ip1+mac1, ip2+mac2, vip+mac3
virtual mac from 00-00-0c-07-ac-xx
(xx is from 00-ff, this xx is equal to hsrp group number 0~255)
multicast address 224.0.0.2, udp port 1985
224.0.0.2 conflict with CGMP leave processing
HSRP v2, since IOS 12.3(4)T
ip1+mac1, ip2+mac2, vip+mac3
virtual mac from 0000.0c9f.f000 to 0000.0c9f.ffff
(000-fff, this is equal to hsrp group number 0~4095)
multicast address 224.0.0.102, udp port ????
VRRP
ip protocol 112
irtual mac from 0000.5e00.01xx
(xx is from 01-ff, this xx is equal to vrrp group number 1~255)
multicast address 224.0.0.18, both udp source port and destination port set to 3222
GLBP
AVG
AVF
multicast address 224.0.0.102,
