The device must remain listening on a port in case another device on the subnet 
is upgrading and needs the firmware.



On Nov 22, 2016, at 9:02 AM, Pawlowski, Adam 
<[email protected]<mailto:[email protected]>> wrote:

I just want to ask this – and it may be unrelated – but it can’t hurt.

When we had attempted to use “Peer Firmware Sharing” in the past, it was a 
total disaster. We applied a new load and a large percentage of devices just 
sat there and did nothing on the firmware download screen until they were 
reset. That was …. Several years ago.

Since it was suggested earlier that we go and look at settings to see what is 
going on, I noted that a number of these devices have PFS enabled in the 
configurations somehow. I plan to turn it off, but, before I do – my 
understanding is that this mechanism is idle once the phone is booted and is 
only applicable when an upgrade is taking place. There are a couple of bugs out 
there for UDP traffic to the PFS port causing issues with the phone, as well as 
the phones getting stuck in configuring IP and not functioning (we have seen 
some at this site just bomb off and refuse to do anything other than arp for 
the gateway, despite a successful DHCP transaction. They won’t communicate with 
anything on the same subnet either until power cycled). Some of these bugs seem 
to be open or in 9.4(2) in general.

Is this mechanism still “alive” while the phone is operating?  Again I plan to 
turn it off, but, just curious.

Adam



From: [email protected]<mailto:[email protected]> [mailto:[email protected]] 
On Behalf Of Brian Meade
Sent: Monday, November 21, 2016 10:55 AM
To: Wes Sisk (wsisk)
Cc: Pawlowski, Adam; 
[email protected]<mailto:[email protected]>
Subject: Re: [cisco-voip] Traffic Issues with 7900 Series Phones

Also are you running any XML applications on the phones that may be bogging 
down the CPU?

On Tue, Nov 15, 2016 at 11:31 AM, Wes Sisk (wsisk) 
<[email protected]<mailto:[email protected]>> wrote:
Adam,

Are you using dot1x? There are some interesting things in that space.

Otherwise, maybe get 9.4.2es3 to pickup the fix for
CSCuq88325    7965 7945 excessive core files cause phone stability problems


-w


On Nov 15, 2016, at 8:50 AM, Pawlowski, Adam 
<[email protected]<mailto:[email protected]>> wrote:

All,

We’re still looking at this with TAC, though the initial response was that the 
7941, 7961, etc done with hardware and software support. There was an 
announcement on October 20th that said software maintenance ended immediately 
(oops). Our timers and such are ubiquitous across our network, all defaults, 
and we don’t have this problem elsewhere. I went with looking for MAC change 
traps and didn’t run into anything, going down that road. The phones don’t log 
any VLAN changes either in their logs.  The phones are going out of service for 
UCM Closed TCP or UCM Reset TCP, and we see what looks like the UCM not 
responding back with the proper SCCP KeepAliveAck, which causes the phone to 
sort of do nothing for 60 seconds. By then, since both the phone is waiting 
60.0 seconds and the UCM is as well to hear from it, the connection is reset 
and closed.

Phones that are not sharing the data VLAN have been fine, but, we cannot 
implement that across this entire area due to the needed cabling, switchports, 
etc.

In another location we have these phones going what appears to be high CPU – 
the latency on the phone goes way up, with ICMP response, the response of the 
phone to buttons and actions, and the call suffers from high jitter and broken 
conversations. Oddly enough, when we cap with SPAN enabled on the phone, the 
data looks fine going through it. Power cycling the phone clears this 
temporarily.

Everyone thus far has wanted to go down the road of loss somewhere on the 
network, but, as we continue to take captures, we see the conversation complete 
at the UCM, and beyond the phone via “SPAN to PC port”, or at it with SPAN at 
the edge – the phone application itself is simply not responding in a timely 
manner, at least based on initial observation.

Given the earlier response that these devices are now done with support, this 
does not bode well, but, we are still looking.

Regards,

Adam Pawlowski
SUNYAB NCS

From: Wes Sisk (wsisk) [mailto:[email protected]]
Sent: Tuesday, November 08, 2016 12:50 PM
To: Pawlowski, Adam
Cc: Tommy Schlotterer; 
[email protected]<mailto:[email protected]>
Subject: Re: [cisco-voip] Traffic Issues with 7900 Series Phones

Not much visibility into L1/L2 on those phones; drop counters on the webpage or 
phone UI is about all you get.

Are the phones randomly unregistering? This is good baseline: 
https://supportforums.cisco.com/document/52176/understanding-sccp-phone-unregistration-and-failover-networks-perspective

If some sort of frame issue, correct, not many options.

What are the nature of messages being retransmitted?
Also, anything interesting looking in the log files?

One age old odd one is CDP timers out of sync btwn phone and switch. Phone 
keeps IP but gets dumped into data vlan.  Your choice on how to approach that.

One possibility: If phones are unregistering then check the lastoutofservice 
reason on the phone, in the CM traces, or in the RTMT reports if you’re on a 
new enough version. I *think* we got these phones fixed to say “vlan change’ or 
‘cdp timeout’ or ‘ip change’ something like that if there were changes in the 
network interface.

Alternatively take a few phones stick them in a port that not trunked but in 
the voice vlan… do these exhibit the same problem?

next ‘heuristic’ guess after that is possibly arp cache refresh on the switch. 
have seen several issues where arp cache timeout was set low, switch re-arp for 
many devices concurrently, arp response dropped by input queue overflow and 
input queue drop. net result the switch ‘forgets’ which port that phone is on.

So…. where do the packets/frames EXIST and NOT EXIST in the network?

-Wes

On Nov 4, 2016, at 4:32 PM, Pawlowski, Adam 
<[email protected]<mailto:[email protected]>> wrote:

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:[email protected]]
Sent: Friday, November 04, 2016 12:52 PM
To: Pawlowski, Adam
Cc: Tommy Schlotterer; 
[email protected]<mailto:[email protected]>
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 
<[email protected]<mailto:[email protected]>> 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:[email protected]]
Sent: Wednesday, November 02, 2016 2:37 PM
To: Pawlowski, Adam; 
[email protected]<mailto:[email protected]>
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<http://www.presidio.com/>
20 N. Saint Clair, 3rd Floor, Toledo, OH 43604
D: 419.214.1415<tel:419.214.1415> | C: 419.706.0259<tel:419.706.0259> | 
[email protected]<mailto:[email protected]>

-----Original Message-----
From: cisco-voip [mailto:[email protected]] On Behalf
Of Pawlowski, Adam
Sent: Wednesday, November 02, 2016 2:23 PM
To: [email protected]<mailto:[email protected]>
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
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