Understanding BGP states is essential to grasp how BGP operates. Similar to interior gateway protocols (IGPs) like EIGRP, OSPF, or ISIS, BGP establishes peering with other routers before exchanging routing information. However, unlike IGPs, BGP...
Last year, we discussed the MED attribute and how it can be useful along the local preference and the AS path as a tool for traffic engineering. In this...
One given in the network world is that bandwidth will increase. So that Gigabit Ethernet link that provided bandwidth to spare a year ago may be insufficient...
Before we look at BGP path hunting, let's first discuss the RIP count to infinity problem. RIP, the Routing Information Protocol, is pretty much the simplest...
It's been a while since we talked about filtering BGP updates. BGP routers need to be configured with the right filters so packets don't flow in directions...
When the BGP session between two routers is established, the two routers exchange prefixes and then start sending traffic for those prefixes to the...
As end-users, we expect to connect to an Internet Service Provider which will take our packets and deliver them to all destinations around the world, and take...
Border Gateway Protocol is unique among routing protocols because it requires a number of parameters to be configured manually on each side before two routers...
The past few weeks we've discussed the main BGP path attributes: the next hop, the AS path, the MED. We also covered the community attribute last year. Today,...
When BGP needs to choose which route to reach a certain destination is best, it first looks at the local preference and AS path attributes, as discussed in...
In earlier articles, we discussed the next hop and local preference attributes. Today we'll be looking at the AS_PATH attribute as well as the AS4_PATH...
In the previous blog post, we looked at the BGP NEXT_HOP attribute. Today we'll cover another attribute: the LOCAL_PREF or local preference. What is...
Once a BGP session is established, routers will exchange two types of messages: KEEPALIVE and UPDATE. Keepalive messages are sent to let a neighboring router...