A Network Artist : BGP Next Hop Issues & How Do We Fix It Using Different Ways .... With Some Troubleshooting Along The Way (Not For Soft Heart People ;-p)

R1
===

!
en
!
conf t
!
no ip do lo
no cdp run
!
ho R1
!
int lo0
ip add 1.1.1.1 255.255.255.255
exit
!
int f0/0
ip add 12.12.12.1 255.255.255.0
no sh
exit
!
router bgp 100
no auto
no sync
nei 12.12.12.2 remote 200
net 1.1.1.1 mask 255.255.255.255
exit
!
end
!
wr
!
#########################

R2
===

!
en
!
conf t
!
no ip do lo
no cdp run
!
ho R2
!
int lo0
ip add 2.2.2.2 255.255.255.255
exit
!
int f1/0
ip add 12.12.12.2 255.255.255.0
no sh
exit
!
int f1/1
ip add 23.23.23.2 255.255.255.0
no sh
exit
!
int f2/0
ip add 24.24.24.2 255.255.255.0
no sh
exit
!
router eigrp 200
no auto
net 2.2.2.2 0.0.0.0
net 23.23.23.2 0.0.0.0
net 24.24.24.2 0.0.0.0
exit
!
router bgp 200
no au
no sync
nei 3.3.3.3 remote 200
nei 3.3.3.3 update lo0
nei 4.4.4.4 remote 200
nei 4.4.4.4 update lo0
nei 12.12.12.1 remote 100
net 2.2.2.2 mask 255.255.255.255
exit
end
!
wr
!
#########################

R3
===

!
en
!
conf t
!
no ip do lo
no cdp run
!
ho R3
!
int lo0
ip add 3.3.3.3 255.255.255.255
exit
!
int f0/0
ip add 23.23.23.3 255.255.255.0
no sh
exit
!
int f0/1
ip add 53.53.53.3 255.255.255.0
no sh
exit
!
router eigrp 200
no auto
net 3.3.3.3 0.0.0.0
net 23.23.23.3 0.0.0.0
exit
!
router bgp 200
no auto
no sync
nei 2.2.2.2 remote 200
nei 2.2.2.2 update lo0
nei 53.53.53.5 remote 300
net 3.3.3.3 mask 255.255.255.255
exit
!
end
!
wr
!
#########################

R4
===

!
en
!
conf t
!
no ip do lo
no cdp run
!
ho R4
!
int lo0
ip add 4.4.4.4 255.255.255.255
exit
!
int f0/0
ip add 24.24.24.4 255.255.255.0
no sh
exit
!
int f0/1
ip add 46.46.46.4 255.255.255.0
no sh
exit
!
router eigrp 200
no auto
net 4.4.4.4 0.0.0.0
net 24.24.24.4 0.0.0.0
net 46.46.46.4 0.0.0.0
exit
!
router bgp 200
no auto
no sync
nei 2.2.2.2 remote 200
nei 2.2.2.2 update lo0
nei 2.2.2.2 route-reflector-client
nei 6.6.6.6 remote 200
nei 6.6.6.6 update lo0
nei 6.6.6.6 route-reflector-client
net 4.4.4.4 mask 255.255.255.255
exit
!
end
!
wr
!
#########################

R5
===

!
en
!
conf t
!
no ip do lo
no cdp run
!
ho R5
!
int lo0
ip add 5.5.5.5 255.255.255.255
exit
!
int f0/0
ip add 53.53.53.5 255.255.255.0
no sh
exit
!
router bgp 300
no auto
no sync
nei 53.53.53.3 remote 200
net 5.5.5.5 mask 255.255.255.255
exit
!
end
!
wr
!
#########################

R6
===

!
en
!
conf t
!
no ip do lo
no cdp run
!
ho R6
!
int lo0
ip add 6.6.6.6 255.255.255.255
exit
!
int f0/0
ip add 46.46.46.6 255.255.255.0
no sh
exit
!
router eigrp 200
no auto
net 6.6.6.6 0.0.0.0
net 46.46.46.6 0.0.0.0
exit
!
router bgp 200
no auto
no sync
nei 4.4.4.4 remote 200
nei 4.4.4.4 update lo0
net 6.6.6.6 mask 255.255.255.255
exit
!
end
!
wr
!
==============================================================

