CCIE

Everyone builds a second DMVPN hub for redundancy. Far fewer people test that the failover actually works - and the ones

BGP is the most powerful choice for the PE-CE protocol in an MPLS L3VPN - it scales, it carries policy,

You have an IPv4 MPLS L3VPN running. Your customers each have their own VRF, their own routing table, their own

Layer 2 problems have a special quality: the switches all say everything is fine, and yet nothing works. There is

The switching features that make headlines are the protocols - spanning tree, VLANs, EtherChannel. The features that actually keep a switch

ARP is the most trusting protocol in the building. A host asks "who has 10.10.10.1?"