那些你不知道的LVS秘密！(4)

4. 既然RS禁止了ARP请求, 那LVS如何把请求转发给RS呢?
解决了上面的问题, 那新的问题又来了, 既然我们说RS禁止了ARP请求, 那LVS是如何把请求转发给RS的呢?其实我告诉你, 是通过修改mac地址, 进行转发的, 这个是DR模式的核心, 那LVS又是如何知道RS的mac地址呢, 其实是通过ARP请求获知的, 那有些人就会问我, 你这个不是自相矛盾吗?别担心, 接着看。
首先我们看一下, 我们的vip都是绑定在lo上的, 我们要理解上面我提出的这个问题, 就要深入的了解一下linux内核参数的配置信息了。
有关arp_ignore的相关介绍：
arp_ignore - INTEGER Define different modes for sending replies in response to received ARP requests that resolve local target IP addresses:0 - (default): reply for any local target IP address, configured on any interface1 - reply only if the target IP address is local address configured on the incoming interface2 - reply only if the target IP address is local address configured on the incoming interface and both with the sender"s IP address are part from same subnet on this interface3 - do not reply for local addresses configured with scope host, only resolutions for global and link addresses are replied4-7 - reserved8 - do not reply for all local addressesThe max value from conf/{all,interface}/arp_ignore is used when ARP request is received on the {interface}