[isapros] Re: OT:Network Porblems
- From: "Thomas W Shinder" <tshinder@xxxxxxxxxxx>
- To: <isapros@xxxxxxxxxxxxx>
- Date: Thu, 20 Jul 2006 10:35:16 -0500
Hi Jerry,
Great tips!
Thanks!
Tom
Thomas W Shinder, M.D.
Site: www.isaserver.org
Blog: http://blogs.isaserver.org/shinder/
Book: http://tinyurl.com/3xqb7
MVP -- ISA Firewalls
> -----Original Message-----
> From: isapros-bounce@xxxxxxxxxxxxx
> [mailto:isapros-bounce@xxxxxxxxxxxxx] On Behalf Of Young, Gerald G
> Sent: Thursday, July 20, 2006 10:21 AM
> To: isapros@xxxxxxxxxxxxx
> Subject: [isapros] Re: OT:Network Porblems
>
> Greg,
>
> He forced the router to 100/Half?? That's not a good thing
> to do unless
> you hard code the switch port that is connected to the router the same
> way. You can end up with a lot of collisions that way. Do have
> statistics on how many collisions you're getting. CRC errors can be
> caused by too many collisions occurring which result in a packet being
> "lost".
>
> Does the switch support 1Gb speeds? Does the router? What happens if
> you hard code the ports connecting the router and switch to
> 1Gb/AutoNegotiate(Full)?
>
> Another thing to look at is whether or not STP is enabled on
> the switch
> port connecting to the router. If it is and you aren't performing any
> trunking between the router and switch, you might want to enable
> portfast on the switch port connected to the router while
> also enabling
> bpduguard. Usually, though, you'd only want to enable the
> two on ports
> that are connected to end devices.
>
> In general, if you can hard code speed/duplex on servers and switch
> ports to which they are connected to the same, you can often
> times avoid
> network communication issues because not all NICs work well in
> AutoDetect.
>
> Cordially yours,
> Jerry G. Young II
> MCSE (4.0/W2K)
> Atlanta EES Implementation Team Lead
> ECNS Microsoft Engineering
> Unisys
>
> 11493 Sunset Hills Rd.
> Reston, VA 20190
> Office: 703-579-2727
> Cell: 703-625-1468
>
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>
> -----Original Message-----
> From: isapros-bounce@xxxxxxxxxxxxx
> [mailto:isapros-bounce@xxxxxxxxxxxxx]
> On Behalf Of Greg Mulholland
> Sent: Wednesday, July 19, 2006 11:48 PM
> To: isapros@xxxxxxxxxxxxx
> Subject: [isapros] Re: OT:Network Porblems
>
> The error itself is not helpful. it says "input error" it helps me
> allot..:)
>
> ----- Original Message -----
> From: "Thomas W Shinder" <tshinder@xxxxxxxxxxx>
> To: <isapros@xxxxxxxxxxxxx>
> Sent: Thursday, July 20, 2006 1:04 PM
> Subject: [isapros] Re: OT:Network Porblems
>
>
> It's important to know exactly what the errors are before replacing
> hardware. Really need to see what's happening on the wire too.
>
> Thomas W Shinder, M.D.
> Site: www.isaserver.org
> Blog: http://blogs.isaserver.org/shinder/
> Book: http://tinyurl.com/3xqb7
> MVP -- ISA Firewalls
>
>
>
> > -----Original Message-----
> > From: isapros-bounce@xxxxxxxxxxxxx
> > [mailto:isapros-bounce@xxxxxxxxxxxxx] On Behalf Of Greg Mulholland
> > Sent: Wednesday, July 19, 2006 10:02 PM
> > To: isapros@xxxxxxxxxxxxx
> > Subject: [isapros] Re: OT:Network Porblems
> >
> > I dont actually know what the definition is. They havent been
> > able to tell
> > me what the exact error means, no source ip or nothing.
> >
> > They were getting CRC errors and frame errors in the log but
> > they seemed to
> > have cleared up this morning.
