BGP Community String for DE-CIX AS6695

   March 10, 2007  Leave a comment

Attention

This BGP Community string information might be outdated. Please contact DE-CIX AS6695 to get more recent one. This BGP communites is ONLY for the customer who has BGP with DE-CIX AS6695. www.ipbalance.com is not maintaining this BGP Community string.

 

BGP Community String Information

You may use BGP communities to control outgoing information via the route server. The meaning and order of evaluation is important.


block of announcement of a route to a certain peer 0:peer-as
announcement of a route to a certain peer 6695:peer-as
block of announcement of a route to all peers 0:6695
announcement of a route to all peers 6695:6695


There are additional BGP communities for controlling announcements.


6695:65000 peer is using bad netmask (80.81.192.0/24)
6695:65001 peer is using bad netmask (80.81.193.0/24)

6695:65003 prefix is injected at DE-CIX1
6695:65004 prefix is injected at DE-CIX2
6695:65005 prefix is injected at DE-CIX3
6695:65006 prefix is injected at DE-CIX4


Please take care when setting 0:x communities as this changes the local-preference:

BGP Community local-preference

0:6695 0
0:x, x!= 6695 50
else or nothing 100


For more information pls contact [email protected] or see http://www.de-cix.net

 

 

 

Applying BGP Community string with sample configuration

1. Get the latest BGP community string from your ISP/upstream provider or check www.ShowipBGP.com web site.

2. Pick the best BGP community string for your traffic shaping plan (mainly incoming traffic). Most of ISPs are providing BGP community string with local preference and AS prepending
option. Cannot tell which one is better than the other. It will depend on your global traffic shaping plan.

3. Follow the below commands ( Cisco only )

The below Sample configuration will tag the 10.0.0.0/24 route with [ISP AS]:120 or [ISP AS]:3 and will not tag any other routes.


router#config t
router(config)#ip bgp-community new-format
router(config)#access-list 10 permit 10.0.0.0 0.0.0.255
router(config)#access-list 10 deny any

router(config)#route-map [to-ISP] permit 10
router(config-route-map)#match ip address 10
router(config-route-map)#set community [ISP AS]:120 <—- using Local Preference

or

router(config-route-map)#set community [ISP AS]:3 <——- using AS prepending
router(config-route-map)#route-map [to-ISP] permit 20
router(config-route-map)#exit

router(config)#router bgp [xxxx] <——————————- xxxx = customer’s ASN
router(config-router)#neighbor x.x.x.x send-community
router(config-router)#neighbor x.x.x.x route-map [to-ISP] out
router(config-router)#exit
router(config)#exit
router#copy running-config startup-config


4. And then, go to www.RouteServer.org and pick one of route server on the map to see your announcement. If you are using AS prepending option, you will see your AS prepends on route servers. Sometime you might not see your route with particular ISP path.
In most of case it might not be any routing problem, just the route path was dropped at somewhere by BGP best path selection scheme. Try Oregon route server, if you can see your route. The Oregon route server is providing many possible and available paths between BGP speakers and neighbors.
If you don’t see your route on there? check other route servers and also check your
BGP configuration. You might need to contact your upstream provider to check what they are learning BGP route from you.

 

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