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How to avoid ARP flux issue in linux?

+2 votes

I have a setup where eth0 and eth1 interfaces are in same broadcast domain.

But i have a virtual IP configured on eth1 and a physical ip on eth0.
It is observed that if eth0 is default route then eth0 will respond to arp request for the IP configured on eth1.

This would cause an issue since traffic will be routed via eth0.

posted Apr 17, 2013 by Prem Chaitanya Prathi

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Try the following too -


Setting net.ipv4.conf.all.arp_ignore=1 and net.ipv4.conf.all.arp_announce=2 in /etc/sysctl.conf provides adequate settings. However, you should check whether these settings work in your network environment, especially if you depend on reaching an IP address from any other than the interface that it is configured on.

1 Answer

+1 vote

Try to disable rp_filter on each interface and try

# sysctl -w net.ipv4.conf.eth0.rp_filter=0
# sysctl -w net.ipv4.conf.eth1.rp_filter=0

Hope it should work.

answer Apr 17, 2013 by anonymous
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I have a process which is running as a linux service and assigns IP addresses using netlink to configued interface in linux.
For IPv4 addresses i do not see any issue with this assignment.

When i try to assign an IPv6 address, the address gets assigned successfully to the interface, but the Neighbour Solication request received for that address is not responded with and hence ping6 from a different machine doesn't work.

When i take the same netlink code and run it in a sample program the address gets assigned and the Neighbour solicitation is responded with a advertisement and hence ping6 works.

IP assigned by the program : 7000::15/32
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Bot machines are connected to same Layer-2 switch.

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0 votes

Lets assume device is a computer which is connected to LAN switch and LAN switch has further links in upward.
Does a computer initiate ARP request for each destination IP ? Or it initiates ARP request only for a specific group of IPs ?