I’ve replicated this issue on several devices and ros versions. Either I’m doing something wrong, or there is a bug. Routerboards apparently cannot use other routerboards set up with vrrp as gateway, as the arp table get a mismatch ip / mac address. Is there a trick to get around this?
In short:
Setup two RB’s with vrrp where the one with the highest value of mac address has the lowest priority in vrrp config. Connect a third RB (without vrrp config) to the interface where the vrrp is defined. Now ping the shared vrrp address from the 3rd rb and have a look at its arp-table: You’d expect to see the mac address of the vrrp router with the state of master (highest vrrp priority). But you’ll find the mac address of the vrrp router with the highest mac address.
Devices tested includes: rb750g, rb750gl, rb751g, rb450g, rb1100AHx2, rb2011
ROS versions tested includes: 3.30, 4.14, 5.08, 5.20, 5.24
Details for replication. Lets start out with 3 rb750gl with default config. I name them V1, V2 and C.
On V1 do the following: (for this example say it’s mac is 11-11-11-11-11-11)
/interface vrrp add arp=enabled authentication=none disabled=no interface=ether2-master-local interval=5s mtu=1500 name=vrrp-lan password="" preemption-mode=yes priority=250 v3-protocol=ipv4 version=3 vrid=11
/ip address
add address=10.61.6.2/24 interface=ether2-master-local
add address=10.61.6.1/32 interface=vrrp-lan
Disable DHCP server
Remove default ip for ether2-master-local
On V2 do the following: (for this example say it’s mac is 22-22-22-22-22-22)
/interface vrrp add arp=enabled authentication=none disabled=no interface=ether2-master-local interval=5s mtu=1500 name=vrrp-lan password="" preemption-mode=yes priority=150 v3-protocol=ipv4 version=3 vrid=11
/ip address
add address=10.61.6.3/24 interface=ether2-master-local
add address=10.61.6.1/32 interface=vrrp-lan
Disable DHCP server
Remove default ip for ether2-master-local
On C do the following:
/ip address
add address=10.61.6.10/24 interface=ether2-master-local
Disable DHCP server
Remove default ip for ether2-master-local
To connect them together; put a cable from V2-port2 to C-port2 and a cable from V1-port2 to C-port3. You may also connect a pc to C-port4 and give the pc static ip 10.61.6.11/24
Now, ping 10.61.6.1 from C and from the PC. Look at the arp tables. ARP on the PC will show mac address 11-11-11-11-11-11, while on C it will show 22-22-22-22-22-22.
At a customer site they have two RB1100AHx2 as routers with vrrp. About 200 pc’s works perfectly with 10.61.6.1 as default route. They also have 6 routerboards set as access points - none of them are able to route anything through 10.61.6.1 as long as V1 is master because they are actually sending packets to V2 (which is backup).