Internetworks: BGP Confederations and configuration.

images
Cisco News
Internetworks: BGP Confederations and configuration.

BGP Confederations

We’ll exchange the BGP Confederation with you in this section. You might know, IBGP requires a comprehensive mesh peering which can become administrative overhead. If you don’t know why we need a comprehensive mesh, I advise consulting BGP peers first. Over the past 16 years, SPOTO is a leader in the IT training, and you can get various exam materials to help you clear all certification exam. Let’s look at the following contents now.

IBGP full mesh issues

·As for iBGP, every router in the BGP autonomous system must fully mesh.

·Large number of TCP sessions

·Unnecessary duplicate of routing traffic

·Manual configuration

Solution

1.Route reflector

2.BGP confederations

A BGP confederation consists of AS and sub-ASes to reduce the number of required IBGP peerings. In brief, BGP Confederations Feature is used to divide an autonomous system into smaller autonomous systems.

Confederations are usable only for huge autonomous systems where you can afford to divide them into several sub-ASes. Each sub-as in a confederation is required to have its internal iBGP peers either fully meshed or use route reflector internally. The confederations are not much of an advantage for small ASes having a few BGP routers.

let's see the configuration for better understanding.

Topology:

Goal:

·configure the topology as per the diagram and assign the IP addresses.

·configure iBGP and EBGP configuration.

·configure BGP peerings using BGP Confederations.

