[cisco-voip] Cisco 8851 not failing over to backup circuit...

[Jonathan Charles]

Just says 'registering'... we did a packet trace and it just shows an
invite and a couple of refers, but no responses to it...



Jonathan

On Fri, Apr 24, 2015 at 4:34 PM, Ryan Huff <ryanhuff at outlook.com> wrote:

> Are you able to see the physical phone during the event? What is the
> physical phone's behavior?
>
> Does the physical phone show un regestered or does the phone show the new
> ccm/tftps addresses eventhough it doesn't register?
>
> Whst load version on the 8851's?
>
> Thanks,
>
> Ryan
>
>
> -------- Original Message --------
> From: Jonathan Charles <jonvoip at gmail.com>
> Sent: Friday, April 24, 2015 04:19 PM
> To: "Chris Ward (chrward)" <chrward at cisco.com>
> Subject: Re: [cisco-voip] Cisco 8851 not failing over to backup circuit...
> CC: cisco-voip at puck.nether.net
>
> Cranked the MTU to 1500, no change, dropped it down to 1100, no change...
> they will not register over the backup link... we have confirmed full
> connectivity over this link...
>
>
> Jonathan
>
> On Fri, Apr 24, 2015 at 11:22 AM, Chris Ward (chrward) <chrward at cisco.com>
> wrote:
>
>>  VPN registration issues usually point to MTU issues. Or at least packet
>> or fragments due to MTU issues. I suspect there is a different in packet
>> size during the registration of these two devices or capabilities that
>> affects packet size.
>>
>>
>>
>> When the primary link is down, you could run some ping tests while
>> setting the ping size to 1X00 and setting the DF bit as well, this will
>> help you find the max size packet with overhead that can fit over the
>> tunnel. Typically VPN tunnels take at least 80 bytes of overhead, so the
>> largest MTU I would expect you could fit over the tunnel would be 1420.
>>
>>
>>
>> I would try and adjust your tunnel MTU down to 1400 or even 1300 just as
>> a test to see if it helps. (In my demo setups with EZVPN tunnels, I can
>> only use 1350 max) Also, are your VPN endpoints able to fragment packets or
>> clear DF bits so that they can fragment large packets? If you can clear
>> df-bit at the interface, that may help move some of the larger packets
>> through IF they have the DF-bit set.
>>
>>
>>
>> +Chris
>>
>> TME - Unity Connection and MediaSense
>>
>>
>>
>> *From:* cisco-voip [mailto:cisco-voip-bounces at puck.nether.net] *On
>> Behalf Of *Jonathan Charles
>> *Sent:* Friday, April 24, 2015 11:44 AM
>> *To:* Charles Goldsmith
>> *Cc:* cisco-voip at puck.nether.net
>> *Subject:* Re: [cisco-voip] Cisco 8851 not failing over to backup
>> circuit...
>>
>>
>>
>> MTU was set to 1440, we set it to Auto, no change...
>>
>>
>>
>>
>>
>>
>>
>> Jonathan
>>
>>
>>
>> On Thu, Apr 23, 2015 at 10:13 PM, Charles Goldsmith <wokka at justfamily.org>
>> wrote:
>>
>> What's your MTU over the backup VPN?  I've seen odd issues on some
>> networks with different providers and MTU and fragmenting packets
>> always caused issues until the MSS was set.
>>
>> I'm not sure why this would affect the 8851's, but we've noticed some
>> other oddities with the 8851's.  For instance, computers with intel
>> nic's behind the phone have issues after we apply config, and we
>> narrowed it down to intel gigabit master slave mode setting on the
>> driver, at least, setting that to slave instead of auto resolves the
>> problem.  Otherwise, you have to reboot the phone a couple of times to
>> get consistent connection through the 8851.  Phones are connected to a
>> 2960 with a basic config, nothing out of the ordinary.
>>
>>
>> On Thu, Apr 23, 2015 at 6:35 PM, Jonathan Charles <jonvoip at gmail.com>
>> wrote:
>> > We have CUCM 8.6.2 with Cisco 8851, Cisco 8831 phones at a remote
>> location;
>> > they are connected over MPLS and a Peplink Balance VPN as a backup.
>> >
>> > When we yank the MPLS, the 8831 registers with CUCM and works fine....
>> the
>> > 8851s do NOT.
>> >
>> > Any reason the 8851 would act differently?
>> >
>> >
>> >
>> >
>> > Jonathan
>> >
>>
>> > _______________________________________________
>> > cisco-voip mailing list
>> > cisco-voip at puck.nether.net
>> > https://puck.nether.net/mailman/listinfo/cisco-voip
>> >
>>
>>
>>
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://puck.nether.net/pipermail/cisco-voip/attachments/20150424/335d5f91/attachment.html>