BGP

I.Communities in advertisements towards downstream
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1.Route type:

2.Where the route has been received:

II.Communities accepted from downstream
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1.Common, prepending to all peers (but not to customers):

9002:6553X, where

X < 5 prepend X times to all peers
X = 5 advertise to customers but not to peers

Note #1. If the downstream's route isn't tagged with 9002:6553X community, then community 9002:65530 is applied on RETN side (advertise everywhere without prepending)

2.Specific, prepending to peer ASN (see the list below):

ASN:6553X, where

X < 5 prepend X times to peer ASN
X = 5 do not advertise to peer ASN

Note #2. If downstream's route is tagged with community ASN:6553X, then community 9002:6553X is ignored while advertising to peer ASN. Otherwise the route is advertised to peer ASN in accordance with community 9002:6553X

Note #3. Unaccepted bgp communities, including well-known ones, are ignored and stripped

Specific communities are applied for a limited subset of ReTN peers, listed below. As a result of ReTN peering relationships extention, this list can be modified at any point. Please check this web page from time to time

IPv4 peers:

IPv6 peers: