Cisco IOS - How to Configure VRF-Lite

What is VRF-Lite? VRF is a feature that allows you to create separate instances of the routing table. In turn allowing you to segregate and isolate different network types. When VRFs are used without MPLS it is classed as VRF-lite. VRF-lite configuration doesn’t need the route-target and can be…

Read More

Cisco IOS - BGP Summarization

Introduction In order to reduce the amount of routing information within the routing table, routing summarization is used. Cisco IOS provides 3 types of BGP summarization: Aggregate Address - BGP is configured to advertise an aggregate network via the aggregate-address command. Manual - A summarized network is added to RIB…

Read More

OSPF Area’s Explained

Introduction In OSPF, a single autonomous system (AS) can be divided into smaller groups called areas. This reduces the number of link-state advertisements (LSAs) and other OSPF overhead traffic sent on the network, and it reduces the size of the topology database that each router must maintain. The routing devices…

Read More

A Look into BGP's LOCAL_PREF Attribute

What is the Local Preference? Local Preference (aka LOCAL_PREF) is a BGP well-known attribute that is used when there are multiple exit paths out from a single AS exist. Whereas the MED is used to tell routers outside of an AS which entrance path to take, the LOCAL_PREF…

Read More

A Look into the BGP MED Attribute

What is the MED? The MED (Multi-Exit Discriminator) is an optional BGP attribute, that is used when there are multiple external points for a single AS. For example, you may want traffic coming into your AS destined for network A to take one path but traffic destined for network B…

Read More