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Larsa
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ICMP Redirect routing cache

Mon May 16, 2022 8:37 pm

We are running a lab test with ICMP Redirects using a number of different test clients. Everything works as expected also when using Mikrotik as a test client on the receiving side for the redirects.

Questions: Regarding ros v6 or v7, is it possible to:
Q1: display the ICMP redirect routing cache?
Q2: alter the expiration time (ie similar to arp-timeout)?
--

Thanks in advance!

Ps... and yes, I'm aware there are various of alternative solutions but these questions are only concerning the icmp redirect cache in ros.
 
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mrz
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Re: ICMP Redirect routing cache

Mon May 16, 2022 10:03 pm

What do you mean by "ICMP redirect routing cache"?
 
msatter
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Re: ICMP Redirect routing cache

Mon May 16, 2022 10:23 pm

In v7, there is no routing cache anymore: viewtopic.php?p=882429#p882429 and read on.
 
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Larsa
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Re: ICMP Redirect routing cache

Mon May 16, 2022 10:24 pm

What do you mean by "ICMP redirect routing cache"?

When receiving a ICMP Redirect. On cisco ios the redirect cache can be shown using "show ip redirects" and on linux "ip route show (cache)"

"Understanding ICMP Redirect Messages"
Last edited by Larsa on Mon May 16, 2022 10:32 pm, edited 1 time in total.
 
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Larsa
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Re: ICMP Redirect routing cache

Mon May 16, 2022 10:27 pm

In v7, there is no routing cache anymore: viewtopic.php?p=882429#p882429 and read on.

Thanks. Does this also concern ICMP redirects that usually are kept in a separate cache?
 
msatter
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Re: ICMP Redirect routing cache

Mon May 16, 2022 10:42 pm

I don't know that, however I remembered the topics about routing cache in v7.

viewtopic.php?p=929460#p929436
 
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mrz
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Re: ICMP Redirect routing cache  [SOLVED]

Mon May 16, 2022 10:56 pm

ROS v6 used old kernel with route cache, redirects were stored in that cache however the actual table was no exposed to users.
ROS v7 has updated kernel that does not have route cache. And there is no separate table for redirect cache, it is part of the FIB structure and also not exposed to the user.
 
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Larsa
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Re: ICMP Redirect routing cache

Mon May 16, 2022 11:18 pm

Thanks, that explains why I didn't find anything regarding this in the help docs. Judging by wireshark it seems that v7 still caches icmp redirects somehow but with varying timers compared to v6.
--

Well, mystery solved (sort of). Have a nice day!

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