¶ Understanding BGP Communities: Enhancing Routing Control and Traffic Engineering
In the world of networking, the Border Gateway Protocol (BGP) stands as a pivotal protocol that plays a crucial role in the operation of the global internet. BGP, which is used to exchange routing and reachability information among autonomous systems (ASes), has evolved over the years to include a powerful feature known as "BGP communities." These communities allow network administrators to exert greater control over routing decisions, enhance traffic engineering, and optimize network performance. In this article, we'll delve into the concept of BGP communities, exploring their significance, applications, and benefits.
BGP communities are tags or labels that network administrators attach to BGP routes to convey specific information about those routes. These labels do not have any inherent meaning to BGP itself; their interpretation is left to the discretion of the network operators who assign and use them. Communities are primarily used as a means of communication between network peers to influence routing behavior.
Each BGP community is a numerical value that consists of two 16-bit numbers, written in the format <AS>:<Value>. The AS number represents the autonomous system that defines the community, and the value can be used to convey specific information or instructions.
- Traffic Engineering: BGP communities offer network engineers the ability to manipulate routing paths and optimize traffic flow. By attaching certain communities to routes, operators can guide traffic to follow desired paths, balance load between links, or prefer certain transit providers over others.
- Prefix-Level Policy Enforcement: Communities can be employed to enforce routing policies at the prefix level. Network administrators can instruct their peers to accept or reject certain routes based on the attached communities, ensuring routes are propagated and handled as intended.
- Route Targeting in MPLS VPNs: In Multiprotocol Label Switching (MPLS) Virtual Private Networks (VPNs), BGP communities are used to define the distribution of routes within a VPN. This enables more granular control over how routes are advertised and propagated within the VPN.
- Blackholing and DDoS Mitigation: BGP communities have been widely adopted in distributed denial-of-service (DDoS) mitigation strategies. Network operators can use communities to signal to their peers that certain routes should be blackholed (discarded) during DDoS attacks, preventing malicious traffic from overwhelming the network.
- Selective Prefix Announcement: Communities can help network administrators choose which prefixes to announce to specific peers or upstream providers. This can be useful for segmenting traffic flow or controlling which routes are shared with partners or customers.
- Flexibility: BGP communities provide a flexible mechanism for conveying routing policies and preferences. Network operators can define their own communities to suit their specific requirements.
- Traffic Optimization: By using BGP communities, network administrators can influence the path that traffic takes through the network, optimizing routes and enhancing overall network performance.
- Simplicity: Communities simplify the process of implementing complex routing policies. They provide a more intuitive way to communicate routing intentions compared to manipulating BGP attributes directly.
- Scalability: BGP communities allow for more efficient routing decision dissemination across the network, contributing to better scalability in large and complex networks.
BGP communities empower network administrators with a powerful toolset to shape and optimize the flow of internet traffic. Through their flexible and versatile nature, BGP communities enable fine-grained control over routing decisions and offer a more efficient means of communication between autonomous systems. As the internet continues to grow and evolve, the strategic use of BGP communities will play an increasingly vital role in maintaining a well-functioning, interconnected digital landscape.
Network Platforms has informational communities which provide you with information on where the prefix(es) were learnt, as well as action communities which allow you to traffic engineer with us.
Learnt From :
37497:40xx - IP Transit
- 37497:4000 - AS328832 NP International London LD8
- 37497:4001 - AS174 Cogent London LD8
- 37497:4003 - AS1299 Telia London LD8
- 37497:4004 - AS3356 Lumen / Level 3 London LD8
- 37497:4011 - AS3491 PCCW Cape Town CT1 and Johannesburg JB1
- 37497:4012 - AS328512 Backspace Cape Town CT1 and Johannesburg JB1
- 37497:4014 - AS20473 Vultr Tokyo (Temp solution)
37497:41xx - South Africa Peering
- 37497:4101 - NAP Africa Johannesburg JB1
- 37497:4102 - NAP Africa Cape Town CT1
- 37497:4103 - NAP Africa Durban DB1
- 37497:4104 - JINX
- 37497:4105 - CINX
- 37497:4106 - DINX
- 37497:4151 - Google Johannesburg
37497:42xx - International Peering Exchanges
- 37497:4201 - LINX LON1
- 37497:4202 - AMS-IX
- 37497:4203 - DE-CIX Frankfurt
37497:5xxx - Clients - At what POP we learnt the prefix
- 37497:5001 - Johannesburg
- 37497:5002 - Cape Town
- 37497:5003 - Durban
- 37497:5004 - Centurion
- 37497:5101 - London Equinix LD8
37497:7xxx - Special
- 37497:7001 - Google Cache Johannesburg
37497:9xxx - IRP improvements
- 37497:9001 - Johannesburg
- 37497:9002 - Cape Town
- 37497:9003 - Durban
37497:66X - Blackhole / DDOS mitigation
- 37497:666 Blackhole : Block prefix everywhere this will accept a /32 prefix
- 37497:667 Blackhole : Block prefix only to international ie IPT and International IXP's this will accept a /32 prefix
- 37497:668 Advertise prefix to Scrubbing and stop advertising it anywhere else *** for clients with Advanced DDOS option
- 37497:669 Advertise prefix to Scrubbing and South Africa peering, excludes international and Liquid / PCCW *** for clients with Advanced DDOS option
37497:10xxx - Local Pref
- 37497:10290 - 290 - Below Default
- 37497:10295 - 295 -
- 37497:10300 - 300 - Default IP Transit Client local pref
- 37497:10305 - 305 -
- 37497:10310 - 310 - Above Default
37497:11xxx - Add Prepends
- 37497:11001 - Default No additional prepends
- 37497:11002 - Add 2 prepends
- 37497:11003 - Add 3 prepends
- 37497:11004 - Add 4 prepends
- 37497:11005 - Add 5 prepends
37497:140xx - Do not advertise to IP Transit up-streams
- 37497:14000 - Do not advertise to NP International AS328832
- 37497:14001 - Do not advertise to Cogent AS174
- 37497:14003 - Do not advertise to Telia AS1299
- 37497:14004 - Do not advertise to Lumen / Level 3 AS3356
- 37497:14011 - Do not adveritse to PCCW AS3491
- 37497:14012 - Do not advertise to Backspace AS328512
37497:141xx - Do not advertise to IXP
- 37497:14101 - LINX LON1
- 37497:14102 - AMS-IX
- 37497:14103 - DE-CIX
- 37497:14111 - NAP Africa JHB
- 37497:14112 - NAP Africa CPT
- 37497:14113 - NAP Africa DBN
- 37497:14121 - JINX
- 37497:14122 - CINX
- 37497:14123 - DINX
- 37497:14777 - Google Cache
- 37497:14778 - AS6939 Hurricane Electric - bilateral peerings
- 37497:14779 - AS30844 Liquid - bilateral peerings
0:XXXXXX - Do not advertise to ASN