*BSD News Article 60519


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From: nate@trout.sri.MT.net (Nate Williams)
Newsgroups: comp.unix.bsd.freebsd.misc
Subject: Re: Please Help! with routing and slip
Date: 31 Jan 1996 19:32:52 GMT
Organization: SRI Intl. - Montana Operations
Lines: 68
Message-ID: <4eog54$1dd@helena.MT.net>
References: <31079315.52BFA1D7@ee.cornell.edu> <4e8hsm$9or@atlas.uniserve.com> <3107DBC7.FF6D5DF@ee.cornell.edu>
Reply-To: "Nate Williams" <nate@sneezy.sri.com>
NNTP-Posting-Host: trout.sri.mt.net

In article <3107DBC7.FF6D5DF@ee.cornell.edu>,
Paul Weber  <weber@ee.cornell.edu> wrote:
>I have ipforwarding turned on and I have arp compiled into the kernel.  What we
>are trying to do is have five static slip ip numbers and use proxyarp to do the
>routing for the five numbers.

proxyarp is only useful for local routing.

>Also, we are using gated.

Un-necessary if you are using proxy-arp.

> Slip seems to semi work
>we can connect to our pop server some of the time, which is on our local
>128.84.239 net, but we can not connect to any WWW servers or ftp sites that are
>not on our local net using slip.

This is a routing problem, not a SLIP problem.

> We always get a domain name lookup failure
>making it impossible to connect to outside sources.

Can your SLIP clients ping your DNS server?

>Many times after doing a
>domain name lookup packets are no longer being forwarded to the slip interface.
>
>I have also tried to point to several different name servers and I still get DNS
>failures.

Again, both of the above are due to routing problems.

>I have also tried using routed -s with about the same results.

With proxy-arp, you don't need routed or gated, since all of the routing
is done in the low-level ethernet code.  Again, this assumes the rest of
your routing is setup correctly.

>I have tried to ping our slip server from the slip client and it seems to work.
>However sometimes after sending 20+ packets the packets no longer get returned to
>the client.

Hmm, this isn't any good.  Is the link still up?

Note, there is a problem with FreeBSD 2.1R and proxy-arp.  In some
situations, the arp entry won't get added correctly into the routing
table, but this only occurs when an I.P. address is re-used quickly.
A common example of this is when a link goes down and the client re-dials and
re-establishes the link in a short period of time ( < 15 mins.).

Some questions.
1) Do you have a special sub-net allocated for the SLIP clients?
2) Do you have a unique IP address you use for the server-end for each of
   SLIP lines?
3) Can your SLIP clients ping any machine that is on the same ethernet
   segment as your SLIP server?
4) What does your routing table look like on your DNS box, and on your SLIP
   server?


Nate


-- 
nate@sneezy.sri.com    | Research Engineer, SRI Intl. - Montana Operations
nate@trout.sri.MT.net  | Loving life in God's country, the great state of
work #: (406) 449-7662 | Montana.
home #: (406) 443-7063 | A fly pole and a 4x4 Chevy truck = Heaven on Earth