Issue with Cisco ip phones plugged into 9200L
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10-11-2021 12:40 PM
Hi Guys
we have come across an issue with one of our new switches, a Cisco 9200L, we have tried the latest firmware, 17.3.4 as well as 17.3.1
basically what we are seeing is the phone is not picking up dhcp when plugged into this switch, we see the MAC address and the phone in dsp neighbours, the switch port is configured for voice vlan.
if we plug the same phone or another model phone into another switch next to it it works fine, the config is identical on both switches.
any ideas what this could be?
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LAN Switching
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10-11-2021 12:58 PM
Are both the switches the same model and the same IOS XE ?
1. do you have uplink port config trunk same config?
2. can you post interface config to look.
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10-11-2021 01:54 PM
Hi
it’s basically the below
switchport access vlan 10
switchport mode access
switchport voice vlan 20
spanning-tree portfast
Auto qos voip Cisco-phone
The other switch is a 2960x
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10-11-2021 02:19 PM
Hello,
does Vlan 20 exist on the switch, and is the SVI for that Vlan reachable from that switch ?
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10-11-2021 02:41 PM
hi, yes to both
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10-11-2021 03:06 PM
Hello,
make sure CDP is enabled on the switch...
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10-12-2021 05:13 AM
Like to see full configuration if possible,
Auto qos voip Cisco-phone - did this created any Global config ?
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10-11-2021 03:16 PM
Does any of the switch members of the stack have any SFP/SFP+ inserted?
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10-12-2021 12:02 AM
Hi, no they dont, its a single switch uplinked via copper
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10-12-2021 12:25 AM
Does the phone work in the same switch but different ports?
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10-22-2021 03:54 AM
Hi Guys
An update on this, we have had to log it with TAC and we are waiting for a response.
Basically we have seen that when we enable auto qos voip cisco-phone it stops working, we have done a packet capture and can confirm that when this command is enabled the switch is not sending any cdp packets, so the phone will never know which voice vlan to tag the packets with, this explains it.
I can only think it may be a bad batch of hardware as our older 9200Ls have this command and its running fine, even with the same firmware.
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10-23-2021 04:36 PM - edited 10-23-2021 04:37 PM
@carl.townshend wrote:
Basically we have seen that when we enable auto qos voip cisco-phone it stops working, we have done a packet capture and can confirm that when this command is enabled the switch is not sending any cdp packets
Thanks for the update, @carl.townshend. Keep us posted for any developments.
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10-25-2021 02:53 AM
Hi All
TAC have come back with a fix for this, a special release of software 17.3.4.b was released week just to fix this issue. It only applies to hardware versions v02 and v03, so I was right in my initial thinking of that it was a hardware issue and a bug fix has been put in place to resolve it. Basically when the QOS was enabled, it caused all traffic to drop in the output queue.
It is a shame as this has taken 2 days of 2 engineers time to get to the bottom of it.
cheers
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10-25-2021 03:03 AM
@carl.townshend wrote:
It is a shame as this has taken 2 days of 2 engineers time to get to the bottom of it.
Pray this bug (CSCvz76172) is really fixed in 17.3.4b.
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06-02-2022 03:41 PM
Thanks for updating this thread with your resolution - helped me out today when I ran into this issue with three 9200L-24 switches that I went to install and couldn't figure out why phones weren't working, but PCs plugged directly into the ports were. Upgraded one of the switches to 17.3.4b and the phone on it is working now. I never would have thought CSCvz76172 was the issue, based solely on the description of the bug.
