7911 "Verifying your network connection"

[akutagawa-zachary]

Let me begin by saying I am not by any means a CISCO certified anything.... I am a telecom tech at a school district who manages and supports the infrastructure, installing phones, WAPs, cabling, switches etc.... We assist in the assigning phones to users with the help of a 3rd party programming and support contractor.

When adding or replacing phones, we have a process... I provide user and device naming info, submit to the programmer, the build the phone and I deploy it. We have in house engineers that manage the network.

Our districts cabling is not 100% out dated yet, but there is a lot of upgrades that need to be done and we are actively working on that to replace past years of bad cabling jobs that were not managed correctly and by that we have discovered some installs that are not to spec or standard by industry or the District.

We are currently in the process of replacing 7965 with 7841 (office staff) and 7942 with 7811 (classrooms).... We have had minor issues with the office rollout but some weird issues, especially what has brought me here today with the 7811.

I have read that the phone port itself has known weak soldering, which is concerning, some out of the box brick phones that are out of warranty from CISCO and now this "Verifying your network connection" display I am getting on a 7811.

All settings up and down in CUCM, the network, on the phone have been verified correct. We did a cable test and discovered there are a group of portable buildings that apparently exceed the 100m data cable length (380 feet on this particular phone location). They have been there for a long time but past 7900 series phones work, a short time where we hav d Polycom phones work, the 7841 works BUT the 7811 phone will not connect.

WHY? What is the main difference with the 7811 and the rest of the 7800 series and the 7900 series that would cause this?
With the newly discovered cable issue, we are looking for a re-cable job but will take some time and have decided to use a 7942 in the meantime since we know it works...

Switches are CISCO 3850 / 9300

Any input is appreciated, and again, I am not certified by any means so some tech lingo may not register with me but I will pass on any suggestions or info that could be help understand why...

[pieterh]

no direct sulution, but some consderations in analyzing this issue
apart from the length of the cabling, also type of cabling can contribute in speed auto negotiation

   The IP Phone 7811, 7821, 7841, and 7861
   ◦      Category 3/5/5e/6 for 10-Mbps cables with 4 pairs
   ◦      Category 5/5e/6 for 100-Mbps cables with 4 pairs

   ●  The IP Phone 7841
   ◦      Category 5/5e/6 for 1000-Mbps cables with 4 pairs

=> check what cabling-type is used
    especially check it is 4-pairs, not 4-wires (2-pair)

for the 7811  : The phone supports IEEE 802.3af PoE (Class 1); power consumption does not exceed 3.84 watts.
for the 7942:  Supports IEEE 802.3af PoE (Class 3)
this doesn't look like switching from 7942 to 7811 you will produce more power loss over the long cables,
visa versa would be more problematic., but if possible verify how much power loss occurs on the cable

from WIKWpedia: Power levels available^[40][41]

Class	Usage	Classification current (mA)	Power range at PD (W)	Max power from PSE (W)	Class description
0	Default	0–5	0.44–12.94	15.4	Classification unimplemented
1	Optional	8–13	0.44–3.84	4.00	Very Low power
2	Optional	16–21	3.84–6.49	7.00	Low power
3	Optional	25–31	6.49–12.95	15.4	Mid power

have you tried using a power-brick/adapter  attached to the phone instead of PoE?

after the phone has booted, it need to 
- negotiate speed and duplex for the data-link

- detect the voice-vlan (if configured on the network switch)

- request a DHCP address

all of this can go wrong when the cabling is too long
=> you need your network guys to monitor the switch end 

one more reminder, the advised 100m limit is end-to-end , so not only the building cabling-system, but including any patch-cables from switch to distribution panel and from wall-outlet to device

[akutagawa-zachary]

Here is a test result using a network tester LinkRunner - (1) test from Switch port (2) test from outlet

Hopefully you can see it...

[pieterh]

this part of output seems all right ,
- correct data-wires used  (1,2,3,6)
- PoE supplied is OK

"no response from DHCP"   sounds problematic enough ?
if this also goes for the voice vlan then your phone does not get an ip-address to communicate

1) does your network use port-authentication ? (MAB or DOT1x)
if so you may need to authenticate first before getting an ip-address, and then the "no response...." is less problematic

2) if there is no DHCP server in your network, the the current phones may have been configured with a fixed IP-addresss ?
if so you should transfer that to the new phone

3) it could also be in the process of replacing the office staff phones, you have run out of available IP-adresses in your DHCP-scope
(the remain reserved for devices already replaced)
-> you need to clear the DHCP lease/reservation for the old phones, so they come available for new devices

[akutagawa-zachary]

I did forget to mention... the 7811, when originally deployed, it registered. Then the user reported that it was not working. Seems that in the mornings it would be registered, then a few hours later it would be trying to verify the network. This would not happen everyday, but happened. Also, the IDF that is running this set of portables does not have a lot of traffic - (10) phones, (10) WAPs, maybe (5) PCs or printers connected and maybe (5 - 7) users at peak usage.

The 7841 "test phone" that I pulled from a room closer to the IDF worked for almost 24 hours in the trouble room with no issues. The 7811 that has the problem, worked fine in the room closer to the IDF for the same time period. I have a 7942 in the trouble room now and has been working fine with no issues.

I am confident that that all the settings, allowances, licensing etc are correct. I am convinced that the cable length is the issue but not understanding if the 7811 requires less power than the other models why is a POE loss an issue? Or is the phone itself not able to pull or request more power over the long distance as maybe the other models will / can and making them able to register?

If that is the case, what feature / component does the 7811 lack is what I am trying to learn.

We do not have a ton of cable length issues in the district. But we tend to correct those issues when we find them.

I appreciate and thank you for your effort and input on this. All is being forwarded to our engineers and programmers for reference and trouble log report.

[pieterh]

>>> I did forget to mention... the 7811, when originally deployed, it registered. Then the user reported that it was not working. Seems that in the mornings it would be registered, then a few hours later it would be trying to verify the network. This would not happen everyday, but happened <<<

in my opinion this is consistent with  problems acquiring a DHCP-address
when another  device  has disconnected, then that IP-address is released and can be assigned to the phone (in the morning)
DHCP leases need to be renewed during the lease interval, this may not happen correctly
and later on the day some other device "steals" the address of the phone
=> investigate the DHCP infrastructure
and investigate the voice-vlan is properly configured on the switch-ports