Yesterday I posted a tricky question to Twitter. If you have a working VPNv4 environment and create a VRF with only a Route Distinguisher (RD) but without Route Targets (RT), will the route be exported? The answer may surprise you!
Path Hunting in BGP
BGP is a path vector protocol. This is similar to distance vector protocols such as RIP. Protocols like these, as opposed to link state protocols such as OSPF and ISIS, are not aware of any topology. They can only act
Valley-free Routing in Leaf and Spine Topology
Valley-free routing is a concept that may not be well known but that is relevant to datacenter design. In this post, we’ll valley-free routing based on a leaf and spine topology. There are many posts about leaf and spine topology
Is One Protocol Simpler Than Two?
I’ve been in a lot of interesting discussions the last couple of days on what protocol to use for the underlay when building a VXLAN datacenter network. Do you use an IGP such as OSPF or ISIS or do you
Modifying Administrative Distance of Specific BGP Route
In one of the Discords that I’m in there was a user with a complex network consisting of a mix of DMVPN, BGP over MPLS VPN circuits, and SD-WAN. For some prefixes, the path via the private MPLS is preferred,
CCDE – Carrier Supporting Carrier
Introduction In the previous post I showed some of the options to interconnect two AS so that a customer can buy a VPN in two different locations from two different SPs. There is another technology called Carrier Supporting Carrier or
CCDE – Inter AS L3 VPNs
Introduction Sometimes a customer needs a L3 VPN between two locations where the same SP is not present. This can be on a national or international basis. It would be possible to buy an Internet circuit and run an overlay
CCDE – BGP Confederations
Introduction BGP Confederations are one of two tools a network designer has to work around the full mesh requirement of iBGP. BGP confederations are defined in RFC 5065 which obsoletes RFC 3065. This is how the RFC defines BGP confederations:
Busting Myths – IPv6 Link Local Next Hop into BGP
In some publications it is mentioned that a link local next-hop can’t be used when redistributing routes into BGP because routers receiving the route will not know what to do with the next-hop. That is one of the reason why
Unique RD per PE in MPLS VPN for Load Sharing and Faster Convergence
This post describes how load sharing and faster convergence in MPLS VPNs is possible by using an unique RD per VRF per PE. It assumes you are already familiar with MPLS but here is a quick recap. The Route Distinguisher