-
Step 0
- Next hop: is it reachable?
- If no route to reach Next_Hop, router cannot use this route.
-
Step 1
- Weight
- Bigger is better; Cisco proprietary
-
Step 2
- LOCAL_PREF
- Bigger is better
-
Step 3
- Locally injected routes;
- Locally injected is better than iBGP/eBGP learned
-
Step 4
AS_PATH length; Smaller
-
Step 5
Origin; Favor internal over external, external over ?
-
-
Step 7
- Neighbor Type
- Prefer eBGP over iBGP
-
Step 8
- IGP metric to Next_Hop;
- Smaller
-
Step 9
Oldest (longest-known) eBGP route
-
Step 10
Lowest neighbor BGP RID
-
Step 11
Lowest neighbor IP address
-
Idle
The BGP process is either administratively down or awaiting the next retry at-tempt.
-
Connect
The BGP process is waiting for the TCP connection to be completed. You can-not determine from this state information whether the TCP connection cancomplete.
-
Active
The TCP connection has been completed, but no BGP messages have beensent to the peer yet.
-
Opensent
The TCP connection exists, and a BGP Open message has been sent to thepeer, but the matching Open message has not yet been received from theother router.
-
Openconfirm
An Open message has been both sent to and received from the other router.The next step is to receive a BGP Keepalive message (to confirm all neighbor-related parameters matched) or BGP Notification message (to learn there issome mismatch in neighbor parameters).
-
Established
All neighbor parameters match, the neighbor relationship works, and the peerscan now exchange Update messages.
|
|