PEERING STATUS
---------------------------

R1#sh ip bgp summary | b N

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

12.12.12.2 4 200 68 61 8 0 0 00:56:14 4

R2#sh ip bgp summary | b N

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

3.3.3.3 4 200 53 58 15 0 0 00:47:01 2

4.4.4.4 4 200 21 17 15 0 0 00:09:43 2

12.12.12.1 4 100 62 70 15 0 0 00:57:26 1

R3#sh ip bgp summary | b N

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

2.2.2.2 4 200 58 53 5 0 0 00:47:25 2

53.53.53.5 4 300 33 34 5 0 0 00:28:57 1

R4#sh ip bgp summary | b N

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

2.2.2.2 4 200 51 51 12 0 0 00:10:46 2

6.6.6.6 4 200 33 39 12 0 0 00:10:35 1

R5#sh ip bgp summary | b N

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

53.53.53.3 4 200 36 35 4 0 0 00:30:11 2

R6#sh ip bgp summary | b N

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

4.4.4.4 4 200 40 34 12 0 0 00:11:48 2

=======================================================================

BGP TABLE VIEW
---------------------------

R1#sh ip bgp | b N

Network Next Hop Metric LocPrf Weight Path

*> 1.1.1.1/32 0.0.0.0 0 32768 i

*> 2.2.2.2/32 12.12.12.2 0 0 200 i

*> 3.3.3.3/32 12.12.12.2 0 200 i

*> 4.4.4.4/32 12.12.12.2 0 200 i

*> 6.6.6.6/32 12.12.12.2 0 200 i

R2#sh ip bgp | b N

Network Next Hop Metric LocPrf Weight Path

*> 1.1.1.1/32 12.12.12.1 0 0 100 i

*> 2.2.2.2/32 0.0.0.0 0 32768 i

r>i3.3.3.3/32 3.3.3.3 0 100 0 i

r>i4.4.4.4/32 4.4.4.4 0 100 0 i

* i5.5.5.5/32 53.53.53.5 0 100 0 300 i

r>i6.6.6.6/32 6.6.6.6 0 100 0 i

R3#sh ip bgp | b N

Network Next Hop Metric LocPrf Weight Path

* i1.1.1.1/32 12.12.12.1 0 100 0 100 i

r>i2.2.2.2/32 2.2.2.2 0 100 0 i

*> 3.3.3.3/32 0.0.0.0 0 32768 i

*> 5.5.5.5/32 53.53.53.5 0 0 300 i

R3#sh ip route 12.12.12.1

% Network not in table

R4#sh ip bgp | b N

Network Next Hop Metric LocPrf Weight Path

* i1.1.1.1/32 12.12.12.1 0 100 0 100 i

r>i2.2.2.2/32 2.2.2.2 0 100 0 i

*> 4.4.4.4/32 0.0.0.0 0 32768 i

r>i6.6.6.6/32 6.6.6.6 0 100 0 i

R4#sh ip route 12.12.12.1

% Network not in table

R5#sh ip bgp | b N

Network Next Hop Metric LocPrf Weight Path

*> 2.2.2.2/32 53.53.53.3 0 200 i

*> 3.3.3.3/32 53.53.53.3 0 0 200 i

*> 5.5.5.5/32 0.0.0.0 0 32768 i

R6#sh ip bgp | b N

Network Next Hop Metric LocPrf Weight Path

r>i2.2.2.2/32 2.2.2.2 0 100 0 i

r>i4.4.4.4/32 4.4.4.4 0 100 0 i

*> 6.6.6.6/32 0.0.0.0 0 32768 i

=======================================================================

Fixing Next Hop Issues
-------------------------------

Method 1 => Advertising Next Hop Into IGP
###########################################

R2(config)#router eigrp 200

R2(config-router)#net 12.12.12.2 0.0.0.0

R2(config-router)#end

R3(config)#router eigrp 200

R3(config-router)#net 53.53.53.3 0.0.0.0

R3(config-router)#end

R4 Before
=========

R4#sh ip bgp | b N

Network Next Hop Metric LocPrf Weight Path

* i1.1.1.1/32 12.12.12.1 0 100 0 100 i

r>i2.2.2.2/32 2.2.2.2 0 100 0 i

*> 4.4.4.4/32 0.0.0.0 0 32768 i

r>i6.6.6.6/32 6.6.6.6 0 100 0 i

R4#sh ip route 12.12.12.1

% Network not in table

R4 After
========

R4#sh ip bgp | b N

Network Next Hop Metric LocPrf Weight Path

*>i1.1.1.1/32 12.12.12.1 0 100 0 100 i

r>i2.2.2.2/32 2.2.2.2 0 100 0 i

*> 4.4.4.4/32 0.0.0.0 0 32768 i

r>i6.6.6.6/32 6.6.6.6 0 100 0 i

R4#sh ip route 12.12.12.1

Routing entry for 12.12.12.0/24

Known via "eigrp 200", distance 90, metric 284160, type internal

Redistributing via eigrp 200

Last update from 24.24.24.2 on FastEthernet0/0, 00:02:25 ago

Routing Descriptor Blocks:

* 24.24.24.2, from 24.24.24.2, 00:02:25 ago, via FastEthernet0/0

Route metric is 284160, traffic share count is 1

Total delay is 1100 microseconds, minimum bandwidth is 10000 Kbit

Reliability 255/255, minimum MTU 1500 bytes

Loading 1/255, Hops 1

R3 Before
=========

R3#sh ip bgp | b N

Network Next Hop Metric LocPrf Weight Path

* i1.1.1.1/32 12.12.12.1 0 100 0 100 i

r>i2.2.2.2/32 2.2.2.2 0 100 0 i

*> 3.3.3.3/32 0.0.0.0 0 32768 i

*> 5.5.5.5/32 53.53.53.5 0 0 300 i

R3#sh ip route 12.12.12.1

% Network not in table

R3 After
========

R3#sh ip bgp | b N

Network Next Hop Metric LocPrf Weight Path

*>i1.1.1.1/32 12.12.12.1 0 100 0 100 i

r>i2.2.2.2/32 2.2.2.2 0 100 0 i

*> 3.3.3.3/32 0.0.0.0 0 32768 i

*> 5.5.5.5/32 53.53.53.5 0 0 300 i

R3#sh ip route 12.12.12.1

Routing entry for 12.12.12.0/24

Known via "eigrp 200", distance 90, metric 284160, type internal

Redistributing via eigrp 200

Last update from 23.23.23.2 on FastEthernet0/0, 00:03:58 ago

Routing Descriptor Blocks:

* 23.23.23.2, from 23.23.23.2, 00:03:58 ago, via FastEthernet0/0

Route metric is 284160, traffic share count is 1

Total delay is 1100 microseconds, minimum bandwidth is 10000 Kbit

Reliability 255/255, minimum MTU 1500 bytes

Loading 1/255, Hops 1

Getting Rid of BGP Split Horizon Issue By Configuring R2 as Route Reflector

==========================================================

R2(config)#router bgp 200

R2(config-router)#nei 3.3.3.3 route-reflector-client

R2(config-router)#nei 4.4.4.4 route-reflector-client

R2(config-router)#end

R3 Before

=========

R3#sh ip bgp | b N

Network Next Hop Metric LocPrf Weight Path

*>i1.1.1.1/32 12.12.12.1 0 100 0 100 i

r>i2.2.2.2/32 2.2.2.2 0 100 0 i

*> 3.3.3.3/32 0.0.0.0 0 32768 i

*> 5.5.5.5/32 53.53.53.5 0 0 300 i

R3 After

========

R3#sh ip bgp | b N

Network Next Hop Metric LocPrf Weight Path

*>i1.1.1.1/32 12.12.12.1 0 100 0 100 i

r>i2.2.2.2/32 2.2.2.2 0 100 0 i

*> 3.3.3.3/32 0.0.0.0 0 32768 i

r>i4.4.4.4/32 4.4.4.4 0 100 0 i

*> 5.5.5.5/32 53.53.53.5 0 0 300 i

r>i6.6.6.6/32 6.6.6.6 0 100 0 i

############################################################################

Reachability Check Using TCL Scripting

======================================

tclsh

foreach address {

1.1.1.1

2.2.2.2

3.3.3.3

4.4.4.4

5.5.5.5

6.6.6.6

} {ping $address source lo0 repeat 3}

R1#tclsh

R1(tcl)#foreach address {

+>(tcl)#1.1.1.1

+>(tcl)#2.2.2.2

+>(tcl)#3.3.3.3

+>(tcl)#4.4.4.4

+>(tcl)#5.5.5.5

+>(tcl)#6.6.6.6

+>(tcl)#} {ping $address source lo0 repeat 3}

Type escape sequence to abort.

Sending 3, 100-byte ICMP Echos to 1.1.1.1, timeout is 2 seconds:

Packet sent with a source address of 1.1.1.1

!!!

