link errors when tag-switching enabled

[midoherty]

I have 4 6506 with SUP720-3BXL connected via 100Mb ethernet links as below. (you may have to copy the diagram to look at it using a fixed font)

r3---utp---r4

|.........|

media......|

converter..|

|.........|

fibre....Telstra 2Mb Ethernet service

|.........|

media......|

converter..|

|.........|

r1--fibre--r2

On the link between r1 and r3 I am getting CRC errors and runts for about 5% of packets.

When I turn off tag-switching on that link I get no errors so it doesn't appear to be a physical link problem.

No other links are showing these symptoms.

Any ideas as to what could be causing this?

Michael

[romccallum]

What software version are you using Michael?

[midoherty]

s72033-pk9sv-mz.122-17d.SXB1

[romccallum]

OK two obvious things to check here.

One - Try upgrading to 18.

two - check your MTU sizes - I know it shouldnt have anything to do with what you are seeing but just check them anyway.

[midoherty]

repeat after me (as many time as necessary)

a layer 1 problem is not an mpls problem

a layer 1 problem is not an mpls problem

a layer 1 problem is not an mpls problem

a layer 1 problem is not an mpls problem

.......

Switch interface is set for 100Mb full-duplex

Media converter is set for 100Mb full-duplex also, but this media converter also has a DIP switch labelled 'force'

I changed this DIP switch and everthing runs perfectly.

I hate media converters.