BGP Community String for TCNET(Telecom Centre Joint Stock Company) AS6854

   March 9, 2007  Leave a comment

Attention

This BGP Community string information might be outdated. Please contact TCNET AS6854 to get more recent one. This BGP communites is ONLY for the customer who has BGP with TCNET AS6854. www.ipbalance.com is not maintaining this BGP Community string.


BGP community String accepted from AS6854 downlinks

6854:0 – Announce this route everywhere, full connectivity
6854:1 – Announce everywhere with longer as_path, full backup
6854:2 – announce everywhere except AS6854 uplinks, Russia connectivity only
6854:3 – announce to AS6854 uplinks only, International connectivity only
6854:4 – announce to AS6854 uplinks with longer as_path announce to other peers with no extra prepending, International connectivity backup & Russia
6854:5 – announce to our uplinks with no extra prepending announce to all other peers with longer as_path, (Russia backup & international connectivity)
6854:6 – announce to AS6854 uplinks only with longer as_path (international connectivity backup only)
6854:7 – announce everywhere except AS6854 uplinks with longer as_path (Russia backup only)
6854:13 – the same policy as for 6854:0 community, preserved for backward compatibility
6854:14 – the same policy as for 6854:4 community, preserved for backward compatibility
6854:6854 – announce to other AS6854 downlinks only, AS-TCNET/AS-RUSMEDIA connectivity only. none or not specified above the same policy as for 6854:0 community, if not stipulated for some another by customer


Note: the rules, described above, are not applied to BGP advertisements accepted from one AS6854 downlink when they are passed to other AS-TCNET/AS-RUSMEDIA
members

Extra BGP communities advertised to AS6854 downlinks

6854:10 – this route was learned from MSK-IX peer
6854:11 – this route was learned from AS6854 uplink

 

Contact Us

Phone: +7 095 9800388, +7 095 2156520
Fax-no: +7 095 9791036
Modified for Russian phone area changes


 

 

 


Applying BGP Community string with sample configuration

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

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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