Catalyst 2960X Link Light Blinking Amber

[nlanich01]

I have a Cat 5e connection to a GB Netgear switch and it blinks green. When I show the interface it says 100 Mb/s full duplex  connection. I ran a Cat 6 connection and now it blinks amber, but the interface still shows 100 Mb/s full duplex connection. The documentation for the switch says blinking amber means STP is blocking the port, but this isn't the case apparently. When I force the interface to speed 1000 the connection drops. I don't understand why I don't have a GB connection in auto-negotiation. Any ideas what is going on?

[Filip Knezevic]

Can you send output of show interface and show run interface?

[nlanich01]

Cat2960-X-9012#show run int g0/5
Building configuration...

Current configuration : 60 bytes
!
interface GigabitEthernet0/5
switchport mode access
end

Cat2960-X-9012#show int g0/5
GigabitEthernet0/5 is up, line protocol is up (connected)
Hardware is Gigabit Ethernet, address is e089.9d82.6005 (bia e089.9d82.6005)
MTU 1500 bytes, BW 100000 Kbit/sec, 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 00:00:01, output 00:00:07, output hang never
Last clearing of "show interface" counters never
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 113
Queueing strategy: fifo
Output queue: 0/40 (size/max)
5 minute input rate 17000 bits/sec, 18 packets/sec
5 minute output rate 0 bits/sec, 0 packets/sec
614531 packets input, 132595423 bytes, 0 no buffer
Received 164350 broadcasts (139633 multicasts)
0 runts, 0 giants, 0 throttles
24 input errors, 3 CRC, 0 frame, 0 overrun, 0 ignored
0 watchdog, 139633 multicast, 0 pause input
0 input packets with dribble condition detected
22058321 packets output, 3312760485 bytes, 0 underruns
0 output errors, 0 collisions, 1 interface resets
0 unknown protocol drops
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

[nlanich01]

Cat2960-X-9012#show run int g0/5
Building configuration...

Current configuration : 60 bytes
!
interface GigabitEthernet0/5
switchport mode access
end

Cat2960-X-9012#show int g0/5
GigabitEthernet0/5 is up, line protocol is up (connected)
Hardware is Gigabit Ethernet, address is e089.9d82.6005 (bia e089.9d82.6005)
MTU 1500 bytes, BW 100000 Kbit/sec, 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 00:00:00, output 00:00:03, output hang never
Last clearing of "show interface" counters never
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 113
Queueing strategy: fifo
Output queue: 0/40 (size/max)
5 minute input rate 12000 bits/sec, 12 packets/sec
5 minute output rate 0 bits/sec, 0 packets/sec
603031 packets input, 131078092 bytes, 0 no buffer
Received 152973 broadcasts (134060 multicasts)
0 runts, 0 giants, 0 throttles
24 input errors, 3 CRC, 0 frame, 0 overrun, 0 ignored
0 watchdog, 134060 multicast, 0 pause input
0 input packets with dribble condition detected
22058237 packets output, 3312750021 bytes, 0 underruns
0 output errors, 0 collisions, 1 interface resets
0 unknown protocol drops
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

[Deepak Kumar]

Hi,

Because both ports are running on 100Mbps but actually physical ports are gigabytes.

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

Check some things as:

1. Is remote device support to 1Gbps link? or it is having only FastEthernet port?

2. Are you using Cat6 or Cat5e cable?

3. You didn't change the interface speed manually of the remote device?

[nlanich01]

Deepak,

Thanks for your response. The Netgear is an unmanaged GB switch, and I am using Cat 6 so it seems like they should use GB/s speed with the port on the 2960 in auto. I forced the interface to speed 1000 and lost the link completely. Other ports on the Netgear are running at GB/s but no matter what port I plug the 2960 into it runs at 100 Mb/s. Also, the port blinks amber which is very odd.

Thanks again!

[nlanich01]

I discovered I mistakenly still had the Netgear switch plugged in hence the amber light. When I removed the other connection the speed of my Cat 6 connection between the 2960 and the GB Netgear settled at 10 Mb/s. Why not GB speed?

[Deepak Kumar · Accepted solution]

Hi,

This would be a nag issue between both physical ports. 

How much is cable length?

Try with some commands as:

no negotiation auto
speed 1000
duplex full

Note: The default configuration of all Cisco switches is auto-negotiation-enabled. If you disable auto-negotiation, it hides link drops and other physical layer problems. Do not disable auto-negotiation between switches unless absolutely required, as physical layer problems can go undetected and result in spanning-tree loops. 

[nlanich01]

Hi Deepak,

The cable length is 33 ft. I can get it to communicate at 100 Mb/s full duplex, but not 1000 Mb/s. That's better than 10 Mb/s. Thanks for your help!