> Hi, I'm a small site and I'm just getting ready to go live with a > cogent connection. But, I'm finding myself a bit confused by their > Peer A / Peer B description. I can find some examples of multihop > things, but none seem very clear. > > Can someone send a basic cogent bgp setup?
[edit protocols bgp] group cogent-in { type external; peer-as 174; local-address $peer-b-local; neighbor $peer-b { description Cogent Transit [CE<-PE] [EMAIL PROTECTED]; multihop ttl 5; } import gen_transit_in; } group cogent-out { type external; peer-as 174; neighbor $peer-a { description Cogent Transit [CE->PE] [EMAIL PROTECTED]; } export transit_cogent_out; import no; } [edit routing-options] static { $peer-b/32 next-hop $peer-a; } For Cisco: neighbor $peer-a remote-as 174 neighbor $peer-a description Cogent Transit [CE->PE] [EMAIL PROTECTED] neighbor $peer-b remote-as 174 neighbor $peer-b description Cogent Transit [CE<-PE] [EMAIL PROTECTED] neighbor $peer-b ebgp-multihop 5 ! set interface loopback1 with $peer-b-local address neighbor $peer-b update-source loop1 ! address-family ipv4 neighbor $peer-a activate neighbor $peer-a send-community both neighbor $peer-a remove-private-as neighbor $peer-a prefix-list To_Cogent out neighbor $peer-a route-map no in neighbor $peer-a route-map transit_export out neighbor $peer-b activate neighbor $peer-b prefix-list ISP-Ingress-Filter in neighbor $peer-b route-map transit_import in neighbor $peer-b route-map no out neighbor $peer-b filter-list 500 in ! ip route $peer-b 255.255.255.255 $peer-a ! Replace peer-a, peer-b with appropriate peer IP's and replace all import/export/route-maps/prefix-lists/etc accordingly to your organization routing policy. Replace peer-b-local with the /32 ip address Cogent assigns you for Loopback1 interface. Peer A is a directly connected neighbor where you announce/advertise your network routes to them. Peer B is a multi-hop peer where you advertise NO routes to them, but receive full internet routing table from them. And one other thing: Cogent sends you IP address of peer B over the bgp session with peer A, so that your router will be able to establish multi-hop session with peer B. I don't like relying on an ebgp peer to receive session address for another ebgp peer (takes longer for peer B to come up) so I generally prefer using manual static-route for peer B, pointed to peer A's directly connected address. Hope this helps. james _______________________________________________ juniper-nsp mailing list juniper-nsp@puck.nether.net https://puck.nether.net/mailman/listinfo/juniper-nsp