Level3 BGP Community String

Level 3 BGP Communities 

Level 3 (AS3356) does not allow any part of 4.0.0.0/8 to be multihomed. If you are a customer who is currently using address space from 4.0.0.0/8 and if you need to multihome your network to another provider, please contact Level 3 for new address space which can be multihomed.

If you are a provider who has been asked to route a more-specific network block that is part of 4.0.0.0/8, please ask your customer to contact Level 3 to obtain a new network block. Level 3 will not accept advertisements for any networks that are part of 4.0.0.0/8 from any non-customer peer.
Note that the import/export designations above are a simplification of our actual policies which cannot be properly described given the limitations of RPSL
They would also be rather tedious to read if we denoted all of the common policy bits applied to every peer, so we have only noted the peer-specific bits.
We have also only documented our customer peers in this object at this time.

 The following import actions are common to every Level 3 customer peering session:
- RFC1918 and other reserved networks and subnets are not permitted.
- Advertisements with reserved ASes in the path (ie 64512 - 65535) are not permitted.
- Prefixes shorter than /3 or longer than /28 are not permitted.
- Advertisements containing the AS of a network with which we have a non-customer peering relationship are not permitted (ie customers are not allowed to advertise transit for UUnet, CW, etc).
- Advertisements tagged with our own "internal use only" BGP communities (ie the city/country/region/etc BGP communities outlined below) will have all of their BGP communities stripped from them at ingress, and any BGP communities meant to affect localpref, prepending, etc are thus ignored.
- Prefixes not matching the per-peer import policy as documented above are not permitted.
- Localpref will be set to 100 by default, subject to modification based on received BGP communities as outlined below.
- A hard limit is placed on the number of routes a peer is allowed to announce to us. This number is based on their registered routes plus a bit of extra overhead.
The following import actions are common to every Level 3 non-customer peering session:
- RFC1918 and other reserved networks and subnets are not permitted.
- Advertisements with reserved ASes in the path (ie 64512 - 65535) are not permitted.
- Prefixes shorter than /3 or longer than /24 are not permitted.
- Any subnet of any Level 3 CIDR block (as documented in rs-Level3) is not accepted unless routing for the subnet in question has been explicitly requested by the multihomed customer in question.
- Advertisements tagged with our own "internal use" or "customer use" BGP communities (as outlined below) will have all of their BGP communities stripped from them at ingress.
- MEDs are overwritten unless special arrangements have been made.
- Peers who register their routes with meaningful policies may have a prefix filter applied based on this policy.
- Localpref is set to 86 or lower (depending on the nature of the facility over which the peering is taking place and several other factors).
- A hard limit is placed on the number of routes a peer is allowed to announce to us. This number is based on their registered routes or on a historical view of the number of routes they have been advertising plus a bit of extra overhead.
 The following export actions are common to every Level 3 peering session:
- RFC1918 and other reserved networks and subnets are not announced.
- Advertisements with reserved ASes in the path (ie 64512 - 65535) are not announced.
- Prefixes shorter than /3 or longer than /24 are not announced.
- Any subnet of any Level 3 CIDR block (as documented in rs-Level3) is not announced unless routing for the subnet in question has been explicitly requested by the multihomed customer in question.
- Suppression and prepend actions as outlined in the BGP community list below are taken for announcements to non-customer peers.

BGP Communities applied at ingress

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prefix type BGP communities
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3356:123 - Customer route

