Re: Beavis is back and I wanna show him a raw IP dump

["Scott M. Stone" <sstone@example.com>]

On Wed, 6 Sep 2000, Stephen J. Turnbull wrote:

> Well, if I configure two hosts so that they can only see each other
> through the router, I can get maybe 20 (to start) to 10 KB/sec
> (bandwidth goes down over time) FTP transfers (10Mbps ethernot[1]).
> 
> There sure _is_ a problem.  UDP-based protocols hardly work at all (no
> surprise, that).  Even X: I'm currently doing ssh tunnels so I can get
> reliable X connections :(
> 
> What I'm seeing is lots of errors in the RX line of ifconfig's report
> (normally >1%, I can push that to almost 20% by doing a high-bandwidth
> transfer as above).  Most (70--90%) of these are "frame" problems.
> 
> (1) What exactly is ifconfig reporting in the "frame" field of the RX
>     line?
> 


framing errors.  ethernet-level troubles.  from the evidence presented
above, I'd say there's either:

	1) a ton of collisions on one or both of the two segments on
either side of the router

	2) faulty cabling somewhere
	3) faulty router


faulty routers can act weird.  My Cisco AS5300 here was behaving normally,
except for the fact that it was dropping calls..  AT&T looped up the T1
PRI going into it, and the remote alarm light on the back comes on, but
the router thinks that the T1 is up (!) ... same thing when I physically
yank the RJ45 cable carrying the T1 out of the unit entirely...
"Controller t1 0 is up, no alarms"... had to get Cisco to replace the PRI
module, now it works fine.

Tell Beavis to replace the router, and make sure there's switches on both
sides of it, not hubs.

> (2) Is there some way I can directly tap this, at both ends of the
>     connection?  Beavis wants evidence; what I would like to do is send
>     him matched transcripts of an FTP transfer of mozilla-M17.tar.bz2
>     if I can get it.
> 

show him the ifconfig output with all of the errors.  "netstat -i" helps,
too.  the transcripts of the FTP would also be helpful, you should be
getting close to 1MByte/sec over 10megabit... I usually get about
1000kbit/sec doing that.  7000-9000 is normal for 100mbit, and, well, the
gigabit transfers at Northpoint were just unreal.

--------------------------
Scott M. Stone, CCNA <sstone@example.com>
UNIX Systems and Network Engineer
Taos - The SysAdmin Company