BGP DECISION PROCESS
1 largest weight ( local orininated path :32768 other 0 )
2 largest local-preefernce (BGP default local-preference )default 100
3 prefer local paths (decreasing preference :default -orininate in neighbor,default -information -orininate in global,network,redistribute,aggregated)
4 shortest as _path ('bgp bestpath as-path ignore' bypasses this step;AS_SET counts as 1 ;as_confed_sequence and as_confed_set are not counted)
5 lowest origin code (0 -igp,1-egp,2-imcomplete0
6 lowest med ('bgp always-compare-med;bgp bestpath med-confed;bgp bestpatch med missing-as-worst;bgp determinstic-med) default 0
7 ebgp prefered over ibgp (confed ,path are treated as internal paths) 8 closest IGP neighbor (best cost)
9 determine if multiple paths require installation (multipath)
10 if paths are external choose the oldest one (flap prevention ) skipped if "bgp bestpath comfare-routerid)
11 lowest router-id
12 minimum cluster-list length (RR enivronment)
13 lowest neighbor address
REGEXP . single character
* zero or more
one or more
? zero or one
[] range
[^] negate range
^ begining of input
$ end of input
_ , () {} ^ $ ,space
escape special character
1 repeat a match ()
| logical OR
PATH ARRTIBUTES
<TYPE ,LENGTH,VALUE>
FLAGES CODE
------------------------------------------------------------------------------------
0 | 1 |2 | 3 | | |
-------------------------------------------------------------------------------------
0--------- 0 Well-Known ; 1 -Optional
1-------- 0 Non-transitive ; 1 =Transitive
2--------- 0 Complete; 1 =Partial
3---------- 0 1bytes ; 1=2bytes (Attr len Field)
1 origin WK M
2 as_path WK M
3 next_hop WK M
4 MED ON T
5 local_pref WK D
6 atomin_aggreagte WK D
7 aggregator O T
8 community O T
9 originator_id O NT
10 cluster_list
12 advertiser
13 rcid_path/cluster_ID
14 mp_reachable NLRI O NT
15 mp_unreachable NLRI O NT
16 extended communities
Filter Sequence :
IN :
1 prefix-list
2 filter-list
3 weight
4 route-map
OUT:
1 prefix-list
2 filter-list
3 router-map
IGP:
1 distribute-list
2 route-map (redistribution)
