What is BGP extended community?

An extended community is an 8-octet value that is also divided into two main sections. The first 2 octets of the community encode a type field while the last 6 octets carry a unique set of data in a format defined by the type field. Extended communities provide a larger range for grouping or categorizing communities.

What is the difference between BGP community and extended community?

The extended community is attached to a BGP route the same way standard BGP communities or any other BGP attributes are. The MP-iBGP update propagates the extended community along with other BGP attributes between PE-routers, and its value determines to which VRF or set of VRFs to import the route.

What is a BGP community?

A BGP community is a 32-bit number that can be included with a route. A BGP community can be displayed as a full 32-bit number (0-4,294,967,295) or as two 16-bit numbers (0-65535):(0-65535) commonly referred to as new-format.

What is BGP route target?

A route-target extended community, or route target, is a type of BGP extended community that you use to define VPN membership. The route target appears in a field in the update messages associated with VPN-IPv4. You create route-target import lists and route-target export lists for each VRF.

How do I check my community in BGP?

To show BGP routes which has specific BGP communities attribute, show ip bgp command can be used. The community value and community list can be used for show ip bgp command. show ip bgp community displays BGP routes which has communities attribute.

What are the types of communities used in BGP?

Well-known BGP Communities

  • No-Advertise Community.
  • No-Export Community.
  • Local AS Community.
  • Graceful Shutdown Community.
  • Extended Community.
  • Route Target Community.
  • Route Origin Community.
  • Large Communities.

How many types of community are there in BGP?

There are 4 well known BGP communities that you can use or you can pick a numeric value that you can use for your own policies.

How do I check my BGP community?

What is RD and RT in BGP?

The Route-Distinguisher (RD) & Route-Target (RT) are two different concepts that are both used in an MPLS VPN. The RD is used to keep all prefixes in the BGP table unique, and the RT is used to transfer routes between VRF’s/VPNS.

What is the difference between MP-BGP and BGP?

MP-BGP (Multiprotocol BGP) is an extension of the BGP protocol. Standard BGP only supports IPv4 unicast address families, whereas MP-BGP supports more than 15 different BGP address families.

How do you create a community in BGP?

To configure router R1 to send prefix marked with community:

  1. R1# configure terminal. R1 (config)# ip bgp- community new-format.
  2. R2# configure terminal.
  3. R1# show bgp ipv4 unicast neighbors 80.50.0.2 | i Community.
  4. R2# show bgp ipv4 unicast 94.70.40.0/24.
  5. R2# configure terminal.
  6. R2# show bgp ipv4 unicast 94.70.40.0/24.

How does BGP choose the best path?

BGP Table path selection

  1. Prefer the highest local-preference value.
  2. Prefer the shortest AS-path length.
  3. Prefer the lowest origin value.
  4. Prefer the lowest MED value.
  5. Prefer routes learned from an EBGP peer over an IBGP peer.
  6. Prefer best exit from AS.
  7. For EBGP-received routes, prefer the current active route.