Probably one of the most confusing topics for people studying BGP/MPLS VPNs are EIGRP SoO and Cost communities. Not the concepts themselves, but rather their purpose. Lack of clear documentation makes it hard to understand why and how the specific features are implemented. In this blog post we discuss the BGP Cost community and EIGRP SoO attribute. First, a brief overview of MP-BGP is given along with general concepts of route redistribution in MPLS/BGP VPNs. Next, the problems that arise when...
Let's say you get a bunch of inexpensive (but a bit outdated) routers (36XX or 72Xx) and some really nice (maybe not so cheap) Cisco switches (e.g. 3550/3560) and you would like to provide a VPLS-like service to your customers. Since VPLS is a service available only on more powerful Cisco platforms, we have to figure a way to simulate Multipoint Ethernet L2 VPN over a packet switching network (PSN) using only "convenient" point-to-point L2 VPN services.