一台服务器配置同一网段IP的ping问题

问题是这样的，我有一台服务器，两个网口分别配置了同一网段的IP，然后将一个网口的网线拔掉，发现该网卡的IP仍然能够ping通，但是arp -a却发现该IP地址返回的确是另一块网卡的mac。百思不得其解。最后发现居然是linux内核的问题。解释如下。

arp_announce/arp_ignore sysctl

The arp_announce/arp_ignore sysctl on interfaces is available at the Linux official kernel since 2.6.4 and 2.4.26. The description about arp_announce/arp_ignore taken from kernel documentation is as follows:

Linux 官方内核自2.6.4和2.4.26开始，interface上的arp_announce/arp_ignore系统调用就可用了。下面是内核文档中关于arp_announce/arp_ignore的描述:

arp_announce - INTEGER
	Define different restriction levels for announcing the local source IP address from IP packets in ARP requests sent on interface:


	0 - (default) Use any local address, configured on any interface

	1 - Try to avoid local addresses that are not in the target's subnet for this interface. This mode is useful when target hosts reachable via this interface require the source IP address in ARP requests to be part of their logical network configured on the receiving interface. When we generate the request we will                                    

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