BGP attribute Details: Origin Property/med Property

In the IGP era, we all know, for example, OSPF, link state protocol, in the routing of the time, than the cost of the link, which link consumption will be more priority, if two of the same link consumption, then do load balancing.

In fact, the 2 principles to achieve the OSPF---shortest path first work principle.

What if, in BGP, there are multiple routes to achieve the goal, how should the choice be made? Which path is the preferred one?

Take a look at the priority of these 11 attributes, and deepen the memory, preferably with a skilled back:

1 Highest Weight--cisco private properties

2 Highest local prerence-----recognized optional

3 ROUTE originated by the ROUTER NEXT hop=0.0.0.0 *-----Recognized must be respected well-known mandatory

4 Shortest as PATH *-----recognized well-known mandatory

5 LOWEST originated igp> Egp>incomplete *-----Recognized well-known mandatory

6 LOWEST MED

7 EBGP path over IBGP path

8 prefer the PATH throgh the closest IGP neighbor

9 Rrefer oldest ROUTER for EBGP PATH

Prefer the PATH with the LOWEST neighbor BGP ROUTER ID

One BGP LOWEST ROUTER ID

MINIMUM Claster LIST LENGTH

In BGP, in addition to a large set of principles to be understood, the principle of route selection is the most important. Must be mastered (to understand and troubleshoot BGP, here must be to grasp rather than understand) the route principle.

Each property is validated by the document one at a time. To be able to reach myself in the mind of these concepts.

Origin attribute detailed: Igp>egp>incompelete.

About this attribute, the network upstream a lot of reference examples.

Here I will say a summary:

Igp>egp>incomelete

BGP Netowrk The routed route will definitely add an I tag > EGP announces the Routing (EGP has been eliminated) > redistribution to BGP routing.

Validating this property does not take much time: