BGP IOS kommandoer Programmering af Routere

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Maria Dalgaard
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1 BGP IOS kommandoer Programmering af Routere

2 ibgp Router ID Routere inden for samme AS anvender Peer Routerens Loopback adresse Et loopback Interface er altid aktivt Hvis der er flere Loopback adresser, er det den højeste Loopback adresse. Hvis der ikke anvendes Loopback adresser, er det den højeste IP adresse på Routeren.

3 ebgp Router ID Routere med forskellige AS anvender Peer Routerens Interface adresse

4 ibgp og ebgp Peer adresser P P2 AS / / /30 Lo0: Lo1: R R2 Lo0: P / P2 AS / / /30 R R4 Lo0:

5 Update-source /30 Lo0: Lo0: R1 5 6 R2 hostname R1! interface loopback 0 ip address ! router bgp neighbor remote-as neighbor update-source loopback 0 hostname R2! interface loopback 0 ip address ! router bgp neighbor remote-as neighbor update-source loopback 0

6 no syncronization Som standard annoncerer ibgp kun netværk som også kan ses i IGP tabellen. Dette er der som oftest ikke brug for. Slås fra med kommandoen no syncronization router isis net ! router bgp no synkronization neighbor remote-as neighbor update-source loopback 0

7 auto-summary Ved at indføre Route summerization reduceres størrelsen af Route tabellen BGP har auto-summary aktiveret default. BGP summerer subprefix til klassebaserede netværk Hvis et netværk redistribueres fra IGP ind i BGP accepteres kun det klassebaserede netværk. ( Klasse A, B eller C)

8 auto-summary Hvis der ikke anvendes summerization der anvendes måske VLSM skal auto-summary deaktiveres. router isis net ! router bgp no synkronization neighbor remote-as neighbor update-source loopback 0 no auto-summary

9 BGP kommandoen network Med network kommandoen kan bestemmes, hvilke netværk der skal annonceres. Direkte forbundne netværk Statiske Router Dynamiske Router (Fra f.eks. IS-IS) Skal være i routetabellen Ellers annonceres de ikke

10 BGP kommandoen network Network network-number [mask network-mask] mask kan bruges hvis der ønskes at subnet skal annonceres. Netværk som læres med network kommandoen annonceres til alle neighbor Medmindre de filtreres network kommandoen bestemmer ikke hvilke interfaces der anvendes. (RIP,OSPF..)

11 Eksempel network / / /30 R1 5 6 R2 AS = 100 AS = 200 hostname R1! router bgp 100 neighbor remote-as 200 network mask hostname R2! router bgp 200 neighbor remote-as 100 network mask

12 show ip bgp neighbors BGP neighbor is , remote AS 200, internal link BGP version 4, remote router ID BGP state = Active Last read 00:00:00, last write 00:00:00, hold time is 180, keepalive interval is 60 seconds Message statistics: InQ depth is 0 OutQ depth is 0 Sent Rcvd Opens: 2 2 Notifications: 0 0 Updates: 0 2 Keepalives: Route Refresh: 0 0 Total: Der er ikke etableret en peer

13 show ip bgp neighbors BGP neighbor is , remote AS 200, internal link BGP version 4, remote router ID BGP state = Established, up for 02:10:57 Last read 00:00:56, last write 00:00:56, hold time is 180, keepalive interval is 60 seconds Neighbor capabilities: Der er Route refresh: advertised and received(old & new) etableret Address family IPv4 Unicast: advertised and received en peer Message statistics: InQ depth is 0 OutQ depth is 0 Sent Rcvd Opens: 1 1 Notifications: 0 0 Updates: 0 1 Keepalives: Route Refresh: 0 0 Total:

14 show ip bgp neighbor options Show ip bgp neighbor [address [ received-routes routes path regular expression dampened routes] Address Specicifer adresse hvor routen er lært

15 show ip bgp neighbor [option] Option address Received Routes Routes Advertised Routes Path Dampened Routes Betydning Specificer adresse hvor Routen er lært Viser alle modtagne Router. Både accepterede og afviste. Viser Router der er accepterede Viser Router som annonceres til naboer Bruges til at matche paths som er modtaget Viser Dampened Routes til naboer, hvis ens IP adresser er opgivet.

16 show ip bgp BGP neighbor is , remote AS 200, internal link BGP version 4, remote router ID BGP state = Established, up for 02:10:57 Last read 00:00:56, last write 00:00:56, hold time is 180, keepalive interval is 60 seconds Neighbor capabilities: Der er Route refresh: advertised and received(old & new) etableret Address family IPv4 Unicast: advertised and received en peer Message statistics: InQ depth is 0 OutQ depth is 0 Sent Rcvd Opens: 1 1 Notifications: 0 0 Updates: 0 1 Keepalives: Route Refresh: 0 0 Total:

17 show ip bgp neighbors Der er kommet 6 opdateringer H1R2#show ip bgp BGP table version is 6, local router ID is 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 *>i / i

18 show ip route H1R2#show ip route Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2 E1 - OSPF external type 1, E2 - OSPF external type 2 i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2 ia - IS-IS inter area, * - candidate default, U - per-user static route o - ODR, P - periodic downloaded static route Gateway of last resort is not set C /16 is directly connected, FastEthernet0/ /24 is subnetted, 5 subnets B [200/0] via , 00:10:09 C is directly connected, Loopback4 C is directly connected, Loopback3 C is directly connected, Loopback2 C is directly connected, Loopback1 C /24 is directly connected, FastEthernet0/ /32 is subnetted, 3 subnets C is directly connected, Loopback0 i L [115/20] via , FastEthernet0/0 i L [115/20] via , FastEthernet0/1

19 Kommandoen: next-hop-self ibgp Routere ved ikke altid hvordan de skal Route til en ebgp Router Interne ibgp routere kender kun next-hop addresser de har lært fra en IGP Se eksempel næste slide / R1 R2 R3 Lo0: Lo0: Lo0: AS = 3292 AS = 200

20 Kommandoen: next-hop-self R2 lærer nettet /16 fra ebgp naboen R3 Next-hop adressen er derfor R1 lærer nettet fra R2 med next-hop R2 kender ikke nettet /30 da det ikke deltager i IGP? / R1 R2 R3 Lo0: Lo0: Lo0: AS = 3292 AS = 200

21 Kommandoen: next-hop-self hostname R1! router bgp 3292 no synchronization neighbor remote-as 3292 neighbor update-source loopback / R1 R2 R3 Lo0: Lo0: Lo0: AS = 3292 AS = 200

22 Kommandoen: next-hop-self hostname R2! router bgp 3292 no synchronization neighbor remote-as 200 neighbor remote-as 3292 neighbor update-source loopback 0 neighbor next-hop-self / R1 R2 R3 Lo0: Lo0: Lo0: AS = 3292 AS = 200

23 Kommandoen: next-hop-self hostname R3! router bgp 200 neighbor remote-as / R1 R2 R3 Lo0: Lo0: Lo0: AS = 3292 AS = 200

24 Peering / Neighbors Indenfor et AS bliver netværk Routnings informationer der er lært via ibgp ikke videresendt. Hvis det blev videresendt kunne der opstå Routenings Loops Derfor skal alle ibgp Routere være forbundet logisk ikke nødvendigvis fysisk Full Meshed.

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