> >
> > ----- Original Message -----
> > From: "Thomas W Shinder" <tshinder@xxxxxxxxxxx>
> > To: <isapros@xxxxxxxxxxxxx>
> > Sent: Thursday, July 20, 2006 12:55 PM
> > Subject: [isapros] Re: OT:Network Porblems
> >
> >
> > What is the definition of an "input error" in this scenario?
> >
> > Thomas W Shinder, M.D.
> > Site: www.isaserver.org
> > Blog: http://blogs.isaserver.org/shinder/
> > Book: http://tinyurl.com/3xqb7
> > MVP -- ISA Firewalls
> >
> >
> >
> > > -----Original Message-----
> > > From: isapros-bounce@xxxxxxxxxxxxx
> > > [mailto:isapros-bounce@xxxxxxxxxxxxx] On Behalf Of Greg Mulholland
> > > Sent: Wednesday, July 19, 2006 4:54 PM
> > > To: isapros@xxxxxxxxxxxxx
> > > Subject: [isapros] OT:Network Porblems
> > >
> > > OK i need some eyes on this one and since jim asked an
> > > exchange question ill
> > > take a stab.
> > >
> > > Previously the client had a 2mb Internet link with ye olde
> > > cisco router, two
> > > vlans. Two weeks ago they upgraded to a 4mb link with a brand
> > > spanker of a
> > > new cisco router, same 2 vlans. The cabling system was
> all the same
> > > basically i had to do was pull the cables out from the old
> > > router and stick
> > > them into the new router, reconfigure the dhcp scopes and any
> > > static devies
> > > on the networks and all is good. Well vlan1 has worked a
> > > treat since, which
> > > brings me to vlan2.
> > >
> > > The client reported "no internet access" a while ago after a
> > > bit of trouble
> > > shooting and a cut to the chase the guys who manage the
> > > router (externally)
> > > tell me they are seeing 3-6 million input errors on vlan2's
> > > interface log.
> > > Rebooting the single switch attached to vlan2 fixes the
> > > problem as it resets
> > > the int but the errors will start occuring shortly after and
> > > eventually
> > > flood the interface and it drops again.
> > >
> > > OK so they tell me that its something on the vlan2 network
> > > thats causing it,
> > > i on the phone with the router guy one by one shutdown each
> > > device then
> > > unplug each cable from the switch then turn everything back
> > > on one by one,
> > > hoping he will say "ahh there it is what did you just turn
> > > on". Mind you i
> > > thought it is a long shot that one pc could genearate that
> > > much traffic.
> > > Anyhow i borrowed another switch of the same model and
> > > plugged that in for
> > > two days, same problem, i tried a different make swicth, same
> > > problem, we
> > > replaced the cables between the rooms as they are separated
> > > by some 40 mtrs,
> > > all the small patach cables, cables on the router, had them
> > > out the other
> > > day to reconfigure the interface and replace the four port
> > > module, still the
> > > same!!!!!!! Last night we turned everything off bar the
> > > switch with the link
> > > cable to the router plugged in and the router itself and its
> > > still the same.
> > > we have ordered a brand new switch which every network gets
> > > given with this
> > > setup, all configured to their specs in the hope that maybe
> > > one day someone
> > > screwed with ours and didnt document it. If that doesnt fix
> > > it im lost. Has
> > > anyone got any more ideas.
> > >
> > > My guts feeling is somethig the router guy told me the other
> > > day in that he
> > > had to force the router to 100half because that what the
> > > swicth was telling
> > > him it had, yet the swicth was all autosensing. I keep
> > > thinking that its a
> > > speed mismatch which can cause the links to drop. They reckon
> > > its not but i
> > > have my doubts
> > >
> > > If anyone has got any ideas, stupid or otherwise im all ears.
> > >
> > > Thanks Heaps
> > > Greg
> > >
> > > p.s the pcs have been scanned for viruses and spyware before
> > > i got to this
> > > stage.
> > >
> > >
> > >
> > >
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