Easynet BGP Policy Description
This document describes two aspects of BGP network control that can be used to form policy decisions throughout the Easynet Group Network. It has a number of purposes:
1) To allow Easynet networks and its’ customers to use BGP communities in order to control how prefixes are handled within the network when announcing to external parties.
2) To provide a coherent and conformant policy on BGP prefix management within the network. 3) To allow Easynet to increase the efficiency of its’ use of external links.
It is divided into the following sections: o Description of BGP communities o The use of BGP communities in the Easynet network (both for classification and for control) o Description of local-preference
BGP Communities String
The notation used to represent BGP community values splits the 32-bit attribute into two 16-bit decimal numbers seperated by a single colon `:’. Nominally, the left-hand value is an AS number and the second is site defined. There are some predefined BGP community values that are common to all AS’s. Refer to RFC1997 and RFC1998 for more details on BGP communities.
There are two uses for BGP communities in the Easynet network: Classification of prefixes and control of prefixes. Only Easynet itself classifies prefixes as they enter the network at its’ borders. Customers and peers should not do so. These attributes can be used by multihomed downstreams to weight traffic in order to distribute it according to local administrative policies. Prefixes are classified according to geographic entry point, class of prefix (Transit, Public Peering, Private Peering) and which entity of each class (Specific Transit provider, Public Peering point etc). Prefix control allows the path-extension or filtering entirely of customer prefixes where they are announced at the borders of Easynets’ network. Only class of network (Transit, Public Peering, Private Peering) and/or class entity (Specific Transit provider, specific Public Peering point etc) can be targeted. As a matter of policy, the AS number used for all BGP community strings is AS4589. This allows for consistency across the network. There are four classes of BGP communities, identified by the number of digits in the right-hand side:
o 3 digits prefix classification by peer or NAP from which it was received
o 4 digits outgoing announcement control
o 5 digits prefix classification by location at which it was received In addition to the BGP communities listed below, the well-known BGP communities (local-AS, no-advertise and no-export) are recognised and can be used (in fact, they’re handled automatically by the routers).
One-digit BGP communities string
These BGP communities are set by Easynet upon entry on the network. They indicate how far a prefix should be distributed. The following BGP communities are used:
o 4589:2 Global network. This is a prefix that is visible in the DFZ (default free zone), e.g. routes received from peers or from upstreams. This is also set on customer routes.
o 4589:3 Confederation network. This prefix is visible only within the AS4589 confederations. Examples include the IPv6 suballocations or the SAP "extranet" prefix. Normally these prefixes will have no-export set too.
o 4589:4 Subconfederaton-local network. This prefix will be restricted to one subconfederation, e.g. AS65044. Customer prefixes held in BGP will have this BGP community. Normally these prefixes will have local-AS/no-export-subconfed set too.
Two-digit BGP communities string
Currently unused. In future it might for example be used to control local-preference.
Three-digit BGP communities string–
Prefixes coming from peers and transit will be tagged with three-digit BGP community values, e.g. a prefix received at DECIX will be tagged with 4589:641. Only the most specific BGP community is added, e.g. a route from DECIX will not have 4589:640 set.
BGP Community Entry point
4589:5xx External Transit
4589:520 unused (was Teleglobe AS6453)
4589:530 Genuity US (AS1)
4589:531 Genuity DE (AS7176)
4589:540 Cable & Wireless US (AS3561)
4589:541 Cable & Wireless UK (AS3561)
4589:542 Cable & Wireless DE (AS1273)
4589:550 unused (was KPNQwest AS286, formerly Ebone AS1755)
4589:560 Sprint IT
4589:565 Level 3 DE (AS3356)
4589:570 Telia FR (AS1299)
4589:580 InfoNet NL (AS3300)
4589:59x Special IPv6 transit
4589:591 Cable & Wireless DE (AS3561)
4589:6xx From an IXP/NAP peer
4589:61x From UK NAPs
4589:611 From LINX (AS65000 – Int’l)
4589:612 From LINX (AS65044 – UK)
4589:613 From LoNAP
4589:614 From MaNAP
4589:615 From Scotix
4589:62x From BE NAPs
4589:621 From BNIX
4589:625 From ES NAPs
4589:626 From ESPANIX
4589:627 From CATNIX
4589:63x From NL NAPs
4589:631 From AMS-IX
4589:635 From CH NAPs
4589:636 From TIX
4589:637 From CERN/CIXP
4589:64x From DE NAPs
4589:641 From DECIX
4589:642 From MAE Frankfurt
4589:643 From INXS Munich
4589:644 From INXS Hamburg
4589:645 From BCIX Berlin
4589:65x From FR NAPs
4589:651 From SFINX
4589:652 From MAE Paris
4589:653 From FreeIX
4589:654 From PARIX
4589:66x From IT NAPs
4589:661 From MiX
4589:662 From TopIX
4589:670 From US NAPs
4589:671 From NYIIX
4589:672 From NY6IX
4589:7xx From a Private Peer
4589:710 From a UK private peering
4589:740 From a DE private peering [To be discussed 4589:8xx From a Distinguished Peer 4589:801 From Telia (AS1299) ] [To be discussed 4589:900 Tunneled IPv6 Peers 4589:901 Tunneled IPv6 peer without transit 4589:902 Tunneled IPv6 peer with (some) transit agreement ]
Four-digit BGP communities string
Customers can set four-digit BGP communities to control where prefixes are announced. The three-digit BGP communities are used as a base for this and prefixed by 1, 2, 3 or 9 to control prepending of the customer’s prefix on announcement to peers or transits on the specified location.
