POE on a 3750g

[dspitzer]

Hello All,

I have a Cisco 3750g up and running right now. We are rolling out an Avaya phone system with 4610 phones using the poe option on the switch. Currently when you plug a phone it it does not get any power. All of the ports are set for auto sensing. If I disable and enable the port the phone comes right up. Any ideas would be great.

Thanks

 

[VinceWhirlwind]

What does your switchport config look like?

 

[dspitzer]

Here is some of the config:

Name: Gi5/0/38
Switchport: Enabled
Administrative Mode: dynamic auto
Operational Mode: static access
Administrative Trunking Encapsulation: negotiate
Operational Trunking Encapsulation: native
Negotiation of Trunking: On
Access Mode VLAN: 1 (default)
Trunking Native Mode VLAN: 1 (default)
Administrative Native VLAN tagging: enabled
Voice VLAN: 100 (Voice-Vlan)
Administrative private-vlan host-association: none



Transmit GigabitEthernet5/0/38 Receive
713378405 Bytes 50022152 Bytes
802946 Unicast frames 382597 Unicast frames
3217869 Multicast frames 28 Multicast frames
2883791 Broadcast frames 5671 Broadcast frames
0 Too old frames 49043862 Unicast bytes
0 Deferred frames 3076 Multicast bytes
0 MTU exceeded frames 799582 Broadcast bytes
0 1 collision frames 0 Alignment errors
0 2 collision frames 0 FCS errors
0 3 collision frames 0 Oversize frames
0 4 collision frames 0 Undersize frames
0 5 collision frames 0 Collision fragments
0 6 collision frames
0 7 collision frames 215216 Minimum size frames
0 8 collision frames 111680 65 to 127 byte frames
0 9 collision frames 30973 128 to 255 byte frames
0 10 collision frames 19910 256 to 511 byte frames
0 11 collision frames 1495 512 to 1023 byte frames
0 12 collision frames 9022 1024 to 1518 byte frames
0 13 collision frames 0 Overrun frames
0 14 collision frames 0 Pause frames
0 15 collision frames
0 Excessive collisions 0 Symbol error frames
0 Late collisions 0 Invalid frames, too large
0 VLAN discard frames 0 Valid frames, too large
0 Excess defer frames 0 Invalid frames, too small
3223808 64 byte frames 0 Valid frames, too small
3231076 127 byte frames
96224 255 byte frames 0 Too old frames
176941 511 byte frames 0 Valid oversize frames
94449 1023 byte frames 0 System FCS error frames
82108 1518 byte frames 0 RxPortFifoFull drop frame
0 Too large frames
0 Good (1 coll) frames
0 Good (>1 coll) frames

GigabitEthernet5/0/38 is up, line protocol is up (connected)
Hardware is Gigabit Ethernet, address is 0015.620a.ffa6 (bia 0015.620a.ffa6)
Description: IP Phone + PC
MTU 1500 bytes, BW 100000 Kbit, DLY 100 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive set (10 sec)
Full-duplex, 100Mb/s, media type is 10/100/1000BaseTX
Media-type configured as connector
input flow-control is off, output flow-control is unsupported
ARP type: ARPA, ARP Timeout 04:00:00
Last input never, output 2w6d, output hang never
Last clearing of "show interface" counters 2w0d
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: fifo
Output queue: 0/40 (size/max)
5 minute input rate 0 bits/sec, 0 packets/sec
5 minute output rate 1000 bits/sec, 1 packets/sec
208574 packets input, 25582408 bytes, 0 no buffer
Received 2701 broadcasts (0 multicast)
0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
0 watchdog, 23 multicast, 0 pause input
0 input packets with dribble condition detected
4506062 packets output, 441836682 bytes, 0 underruns
0 output errors, 0 collisions, 2 interface resets
0 babbles, 0 late collision, 0 deferred
0 lost carrier, 0 no carrier, 0 PAUSE output
0 output buffer failures, 0 output buffers swapped out

interface GigabitEthernet5/0/38
description IP Phone + PC
switchport voice vlan 100
srr-queue bandwidth share 1 25 75 5
priority-queue out
mls qos trust dscp
no cdp enable
spanning-tree portfast

5 52 WS-C3750G-48PS 12.2(25)SEB2 C3750-IPBASE-M
Administrative private-vlan mapping: none
Administrative private-vlan trunk native VLAN: none
Administrative private-vlan trunk Native VLAN tagging: enabled
Administrative private-vlan trunk encapsulation: dot1q
Administrative private-vlan trunk normal VLANs: none
Administrative private-vlan trunk private VLANs: none
Operational private-vlan: none
Trunking VLANs Enabled: ALL
Pruning VLANs Enabled: 2-1001
Capture Mode Disabled
Capture VLANs Allowed: ALL

Protected: false
Unknown unicast blocked: disabled
Unknown multicast blocked: disabled
Appliance trust: none

 

[DallasBPF]

can you also do a show power inline and post that?

