chapter 8: vrrp communications  

Thursday, August 6, 2009

-> Vrrp version 2 uses common advertisement packet (Buzz word) to communicate with other vrrp routers.

-> vrrp uses multicast address of and has TTL of 255.

-> Default interval can be changed if needed . default being 1 and range being 1-255 subseconds can also be configured from 100-999 milliseconds which must be supported by all vrrp routers.

-> The above can be done with "fast-interval" option

-> Fields which should match in a vrrp packet for all vrrp routers

-> Authentication Parameters

if not then packets are discarded

-> Vrrp router uses Virtual mac address as its mac address when it sends a packet.
format may be some thing like this 00-00-5E-00-01-VRID

Determining Master:

-> Higher priority wins in a vrrp election process. The default being 100 and range being 1-255

-> A router can become a Master Router only when it has VIP address and in that case the priority must be set to 255. preemption is supported by default . If master happens to fail the other router which has higher priority will take over and if by chance master returns the other router will be down and this will take over the master role.

-> We can administratively disable preemption where vrrp routers do not own VIP address.

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