3356:666 - Peer route

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error type BGP communities
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3356:911 - "internal use" BGP communities received from peer
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city BGP communities
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3356:2001 - CHI - Chicago
3356:2002 - SDG - San Diego
3356:2003 - LAX - Los Angeles
3356:2004 - DEN - Denver
3356:2005 - PHI - Philadelphia
3356:2006 - WDC - Washington DC
3356:2007 - DET - Detroit
3356:2008 - DAL - Dallas
3356:2009 - SFO - San Francisco
3356:2010 - NYC - New York City
3356:2011 - SJO - San Jose
3356:2012 - SEA - Seattle
3356:2013 - ATL - Atlanta
3356:2014 - HOU - Houston
3356:2015 - BOS - Boston
3356:2016 - MIN - Minneapolis
3356:2017 - HON - Honolulu
3356:2018 - WEE - Weehawken
3356:2019 - BAL - Baltimore
3356:2020 - CIN - Cincinnati
3356:2021 - STM - Stamford
3356:2022 - MIA - Miami
3356:2023 - TMP - Tampa
3356:2024 - ORL - Orlando
3356:2025 - STL - St Louis
3356:2026 - PHX - Phoenix
3356:2027 - RCH - Richmond
3356:2028 - MEM - Memphis
3356:2029 - SLC - Salt Lake City
3356:2030 - SAC - Sacramento
3356:2031 - RAL - Raleigh
3356:2032 - SAT - San Antonio
3356:2033 - LVG - Las Vegas
3356:2034 - CLT - Charlotte
3356:2035 - CLE - Cleveland
3356:2036 - OAK - Oakland
3356:2037 - NVL - Nashville
3356:2038 - TUS - Tustin
3356:2039 - NWR - Newark
3356:2064 - LON - London
3356:2065 - FRF - Frankfurt
3356:2066 - PAR - Paris
3356:2067 - AMS - Amsterdam
3356:2068 - BRU - Brussels
3356:2069 - DUS - Dusseldorf
3356:2070 - HAM - Hamburg
3356:2071 - BER - Berlin
3356:2072 - MUN - Munich
3356:2074 - MLN - Milan
3356:2075 - ZUR - Zurich
3356:2076 - STK - Stockholm
3356:2077 - MAD - Madrid
3356:2078 - GEN - Geneva
3356:2079 - MAN - Manchester
3356:2080 - DUB - Dublin
3356:2081 - COP - Copenhagen
3356:2082 - VIE - Vienna
3356:2083 - PRG - Prague
3356:2084 - WAW - Warsaw

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country BGP communities
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3356:500 - UK
3356:501 - Germany
3356:502 - France
3356:503 - Netherlands
3356:504 - Belgium
3356:505 - Italy
3356:506 - Switzerland
3356:507 - Sweden
3356:508 - Spain
3356:509 - Ireland
3356:510 - Denmark
3356:511 - Austria
3356:512 - Czech Republic
3356:513 - Poland
3356:575 - USA
3356:576 - Canada

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regional BGP communities
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3356:2 - Europe
3356:3 - North America

BGP Communities accepted from customers

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Customer traffic engineering (TE) notes
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BGP Communities allow suppress or prepend to peer AS, where
- peer AS has a peering connection to Level 3
- peer AS is not a customer of Level 3

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Customer traffic engineering BGP communities - Suppression
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64960:XXX - announce to AS XXX if 65000:0
65000:0 - announce to customers but not to peers
65000:XXX - do not announce at peerings to AS XXX

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Customer traffic engineering BGP communities - Prepending
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65001:0 - prepend once to all peers
65001:XXX - prepend once at peerings to AS XXX
65002:0 - prepend twice to all peers
65002:XXX - prepend twice at peerings to AS XXX
65003:0 - prepend 3x to all peers
65003:XXX - prepend 3x at peerings to AS XXX
65004:0 - prepend 4x to all peers
65004:XXX - prepend 4x at peerings to AS XXX

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Customer traffic engineering BGP communities - Regional
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Will only work for regional peers
64980:0 - announce to customers but not to EU peers
64981:0 - prepend once to all EU peers
64982:0 - prepend twice to all EU peers
64983:0 - prepend 3x to all EU peers
64984:0 - prepend 4x to all EU peers

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Customer traffic engineering BGP communities - LocalPref
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3356:70 - set local preference to 70
3356:80 - set local preference to 80
3356:90 - set local preference to 90

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Customer traffic engineering BGP communities - Blackhole
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3356:9999 - blackhole (discard) traffic

Traffic destined for any prefixes tagged with this
BGP community will be discarded at ingress to the Level 3
network. The prefix must be one permitted by the
customer's existing ingress BGP filter.
Support@Level3.com This e-mail address is being protected from spambots. You need JavaScript enabled to view it  may need to be contacted to allow
in some cases. For some router vendors the peering
must be changed to an eBGP multihop session.
Please contact  support@Level3.com This e-mail address is being protected from spambots. You need JavaScript enabled to view it  with any questions
regarding this functionality.

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