7

I have one switch that I want to use as an 802.1q tunnel, to make the spanning tree and etherchannel transparent, a pass through switch between a core switch and access closets, because I do not have enough phyiscal cabling to run to the core from each access.

So what is considers point-to-point?

I have one connection to the core, and on my dot1q tunnel switch each access switch has a separate connection, would the access switches be considered point-to-point to the core?

          CORE
            |          
       dot1qswitch
       /     |     \
 access1   acess2  access 3

After connections are made, i want etherchannel and cdp neighbors and spanning tree to see the core and the access switches as if they were cabled up directly port to port core to access.

  • Hi mate, Can you post some configs? Point-to-point it is a well known term used either in tunneling between two specific tunnel end points and also used by protocols like RSTP, underlining a connection between two RSTP participants (L2 bridges). – laf Aug 1 '13 at 5:26
  • point-to-point in this context should mean that behind switch port there is exactly 1 switch, which is not always true. Rapid convergence for example won't work if 1 port has >1 switch neighbors, because when one neighbor gives you permission to go into forwarding it reasonably expects you can, but if you have other neighbors behind same port, you obviously cannot. – ytti Aug 1 '13 at 6:44
  • @GarryBaker, you are hearing a lot about what you can't do... you can use QinQ w/ Layer2 Protocol Tunneling to emulate a point-to-point connection from an STP / VTP / CDP / LLDP perspective... see Layer2 Protocol Tunneling for Cat6500 – Mike Pennington Aug 1 '13 at 10:31
  • I deleted my answer since I was apparently out of my mind when I wrote it, but I'd like to ask you what the underlying reason is for wanting to get the aggregation switch out of the STP domain? – totallystubby Aug 1 '13 at 22:37
  • 1
    What I need to do to solve this problem is have a 'dot1qswitch' at each location the core and access switches are separate by a distance but we do not have enough fiber to make all the connections. Creating a mini SP backbone and cable the core and access to individual Vlans to cross the mini SP backbone and terminate on ports that map to the SP vlans to make them point-to-point, utilizing the 1 fiber that I do have between the access and core buildings. – Garry Baker Aug 2 '13 at 1:29
3

I created a QinQ tunnel over dot1q trunk between a 3750 switch stack at each location, with physical cat5 cables off the 6500 core switch to create point to point tunnels to do the PAgP to each access switch. This is working so far as a good work around for lack of cable infrastructure between the 2 buildings.

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