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
Choosing the Underlay Protocol in a VXLAN Network
When building a VXLAN network, what are the considerations for choosing the underlay protocol such as OSPF, IS-IS, or BGP? You obviously want the design to be supported by your vendor of choice. Your staff should also be able to
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,
Route Replication the Easy Way
Easy Virtual Network (EVN) was a technology Cisco came up with back in the days to make it easier to implement VRFs without the pain of running VRF lite or the complexity of running a full MPLS + BGP network.
Lessons Learned in Cloud Networking – AWS vs Azure
I’ve been working a lot with cloud networking lately. I will share some of my findings as this is still quite new and documentation around some topics is poor. Especially on the Azure side. Let me just first start with
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:
CCDE – BGP Convergence
Introduction This post will look at the steps involved in BGP convergence and how it interacts with IGP to converge. Any network of scale will use route reflectors (RRs) so this post will focus on deployments with RRs. Networks running
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