4 Replies Latest reply: Oct 20, 2015 6:23 AM by Raghul RSS

    Layer 2 connection Site to site

    Raghul

      HI All,

       

       

      Recently I came across a scenario where 2 different sites were connected using Layer 2. The sites were several miles away.

      Reason for using Layer 2 was both the sites shared the same BGP Address space.

       

       

      Site 2 was used for disaster recovery.

      Site 2 was shutdown due to maintenance and this caused spanning tree convergence on Site 1.

       

       

      Reason - switch at Site 2 was root (because of lower priority)  and when that site went down STP had to compute again as root was not available.

       

       

      I understand this bit. But my question is how can someone connect 2 sites miles apart using layer 2 please?

       

       

      I don't believe someone is going to run a long cable between sites. Not sure if they were using EOMPLS or VPLS etc as I believe this should not cause the STP issue when site 2 went down?

       

       

      So how does layer 2 connection between sites work please?

       

      Sorry didn't know which section to post this question, so used CCNP R&S. If needed I can change (if that's possible).

       

       

      Regards,