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merkava
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different behavior between Linux router and Cisco router

Thu Jan 12, 2012 3:12 am

Hi guys

you can see topology below. Every thing is clear on the diagram.
The question is when routers are a cisco router, I can ping both R1 interfaces(192.168.3.1, 192.168.5.1) from client.But when they are linux router I can only ping 192.168.5.1.
I mean linux is trying to response from the interface it recieved the requests, But it can not find next hop on that. But cisco router can recieve ping requests from one interface and send replies on other interface.

Can anyone help what is gong on?
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MERKAVA

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kerpap
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Re: different behavior between Linux router and Cisco route

Thu Jan 12, 2012 3:23 am

other than CDP, they should be the same.

by linux router, what platform are you referring to?
there are many routers with a linux or unix kernel but some operate slightly different than others. not in anyway that would cause this however it might be something you overlooked in the config.
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merkava
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Re: different behavior between Linux router and Cisco route

Thu Jan 12, 2012 3:47 am

I'm using fedora 16 with kernel-3.1.7-1.fc16.x86_64. I have only enabled net.ipv4.ip_forward = 1. nothing more
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MERKAVA

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merkava
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Re: different behavior between Linux router and Cisco route

Sun Jan 15, 2012 5:55 am

I asked this question in http://ask.fedoraproject.org/question/870/different-behavior-between-linux-router-and-cisco
The answer is:
we should disable reverse path filtering on Linux. it is enabled by default. Edit this line in sysctl.conf:
Code: Select all
net.ipv4.conf.default.rp_filter = 0
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MERKAVA

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