------------------------------------
Dallas, Texas
Telecommunications Tech
CCVP, CCNA, Net+

CCNP in the works

 

[dspitzer]

Gi5/0/38 auto on 7.0 Ieee PD 2 15.4

 

[DallasBPF]

its not near the max power of 15.4, but you said it works fine and boots up only AFTER you shut/no shut the interface, correct?

------------------------------------
Dallas, Texas
Telecommunications Tech
CCVP, CCNA, Net+

CCNP in the works

 

[VinceWhirlwind]

I wouldn't use "Switchport Voice" for non-Cisco phones. Plus with CDP disabled, it looks a bit odd. Without CDP, I didn't think "Switchport Voice" could work.

Normally, for non-Cisco phones, I would configure the ports as .1q trunks (not auto-negotiate) and then define the native VLAN and prune it to the required Voice/Data VLANs. And then change it to spanning-tree portfast trunk.
sw tr en do
sw mo tr
sw tr nat vlan 10
sw tr all vlan 10,100
spanning-tree portfast tr

You can enable LLDP instead of CDP, if Avaya phones use LLDP.

 

[dspitzer]

Dallas, yes after I disable and enable the port works just fine.

 

[ADB100]

Normally, for non-Cisco phones, I would configure the ports as .1q trunks (not auto-negotiate) and then define the native VLAN and prune it to the required Voice/Data VLANs. And then change it to spanning-tree portfast trunk.

This isn't needed and isn't recommended with Cisco or any other vendor's IP Phones. Only Cisco & Mitel phones will use CDP to discover the Voice VLAN, however other methods exist to inform the IP Phones of the voice VLAN. Ericsson/Aastra, Nortel & Avaya all use DHCP - they boot on the access VLAN and via DHCP options discover the Voice VLAN, they then release the IP address and restart using 802.1q tagged frames.
Although the functionality of an Access port configured like this:

switchport mode access
switchport access vlan 10
switchport voice vlan 100

is the same as a trunk configured like this

switchport trunk encapsulation dot1q
switchport mode trunk
switchport nonegotiate
switchport trunk native vlan 10
switchport trunk allowed vlan 10,100

there are other implations of hard-coding the port as a trunk which is why I wouldn't recommend it.
I have sucessfully deployed several Nortel, Ericsson & Mitel IP Telephony systems using access ports with voice vlans.

Back to the original problem though... Are you plugging the phones directly into the switch using a fully-wired patch cable (i.e. not via the infrastructure cabling)? Are you trying to hard-code speed & duplex (don't....). Have you done any debugging?

Andy

 

[dspitzer]

We have done debbugging to no avail. The config for the ports is correct. The issue is with the ports seeing that power is needed. We are going to try a upgrade to see if that will help.

 

[VinceWhirlwind]

I've always understood from Cisco that non-cisco devices should have a proper .1q trunk configured.

For example:

http://www.cisco.com/en/US/products...s_configuration_example09186a0080891554.shtml

It doesn't make a huge difference, I suppose, because you end up with something similar in either case.

Like you, I have deployed Nortel, Ericsson and Siemens IP phones using my particular bias when it comes to switch configuration.

Not that I've often had power issues. Once I found a switch that was refusing to grant power due to being "out of memory", which was somehow caused by a damaged stackport.

To try to get to the bottom of this, I would try plugging a whole lot of phones into switch ports that are all configured differently:
- nail a port to 100 Mb
- power inline auto
- power inline static

Show us a show int after you've plugged the phone in and while it's still in the "not giving any power" state?

 

[burtsbees]

Andy...

"Only Cisco & Mitel phones will use CDP to discover the Voice VLAN"

I have some Polycom phones going to an Adtran T1 L3 switch (PoE, basically a Cisco!) that they say can use CDP. The phones are SPIP-500/501

Burt

 

[VinceWhirlwind]

I recall HP switches used CDP until firmware updates in 2005/2006.

Don't forget Cisco supports LLDP, though, if your phones support it.

 

[ADB100]

I wasn't aware any of the Polycom phones supported CDP, however don't Cisco rebadge the conference stations? In which case it makes sense for them to port the CDP code across.

LLDP - now theres a thing. Yes this should work but its only supported on the newer Catalysts (2960, 3560, 3750) and 6500's. For some reason (to sell more product...) Cisco have refused to add LLDP to the older switches. I know Nortel support LLDP as well as the newer Cisco IP Phones. Ericsson/Aastra certainly don't in the latest firmware but its supposed to be coming? Not sure about Mitel or Avaya?

Andy

 

[tanderson3733]

Avaya does support LLDP. Avaya phones also work with either switchport voice vlan OR 802.1Q trunk ports using DHCP/Text files to configure VLAN assignment.

 

[dspitzer]

Thanks for the help. I just manually reset the ports as we installed the phones. There is a bug in there somewhere. Hopefully updating the IOS will fix it.

 

[gulan]

I have heard, If we add one by one Avaya or Nortel IP Phones to cisco switches (mostly 48 port), SOME TIMES last couple of phone finds not enough power to bootup. This usually happens when all the 48 ports are used.