-<vrid>
This way even when less than 7 VRIDs are created, possibly the limit of MAC addresses can be surpassed.

MAC for IPv4 VRRP VRID 1: 00:00:5e:00:01:01
MAC for IPv6 VRRP VRID 1: 00:00:5e:00:02:01

This causes the switch to possibly not have the correct entries in hardware and therefore the switch does not forward VRRP hellos on some VLANs to the CPU, causing this dual-mastership on certain VLANs.
Resolution
Change the VRRP configuration to use as little VRIDs as necessary to stay within the limits of 7 MAC addresses or upgrade to EXOS 16.2 or one of the newer releases.
Additional notes
* switch1# show vrrp
                      Virtual                 Master                        
   VLAN Name VRID Pri IP Address        State MAC Address       TP/TR/TV/P/T
emtele-(En) 0003 100 212.68.11.62       BKUP 00:00:5e:00:01:03  0  0  0 Y 1
hosting(En) 0001 100 2a02:4880:10:1::1  BKUP 00:00:5e:00:02:01  0  0  0 Y 1
hosting(En) 0005 100 212.68.18.33       BKUP 00:00:5e:00:01:05  0  0  0 Y 1
hosting(En) 0002 100 2a02:4880:10:1::201
                                        BKUP 00:00:5e:00:02:02  0  0  0 Y 1
hosting(En) 0003 100 212.68.11.17       BKUP 00:00:5e:00:01:03  0  0  0 Y 1
i2-host(En) 0006 110 212.68.16.97       MSTR 00:00:5e:00:01:06  0  0  0 Y 1
i2-host(En) 0012 110 2a02:4880:10:1::101
                                        MSTR 00:00:5e:00:02:0c  0  0  0 Y 1
innofac(En) 0002 100 212.68.7.145       BKUP 00:00:5e:00:01:02  0  0  0 Y 1
omnia-i(En) 0001 100 212.68.10.1        MSTR 00:00:5e:00:01:01  0  0  0 Y 1
poistat(En) 0001 100 212.68.18.99       MSTR 00:00:5e:00:01:01  0  0  0 Y 1
poistat(En) 0012 100 2a02:4880:0:1::1   BKUP 00:00:5e:00:02:0c  0  0  0 Y 1
 popwan(En) 0004 100 212.68.11.177      MSTR 00:00:5e:00:01:04  0  0  0 Y 1
 
* switch2 # sh vrrp
                      Virtual                 Master                        
   VLAN Name VRID Pri IP Address        State MAC Address       TP/TR/TV/P/T
emtele-(En) 0003 110 212.68.11.62       MSTR 00:00:5e:00:01:03  0  0  0 Y 1
hosting(En) 0001 110 2a02:4880:10:1::1  MSTR 00:00:5e:00:02:01  0  0  0 Y 1
hosting(En) 0005 110 212.68.18.33       MSTR 00:00:5e:00:01:05  0  0  0 Y 1
hosting(En) 0002 110 2a02:4880:10:1::201
                                        MSTR 00:00:5e:00:02:02  0  0  0 Y 1
hosting(En) 0003 110 212.68.11.17       MSTR 00:00:5e:00:01:03  0  0  0 Y 1
i2-host(En) 0006 100 212.68.16.97       BKUP 00:00:5e:00:01:06  0  0  0 Y 1
i2-host(En) 0012 100 2a02:4880:10:1::101
                                        BKUP 00:00:5e:00:02:0c  0  0  0 Y 1
innofac(En) 0002 110 212.68.7.145       MSTR 00:00:5e:00:01:02  0  0  0 Y 1
omnia-i(En) 0001 110 212.68.10.1        MSTR 00:00:5e:00:01:01  0  0  0 Y 1
poistat(En) 0001 110 212.68.18.99       MSTR 00:00:5e:00:01:01  0  0  0 Y 1
poistat(En) 0012 110 2a02:4880:0:1::1   MSTR 00:00:5e:00:02:0c  0  0  0 Y 1
 popwan(En) 0004 110 212.68.11.177      MSTR 00:00:5e:00:01:04  0  0  0 Y 1
                               
                Only the following entries could be found for PIQ 26 on switch1:
 
mac=00:00:5e:00:01:03 vlan=2225 GPORT=0x1a modid=0 port=26/xe0 Hit ESM
mac=00:00:5e:00:02:01 vlan=4021 GPORT=0x1a modid=0 port=26/xe0 Hit ESM
mac=00:00:5e:00:01:05 vlan=4021 GPORT=0x1a modid=0 port=26/xe0 Hit ESM
mac=00:00:5e:00:02:02 vlan=4023 GPORT=0x1a modid=0 port=26/xe0 Hit ESM
mac=00:00:5e:00:01:03 vlan=4023 GPORT=0x1a modid=0 port=26/xe0 Hit ESM
mac=00:00:5e:00:01:02 vlan=3809 GPORT=0x1a modid=0 port=26/xe0 Hit ESM
mac=00:00:5e:00:02:0c vlan=1111 GPORT=0x1a modid=0 port=26/xe0 Hit ESM
 
        The following entries don’t have the correct port-information:
 
mac=00:00:5e:00:01:04 vlan=1311 GPORT=0x0 modid=0 port=0/cpu0 Static Hit L3
mac=00:00:5e:00:01:01 vlan=3600 GPORT=0x0 modid=0 port=0/cpu0 Static Hit L3
mac=00:00:5e:00:01:01 vlan=1111 GPORT=0x0 modid=0 port=0/cpu0 Static Hit L3
 

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