Injecting routes into BGP.
- Use the network command.
- Different than the network command in iGP; it isn’t used to listen/active interfaces.
- the BGP network command looks for the prefix in the routing table and originates that into the BGP table.
- If no mask is defined, IOS assumes a classful network.
- Classful route is added if:
- the exact route is in the ip routing table
- Any subset of routes are in the routing table (only with auto-summery)
- create a null0 route
- ip route 18.104.22.168 255.255.255.0 null0
router bgp 20 bgp log-neighbor-changes network 22.214.171.124 mask 255.255.255.0 neighbor 10.10.10.1 remote-as 10 neighbor 10.10.10.1 ebgp-multihop 255 neighbor 10.10.10.1 update-source Loopback1
- Route redistribution.
- redistribute iGP into BGP.
- Internal routes are prefered over external routes.
R2(config)#router bgp 20 R2(config-router)#redi R2(config-router)#redistribute ? bgp Border Gateway Protocol (BGP) connected Connected eigrp Enhanced Interior Gateway Routing Protocol (EIGRP) isis ISO IS-IS iso-igrp IGRP for OSI networks lisp Locator ID Separation Protocol (LISP) mobile Mobile routes odr On Demand stub Routes ospf Open Shortest Path First (OSPF) ospfv3 OSPFv3 rip Routing Information Protocol (RIP) static Static routes vrf Specify a source VRF
- Route summarization/aggregation
- aggregate-address 126.96.36.199 255.255.255.0 [summary-only]
BGP for outbound routing
- Single homed ( 1 link per ISP, 1 ISP ).
- Default route will suffice.
- BGP probably not necessary.
- Dual homed ( 2+ links per ISP, 1 ISP ).
- BGP is useful.
- Static route can also be used:
- Load share traffic between both circuits
- prefer one link over the other
- Single multihomed ( 1link per ISP, 2+ ISPs ).
- same concept as dualhomed.
- Dual multihomed (2+ link per ISP, 2+ ISPs).
- Using BGP takes full advantage