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Community Member

Trunk between 6500 and 3750.

I'm using a stack of two 3750 (one 3750G-12 and one 3750-48). This stack is connected to a 6500 via a 1000SX link (SFP). This link is a .1Q trunk. If I use a port on the first switch (3750G) I have many input error,

0 runts, 391 giants, 0 throttles

17767355 input errors, 20941 CRC, 0 frame, 0 overrun, 0 ignored

but if I move to a port on the other 3750 no more errors appear!

Any ideas!?




Re: Trunk between 6500 and 3750.


Can u paste the config of the devices.



Community Member

Re: Trunk between 6500 and 3750.

Now I'm using g2/0/2 to connect the stack to the port 4/1 on 6500. Errors appear using g1/0/1.



Community Member

Re: Trunk between 6500 and 3750.

Hi Andrea.

1) This problem ocurr with any port of the 3750G-12?

2) Can you copy the sh int gi1/0/1 please?

3) You use the same SPF adapter?


Community Member

Re: Trunk between 6500 and 3750.

Hi Guido.

1) I don't know. I don't have a free port.

Today I'll try to switch with another port on 3750G-12.

2) Sorry, a clear counter command already applied.

C3750-12g-P1#sh int g1/0/1

GigabitEthernet1/0/1 is down, line protocol is down (notconnect)

Hardware is Gigabit Ethernet, address is 000f.8fd6.3181 (bia 000f.8fd6.3181)

Description: Link P1 - Catalyst6500 Pal3B

MTU 1500 bytes, BW 10000 Kbit, DLY 1000 usec,

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

Encapsulation ARPA, loopback not set

Keepalive not set

Auto-duplex, Auto-speed, link type is auto, media type is Not Present

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 3d22h, output 3d22h, output hang never

Last clearing of "show interface" counters 15:26:19

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 0 bits/sec, 0 packets/sec

0 packets input, 0 bytes, 0 no buffer

Received 0 broadcasts (0 multicasts)

0 runts, 0 giants, 0 throttles

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

0 watchdog, 0 multicast, 0 pause input

0 input packets with dribble condition detected

0 packets output, 0 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

3) Yes, I'm moving the SFP to a port on 3750-48 without any errors!

Many thank for your help.


Community Member

Re: Trunk between 6500 and 3750.

Some IOS allow that "SFP" ports can be set to "full duplex", disabling the "auto-sense." If the other end is set to "auto", you have a duplex mismatch and a lot of errors. Connect the fiber and check if it is full-duplex on both sides or auto on both.

If not, try hardcoding media-type and duplex to auto on both ends or full on both.

Switch(config)#int gi 1/0/1

Switch(config-if)#no media-type

Switch(config-if)#media-type sfp

Switch(config-if)#duplex auto


Please rate all the helpful comments.

Community Member

Re: Trunk between 6500 and 3750.

Hi Guido and many thanks for your help.

Now I'm using g1/0/7 on 3750G-12 without any errors!

May be an damaged ASIC?

I believe I'll replace this switch.



Community Member

Re: Trunk between 6500 and 3750.

I have seen a lot of switchs with a failed port, running perfect, but maybe is a good idea move this sw to a lab or keep for backup.

(A client have a 2950 with 5 failed ports but the other 19 work normaly.)

Best regards!


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