What is set community no-export?

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If you set the community as no-export when RTB/AS100 advertises routes to RTD/AS300, then RTD/AS300 receives the route with the community no-export. This means that the route will be used inside AS300, but will not go any further.

How do we enable community propagation?

The neighbor send-community enables the community propagation. Without this option, no BGP communities will be sent to the BGP neighbor, even if they are attached to entries in the local BGP table.

What is no-advertise community?

The BGP no-advertise community can be used to ensure a prefix does not get advertised to any other peer (internal, or external). In the lab below I’m going to use the feature on R2 so that the 100.100. 100.0/24 network learned from R1 does not get advertised to R3 or R4.

What is BGP confederation?

A BGP confederation is an alternative method to route reflectors, used to reduce the number of BGP peerings within a single AS. Furthermore it is a single AS that has been subdivided into a number of internal sub-AS’s, yet still, advertise as a single AS to external peers .

What is additive in BGP?

If BGP updates already has BGP communities value, the existing BGP communities value is replaced with specified community value. When additive keyword is specified, community is appended to the existing communities value.

Does SD WAN use BGP?

SD-WAN rules can use Border Gateway Protocol (BGP) learned routes as dynamic destinations.

What does community-number additive None Mean?

Syntax Description community-number additive none Specifies that community number. Valid values are 1 to 4294967200, no-export, or no-advertise. (Optional) Adds the community to the already existing communities. (Optional) Removes the COMMUNITY attribute from the prefixes that pass the route-map.

What is the use of no export community?

An example scenario where the no-export community is used is the case of remote-triggered blackhole filtering (as one of the possible safety measures that help avoid a leaking of specific routes that blackhole specific IP addresses from the AS that decides to blackhole them towards other AS’s).

What is the community-number additive for BGP?

What is a BGP community no export?

The well known BGP community no export tells BGP neighbors to advertise a prefix only to iBGP neighbors. If you are not sure what BGP communities are and how they work then I advise you to read my introduction to BGP communities first before you continue.