[cisco-voip] Traffic Issues with 7900 Series Phones

[Pawlowski, Adam]

Wes,

	Thanks, that's good to know about ICMP. We've seen phones that get into a state where they reply with response times all over the board, lossy, which, Reset/Restart from the UCM does not rectify. Powering the device down does clear the condition - the set is otherwise idle. I need to get into one of those via SSH and pull the CPU to see if it is up at that time, to see if there's an identifiable process that covers this. 

	We did get some captures from in front of the firewall where the UCM resides, and from a monitor session from the switch out at the edge where the phone is connected. We can see the UCM sending re-transmissions to the phone, and the phone eventually replying some time later. Unless there is a reason for us to try and get a copper tap on the segment between the switch and the phone, then, it would seem to be that there is some reason the phone is not replying to the UCM. There is nothing behind the phone, or any output buffer drops. Our delay here in reply is in some number of seconds, so I don't believe there's any buffering involved that would be to that extent.  

	What I fear is that if we get to a point where we can determine there is some frame that is an issue, these devices are past the point of any patching being done.... as of a few weeks ago. But, since replacing phones is not free and takes a bunch of time, I still have to come up with something. I only saw a bug for large sized ICMPv6 with nothing particularly helpful in the wording and the workaround of "don't do that" so I'm not hopeful. 

	We have our AM and SE aware of what is going on, and they've offered to help, so I'm hopeful we can eventually confirm the reason we're having trouble, even if we can't directly fix it.


Adam

> -----Original Message-----
> From: Wes Sisk (wsisk) [mailto:wsisk at cisco.com]
> Sent: Friday, November 04, 2016 12:52 PM
> To: Pawlowski, Adam
> Cc: Tommy Schlotterer; cisco-voip at puck.nether.net
> Subject: Re: [cisco-voip] Traffic Issues with 7900 Series Phones
> 
> Phones process ICMP traffic with low priority and throttling. This was
> implemented to stem DoS attempts. Consider looking more at Voice Quality
> effects, retransmits in packet captures, or parsing CCM traces for round
> trip times. As you state these phones are relatively late in life and
> therefore relatively stable.
> 
> -Wes
> 
> 
> On Nov 2, 2016, at 2:42 PM, Pawlowski, Adam <ajp26 at buffalo.edu> wrote:
> 
> Tommy,
> 
> 	Sorry about that. These are a mixed bag. 41/61 both G and G-GE
> phones, with the gigabit ones primarily. Some SCCP, some SIP, mostly
> 9.4.2SR1-1, but seen on 9.4.2SR2-2. PC attached or not, no difference, the
> only difference we've been able to create that stops this, is changing the
> data VLAN that runs through the phone to a different one, or something
> null (with no PC).
> 
> Adam
> 
> > -----Original Message-----
> > From: Tommy Schlotterer [mailto:tschlotterer at presidio.com]
> > Sent: Wednesday, November 02, 2016 2:37 PM
> > To: Pawlowski, Adam; cisco-voip at puck.nether.net
> > Subject: RE: Traffic Issues with 7900 Series Phones
> >
> > What specific Models of phones eg. 41s/61s? or 40s/60s?
> >
> > Thanks
> >
> > Tommy
> >
> > Tommy Schlotterer | Systems Engineer
> > Presidio | www.presidio.com
> > 20 N. Saint Clair, 3rd Floor, Toledo, OH 43604
> > D: 419.214.1415 | C: 419.706.0259 | tschlotterer at presidio.com
> >
> > -----Original Message-----
> > From: cisco-voip [mailto:cisco-voip-bounces at puck.nether.net] On Behalf
> > Of Pawlowski, Adam
> > Sent: Wednesday, November 02, 2016 2:23 PM
> > To: cisco-voip at puck.nether.net
> > Subject: [cisco-voip] Traffic Issues with 7900 Series Phones
> >
> > After much hair pulling and frustration, I wanted to ask the group
> > here in case anyone has seen this or has any thought on what we should
> > be looking for.
> >
> > We have a number of 7900 series phones that have been exhibiting
> > issues that appear to me to be that the phone is getting hung up on
> something.
> > Some sort of frame or packet is screwing with the network chip/board
> > or the OS which is causing it trouble. I see missed traffic, missed
> > responses, high ICMP echo times - and phones that eventually get stuck
> > with their ICMP echo response times being all over the board - with
> > some report of call trouble and CMR showing crazy jitter. If I power
> > cycle the phone that clears and it works fine for a while.
> >
> > I realize these items are pretty much end of useful life, pretty much
> > all done with software support, and are going to drop off of the
> > compatibility matrix and probably functional support in the near
> > future. But, while we still have a ton of them - has anyone noted any
> > particular type of traffic that causes the 7900 series phones grief?
> >
> > I don't have loss on the network, there do not seem to be any
> > transient broadcast storms rolling by. We do see an increased amount
> > of mDNS, IPv6 (phones are v4 only) etc, but nothing stands out as
> > causing a particular problem. It just seems that whatever this is, is
> > causing a memory leak or something, wherein it gets bad enough that
> things go to hell eventually.
> >
> > Any thoughts?
> >
> > Adam P
> > SUNYAB
> > _______________________________________________
> > cisco-voip mailing list
> > cisco-voip at puck.nether.net
> > https://puck.nether.net/mailman/listinfo/cisco-voip
> >
> >
> > This message w/attachments (message) is intended solely for the use of
> > the intended recipient(s) and may contain information that is
> > privileged, confidential or proprietary. If you are not an intended
> > recipient, please notify the sender, and then please delete and
> > destroy all copies and attachments. Please be advised that any review
> > or dissemination of, or the taking of any action in reliance on, the
> > information contained in or attached to this message is prohibited.
> 
> _______________________________________________
> cisco-voip mailing list
> cisco-voip at puck.nether.net
> https://puck.nether.net/mailman/listinfo/cisco-voip