cancel
Showing results for 
Search instead for 
Did you mean: 
cancel
5518
Views
10
Helpful
3
Replies

Interface Up/Up on one side Down/Down on the other?

tjalbrecht
Level 1
Level 1

I have a 3750 that has a TW circuit connected to it.  I stopped incrementing packets input, but the link was up/up.  When I escalated to TW, they said their side was down/down.  I didn't think this was possible?

TW said they would bounce the interface.  I saw them shut it down, as my side went down/down.  They turned it back on, and my side went up/up.  Still no packets input from them, and they could not see my MAC.  The TW tech verified we are both 100/Full.  We changed that to Auto/Auto on both sides, and the link came up.  We then changed back to 100/Full and the link remained up.

I am thinking the TW tech had me change the speed/duplex to buy time, but I cannot put my finger on exactly what happened.  This is our primary link, and because of the way this circuit failed, EIGRP did not re-route us over the backup.  I tested failover just hours afterward by shutting this TW link down, and failover proceeded successfully.

Anyone experience this?  I think TW is not being open and honest, and this concerns me greatly.  The TW tech noted they had a 3400 connected directly into our switch, and they have a 7609 behind that.  Any thoughts by others in the field would be greatly appreciated.

Thank you,

T.J.

3 Replies 3

Jon Marshall
Hall of Fame
Hall of Fame

tjalbrecht wrote:

I have a 3750 that has a TW circuit connected to it.  I stopped incrementing packets input, but the link was up/up.  When I escalated to TW, they said their side was down/down.  I didn't think this was possible?

TW said they would bounce the interface.  I saw them shut it down, as my side went down/down.  They turned it back on, and my side went up/up.  Still no packets input from them, and they could not see my MAC.  The TW tech verified we are both 100/Full.  We changed that to Auto/Auto on both sides, and the link came up.  We then changed back to 100/Full and the link remained up.

I am thinking the TW tech had me change the speed/duplex to buy time, but I cannot put my finger on exactly what happened.  This is our primary link, and because of the way this circuit failed, EIGRP did not re-route us over the backup.  I tested failover just hours afterward by shutting this TW link down, and failover proceeded successfully.

Anyone experience this?  I think TW is not being open and honest, and this concerns me greatly.  The TW tech noted they had a 3400 connected directly into our switch, and they have a 7609 behind that.  Any thoughts by others in the field would be greatly appreciated.

Thank you,

T.J.

T.J

It really depends on whether the connection is literally a point to point or whether there are other switch(es) in between. If there are and there end goes down your end will still be up/up. This is one of the issues with ethernet.

If you want to remedy the situation in future you should take a look at IP SLA which allows you to monitor via ping the other end of the link and it fails you can then failover to the other link.

Edit - you would need the IPServices image on your 3750 to have IP SLA support.

Jon