R1#show ip interface brief

Interface              IP-Address      OK? Method Status                Protocol

FastEthernet0/0        10.1.1.1        YES manual up                    up

Serial3/0              1.1.1.1         YES manual up                    up

Serial3/5              6.1.1.2         YES manual up                    up

Loopback0            11.0.0.1        YES manual up                    up

R2#show ip interface brief

Interface              IP-Address      OK? Method Status                Protocol

FastEthernet0/0        20.1.1.1        YES manual up                    up

Serial3/0              1.1.1.2         YES manual up                    up

Serial3/1              2.1.1.1         YES manual up                    up

Loopback0            12.0.0.1        YES manual up                    up

R3#show ip interface brief

Interface              IP-Address      OK? Method Status                Protocol

FastEthernet0/0    30.1.1.1        YES manual up                    down

Serial3/1               2.1.1.2         YES manual up                    up

Serial3/2              3.1.1.1         YES manual up                    up

Loopback0           13.0.0.1        YES manual up                    up

R4#show ip interface brief

Interface              IP-Address      OK? Method Status                Protocol

FastEthernet0/0    40.1.1.1        YES manual up                    up

Serial3/2              3.1.1.2         YES manual up                    up

Serial3/3              4.1.1.1         YES manual up                    up

Loopback0             14.0.0.1        YES manual up                    up

R5#show ip interface brief

Interface              IP-Address      OK? Method Status                Protocol

FastEthernet0/0        50.1.1.1        YES manual up                    up

Serial3/3              4.1.1.2         YES manual up                    up

Serial3/4              5.1.1.1         YES manual up                    up

Loopback0             15.0.0.1        YES manual up                    up

R6#show ip interface brief

Interface              IP-Address      OK? Method Status                Protocol

FastEthernet0/0        30.1.1.2        YES manual up                    up

Serial3/4              5.1.1.2         YES manual up                    up

Serial3/5              6.1.1.1         YES manual up                    up

Loopback0             16.0.0.1        YES manual up                    up

R1(config)#router bgp 650012

R1(config-router)#neighbor 6.1.1.1 remote-as 650006

R1(config-router)#neighbor 1.1.1.2 remote-as 650012

R1(config-router)#network 10.0.0.0

R1(config-router)#network 1.0.0.0

R1(config-router)#network 6.0.0.0

R1(config-router)#network 11.0.0.0 mask 255.255.255.0

R1(config-router)#no auto-summary

R1(config-router)#no synchronization

R1(config-router)#exit

R2(config)#router bgp 650012

R2(config-router)#neighbor 1.1.1.1 remote-as 650012

R2(config-router)#neighbor 2.1.1.2 remote-as 650345

R2(config-router)#network 1.0.0.0

R2(config-router)#network 2.0.0.0

R2(config-router)#network 20.0.0.0

R2(config-router)#network 12.0.0.0 mask 255.255.255.0

R2(config-router)#no auto-summary

R2(config-router)#no synchronization

R2(config-router)#exit

R3(config)#router bgp 650034

R3(config-router)#bgp confederation identifier 650345

R3(config-router)#neighbor 2.1.1.1 remote-as 650012

R3(config-router)#neighbor 3.1.1.2 remote-as 650034

R3(config-router)#network 30.0.0.0

R3(config-router)#network 3.0.0.0

R3(config-router)#network 2.0.0.0

R3(config-router)#network 13.0.0.0 mask 255.255.255.0

R3(config-router)#no auto-summary

R3(config-router)#no synchronization

R3(config-router)#exit 

R4(config)#router bgp 650034

R4(config-router)#bgp confederation identifier 650345

R4(config-router)#bgp confederation peers 650005

R4(config-router)#neighbor 3.1.1.1 remote-as 650034

R4(config-router)#neighbor 4.1.1.2 remote-as 650005

R4(config-router)#network 40.0.0.0

R4(config-router)#network 4.0.0.0

R4(config-router)#network 3.0.0.0

R4(config-router)#network 14.0.0.0 mask 255.255.255.0

R4(config-router)#no synchronization

R4(config-router)#no auto-summary

R4(config-router)#exit

R5(config-if)#router bgp 650005

R5(config-router)#bgp confederation identifier 650345

R5(config-router)#bgp confederation peers 650034

R5(config-router)#neighbor 4.1.1.1 remote-as 650034

R5(config-router)#neighbor 5.1.1.2 remote-as 650006

R5(config-router)#network 50.0.0.0

R5(config-router)#network 5.0.0.0

R5(config-router)#network 4.0.0.0

R5(config-router)#network 15.0.0.0 mask 255.255.255.0

R5(config-router)#no auto-summary

R5(config-router)#no synchronization

R5(config-router)#exit

R6(config-if)#router bgp 650006

R6(config-router)#neighbor 5.1.1.1 remote-as 650345

R6(config-router)#neighbor 6.1.1.2 remote-as 650012

R6(config-router)#network 6.0.0.0

R6(config-router)#network 5.0.0.0

R6(config-router)#network 60.0.0.0

R6(config-router)#network 16.0.0.0 mask 255.255.255.0

R6(config-router)#no synchronization

R6(config-router)#no auto-summary

R6(config-router)#exit

R1#show ip bgp summary

BGP router identifier 11.0.0.1, local AS number 650012

BGP table version is 27, main routing table version 27

16 network entries using 2304 bytes of memory

26 path entries using 2080 bytes of memory

5/4 BGP path/bestpath attribute entries using 680 bytes of memory

3 BGP AS-PATH entries using 72 bytes of memory

0 BGP route-map cache entries using 0 bytes of memory

0 BGP filter-list cache entries using 0 bytes of memory

BGP using 5136 total bytes of memory

BGP activity 21/5 prefixes, 31/5 paths, scan interval 60 secs

Neighbor        V           AS MsgRcvd MsgSent   TblVer  InQ OutQ Up/Down  State/PfxRcd

1.1.1.2         4       650012      94      87       27    0    0 01:13:02       12

6.1.1.1         4       650006      31      31       27    0    0 00:21:31       10

R1#show ip bgp

BGP table version is 27, local router ID is 11.0.0.1

Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,

              r RIB-failure, S Stale, m multipath, b backup-path, f RT-Filter,

              x best-external, a additional-path, c RIB-compressed,

Origin codes: i - IGP, e - EGP, ? - incomplete

RPKI validation codes: V valid, I invalid, N Not found

     Network          Next Hop            Metric LocPrf Weight Path

 * i 1.0.0.0          1.1.1.2                  0    100      0 i

 *>                   0.0.0.0                  0         32768 i

 *>i 2.0.0.0          1.1.1.2                  0    100      0 i

 *   3.0.0.0          6.1.1.1                                0 650006 650345 i

 *>i                  2.1.1.2                  0    100      0 650345 i

 *   4.0.0.0          6.1.1.1                                0 650006 650345 i

 *>i                  2.1.1.2                  0    100      0 650345 i

 * i 5.0.0.0          2.1.1.2                  0    100      0 650345 i

 *>                   6.1.1.1                  0             0 650006 i

 *   6.0.0.0          6.1.1.1                  0             0 650006 i

 *>                   0.0.0.0                  0         32768 i

 *>  10.0.0.0         0.0.0.0                  0         32768 i

 *>  11.0.0.0/24      0.0.0.0                  0         32768 i

 *>i 12.0.0.0/24      1.1.1.2                  0    100      0 i

     Network          Next Hop            Metric LocPrf Weight Path

 *   13.0.0.0/24      6.1.1.1                                0 650006 650345 i

 *>i                  2.1.1.2                  0    100      0 650345 i

 *   14.0.0.0/24      6.1.1.1                                0 650006 650345 i

 *>i                  2.1.1.2                  0    100      0 650345 i

 *   15.0.0.0/24      6.1.1.1                                0 650006 650345 i

 *>i                  2.1.1.2                  0    100      0 650345 i

 *>  16.0.0.0/24      6.1.1.1                  0             0 650006 i

 *>i 20.0.0.0         1.1.1.2                  0    100      0 i

 *   40.0.0.0         6.1.1.1                                0 650006 650345 i

 *>i                  2.1.1.2                  0    100      0 650345 i

 *   50.0.0.0         6.1.1.1                                0 650006 650345 i

 *>i                  2.1.1.2                  0    100      0 650345 i

R1#show ip route bgp

Codes: L - local, 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, H - NHRP, l - LISP

       + - replicated route, % - next hop override



Cisco Pass Report View More >

CCIE RS Written
May 23, 2019
CCIE RS Written
CCIE Wireless Written
May 23, 2019
CCIE Wireless Written
CCIE Wireless Written
May 22, 2019
CCIE Wireless Written
CCIE RS Written
May 22, 2019
CCIE RS Written
CCIE Security Written
May 22, 2019
CCIE Security Written
CCIE Wireless Written
May 22, 2019
CCIE Wireless Written
CCIE Security Lab
May 22, 2019
CCIE Security Lab
CCIE Security Lab
May 22, 2019
CCIE Security Lab
CCIE RS Written
May 21, 2019
CCIE RS Written
CCIE Security Written
May 21, 2019
CCIE Security Written