• ENCORE #1 – Layer 2 stuffs

    In the beginning of LANs the Layer 1 media was shared between all devices in said LAN. They all received and transmitted on the same wires, at the same time. This is whats known as half-duplex (only send or received, not both). In this configuration devices would sometimes send traffic at the same time, which…

  • DC@Home 4 – MPLS WAN improvements, monitoring and backup

    DC@Home 4 – MPLS WAN improvements, monitoring and backup

    So I have been working quite a bit on the MPLS WAN setup the past few weeks. Currently I have two sites running the new MPLS nodes as their gateway and one more currently staged which will be installed in the coming weeks. I still have some work to do for the sites which use…

  • MTU and PMTUD on L2VPNs

    I recently ran into an interesting issue at work today. One of our customers were having issues with a site in Gothenburg. They were using L2VPNs as circuits between their central site and the remote sites. Across this L2VPN they are running MPLS MP-eBGP peering using inter AS option 2b to allow multiplexing of different…

  • MPLS basics – tips & trix

    This will be a living document, for troubleshooting and tracing MPLS traffic. The idea is for me and others to be able to reference this post for basic MPLS troubleshooting. < MPLS purpose and MPLS packet headers The original purpose of MPLS was to allow for faster packet routing through a provider network. This is…

  • DC@Home 3 – Configuring the MPLS WAN

    DC@Home 3 – Configuring the MPLS WAN

    The past two weeks I have been working hard at getting the new MPLS WAN up and running. The idea is to build a scaleable solution, even though my MPLS cloud never will grow large enough to require the scalability. The plan is also to allow my colleagues to join the MPLS WAN, which means…

  • Route-maps for VPNv4 filtering

    In my series DC@Home I recently ran into the issue of how to filter which VRF:s should be allowed to propagate from the provider core, out to the customer sites. It turns our it is quite simple and can be done in a manner similar to prefix-lists for regular BGP peering. For VPNv4 multiplexing the…