CCNP - BGP Weight

 

Lab 11 BGP Weight

BGP Dualhoming yaitu Dua Link ke ISP yang sama dengan fitur sebagai berikut
a. Main-Backup Mode
b. Load Sharing Mode
Sedangkan BGP multihoming yaitu Dua Link ke ISP yang berbeda dengan fitur :
a. Main-Backup Mode
b. Load Sharing Mode

konfigurasi dasar 

R1

R1(config)#int g1/0
R1(config-if)#ip add 12.12.12.1 255.255.255.0
R1(config-if)#no sh
R1(config)#int g2/0
R1(config-if)#ip add 13.13.13.1 255.255.255.0
R1(config-if)#no sh
R1(config)#int lo0
R1(config-if)#ip add 1.1.1.1 255.255.255.255
R1(config-if)#router bgp 1
R1(config-router)#neighbor 12.12.12.2 remote-as 23
R1(config-router)#neighbor 13.13.13.3 remote-as 23
R1(config-router)#net 1.1.1.1 mask 255.255.255.255

R2

R2(config)#int g2/0
R2(config-if)#ip add 12.12.12.2 255.255.255.0
R2(config-if)#no sh
R2(config-if)#int f0/0
R2(config-if)#ip add 23.23.23.2 255.255.255.0
R2(config-if)#no sh
R2(config-if)#int g1/0
R2(config-if)#ip add 24.24.24.2 255.255.255.0
R2(config-if)#no sh
R2(config)#int lo0
R2(config-if)#ip add 2.2.2.2 255.255.255.255
R2(config-if)#router bgp 23
R2(config-router)#neighbor 12.12.12.1 remote-as 1
R2(config-router)#neighbor 23.23.23.3 remote-as 23
R2(config-router)#neighbor 24.24.24.4 remote-as 4
R2(config-router)#net 2.2.2.2 mask 255.255.255.25
R2(config-router)#neighbor 23.23.23.3 next-hop-self

R3

R3(config)#int g1/0
R3(config-if)#ip add 13.13.13.3 255.255.255.0
R3(config-if)#no sh
R3(config)#int f0/0
R3(config-if)#ip add 23.23.23.3 255.255.255.0
R3(config-if)#no sh
R3(config-if)#exit
R3(config)#int g2/0
R3(config-if)#ip add 34.34.34.3 255.255.255.0
R3(config-if)#no sh
R3(config)#router bgp 23
R3(config-router)#neighbor 13.13.13.1 remote-as 1
R3(config-router)#neighbor 23.23.23.2 remote-as 23
R3(config-router)#neighbor 34.34.34.4 remote-as 4
R3(config-router)#neighbor 23.23.23.2 next-hop-self

R4

R4(config)#int g1/0
R4(config-if)#ip add 24.24.24.4 255.255.255.0
R4(config-if)#no sh
R4(config)#int g2/0
R4(config-if)#ip add 34.34.34.4 255.255.255.0
R4(config-if)#no sh
R4(config)#int lo0
R4(config-if)#ip add 4.4.4.4 255.255.255.255
R4(config)#router bgp 4
R4(config-router)#neighbor 24.24.24.2 remote-as 23
R4(config-router)#neighbor 34.34.34.3 remote-as 23s
R4(config-router)#net 4.4.4.4 mask 255.255.255.255 

kita verifikasi

R1

R1(config)#do show ip bgp
    Network                 Next Hop     Metric LocPrf Weight Path
*> 1.1.1.1/32         0.0.0.0                 0 32768 i
* 2.2.2.2/32             13.13.13.3         0 23 i
*>                               12.12.12.2         0 0 23 i
* 4.4.4.4/32             13.13.13.3         0 23 4 i
*>                             12.12.12.2             0 23 4 i 

Kesimpulannya, walaupun sudah menggunakan 2 link, namun tetap saja hanya
1 link yang digunakan. Sekarang kita akan shutdown port int s0/0
(12.12.12.1/24) sehingga paket tidak lagi melalui R2.
R1(config)#int g1/0
R1(config-if)#sh
R1(config)#do sh ip bgp
        Network         Next Hop     Metric     LocPrf Weight Path
*> 1.1.1.1/32         0.0.0.0             0 32768 i
*> 4.4.4.4/32         13.13.13.3     0 23 4 i
R1(config)#do show ip route bgp
        4.0.0.0/32 is subnetted, 1 subnets
B         4.4.4.4 [20/0] via 13.13.13.3, 00:03:06

Saat ini linknya sudah berpindah melalui R3. Kemudian, kita tes kembali
dengan cara kita no shutdown pada port yang menuju ke R2.

R1(config)#int g1/0
R1(config-if)#no sh

R1#sh ip bgp
BGP table version is 5, local router ID is 1.1.1.1
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
*> 1.1.1.1/32         0.0.0.0                 0 32768 i
* 4.4.4.4/32             12.12.12.2             0 23 4 i
*>                                 13.13.13.3         0 23 4 i

R1#sh ip route bgp
            4.0.0.0/32 is subnetted, 1 subnets
B             4.4.4.4 [20/0] via 13.13.13.3, 00:32:17 

 kita konfigurasikan attribute weight

R1(config)#route-map WEIGHT
R1(config-route-map)#set weight 100
R1(config-route-map)#ex
R1(config)#router bgp 1
R1(config-router)#neighbor 12.12.12.2 route-map WEIGHT in
R1(config-router)#ex
R1(config)#do clear ip bgp *

R1#sh ip bgp
BGP table version is 3, local router ID is 1.1.1.1
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
*> 1.1.1.1/32     0.0.0.0                 0 32768 i
*> 4.4.4.4/32     12.12.12.2         100 23 4 i
*                             13.13.13.3             0 23 4 i

R1#sh ip route bgp
        4.0.0.0/32 is subnetted, 1 subnets
B         4.4.4.4 [20/0] via 12.12.12.2, 00:02:09 

kita tes lagi shutdown interface ke R2. 