1 Prepend announcement with "4589" on its AS-path
2 Prepend announcement with "4589 4589"
3 Prepend announcement with "4589 4589 4589" 9 Filter announcement, i.e. don’t announce For example, setting the BGP community 4589:9641 will have the effect that the network on which it is set will not be announced to DE-CIX. These BGP communities may not be implemented in the whole network. When used, it should be verified that the specific BGP community is honored. Otherwise you can request that it is implemented. For a wider range, the "x" in the list of entry points can be replaced by "0". So for example "4589:2640" will result in a prepend of length two on all IXPs in Germany, and "4589:2500" has the effect of prepending 4589 to all transits.
Five-digit BGP communities string
Every prefix has a five-digit BGP community set which tells on which location it was received. This BGP community has the following format: 4589:1 where usually is the country code with possible additions or modification, and is a number for each of the POPs/locations in the country.
BGP Community Entry point
- 4589:101xx US
4589:10101 60 Hudson Street (TelX, NYC) [hsnyc]
4589:10102 25 Broadway (Telehouse, NYC) [bwnyc]
4589:131xx NL
4589:132xx BE
4589:13200 Unspecified location (self-originated prefixes)
4589:13201 gdbru (Gulledelle, Brussels)
4589:13202 ixbru (InterXion, Brussels)
4589:13203 bnbru (Belnet, Brussels)
4589:133xx FR
4589:134xx ES
4589:13400 Unspecified location (self-originated prefixes)
4589:13401 Mad (Alfonso XI) [almad]
4589:13402 Madrid (ESPANIX, Colonia Banesto) [exmad]
4589:13403 Barcelona (C&W, Pedrosa) [cwbcn]
4589:13404 Barcelona (CATNIX, Cesca) [cxbcn]
4589:139xx IT
4589:13900 Unspecified location (self-originated prefixes)
4589:13901 Milan (Fulvio Testi 7) [ftmil]
4589:13902 Milan (Via Caldera 22) [camil]
4589:13903 Milan (Redbus) [rbmil]
4589:13904 Milan (San Donato M.) [sdmil]
4589:13905 Milan (MiX) [ixmil]
4589:13906 Rome (Simone Martini) [smrom]
4589:141xx CH
4589:14100 Unspecified location (self-originated prefixes)
4589:14101 Zuerich (Hardturmstrasse 135) [htzrh]
4589:14102 Zuerich (TIX, Telehouse) [thzrh]
4589:14103 Geneva (CIXP, Telehouse) [thgva]
4589:144xx UK
4589:14411 London (44 Whitfield) [wslon]
4589:14412 London (39 Whitfield) (deprecated)
4589:14413 London (Telehouse) [thlon]
4589:14414 London (Telecity) [tclon]
4589:14415 London (1 Brick Lane) [bllon]
4589:14416 London (Slough) 4589:14417 London (Redbus – Harbour Exchange)
4589:14418 London (Redbus – Meridian
Gate 4589:14419 London (Redbus – Sovereign House)
4589:14420 London (InterXion)
4589:14431 Scotland (Scolocate Edinburgh)
4589:14432 Scotland (Easynet Edinburgh)
4589:peering, apart from
4589:xxxx from customers which they can use to control announcements.