Success rate is 100 percent (3/3), round-trip min/avg/max = 4/4/4 ms

Type escape sequence to abort.

Sending 3, 100-byte ICMP Echos to 2.2.2.2, timeout is 2 seconds:

Packet sent with a source address of 1.1.1.1

!!!

Success rate is 100 percent (3/3), round-trip min/avg/max = 112/306/496 ms

Type escape sequence to abort.

Sending 3, 100-byte ICMP Echos to 3.3.3.3, timeout is 2 seconds:

Packet sent with a source address of 1.1.1.1

!!!

Success rate is 100 percent (3/3), round-trip min/avg/max = 416/597/876 ms

Type escape sequence to abort.

Sending 3, 100-byte ICMP Echos to 4.4.4.4, timeout is 2 seconds:

Packet sent with a source address of 1.1.1.1

!!!

Success rate is 100 percent (3/3), round-trip min/avg/max = 232/378/552 ms

Type escape sequence to abort.

Sending 3, 100-byte ICMP Echos to 5.5.5.5, timeout is 2 seconds:

Packet sent with a source address of 1.1.1.1

!!!

Success rate is 100 percent (3/3), round-trip min/avg/max = 616/1136/1624 ms

Type escape sequence to abort.

Sending 3, 100-byte ICMP Echos to 6.6.6.6, timeout is 2 seconds:

Packet sent with a source address of 1.1.1.1

!!!

Success rate is 100 percent (3/3), round-trip min/avg/max = 376/642/796 ms

Fixing Next Hop Issues

--------------------------

Method 2 => Redistributing Specific Connected Route Into IGP

#############################################################

Let's Rollback Method 1

===================

R2(config)#router eigrp 200

R2(config-router)#no network 12.12.12.2 0.0.0.0

R2(config-router)#end

R3(config)#router eigrp 200

R3(config-router)#no network 53.53.53.3 0.0.0.0

R3(config-router)#end

Let's do reachability test again from R1

==============================

R1#tclsh

R1(tcl)#foreach address {

+>(tcl)#1.1.1.1

+>(tcl)#2.2.2.2

+>(tcl)#3.3.3.3

+>(tcl)#4.4.4.4

+>(tcl)#5.5.5.5

+>(tcl)#6.6.6.6

+>(tcl)#} {ping $address source lo0 repeat 3}

Type escape sequence to abort.

Sending 3, 100-byte ICMP Echos to 1.1.1.1, timeout is 2 seconds:

Packet sent with a source address of 1.1.1.1

!!!

Success rate is 100 percent (3/3), round-trip min/avg/max = 1/3/4 ms

Type escape sequence to abort.

Sending 3, 100-byte ICMP Echos to 2.2.2.2, timeout is 2 seconds:

Packet sent with a source address of 1.1.1.1

.!!

Success rate is 66 percent (2/3), round-trip min/avg/max = 288/334/380 ms

Type escape sequence to abort.

Sending 3, 100-byte ICMP Echos to 3.3.3.3, timeout is 2 seconds:

Packet sent with a source address of 1.1.1.1

...

Success rate is 0 percent (0/3)

Type escape sequence to abort.

Sending 3, 100-byte ICMP Echos to 4.4.4.4, timeout is 2 seconds:

Packet sent with a source address of 1.1.1.1

...

Success rate is 0 percent (0/3)

Type escape sequence to abort.

Sending 3, 100-byte ICMP Echos to 5.5.5.5, timeout is 2 seconds:

Packet sent with a source address of 1.1.1.1

...

Success rate is 0 percent (0/3)

Type escape sequence to abort.

Sending 3, 100-byte ICMP Echos to 6.6.6.6, timeout is 2 seconds:

Packet sent with a source address of 1.1.1.1

...

Success rate is 0 percent (0/3)

Let's try to fix it with second option:

