BGP auto-summary

• Cho topology:
  
• R1 va R2 thiet lap eBGP
• R1 tao ra 3 interface loopback:
• L0: 1.1.1.0/24
• L1: 1.1.2.0/24
• L3: 1.1.3.0/24
• Tien hanh test cac truong hop sau day :)

• Summary trong BGP tuong doi khac biet doi voi cac giao thuc dinh tuyen IGP.
• Chia lam 3 truong hop chinh:
• Network + mask se adver chinh xac routes trong RIB bat ket la co su dungj auto-summary/ no auto-summary.

R1#router bgp 1  network 1.1.1.0 mask 255.255.255.0  neighbor 10.1.12.2 remote-as 2  auto-summary

R2#show ip bgp BGP table version is 4, local router ID is 2.2.2.2 Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,               r RIB-failure, S Stale Origin codes: i - IGP, e - EGP, ? - incomplete    Network          Next Hop            Metric LocPrf Weight Path *> 1.1.1.0/24       10.1.12.1                0             0 1 I

R1# router bgp 1  network 1.1.1.0 mask 255.255.255.0  neighbor 10.1.12.2 remote-as 2  no auto-summary

R2#show ip bgp BGP table version is 4, local router ID is 2.2.2.2 Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,               r RIB-failure, S Stale Origin codes: i - IGP, e - EGP, ? - incomplete    Network          Next Hop            Metric LocPrf Weight Path *> 1.1.1.0/24       10.1.12.1                0             0 1 I

• Network + auto-summary --> adver only classful network

R1#router bgp 1   network 1.0.0.0   network 1.1.1.0 mask 255.255.255.0   neighbor 10.1.12.2 remote-as 2  auto-summary

R2#show ip bgp BGP table version is 6, local router ID is 2.2.2.2 Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,               r RIB-failure, S Stale Origin codes: i - IGP, e - EGP, ? - incomplete    Network          Next Hop            Metric LocPrf Weight Path *> 1.0.0.0          10.1.12.1                0             0 1 I *> 1.1.1.0          10.1.12.1                0             0 1 i

Chu y: command Network phai go network o dang classful, neu "network 1.1.1.0" thi command no se k tu dong summary ve /8

    Neu them lenh "network 1.1.1.0/24" thi mang 1.1.1.0/24 se adver cung 1.0.0.0/8

• Network + no auto-summary --> match chinh xac route classful trong RIB va adver chinh xac no.

-> giong truong hop no auto-summary

• Khi su dung command "redistribute + auto-summary" --> adver only classfull network.

• R1#router bgp 1  redistribute connected  neighbor 10.1.12.2 remote-as 2  auto-summary

  R2#show ip bgp BGP table version is 9, local router ID is 2.2.2.2 Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,               r RIB-failure, S Stale Origin codes: i - IGP, e - EGP, ? - incomplete    Network          Next Hop            Metric LocPrf Weight Path *> 1.0.0.0          10.1.12.1                0             0 1 ? *> 10.0.0.0         10.1.12.1                0             0 1 ?