R1(config)#int g1/0
R1(config-if)#sh


 R1(config)#do sh ip bgp
BGP table version is 4, local router ID is 1.1.1.1
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
*> 1.1.1.1/32         0.0.0.0                     0 32768 i
*> 4.4.4.4/32         13.13.13.3                 0 23 4 i


R1(config)#do sh ip route bgp
        4.0.0.0/32 is subnetted, 1 subnets
B         4.4.4.4 [20/0] via 12.12.12.2, 00:00:02

kita juga bisa mengatur trafik yang dating dengan menggunakan (MED)


R1(config)#router bgp 1
R1(config-router)#ip access-list standard LAN
R1(config-std-nacl)#permit 1.1.1.1
R1(config-std-nacl)#route-map R2MED permit 10
R1(config-route-map)#match ip address LAN
R1(config-route-map)#set metric 110
R1(config)#router bgp 1
R1(config-router)#neighbor 12.12.12.2 route-map R2MED out
R1(config-router)#neighbor 13.13.13.3 route-map R3MED out

verifikasi 

R3#sh ip route 1.1.1.1
Routing entry for 1.1.1.1/32
Known via "bgp 23", distance 20, metric 100
Tag 1, type external
Last update from 13.13.13.1 00:00:10 ago
Routing Descriptor Blocks:
* 13.13.13.1, from 13.13.13.1, 00:00:10 ago
    Route metric is 100, traffic share count is 1
    AS Hops 1
    Route tag 1


R2(config)#do show ip bgp 1.1.1.1
BGP routing table entry for 1.1.1.1/32, version 23
Paths: (2 available, best #1, table Default-IP-Routing-Table)
Advertised to update-groups:
3
1
23.23.23.3 from 23.23.23.3 (34.34.34.3)
Origin IGP, metric 100, localpref 100, valid, internal, best
1
12.12.12.1 from 12.12.12.1 (1.1.1.1)
Origin IGP, metric 110, localpref 100, valid, external


R2(config)#do show ip bgp
BGP table version is 24, 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
*>i1.1.1.1/32            23.23.23.3     100 100 0 1 i
*                                     12.12.12.1 110 0 1 i
*> 2.2.2.2/32                0.0.0.0         0 32768 i
* i4.4.4.4/32             23.23.23.3     0 100 0 4 i
*>                             24.24.24.4         0 0 4 i 


R2#traceroute 1.1.1.1 source 2.2.2.2
Type escape sequence to abort.
Tracing the route to 1.1.1.1
    1 23.23.23.3 20 msec 20 msec 8 msec
    2 13.13.13.1 28 msec 24 msec 8 msec

Seperti yang kita lihat diatas, maka dari R2 (AS 23) untuk menuju ke R1 (AS 1)
akan melalui R3 terlebih dahulu.
Selain kita menggunakan attribute MED, kita juga bisa menggunakan attribute
AS-Path. Terlebih dahulu kita hapus konfigurasi MED sebelumnya.


R1(config)#router bgp 1
R1(config-router)#no neighbor 12.12.12.2 route-map R2MED out
R1(config-router)#no neighbor 13.13.13.3 route-map R3MED out

konfigurasikan AS-Path


R1(config)#router bgp 1
R1(config-router)#neighbor 12.12.12.2 route-map AS-PREPEND out
R1(config-router)#route-map AS-PREPEND
R1(config-route-map)#set as-path prepend 1 1 1
R1(config-route-map)#do clear ip bgp

R2#sh ip bgp
BGP table version is 29, 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
*>i1.1.1.1/32         23.23.23.3         0 100 0 1 i
*                                 12.12.12.1         0 0 1 1 1 1 i
*> 2.2.2.2/32         0.0.0.0                     0 32768 i
* i4.4.4.4/32         23.23.23.3             0 100 0 4 i
*>                             24.24.24.4             0 0 4 i 


R2#sh ip route bgp
    1.0.0.0/32 is subnetted, 1 subnets
B         1.1.1.1 [200/0] via 23.23.23.3, 00:05:20
    4.0.0.0/32 is subnetted, 1 subnets
B         4.4.4.4 [20/0] via 24.24.24.4, 02:23:15 


R2#traceroute 1.1.1.1 source 2.2.2.2
Tracing the route to 1.1.1.1
1 23.23.23.3 20 msec 20 msec 24 msec
2 13.13.13.1 20 msec 24 msec 12 msec


R3#sh ip bgp
BGP table version is 18, local router ID is 34.34.34.3
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
*> 1.1.1.1/32 13.13.13.1 0 0 1 i
*>i2.2.2.2/32 23.23.23.2 0 100 0 i
* i4.4.4.4/32 23.23.23.2 0 100 0 4 i
*> 34.34.34.4 0 0 4 i


 R4#sh ip bgp
BGP table version is 13, local router ID is 4.4.4.4
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
* 1.1.1.1/32 34.34.34.3 0 23 1 i
*> 24.24.24.2 0 23 1 i
* 2.2.2.2/32 34.34.34.3 0 23 i
*> 24.24.24.2 0 0 23 i
*> 4.4.4.4/32 0.0.0.0 0 32768 i


R4#trace 1.1.1.1 source 4.4.4.4
Type escape sequence to abort.
Tracing the route to 1.1.1.1
1 24.24.24.2 8 msec 24 msec 20 msec
2 23.23.23.3 16 msec 20 msec 20 msec
3 13.13.13.1 44 msec 48 msec 32 msec




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