What does U.U.U signify after ping ?

[David Haggett]

===== Original Message from Thomas Porter <tpo...@dtool.com> at 05/05/00
16:28
>Unreachable?? Why every other ping??
>

===== Comments by david....@readprocess.co.uk (David Haggett) at
05/05/00 16:44
This is a guess, from a newbie. If it's wrong you may shoot me :)

Could it be that somewhere between the source and target there is some load
balancing going on. Every second ping packet is diverted through a
different link, but a link further along has failed.

You just happened to hit the failed link after it had failed, but before the
routing table of the router doing the load balancing had been updated?

Like I say, a mere guess, but is it possible?

--

David W. Haggett Tel: 020 8288 7119
Project Manager Fax: 020 8288 0780
READ Process Engineering A/S (UK)
http://www.readgroup.com/process/

[frint...@my-deja.com]

In article <39127E8E@READ27>,

what does you're traceroute shows? both directions. This show give you a
clue to the path that the packets are taking.

Sent via Deja.com http://www.deja.com/
Before you buy.

[Paul Froutan]

David Haggett wrote:
>
> ===== Original Message from Thomas Porter <tpo...@dtool.com> at 05/05/00
> 16:28
> >Unreachable?? Why every other ping??
> >
>
> ===== Comments by david....@readprocess.co.uk (David Haggett) at
> 05/05/00 16:44
> This is a guess, from a newbie. If it's wrong you may shoot me :)
>
> Could it be that somewhere between the source and target there is some load
> balancing going on. Every second ping packet is diverted through a
> different link, but a link further along has failed.
>
> You just happened to hit the failed link after it had failed, but before the
> routing table of the router doing the load balancing had been updated?
>
> Like I say, a mere guess, but is it possible?
>
> --
>
> David W. Haggett Tel: 020 8288 7119
> Project Manager Fax: 020 8288 0780
> READ Process Engineering A/S (UK)
> http://www.readgroup.com/process/

That is a possiblity. Also, I believe that the routers may not respond
to all packets. There is a limit on how many unreachables, echo
requests, etc. that they respond to.

--
** Please don't send replies to me. Send them to the group and share.
**

Paul Froutan www.rackspace.com
pfro...@rackspace.com
The Pioneers in Outsourced Internet Servers (TM)

[Imre Fitos]

Thomas Porter <tpo...@dtool.com> wrote:
: Unreachable?? Why every other ping??
: I should know this...

I've seen this behavior on routers running early version of CEF switching.

I've also seen it on routers that had duplicate routes (for loadbalancing
for example).

[Farhan Memon]

In fact you could check for some filters
Imre Fitos <b...@danger.island.one.net> wrote in message
news:3914e...@news2.one.net...

[Aaron Leonard]

IOS generally rate-limits its ICMP error generation to 1 per second per
destination (per some recommendation in some RFC, I think maybe 1122.)
So that's you see unreachables on 1/2 of the pings and timeouts on the
other 1/2.

Aaron

---

~ Unreachable?? Why every other ping??
~
~ I should know this...
~
~ Thanks, Tom
~ *****************************
~ Thomas Porter, Ph.D.
~ http://www.dtool.com
~ There is magic in the web.
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~ Othello, Act 3, Scene 4
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