Catalyst 3560 <-> 3560 Bandwidth / Error Issues

caymanport · ‎10-02-2015

We have a pair of Cisco Catalyst 3560 switches that are connected using a leased (from the local telco) gigabit single-mode fiber. It is about 2 miles line of sight between the switches but I don't know how long the actual cable run is. This line is receiving very low bandwidth and looking at the link stats, one side is showing an ever increasing number of errors:

First switch:

GigabitEthernet0/1 is up, line protocol is up (connected)
Hardware is Gigabit Ethernet, address is 0014.1c9b.d101 (bia 0014.1c9b.d101)
Description: HDSwitch SM-Fiber
MTU 1500 bytes, BW 1000000 Kbit, DLY 10 usec,
     reliability 246/255, txload 3/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive not set
Full-duplex, 1000Mb/s, link type is auto, media type is 1000BaseLX SFP
input flow-control is off, output flow-control is unsupported
ARP type: ARPA, ARP Timeout 04:00:00
Last input 00:00:01, output 00:00:00, output hang never
Last clearing of "show interface" counters 00:19:25
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 7508000 bits/sec, 1793 packets/sec
5 minute output rate 12090000 bits/sec, 2124 packets/sec
     2199784 packets input, 1041317090 bytes, 0 no buffer
     Received 11319 broadcasts (8249 multicasts)
     0 runts, 0 giants, 0 throttles
     166031 input errors, 1679 CRC, 0 frame, 0 overrun, 0 ignored
     0 watchdog, 8249 multicast, 0 pause input
     0 input packets with dribble condition detected
     2632177 packets output, 1948955584 bytes, 0 underruns
     0 output errors, 0 collisions, 0 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

Other end of link on 2nd switch:

GigabitEthernet0/1 is up, line protocol is up (connected)
Hardware is Gigabit Ethernet, address is 0014.1c9b.cc01 (bia 0014.1c9b.cc01)
Description: CDCSwitch SM-Fiber
MTU 1500 bytes, BW 1000000 Kbit, DLY 10 usec,
     reliability 255/255, txload 1/255, rxload 3/255
Encapsulation ARPA, loopback not set
Keepalive not set
Full-duplex, 1000Mb/s, link type is auto, media type is 1000BaseLX SFP
input flow-control is off, output flow-control is unsupported
ARP type: ARPA, ARP Timeout 04:00:00
Last input 00:00:01, output 00:00:01, output hang never
Last clearing of "show interface" counters 00:19:22
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 12066000 bits/sec, 2126 packets/sec
5 minute output rate 7508000 bits/sec, 1933 packets/sec
     2621228 packets input, 1938324356 bytes, 0 no buffer
     Received 17935 broadcasts (7536 multicasts)
     0 runts, 0 giants, 0 throttles
     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
     0 watchdog, 7536 multicast, 0 pause input
     0 input packets with dribble condition detected
     2353278 packets output, 1039344313 bytes, 0 underruns
     0 output errors, 0 collisions, 0 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

As you can see, errors are only appearing on one side of the link and the reliability is down to 246/255. Is there anyway to tell if this is due to the leased line itself, the SFPs or the switch?

Thanks!

Zach S · ‎10-02-2015

A good first step when you get errors that only affect one side of a fiber link is to clean your fiber on that side. You can pick up an isopropyl alcohol wipe for fiber cleaning at little cost.

http://www.cisco.com/c/en/us/support/docs/optical/synchronous-digital-hierarchy-sdh/51834-cleanfiber2.html

caymanport · ‎10-03-2015

I will try this on Monday. Thanks.

paul driver · ‎10-02-2015

Hello

Have you changed the cabling- if not please do so.

clear the counters again and see it these error return

res

paul

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Kind Regards
Paul

caymanport · ‎10-03-2015

Which cabling are you referring to? I can change the patch cable between the fiber panel and the switch on either end (or both) but that's about it. The rest is owned by the local telco.

caymanport · ‎10-06-2015

Well, I swapped SFPs and what cables I could and still having problems so it looks like the issue is with the telco. Thanks for everyone who assisted.