2960-s GLC-FE-100FX packet loss

[gwillis]

Hi,

I have two 2960-s switches with GLC-FE-100FX fibre modules in and I am seeing packet loss over the link that is connected to the modules. When the interface is shutdown and brought back up it always comes up in half duplex even thought it is set to full in the config. I've seen other posts where you have to use the command no duplex then full duplex to get it to come up int full duplex. This does appear to work when I do a show int it says its full duplex however I'm stil seeing 20 - 40% packet loss on the link which suggests to me there is still a speed/duplex issue. The device at the other end is a Cisco 7200 which is set to 100Full. If I plug a Cisco 2811 into the fibre link I get zero packet loss which suggests its a problem with the switch.

I have changed the modules and fibre cables which makes no difference. As I stated at the start I have two 2960's both are showing exactly the same issue. Details of the switch are below the SFP are cisco branded:

Switch Ports Model              SW Version            SW Image

------ ----- -----              ----------            ----------

*    1 28    WS-C2960S-24TS-L   12.2(55)SE5           C2960S-UNIVERSALK9-M

interface GigabitEthernet1/0/25

switchport trunk allowed vlan 380,382,384,386

switchport mode trunk

duplex full

NAME: "GigabitEthernet1/0/25", DESCR: "100BaseFX-FE SFP"

PID: Unspecified       , VID:      , SN: OCP11291456

GigabitEthernet1/0/25 is up, line protocol is up (connected)

  Hardware is Gigabit Ethernet, address is 203a.07d2.1019 (bia 203a.07d2.1019)

  MTU 1500 bytes, BW 100000 Kbit, DLY 100 usec,

     reliability 255/255, txload 1/255, rxload 1/255

  Encapsulation ARPA, loopback not set

  Keepalive not set

  Full-duplex, 100Mb/s, link type is auto, media type is 100BaseFX-FE SFP

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

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

  Last input 17:29:08, output 00:00:01, 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 0 bits/sec, 0 packets/sec

  5 minute output rate 1000 bits/sec, 2 packets/sec

     6973 packets input, 1630298 bytes, 0 no buffer

     Received 1580 broadcasts (1284 multicasts)

     0 runts, 0 giants, 0 throttles

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

     0 watchdog, 1284 multicast, 0 pause input

     0 input packets with dribble condition detected

     128553 packets output, 10257704 bytes, 0 underruns

     0 output errors, 0 collisions, 1 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

Any one have any ideas its driving me mad.

Thanks,

Gareth

[Bilal Nawaz]

Hello, it seems like you are using a SFP only capable of up to 100mb speed, whereas your interface is 1000.

You can get a SFP capable of gigabit speeds:

Gigabit SFPs only support speed 1000, duplex full.

This will need to be done on both sides.

Hope this helps

Sent from Cisco Technical Support iPhone App

[gwillis]

Hi,

Thanks for the suggestion the GLC-FE-100FX module is on the compatibility list on the Cisco site for this switch model. It is being detected by the switch as a 100mb interface. I assumed it just says GigabitEthernet because thats what the config specifies rather than it being an issue with the module compatibility.

Thanks,

Gareth

[Bilal Nawaz]

Hello, since its accepting 100mb speeds then, could you kindly try this:

Interface gix/x
Speed 100
Duplex full

Save the config, reload both sides and see if that works?

Hope this helps

Sent from Cisco Technical Support iPhone App

[gwillis]

Thanks for your help but I cant set the speed, the option is not avaiable.

CSW01SLO(config)#int gi1/0/25

CSW01SLO(config-if)#speed ?

% Unrecognized command

CSW01SLO(config-if)#speed

The only command I can get for speed is when there is no module connected and I can use "speed nonegotiate".

[Bilal Nawaz]

You said that it worked in the 2800 router, what type on interface was that(assuming fastethernet)?
And what type of interface is in the 7200(assuming gigabiteternet)?
In which can we manually set the speed and duplex on the other side?

Could we set both sides to 'auto negotiate' please? Without any duplex full commands, Cisco recommend this approach.

Hope this helps

Sent from Cisco Technical Support iPhone App

[gwillis]

Yes the 2811 is a fastethernet interface, set to 100full it works fine. The 7200 is a fastethernet interface as well. Both ends are fixed at 100full, we have tried autoduplex at both ends and the 2960 always goes to half duplex.

[Bilal Nawaz]

That's strange... Could we do a 'no duplex' on both sides, reset and then either do a 'duplex full' or 'duplex auto'

Sent from Cisco Technical Support iPhone App

[gwillis]

Yes I dont understand it either. I dont control 7200 but the 2811 works without having to do the no duplex at the other end.

[Bilal Nawaz]

Oh I see... Since we know that the 2811 works with the 2960 switch, Can we try plugging the 2811 in to the 7200 so that we can rule out if its a problem with the switch or 7200.
Leave the 2800 router with the same settings as the 2960 when they both are working. And see if you get the same problem.

Sent from Cisco Technical Support iPhone App

[gwillis]

sorry the 2811 doesnt connect to the 2960, the fibre link is either connected to the 2960 or the 2811. Appologies for the confusion.

[Bilal Nawaz]

Oh okay, so we have the router and the switch, both exactly the same config on them in terms of speed and duplex... The router does work properly, but the switch does not..?

Sent from Cisco Technical Support iPhone App

[gwillis]

Yes thats correct.

[Bilal Nawaz]

Hello Gareth,

Please see this thread: https://supportforums.cisco.com/thread/2110218
Seems like the same problem that got fixed with an IOS upgrade..

Hope this helps

Sent from Cisco Technical Support iPhone App

[gwillis]

Thank you I will give it a go