BGP Community String for Golden Telecom AS3216

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BGP Community String for Golden Telecom AS3216

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3216:500x When advertising to UUNET...
3216:501x When advertising to C&W...
3216:502x When advertising to Level3...
3216:503x When advertising to Global Crossing...
3216:590x When advertising to any INTERNATIONAL peer...
3216:505x When advertising to any M9-IX peer...
3216:506x When advertising to any SPB-IX peer...
3216:507x When advertising to any NSK-IX peer...
3216:521x When advertising to Rostelecom private peer (Moscow)...
3216:522x When advertising to MTU private peer...
3216:523x When advertising to Masterhost private peer...
3216:524x When advertising to TTK private peer...

...x=0 - do not advertise
...x=1,2,4 or 6 - prepend 3216 1,2,4 or 6 times

3216:58xx Set local preference to xx, where...
...xx=70 - the lowest value used in the network (BACKUP)
...xx=80 - less by 1 than the lowest value of INTERNATIONAL
...xx=90 - less by 1 than the lowest value of NATIONAL peer

Other communities in range 3216:5000-3216:5999 are accepted but ignored.
Other 3216:* communities are deleted.
Other *:* communities are passed intact but not to all peers.

Customers' routes get local preference of 100 (highest).
Peers' routes get local preference in the range of 91-99.
Uplinks' routes get local preference in the range of 81-89.

Internal BGP communities are assigned only internally.
They are in range 3216:0000-3216:4999 and 3216:6000-3216:65535 and are always deleted from incoming updates at the border routers.
They may be used by peers to filter some prefixes.

BGP Community String

3216:1000 Russian peer (receieved from IX or private peer)
3216:1003 SPB peer
3216:1004 Moscow peer
3216:1005 NSK peer
3216:1006 Almaty peer
3216:1007 Vladivostok peer
3216:1008 Ekaterinburg peer
3216:1010 Arkhangelsk peer
3216:1101 Rostelecom private peering (Moscow)
3216:1102 MTU private peering (Moscow)
3216:1103 Vladivostok Electrosvyaz private peering
3216:1104 Ekaterinburg Ural-Relcom private peering
3216:1106 Arkhangelsk Artelecom private peering
3216:1107 Masterhost private peering (Moscow)
3216:1108 TTK private peering (Moscow)
3216:2001 Full transit customer and own networks
3216:3000 Receieved from an international peer, specifically:
3216:3001 C&W
3216:3002 UUNET
3216:3003 Level3
3216:3004 Global Crossing
3216:4000 Originated in any region, specifically:
3216:4001 Originated in SPB
3216:4002 Originated in Novosibirsk
3216:4003 Originated in Vladivostok
3216:4004 Originated in Samara
3216:4005 Originated in NNovgorod
3216:4006 Originated in Arkhangelsk
3216:4007 Originated in Tyumen
3216:4008 Originated in Ekaterinburg
3216:4009 Originated in Almaty
3216:4010 Originated in Arkhangelsk
3216:4100 Originated in Moscow
3216:4200 Internal prefixes originated in Moscow
3216:4201 Internal prefixes originated in SPB
3216:4202 Internal prefixes originated in Ufa
3216:4203 Internal prefixes originated in Samara
3216:4204 Internal prefixes originated in Khabarovsk

---------------------------------------
phone: +7 095 7871001
fax-no: +7 095 7871010
formely Sovam Teleport NOC
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 new.CiscoNET.com web site.

2. Pick the best BGP community string for your traffic shaping plan (mainly incoming traffic).
Most of ISPs are providing 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

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.CiscoNET.com 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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