Metro Ethernet Trunk Connection

[dstrongcisco]

Hello All,

I am having trouble with the trunk connection staying consistenly up between 2 devices connected by a Metro Ethernet circuit .The connections show up and down every couple of seconds. The trunk is between two 4507 switches. Both are configured with the same speed and duplex settings as well as sw nonegotiate.  At one point i would play with the configs and one side of the connection would have an "UP/ Down" state and the other would be completely down ( which means the trunking protocol had not been intiated on both sides ".    When I had the ports routed and terminating on a 6509 switch, the connection was consistent but i was still not able to bring up the trunk, but i was able to keep it working as a routed port.   Has anyone had any experience troubleshooting this issue. I would rather the port be used as a trunk rather than routed.  You will see the up and down states when I enable to trunk between the 2 devices.( see attached ) Thanks

[durgesh.p]

can u change the cable ...

please share both end port config also

[dstrongcisco]

HI , 

I actually changed the cable on yesterday , and will be going in the morning to change on the other side.

The config is standard on both ends

interface GigabitEthernet7/40
description Metro Ethernet
switchport mode trunk
switchport nonegotiate
duplex full

I actually had speed configured to 100mbps , becuase the its a 100 meg circuit but that didnt allow for the connection to come up at all!.  Both are configured with the above statements.

Thanks

[jbowman1985]

Do you see input or crc errors on either interfaces?  Do you control the devices you are connecting to on the Metro Ethernet cloud?  It could be a problem with the Metro Ethernet SP equipment.

What was your setup when you had the interfaces connected as routed ports?  Did you have a direct connection to the 6509 switch?  What I am getting at is what all changed when you converted from routed ports to layer 2 trunk ports?  Make a list of what changed and then start looking at each one crossing it off the list after testing.  

[dstrongcisco]

Ok so with the 6509, the connection was the same as it is now. The difference is I couldnt get the trunk to come up at all, or at least i didnt notice the interfaces flappin when i continously did a sh int " gi7/40" on the port. I think thought to go ahead and make the port routed on both ends and just place them on a point to point network and advertise that into ospf.  I decoommed the 6509 becuase I replaced it with Nexus 5 k's. The nexus 5k cannot support 100 mbps speed on the actual device ,and you cannot configure a routed port on the fex.  I then thought to use the 4507 that is sitting directly next to the 5k in our server room.Being that both devices across the metro ethernet would be a 4507, i shouldnt have any problem bringing up the trunk, which is the proper way for the metro E to work. I could make the port routed, but i really want to bring it up as a trunked port. I do not have access to the cloud devices but have opened up a ticket with Time warner / Level 3 to investigate.  I am going to change the cables out on tomorrow. I cleared the counters on the interfaces so that i could get a clear reading of what is going on .

[Andre Neethling]

Have you tried hard coding the encapsulation to dot1q?

[jbowman1985]

Usually you receive an error when you attempt to set a port to trunk and you are required to specify a trunking protocol.  At least, that is how it works on the 3560s but I am not sure sure on the 4507.  Are the native VLANs the same on both interfaces?  When you had a direct connection to the 6509 you were not connecting through the ISP network correct?  The Metro Ethernet link seems to be culprit.  Once you swap out the cables and verify the trunk configs on your 4507 the only thing left would be the Metro E ISP equipment.

[dstrongcisco]

When i was connecting to the 6509, it was through the ISP, but it was a routed port. I will update you all in a couple of hours after I change the cables. Thanks Everyone

[dstrongcisco]

Jbow, I didnt set Native vlans between the 2, maybe that  is my issue. Maybe its necessary for a trunk across this circuit.  I changed the cables and still no success. The provider verified that the circuit is running clean. 

[jbowman1985]

dstrongcisco,

Native VLANs need to match on both ends.  Resolve that configuration issue and see if that fixes the issue.  If you replaced the cabling and had the ISP verify their equipment we can probably rule out a layer 1 issue.  Next step is check layer 2.  What type of Metro Ethernet link is the ISP providing?  If you are trying to configure a trunk between your equipment I take it you want to send multiple VLANs accross this link?  

If you fix the native VLAN config, then I would say your config looks good.  Next you need to find out what type of traffic your ISP Metro Ethernet is expecting.  Is it expecting tagged VLANs or just one untagged VLAN.  

[dstrongcisco]

On the 4507, Dot Q is automatcally the encapsulation type, you do not have to set it as you do on a 3560, ect.