Unix administration - Re: Diagnosing network slowness: server or network?

This is Interesting: Free IT Magazines  
Home > Archive > Unix administration > June 2005 > Re: Diagnosing network slowness: server or network?





You are viewing an archived Text-only version of the thread. To view this thread in it's original format and/or if you want to reply to this thread please [click here]

Author Re: Diagnosing network slowness: server or network?
Michael Heiming

2005-06-25, 2:49 am

In comp.unix.admin Walter Roberson <roberson@ibd.nrc-cnrc.gc.ca>:
> In article <bqVue.295$Tk2.256@trnddc02>,
> sinister <sinister@nospam.invalid> wrote:
> :The curious thing is that all the cheap Suns with *really* bad problems
> i.e., graphics taking minutes to load, not just ftp slowness) show no
> :intervening hosts/switches/whatever when I run traceroute. Hosts that show
> :ftp slowness but graphics relatively unaffected show intermediate switches
> :according to traceroute.


> switches don't show up in traceroute -- only layer 3 hops decrement
> the TTL field so only layer 3 hops can return icmp ttl exceeded messages.


> Your v1280 server is unlikely to have more than a couple of ports,
> so you almost certainly have a layer 2 switch in the middle that is
> not showing up.



> Anyhow, your description sounds very much like duplex problems to me.


Second that.

> I would suggest that you should launch right in to forcing the
> speed and duplex on the v1280 server and the switchport it is
> connected to: instances in which forcing speed and duplex on
> both ends make things -worse- are quite uncommon (but not unknown )


> The test after that would be to force speed and duplex on one of
> the cheap Suns you mention (and corresponding switchport).



> There is no firm agreement about autonegotiation vs forced
> speed and duplex. The rule of thumb that seems to be most common
> is that speed and duplex should be fixed for critical infrastructure
> (switches, routers, key servers), but that autonegotiation should be
> used for desktops. (Opinions vary on this, though!!) The practical


Yep, from my experience the only OS able to handle
auto-negotiation perfectly is Linux. Most distro come with
mii-tool or/and eth-tool, allowing to check/set settings on the
system (all good NICs) on Solaris ndd can do this for you. But
mii-tool allows in addition to see what the other side of the
link is advertising:

# mii-tool -v eth2
eth2: negotiated 100baseTx-FD, link ok
product info: vendor 00:aa:00, model 56 rev 0
basic mode: autonegotiation enabled
basic status: autonegotiation complete, link ok
capabilities: 100baseTx-FD 100baseTx-HD 10baseT-FD 10baseT-HD
advertising: 100baseTx-FD 100baseTx-HD 10baseT-FD 10baseT-HD
link partner: 100baseTx-FD 100baseTx-HD 10baseT-FD 10baseT-HD
^^^^^^^^^^^^ flow-control

[..]

--
Michael Heiming (X-PGP-Sig > GPG-Key ID: EDD27B94)
mail: echo zvpunry@urvzvat.qr | PERL -pe 'y/a-z/n-za-m/'
#bofh excuse 224: Jan 9 16:41:27 huber su: 'su root' succeeded
for .... on /dev/pts/1
Sponsored Links






Free braindumps | Software forum | Database administration forum

Copyright 2003 - 2008 webservertalk.com