Duplex problems on Catalyst 2960

zach.koncir · ‎11-21-2012

I'm running into a very confusing duplex issue that I just can't figure out.

At one of my sites, I have a 100mbit TLS. For this connection to work properly, the port on my end needs to be setup for 100mbit, full duplex. When I connect the TLS to an interface on my Cisco 2821, configured at 100/full, it works perfectly. Now the confusing part, I'm trying to connect the TLS to a Catalyst 2960. I configure the necessary port for 100/full, and get 'notconnect' on that interface. I set the interface to auto/auto, and it negotiates at 100/half and causes collisions and packet loss.

I have no access to the ISP's switch at this time.

Anybody know what might cause an issue like this?

ALIAOF_ · ‎11-21-2012

Is that 100 Meg TLS coming into one of those Cieana devices? And hand off to you is fiber?

zach.koncir · ‎11-22-2012

TLS hand off is Ethernet. Port is connected to a switch, model unknown, somewhere in the building (which I have no access to).

m.kafka · ‎11-21-2012

the 100/half is the recommended result for autoconfigured 100Mbit/s ports which can't complete the negotiation

notconnected might have several reasons. udld, some port security settings, err-disable settings

what's the show interface, sh errdisable, sh interface transc properties etc...

zach.koncir · ‎11-22-2012

Well I'm going to rule out port security right away because it works at 100/half. Same goes for udld.

Why would I be able to force a router interface to 100/full, but not a switchport?

Here's the switch autoconfiguring 100/half:

Switch#sh int Gi0/4

GigabitEthernet0/4 is up, line protocol is up (connected)

Hardware is Gigabit Ethernet, address is 64ae.0cb9.f084 (bia 64ae.0cb9.f084)

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)

Half-duplex, 100Mb/s, media type is 10/100/1000BaseTX

input flow-control is off, output flow-control is unsupported

ARP type: ARPA, ARP Timeout 04:00:00

Last input 00:00:04, output 00:00:05, output hang never

Last clearing of "show interface" counters never

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 192000 bits/sec, 31 packets/sec

5 minute output rate 49000 bits/sec, 20 packets/sec

12073490 packets input, 7649871485 bytes, 0 no buffer

Received 397983 broadcasts (27912 multicasts)

0 runts, 0 giants, 0 throttles

0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored

0 watchdog, 27912 multicast, 0 pause input

0 input packets with dribble condition detected

12190225 packets output, 9134113547 bytes, 0 underruns

0 output errors, 54848 collisions, 1 interface resets

0 babbles, 88355 late collision, 0 deferred

0 lost carrier, 0 no carrier, 0 PAUSE output

0 output buffer failures, 0 output buffers swapped out

Now forced to 100/full:

Switch#sh int Gi0/4

GigabitEthernet0/4 is down, line protocol is down (notconnect)

Hardware is Gigabit Ethernet, address is 64ae.0cb9.f084 (bia 64ae.0cb9.f084)

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

input flow-control is off, output flow-control is unsupported

ARP type: ARPA, ARP Timeout 04:00:00

Last input 00:00:13, output 00:00:17, output hang never

Last clearing of "show interface" counters never

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 250000 bits/sec, 41 packets/sec

5 minute output rate 26000 bits/sec, 23 packets/sec

12086279 packets input, 7659696828 bytes, 0 no buffer

Received 398465 broadcasts (27945 multicasts)

0 runts, 0 giants, 0 throttles

0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored

0 watchdog, 27945 multicast, 0 pause input

0 input packets with dribble condition detected

12198220 packets output, 9134974749 bytes, 0 underruns

0 output errors, 54882 collisions, 1 interface resets

0 babbles, 88359 late collision, 0 deferred

0 lost carrier, 0 no carrier, 0 PAUSE output

0 output buffer failures, 0 output buffers swapped out

Sebju Varghese · ‎11-22-2012

Does Your TLS device support autonegotiation. Can you try 'speed nonegotiate' on 2960?

Leo Laohoo · ‎11-22-2012

Same goes for udld.

You have UDLD enabled on a copper port???? Turn it OFF! You won't get any benefits unless you have fibre optic.

In regards to the 100 Mbps half duplex, try the interface command "speed auto 100".

Alessio Andreoli · ‎11-22-2012

Hi Zach,
Force the speed to full/100, change cable on your side and issue the speed nonegotiate command below interface config. This should work. By the way, if the collisions increase(issue a clear counters command to reset the value) once you force the duplex parameters , there is a massive possibility that the layer 1 is the problem. Do not keep 100/half because it is a very unstable configuration. Hard coding speed and duplex is a best practise.

Hope this helps
Alessio

Sent from Cisco Technical Support iPad App

ALIAOF_ · ‎11-26-2012

What is the TLS device that Verizon gave you? It can also be an issue with the firmware. I encountered something similar but with Fiber. Found out that the Firmware on the Ciena 311v was way to old to handle the latest IOS on the Cisco switch.

bharat.rajwanshi · ‎11-23-2012

better if you contact with your TLS ISP as they migh have set 100/half thats why you are negotiating with 100/half too, and once you force set it to 100/Full it will break the connection

call them and ask for their device edge setting and request them to set it to 100/Full

Just guessing, problem may be at TLS ISP edge