Learned something new about VRRP

late_collision

I may be a little late to the party, but I learned a new one about VRRP tonight.

When configuring VRRP priority, it always struck me as odd that the valid range is 1-254. Priority 0 has a special meaning and so does 255 (which can be configured). Before I give the answer, does everyone else know what priority 255 means?

(I would tell you why I got excited about this discovery, but it would indirectly violate the NDA)

late_collision

Priority 0 indicates that the VRRP Master is no longer participating in the VRRP group. For example, if you reboot the VRRP Master, it will send an advertisement with a priority of 0 before shutting down. Any VRRP backup members that hear this will begin electing a new VRRP Master immediately, without waiting for the hold down timer to expire.


Priority 255 is configured by setting the virtual IP of the VRRP group to one of the real IP's of a participating member. In HSRP, the virtual IP must be different than the IP of any participating members. From what I understand, in the name of efficiency and conserving every last IP, VRRP will allow you to use one of the members real IP's as the virtual IP for the group. The only drawback of doing this, tracking is not supported on the VRRP member who owns the real IP address.




I had a hard time finding this information, so hopefully someone will find it interesting as well.