All other BGP communities are accepted and passed unchanged.
BGP Local Preference
150 Customer or Easynet route, learnt directly
100 Normal transit/peer route
50 Low preference Transit Route
Legacy BGP Communities String
The BGP communities listed here were used previously and will be phased out.
BGP Community Entry point
11341:1 Easynet or Customer network
11341:10 UK
11341:11 London (44 Whitfield) [wslon]
11341:12 London (39 Whitfield) (deprecated)
11341:13 London (Telehouse) [thlon]
11341:14 London (Telecity) [tclon]
11341:15 London (1 Brick Lane) [bllon]
11341:16 London (Slough)
11341:20 UK National Network
11341:21 Manchester (Telecity) [tcman]
11341:30 DE
11341:31 Frankfurt (WCOM/MAE Frankfurt) [mafra]
11341:32 Frankfurt (DECIX) [ixfra]
11341:33 Frankfurt (NT Telehouse) [ttfra]
11341:34 Munich (INXS/ECRC) [ixmuc]
11341:35 Hamburg (NT Telcotrust) [ttham]
11341:36 Berlin (NT Telcotrust) [ttber]
11341:37 Hamburg (C&W, INXS) [ixham]
11341:40 US
11341:41 60 Hudson Street (TelX, NYC) [hsnyc]
11341:42 25 Broadway (Telehouse, NYC) [bwnyc]
11341:50 FR
11341:51 Paris (Telehouse) [thpar]
11341:52 Parid (Beaubourg) [bbpar]
11341:60 BE
11341:61 Brussels Office [gdbru]
11341:62 Brussels (Belnet) [bnbru]
11341:63 Brussels (InterXion) [ixbru]
11341:70 NL
11341:71 Amsterdam (Level 3) [l3ams]
11341:72 Amsterdam (Telecity) [tcams]
11341:73 Amsterdam (Hoofddorp) [enhfd]
11341:80 ES
11341:81 Madrid (Alfonso XI) [almad]
11341:82 Madrid (Espanix)
11341:82 Madrid (Redbus)
11341:85 Barcelona (Cable & Wireless)
11341:86 Barcelona (Catnix)
11341:90 CH 11341:91 Zurich Office [htzur]
11341:92 Zurich (TIX)
11341:95 Geneva (Office)
11341:96 Geneva (Telehouse)
11341:97 Geneva (CERN)
11341:100 IT
11341:101 Milan Office [ftmil]
11341:102 Milan (MiX)
11341:103 Milan (Redbus)
11341:105 Rome (Colt)
11341:n500 From external Transit
11341:n520 From Teleglobe
11341:n530 From Genuity
11341:n540 From Cable & Wireless
11341:n550 From KPNQwest [was Ebone]
11341:n560 From ECRC
11341:n600 From an IXP/NAP peer
11341:n610 From UK NAPs
11341:n611 From LINX (AS11341)
11341:n612 From LINX (AS5607)
11341:n613 From LoNAP
11341:n614 From MaNAP
11341:n615 From Scotix
11341:n620 From BE NAPs
11341:n621 From BNIX
11341:n625 From ES NAPs
11341:n626 From ESPANIX
11341:n627 From CATNIX
11341:n630 From NL NAPs
11341:n631 From AMS-IX
11341:n635 From CH NAPs
11341:n636 From TIX
11341:n637 From CERN/CIXP
11341:n640 From DE NAPs
11341:n641 From DECIX
11341:n642 From MAE Frankfurt
11341:n643 From INXS Munich
11341:n644 From INXS Hamburg
11341:n650 From FR NAPs
11341:n651 From SFINX
11341:n652 From MAE Paris
11341:n653 From FreeIX
11341:n654 From PARIX
11341:n660 From IT NAPs
11341:n661 From MIIX
11341:n670 From US NAPs
11341:n671 From NYIIX
11341:n700 From a Private Peer
11341:n701 From AboveNET (AS6461)
11341:n702 From DTAG (AS3320)
Where a BGP community specifies "n", replace "n" with the appropriate value:
2 Prepend announcement with "11341 11341 11341" on its AS-path, for outbound prefixes
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.
The www.ipBalance.com runs by a volunteer group with IT professionals and experts at least over 25 years of experience developing and troubleshooting IT in general. ipBalance.com is a free online resource that offers IT tutorials, tools, product reviews, and other resources to help you and your need.
