![]() ![]() Shutdown Administratively shut down this neighbor Send-community Send Community attribute to this neighbor Route-reflector-client Configure a neighbor as Route Reflector client Remove-private-as Remove private AS number from outbound updates Prefix-list Filter updates to/from this neighbor Next-hop-unchanged Propagate the iBGP paths’s next hop unchanged for Next-hop-self Disable the next hop calculation for this neighbor Maximum-prefix Maximum number of prefixes accepted from this peer R1(config-router)#neighbor 172.12.123.2 ?Īctivate Enable the Address Family for this NeighborĪdvertise-map specify route-map for conditional advertisementĪdvertisement-interval Minimum interval between sending BGP routing updatesĪllowas-in Accept as-path with my AS present in itĬapability Advertise capability to the peerĭefault-originate Originate default route to this neighborĭescription Neighbor specific descriptionĭisable-connected-check One-hop away EBGP peer using loopback addressĭistribute-list Filter updates to/from this neighborĭmzlink-bw Propagate the DMZ link bandwidthĮbgp-multihop Allow EBGP neighbors not on directly connectedįall-over session fall on peer route lost So for that very reason, we will choose option 2, configuring R1 as a Route Reflector, and I’ll have to include some ? output to point out the most obvious command in IOS help: To solve this we could Peer R2 and R3 to make a full mesh, but we want to stay away from that, because of the scalability issues if we add 20 or 30 more routers into the mix in a real world or CCIE Lab environment. However, lets advertise it’s loopback as well here and verify it on R1 so we can see if we can get it both routes advertising both ways:Įnter configuration commands, one per line. Split Horizon is still blocking the route from propagating to iBGP Peers, so I won’t bother with R2’s output, because there is nothing to show as indicated. Origin IGP, metric 0, localpref 100, valid, internal, best Paths: (1 available, best #1, table Default-IP-Routing-Table) ![]() Now we are on the right track here, however:īGP routing table entry for 4.4.4.4/32, version 2 R3(config-router)#neighbor 172.12.123.1 next-hop-selfīGP table version is 2, local router ID is 172.16.11.1 Also it shows “Not advertied to any peer router” which indicates BGP Split-Horizon in effect for that route, and finally (inaccessible) meaning it does not have a route to the destination network.Īlso we have the expected BGP behavior of an iBGP Peer not advertising its interface as the Next Hop due to the route coming from a non-local AS, which we would either do some static routing, or the easier option issuing “neighbor 172.12.123.1 next-hop-self” on R3 so routes from remote AS’s are reachable. First we note the route is valid, but does not have it’s fellow >, and we need to see both of those for a route in the ip bgp table. Origin IGP, metric 0, localpref 100, valid, internal Network Next Hop Metric LocPrf Weight PathīGP table version is 2, local router ID is 3.3.3.3īGP table version is 1, local router ID is 172.16.11.1īGP routing table entry for 4.4.4.4/32, version 0ġ72.12.23.4 (inaccessible) from 172.12.123.3 (3.3.3.3) Origin codes: i – IGP, e – EGP, ? – incomplete R RIB-failure, S Stale, m multipath, b backup-path, x best-external, f RT-Filter ![]() Status codes: s suppressed, d damped, h history, * valid, > best, i – internal, ![]() *Apr 16 08:22:56.783: %SYS-5-CONFIG_I: Configured from console by consoleīGP table version is 2, local router ID is 44.4.4.4 So let’s get into the configuration, all the Peerings are already configured, so I’ll start by configuring 4.4.4.4/32 to be advertised by R4, verify its in the ip bgp table, and move along to configuring R1 as the Route Reflector: Also note that R2 does not have an interface in the Ethernet segment to R4 in this lab.Ī BGP Speaker with a Peering does not HAVE to be a client, these are known as “nonclients”, however they do require a TCP connection to every other router in the AS (which we are trying to avoid in the first place with the reflector). Now as seen in the Topology I’ve changed it so the Spoke routers Peer to the Hub to avoid creating a full mesh network, and the Hub will reflect routes advertised from R2 to R3 and vice versa. IBGP Peers that send routes to the route reflector are called “clients”, and when the Reflector receives routes from clients, it reflects the routes to other clients all the while the clients have no idea they are getting their routes from a Route Reflector. A router configure to be a BGP Route Reflector can take a route learned from one iBGP Peer and advertise it to another iBGP Peer, which basically is the equivalent of “no ip split-horizon” only BGP style! ![]()
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