BGP Communities – Knowledgebase
Inter.link offers a pan-european 100G network with high-quality connectivity to carriers, content providers, and internet exchanges.
This section explains Inter.link’s BGP communities for traffic engineering. BGP communities are provided on a best effort basis and not subject to product-specific SLAs. They are subject to change and customers and peers should check this site for updates.
BGP Origin Communities
Learned BGP routes are tagged at ingress with origin communities. These have informational value and indicate where a prefix was learned and from whom. The corresponding IDs are listed in the Appendix shown below.
| Community | Purpose | Remarks |
| 5405:P | Learned from peer type (P) | Customers, Transit, Peering or PNI |
| 5405:1R | Learned at scope continent (1), on continent (R) | |
| 5405:2CC | Learned at scope country (2), in country (CC) | |
| 5405:3ZZZ | Learned at scope city (3), in city (ZZZ) | |
| 5405:4SSS | Learned at scope PoP (4), in PoP (SSS) |
The community combination 5405:3 5405:15 5405:208 5405:3003 5405:4004 attached to a route tells the following about the origin:
| Community | Explanation |
| 5405:3 | Peering IXP (3) |
| 5405:15 | continent (1) Europe (5) |
| 5405:208 | country (2) Germany (08) |
| 5405:3003 | city (3) Berlin (003) |
| 5405:4004 | PoP (4) BER1-DE (004) |
BGP Signalling Communities
BGP Large Communities can be used to control the behaviour of the routing service. Multiple of them can be attached to a single BGP announcement. They are stripped upon annuncement to other peers.
| Abbreviation | Name | Remarks |
| R | Continent Identifier | 0 = all continents (1) |
| CC | Country Identifier | 00 = all countries (1) |
| ZZZ | City Identifier | 000 = all cities (1) |
| P | Peer Type Identifier | 0 = all peer types (1) |
| AAA | 4 Byte ASN | 0 = all ASNs (1) |
PATH PREPENDING COMMUNITIES
- Path prepends of the ASN 5405 are supported up to three times (x = 1, 2, 3).
- Prepends within a scope (e. g. country) are non-additive, the lower value is processed.
- Prepends in multiples scopes (e. g. country and city) are additive.
- Prepending (x = 1, 2, 3) supersedes filtering (x = 9).
| Community | Purpose |
| 5405:1 RPx:AAA | scope continent (1), continent, peer type, prepend x times to ASN |
| 5405:2 CCPx:AAA | scope country (2), country, peer type, prepend x times to ASN |
| 5405:3 ZZZPx:AAA | scope city (3), city, peer type, prepend x times to ASN |
RESTRICT PROPAGATION
| Community | Purpose |
| 5405:1 RP9:AAA | scope continent (1), continent, peer type, do not advertise (9) to ASN |
| 5405:2 CCP9:AAA | scope country (2), country, peer type, do not advertise (9) to ASN |
| 5405:3 ZZZP9:AAA | scope city (3), city, do not advertise (9) to ASN |
WELL-KNOWN COMMUNITIES
The following well-known communities are honoured.
| Community | Purpose | Remarks |
| GRACEFUL_SHUTDOWN (65535:0) | lower local-pref to 1 | RFC8326 |
| BLACKHOLE (65535:666) | blackhole traffic, see RTBH | RFC7999 |
| NO_EXPORT (65535:65281) | do not announce to any other ASN | RFC1997 |
| NO_ADVERTISE (65535:65282) | do not announce beyond receiving PE router | RFC1997 |
| Altering of LOCAL_PREF (5405:30) | decrease local-pref by 30 | RFC1998 |
| Altering of LOCAL_PREF (5405:50) | decrease local-pref by 50 | RFC1998 |
REMOTE TRIGGERED BLACKHOLING (RTBH)
We support Remote Triggered Blackholing (RTBH) announcements that can activate across our global backbone, or more specific regions of it, depending on the attached community. See below for examples for choosing the right region. RTBH announcements are discarded if the prefix isn’t covered by the prefix filters configured for the peer announcing the route.
| Community | Purpose | Remarks |
| 65535:666 | Global RTBH | well-known community defined in RFC7999 |
| 5405:666:1R | RTBH inside a continent (R) | |
| 5405:666:2CC | RTBH inside a country (CC) | |
| 5405:666:3ZZZ | RTBH inside a city (ZZZ) |
The accepted IDs for R,CC,ZZZ can be found in the Appendix below.
If the scope of the selective blackholing matches the only origin of the route, a global blackhole is the result.
Maximum prefix length for RTBH routes is restricted to /20 to /32 for IPv4 and /48 to /128 for IPv6. Routes with the well-known community 65535:666 are propagated to other peer/upstream ASNs as well.
For peers supporting the BLACKHOLE community, different blackhole route prefix lengths might lead to different results:
- Announcements carrying Hostroutes (IPv4 /32 and IPv6 /128) are usually accepted and the traffic is dropped in the peer network.
- Announcements carrying IPv4 prefixes with a length between /20 and /32 or IPv6 prefixes with a length between /48 and /128 might be accepted or rejected depending on the peer’s routing policy.
