Lab 5. BGP Next-Hop-Self

What is BGP Next-Hop-Self? Actually BGP next hop is different like IGP. For example, please see below picture,  R1 want to route Network A, the next hop in R1 is f0/0 in R3!!! That's why we need 'next-hop-self' to inform other router to pass the route via this router with 'next-hop-self'. Please correct me if I am wrong!

Let's try the lab

R1#

interface Loopback0

 ip address 1.1.1.1 255.255.255.255

!

interface Loopback1

 ip address 100.100.100.1 255.255.255.255

!

interface FastEthernet0/0

 ip address 12.12.12.1 255.255.255.0

R2#

interface Loopback0

 ip address 2.2.2.2 255.255.255.255

!

interface Loopback1

 ip address 200.200.200.2 255.255.255.255

!

interface FastEthernet0/0

 ip address 12.12.12.2 255.255.255.0

!

interface FastEthernet0/1

 ip address 23.23.23.2 255.255.255.0

R3#

interface Loopback0

 ip address 3.3.3.3 255.255.255.255

!

interface Loopback1

 ip address 33.33.33.33 255.255.255.255

!

interface FastEthernet0/0

 ip address 23.23.23.3 255.255.255.0

Make sure loopback can be ping… Solution using IGP

R1#

router rip

 network 1.0.0.0

 network 12.0.0.0

R2#

router rip

 network 2.0.0.0

 network 12.0.0.0

 network 23.0.0.0

R3#

router rip

 network 3.0.0.0

 network 23.0.0.0

After loopback can be ping, we can activate BGP

R1#

router bgp 12

neighbor 2.2.2.2 remote-as 12

neighbor 2.2.2.2 update-source loopback0

net 100.100.100.1 mask 255.255.255.255

R2#

router bgp 12

nei 1.1.1.1 remot 12

nei 1.1.1.1 upd lo0

nei 3.3.3.3 remot 3

nei 3.3.3.3 upd lo0

nei 3.3.3.3 ebgp

net 200.200.200.2 mask 255.255.255.255

R3#

router bgp 3

nei 2.2.2.2 remot 12

nei 2.2.2.2 upd lo0

nei 2.2.2.2 ebgp

net 33.33.33.33 mask 255.255.255.255

Check bgp

R1(config-router)#do sh ip bgp

BGP table version is 3, local router ID is 100.100.100.1

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

* i33.33.33.33/32   3.3.3.3                     0    100      0 3 i

*> 100.100.100.1/32 0.0.0.0                  0          32768 i

*>i200.200.200.2/32 2.2.2.2                  0    100        0 i

R2(config-router)#do sh ip bgp

BGP table version is 4, local router ID is 200.200.200.2

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

*> 33.33.33.33/32   3.3.3.3                  0             0 3 i

*>i100.100.100.1/32 1.1.1.1                  0    100      0 i

*> 200.200.200.2/32 0.0.0.0                  0         32768 i

R3(config-router)#do sh ip bgp

BGP table version is 4, local router ID is 33.33.33.33

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

*> 33.33.33.33/32   0.0.0.0                  0         32768 i

*> 100.100.100.1/32 2.2.2.2                                0 12 i

*> 200.200.200.2/32 2.2.2.2                  0             0 12 i

Check ping

R1(config-router)#do ping 200.200.200.2

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 200.200.200.2, timeout is 2 seconds:

!!!!!

Success rate is 100 percent (5/5), round-trip min/avg/max = 24/48/68 ms

R1(config-router)#do ping 33.33.33.33

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 33.33.33.33, timeout is 2 seconds:

.....

Success rate is 0 percent (0/5)

R2(config-router)#do ping 33.33.33.33

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 33.33.33.33, timeout is 2 seconds:

!!!!!

Success rate is 100 percent (5/5), round-trip min/avg/max = 28/48/68 ms

R2(config-router)#do ping 100.100.100.1

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 100.100.100.1, timeout is 2 seconds:

!!!!!

Success rate is 100 percent (5/5), round-trip min/avg/max = 20/48/64 ms

R3(config-router)#do ping 100.100.100.1

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 100.100.100.1, timeout is 2 seconds:

.....

Success rate is 0 percent (0/5)

R3(config-router)#do ping 200.200.200.2

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 200.200.200.2, timeout is 2 seconds:

!!!!!

Success rate is 100 percent (5/5), round-trip min/avg/max = 28/41/64 ms

Oupss, R1 can not ping to loopback R2 and vice versa!!! Let’s add command ‘next-hop-self’ in R2

R2#

router bgp 12

neighbor 1.1.1.1 next-hop-self

Now verify BGP routing

R1(config-router)#do sh ip bgp

BGP table version is 114, local router ID is 100.100.100.1

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

*>i33.33.33.33/32   2.2.2.2                  0    100      0 3 i

*> 100.100.100.1/32 0.0.0.0                  0         32768 i

*>i200.200.200.2/32 2.2.2.2                  0    100      0 i

R1(config-router)#do ping 33.33.33.33

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 33.33.33.33, timeout is 2 seconds:

!!!!!

Success rate is 100 percent (5/5), round-trip min/avg/max = 36/58/88 ms