Date: Wed, 23 Feb 2000 09:59:27 +0100 From: DRHAGER@de.ibm.com To: Joao Pedras <jpedras@webvolution.net> Cc: freebsd-net@FreeBSD.ORG, Freebsd-net@FreeBSD.ORG Subject: Re: dropping connection Message-ID: <C125688E.003164C1.00@d12mta01.de.ibm.com>
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I had a similar problem:
The ISDN link kept coming up every 10 min, and in tcpdump
I found ICMP ECHO-REQUEST in this intervall.
(*from* my net....)
So the link came up and down constantly.
This turned out to be PMTU Discovery re-checking a route via
the link.
You can find the IP of the offending machine and the process ID
in the packet - I am not familiar with the tcpdump-output, sorry.
Orm
########################################################################
Hello all.
I have been using FreeBSD to use ordinary pc's as routers. Several of those
machines use the i4b daemon.
Althought this IS NOT a FreeBSD or i4b problem, I would like to submit it
to
your consideration, so I could have an independent opinion about it.
Several of these routers connect through one of the major isp in our
country.
Only in these installations I face the problem of disconnection when idle
after
'x' time, to don't work (i.e. no matter how I configure the isdnd it never
drops the connection). The exact same configuration on other isp works
properly
and performs the disconnect.
The problem is that this particular isp has their routers configured to
send
some kind of keep alive, whenever the connection is idle.
I ran tcpdump on the isp0 interface and got the following :
19:45:36.787026 ID-063 LCP: Echo-Request, Magic-Number=-495599889
093f 000c e275 beef 0258 d272
19:45:36.787052 ID-063 LCP: Echo-Reply, Magic-Number=1285595741
0a3f 000c 4ca0 a25d 0258 d272
19:45:46.789844 ID-064 LCP: Echo-Request, Magic-Number=-495599889
0940 000c e275 beef 0258 d272
19:45:46.789865 ID-064 LCP: Echo-Reply, Magic-Number=1285595741
0a40 000c 4ca0 a25d 0258 d272
19:45:56.793551 ID-065 LCP: Echo-Request, Magic-Number=-495599889
0941 000c e275 beef 0258 d272
19:45:56.793570 ID-065 LCP: Echo-Reply, Magic-Number=1285595741
0a41 000c 4ca0 a25d 0258 d272
19:46:06.796127 ID-066 LCP: Echo-Request, Magic-Number=-495599889
0942 000c e275 beef 0258 d272
19:46:06.796147 ID-066 LCP: Echo-Reply, Magic-Number=1285595741
0a42 000c 4ca0 a25d 0258 d272
Frankly, I do not know of to interpret this data.
Do you find this situation normal ? I spoke with them and they didn't gave
me
any 'real' reason to be doing this. They said they won't change their
configuration.
They suggested me to write some kind of filter to ignore this. Is this
easily
achiavable ?
Just for curiosity, I read in the IOS 12.0 Configurartion book, that the
keep
alive in Cisco routers could be enabled optionally.
I really don't see any use to this configuration. ]:(
Thanks for your help
Joao
^\ /^
O O
----------------------------------------o00-(_)-00o--------------------------
I often quote myself; it adds spice to my conversation.
-- G. B. Shaw
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