Arp_announce and Arp_ignore understand the explanation

The LVS realserver lo port configuration involves adjusting the two network parameters arp_announce=2 and arp_ignore=1, ignoring the complex and obscure representations of official documents, which we can actually understand:

arp_ignore=2 indicates that for ARP broadcast packets sent over the network, the LO port of the realserver will be discarded because if the answer is made, according to the ARP protocol, the MAC address of the VIP corresponding to the other host on the notification network is the MAC address of Realserver. Instead of the LVs MAC address, so that the client will bypass LVS, directly with the back-end of the realserver communication, load scheduling loss of meaning;

Arp_announce:

Realserver generally at least two ports two ip,eth0 have ip,lo:0 also bound a VIP, according to the ARP protocol,

The ARP Request packet must contain the source host's IP address and the MAC address, the other party receives the request package, records the source address and the MAC address, establishes one-to-one mapping, then for this multi-IP situation, Realserver sends the ARP request the time to choose, which IP as the source address?

Parameter arp_anonunce is precisely used to solve this problem, arp_announce=2 official statement for the use of the most appropriate local address, in fact, the eth0 on the IP as the source address, if the VIP as the source address, The other side will be the VIP and Realserver's MAC address map, resulting in the request package is sent to Realserver, without the LVS.

Arp_announce and Arp_ignore understand the explanation