[c-nsp] Simultaneous drops - 2 upstream providers

Tue Aug 20 03:41:20 EDT 2013

Hi - No we are not doing any stp to our upstreams.

Date: Tue, 20 Aug 2013 09:15:14 +0200
Subject: Re: [c-nsp] Simultaneous drops - 2 upstream providers
From: mrantoinemonnier at gmail.com
To: cisconsp_list at hotmail.com
CC: mattias at gyllenvarg.se; ikiris at gmail.com; cisco-nsp at puck.nether.net

I thought fibre optic cable were immune from electrical interference.
What about Spanning-Tree ? Is your 3750X talking STP with any of the third party equipment?

On Tue, Aug 20, 2013 at 7:16 AM, CiscoNSP List <cisconsp_list at hotmail.com> wrote:

Not that I am aware of, and not that they have advised (I have asked)

fibre x-connect to carrier A from our rack, ME3400 in our rack for carrier B to x-connect back to there rack

Can electrical interference cause something like this on the x-connects? (And not present as drops/errors on the ports?)

Going to try an alternate port on the 3750 tonight for carrier A

Date: Tue, 20 Aug 2013 07:03:45 +0200

Subject: Re: [c-nsp] Simultaneous drops - 2 upstream providers

From: mattias at gyllenvarg.se

To: cisconsp_list at hotmail.com

CC: ikiris at gmail.com; cisco-nsp at puck.nether.net

A and B uses A or Bs infrastructure at eighter end of the link? Or a common third party somewhere in the signal path.

Den 20 aug 2013 05:23 skrev "CiscoNSP List" <cisconsp_list at hotmail.com>:

Thanks Blake -

Both links (that drop) are doing minimal traffic (One is only a backup link, so isnt used) - the link that is not affected is doing ~100-150Mb/sec, Carrier A link is doing 5-10Mb/sec and Carrier B virtually zero(As it's a backup link as mentioned)....seeing minimal output drops on each port

All links are Gb (physical), and carrier rate limits (Carrier A 50M, Carrier B 200M and carrier C 1Gb)

From: ikiris at gmail.com

Date: Mon, 19 Aug 2013 21:51:10 -0500

Subject: Re: [c-nsp] Simultaneous drops - 2 upstream providers

To: cisconsp_list at hotmail.com

CC: cisco-nsp at puck.nether.net

You don't give too much information here, so its hard to speculate.

My guess as to the first thing to check would be out of buffer drops on the 37x, but like I said above, it's only really a wild guess, since you don't specify port layout or link speeds. You can verify by looking at the ASIC stats, as the interface stats can be unreliable for that type of drop.

-Blake

On Mon, Aug 19, 2013 at 9:11 PM, CiscoNSP List <cisconsp_list at hotmail.com> wrote:

Hi - bit of a strange one - We have 3 interpop links (3 different carriers) terminating on a 3750X+ASR at one of our POPs, and are seeing intermittent drops on 2 of the links(And ospf loses adjancency) at the same time

Carrier A - POPA -> POPB - We see drops/ospf adjancency issues once/twice a dayCarrier B - POPA -> POPC - We see drops/ospf adjancency issues once/twice a dayCarrier C - POPA -> POPB - No issues at all

All links terminate on the same 3750, and then are trunked to an ASR1006 for L3 - There are no errors/physical link issues on the 3750, and both carriers also do not see any errors/link drops.

It would be improbable that both carriers have issues on there networks at precisely the same time, so it is either our switch(3750), or something weird happening with the x-connects that doesnt cause the links to drop, doesnt cause any errors etc, but causes ospf to lose adjacency (but only for 2 providers, not the third?)

Any suggestions/assistance is greatly appreciated

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