Advanced Tuning of BGP Using Known Attributes

BGP is about tuning. The actual non-tuned BGP is essentially a new TEAR, although as soon as you adapt this on your requires - simply no other redirecting standard protocol may come perhaps in close proximity.

The normal along with well-known BGP Tuning Features usually are:


1. AS-Path (The a lesser amount of Bum inside path - the particular Better)

Helpful to impact yet another BECAUSE by adding or perhaps PREPENDING the particular AS's towards prefix when using the Course Chart.

You're able to do a pretty granular manage right here when using the AS-PATCH Admittance Directories. You are doing desire a essential familiarity with TCL for this, therefore essentially you need to go with all the prefixes of which cross used the particular BECAUSE 65505 you are doing this particular:

(config)#ip as-path access-list 10 enable ^65505$ <--- you possibly can head out crazy while using filter systems
*in this particular circumstance we have been selection the particular prefixes origineted along with publicized right through BECAUSE 2 hundred


The actual AS-PATH ACL may also be given to a new neighbor being a FILTER-LIST

(config-router)#neighbor 172. 25. 185. 45 filter-list 10 within



REMINDER on the META Personas:

^ - BEGIN associated with Brand
$ - END associated with Brand
| - Reasonable OR MAYBE
_ - ALMOST ANY DELIMETER
? - ABSOLUTELY NO cases of the particular EARLIER character
* - ABSOLUTELY NO OR MAYBE MANNER cases of the particular EARLIER character
+ - SEVERAL cases of the particular EARLIER character
(x) - Combine the particular encased Sequence being a solitary entity
[x] - Wildcard wherever any placement can certainly go with the positioning within AS-Path
. - Any Character

In which case you simply just go with this disorder inside route-map in order to arranged many parameter later:

(config-route-map)#match as-path 10


3. Excess weight (the Greater - the particular Better)

It's really a CISCO Exclusive Capability, Utilized ONLY LOCALY to impact your neighborhood BECAUSE through setting the particular FAT attribute to prefixes released from the BGP Next door neighbor

1st you have to create the particular route-map. You should use the particular MATCH UP situation, however you don't ought to. In this case we all will employ the particular fat to all the particular prefixes released by way of neighbor.

route-map SET_WEIGHT enable 10
go with...
arranged fat 500

And from now on employ the particular route-map to some neighbor inside INCOMING direction (prefixes being released in, significance - usually are released through of which neighbor):

router bgp 65535
neighbor 172. 21 years of age. 12. 3 remote-as 64500
neighbor 172. 21 years of age. 12. 3 route-map SET_WEIGHT within

As well as you possibly can just employ the particular FAT attribute towards neighbor right:

router bgp 65535
neighbor 172. 21 years of age. 12. 3 remote-as 64500
neighbor 172. 21 years of age. 12. 3 fat 500

3. MEDITERRANEAN (Multi Depart Discriminator) Capability; RFC 1771 - Optional along with Non-Transitive; Small the higher quality

This can be a almost all identical Capability towards OSPF Metric that there's within BGP. The nature in this attribute is comparable to the particular AS-Path, since they are each accustomed to impact the other BECAUSE through tuning the particular features on the Locally Originated&Advertised Prefixes
You possibly can just arranged this (set metric X) in the route-map construction, along with use it towards BGP Next door neighbor inside OUTBOUND direction

If you would like RE-ARRANGE the particular Capability Contrast obtain, along with for example want to compare the particular MEDITERRANEAN worth prior to AS-Path (meaning - prefer the reduce MEDITERRANEAN, regardless of the AS-Path), you need to use this particular get under the BGP construction:

(config-router)#bgp always-compare-med <--- to compare MEDITERRANEAN worth perhaps if you find larger positioned attribute of which decides
(config-router)#bgp bestpath as-path dismiss <--- to Ignore the AS-Path attribute, INVISIBLE ORDER on IOS!!!
*BE CAREFULL while using next get, the particular CASE crucial won't operate along with the "? " won't teach you the particular "as-path" alternative

By default the particular ABSENT MEDITERRANEAN worth is considered the IDEAL one particular simply because on most IOS-s this accumulates the significance 0. To switch this particular employ:

(config-router)#bgp bestpath mediterranean missing-as-worst <--- Treat the particular non-defined MEDITERRANEAN for the reason that TOUGHEST