EXAMPLES
| Community | Explanation |
| 5405:1002:65550 | scope continent (1), all continents (0), all peer types (0), prepend twice (2), to ASN 65550 |
| 5405:1539:0 | scoper continent (1), Europe (5), all IXP peerings (3), do not announce (9), all ASNs (0) |
| 5405:666:3003 | Selective Blackhole, scope city (3), city Berlin (003) |
| 5405:21749:0 | scope country (2), Spain (17), PNI peerings (4), do not advertise (9), all (0) |
| 5405:1039:0 | scope continent (1), all continents (0), IXP peerings (3), do not announce (9), all ASNs (0) |
| 5405:1049:0 | scope continent (1), all continents (0), PNI peerings (4), do not announce (9), all ASNs (0) |
| 5405:1039:0 5405:1049:0 | The combination of these two communities mimics NOPEER community |
APPENDIX
Continent IDs
| Continent ID (R) | Continent Name |
| 1 | Africa |
| 2 | Antarctica |
| 3 | Asia |
| 4 | Australia |
| 5 | Europe |
| 6 | North America |
| 7 | Central America |
| 8 | South America |
Country IDs
| Country Name | Country ID (CC) |
| Australia | 1 |
| Austria | 2 |
| China | 3 |
| Czechia | 4 |
| Denmark | 5 |
| Finland | 6 |
| France | 7 |
| Germany | 8 |
| Hong Kong | 9 |
| Ireland | 10 |
| Italy | 11 |
| Japan | 12 |
| Netherlands | 13 |
| Norway | 14 |
| Portugal | 15 |
| Singapore | 16 |
| Spain | 17 |
| Sweden | 18 |
| Switzerland | 19 |
| United Arab Emirates | 20 |
| United Kingdom of Great Britain and Northern Ireland | 21 |
| United States of America | 22 |
| Hungary | 23 |
| Slovenia | 24 |
| Romania | 25 |
| Bulgaria | 26 |
| Greece | 27 |
City IDs
| City Name | City ID (ZZZ) |
|
Amsterdam |
001 |
|
Ashburn |
002 |
|
Berlin |
003 |
|
Copenhagen |
004 |
|
Dubai |
005 |
|
Dublin |
006 |
|
Dusseldorf |
007 |
|
Frankfurt |
008 |
|
Helsinki |
009 |
|
Hongkong |
010 |
|
Lisbon |
011 |
|
London |
012 |
|
Los Angeles |
013 |
|
Madrid |
014 |
|
Miami |
015 |
|
Milan |
016 |
|
Munich |
017 |
|
New York |
018 |
|
Nuremberg |
019 |
|
Oslo |
020 |
|
Paris |
021 |
|
Prague |
022 |
|
Seattle |
023 |
|
Silicon Valley |
024 |
|
Singapore |
025 |
|
Stockholm |
026 |
|
Stuttgart |
027 |
|
Sydney |
028 |
|
Tokyo |
029 |
|
Vienna |
030 |
|
Zurich |
031 |
|
Marseille |
032 |
|
Budapest |
033 |
|
Ahrensburg |
034 |
|
Hamburg |
035 |
|
Reston |
036 |
|
Ljubljana |
037 |
|
Bucharest |
038 |
|
Aarhus |
039 |
|
Skanderborg |
040 |
| Sofia | 041 |
| Thessaloniki | 042 |
PoP IDs
| PoP Name | PoP ID (SSS) |
|
AMS1-NL |
1 |
|
AMS2-NL |
2 |
|
ASH1-US |
3 |
|
BER1-DE |
4 |
|
BER2-DE |
6 |
|
BER3-DE |
7 |
|
BER4-DE |
8 |
|
CPH1-DK |
14 |
|
DUB1-IE |
15 |
|
DUS1-DE |
16 |
|
FRA1-DE |
18 |
|
FRA2-DE |
19 |
|
FRA3-DE |
20 |
|
LON1-GB |
24 |
|
MAD1-ES |
26 |
|
MIL1-IT |
28 |
|
MUC1-DE |
29 |
|
NUE1-DE |
30 |
|
NYC1-US |
31 |
|
PAR1-FR |
33 |
|
PRG1-CZ |
34 |
|
SEA1-US |
35 |
|
STO1-SE |
38 |
|
STO2-SE |
39 |
|
STR1-DE |
40 |
|
VIE1-AT |
43 |
|
VIE2-AT |
44 |
|
ZRH1-CH |
45 |
|
MRS1-FR |
47 |
|
BUD1-HU |
48 |
|
AHR1-DE |
49 |
|
HAM1-DE |
50 |
|
RTV1-US |
51 |
|
LJU1-SI |
52 |
|
BUH1-RO |
53 |
|
AAR1-DK |
54 |
|
AAR2-DK |
55 |
|
CPH2-DK |
56 |
|
CPH3-DK |
57 |
|
SKG1-DK |
58 |
|
SKG2-DK |
59 |
|
MUC2-DE |
60 |
|
SOF1-BG |
61 |
|
SKG1-GR |
62 |
|
QAS1-US |
69 |
Peer Type IDs
| Peer Type ID (P) | Peer Type Name |
| 1 | Customers |
| 2 | Transit |
| 3 | Peering IXP and IXP Router Servers |
| 4 | Peering PNI |