===========================

###

R2(config)#route-map CONN-F1/0 per 10

R2(config-route-map)#match interface f1/0

R2(config-route-map)#exit

R2(config)#router eigrp 200

R2(config-router)#redistribute connected metric 1 1 1 1 1 route-map CONN-F1/0

R2(config-router)#end

###

R3(config)#ip prefix-list CONN-F0/1 pe

R3(config)#ip prefix-list CONN-F0/1 permit 53.53.53.3/24

R3(config)#route-map CONN-F0/1 per 10

R3(config-route-map)#match ip add prefix-list CONN-F0/1

R3(config-route-map)#exit

R3(config)#router eigrp 200

R3(config-router)#redis conn metric 1 1 1 1 1 route-map CONN-F0/1

R3(config-router)#end

Reachability Check Using TCL Scripting From R1

=====================================

tclsh

foreach address {

1.1.1.1

2.2.2.2

3.3.3.3

4.4.4.4

5.5.5.5

6.6.6.6

} {ping $address source lo0 repeat 3}

R1#foreach address {

+>(tcl)#1.1.1.1

+>(tcl)#2.2.2.2

+>(tcl)#3.3.3.3

+>(tcl)#4.4.4.4

+>(tcl)#5.5.5.5

+>(tcl)#6.6.6.6

+>(tcl)#} {ping $address source lo0 repeat 3}

Type escape sequence to abort.

Sending 3, 100-byte ICMP Echos to 1.1.1.1, timeout is 2 seconds:

Packet sent with a source address of 1.1.1.1

!!!

Success rate is 100 percent (3/3), round-trip min/avg/max = 1/3/4 ms

Type escape sequence to abort.

Sending 3, 100-byte ICMP Echos to 2.2.2.2, timeout is 2 seconds:

Packet sent with a source address of 1.1.1.1

!!!

Success rate is 100 percent (3/3), round-trip min/avg/max = 12/104/168 ms

Type escape sequence to abort.

Sending 3, 100-byte ICMP Echos to 3.3.3.3, timeout is 2 seconds:

Packet sent with a source address of 1.1.1.1

!!!

Success rate is 100 percent (3/3), round-trip min/avg/max = 408/572/868 ms

Type escape sequence to abort.

Sending 3, 100-byte ICMP Echos to 4.4.4.4, timeout is 2 seconds:

Packet sent with a source address of 1.1.1.1

!!!

Success rate is 100 percent (3/3), round-trip min/avg/max = 388/557/812 ms

Type escape sequence to abort.

Sending 3, 100-byte ICMP Echos to 5.5.5.5, timeout is 2 seconds:

Packet sent with a source address of 1.1.1.1

!!!

Success rate is 100 percent (3/3), round-trip min/avg/max = 688/1002/1364 ms

Type escape sequence to abort.

Sending 3, 100-byte ICMP Echos to 6.6.6.6, timeout is 2 seconds:

Packet sent with a source address of 1.1.1.1

!!!

Success rate is 100 percent (3/3), round-trip min/avg/max = 996/1112/1212 ms

Method 3 => Neighbor Next Hop Self Command

###########################################

Let's Rollback Method 2

==================

R2(config)#router eigrp 200

R2(config-router)#no redistribute connected metric 1 1 1 1 1 route-map CONN-F1/0

R2(config-router)#end

R3(config)#router eigrp 200

R3(config-router)#no redistribute connected metric 1 1 1 1 1 route-map CONN-F0/1

R3(config-router)#end

Reachability Check Using TCL Scripting From R1

=====================================

tclsh

foreach address {

1.1.1.1

2.2.2.2

3.3.3.3

4.4.4.4

5.5.5.5

6.6.6.6

} {ping $address source lo0 repeat 3}

R1(tcl)#foreach address {

+>(tcl)#1.1.1.1

+>(tcl)#2.2.2.2

+>(tcl)#3.3.3.3

+>(tcl)#4.4.4.4

+>(tcl)#5.5.5.5

+>(tcl)#6.6.6.6

+>(tcl)#} {ping $address source lo0 repeat 3}

Type escape sequence to abort.

Sending 3, 100-byte ICMP Echos to 1.1.1.1, timeout is 2 seconds:

Packet sent with a source address of 1.1.1.1

!!!

Success rate is 100 percent (3/3), round-trip min/avg/max = 1/3/4 ms

Type escape sequence to abort.

Sending 3, 100-byte ICMP Echos to 2.2.2.2, timeout is 2 seconds:

Packet sent with a source address of 1.1.1.1

!!!

Success rate is 100 percent (3/3), round-trip min/avg/max = 32/50/64 ms

Type escape sequence to abort.

Sending 3, 100-byte ICMP Echos to 3.3.3.3, timeout is 2 seconds:

Packet sent with a source address of 1.1.1.1

...

Success rate is 0 percent (0/3)

Type escape sequence to abort.

Sending 3, 100-byte ICMP Echos to 4.4.4.4, timeout is 2 seconds:

Packet sent with a source address of 1.1.1.1

...

Success rate is 0 percent (0/3)

Type escape sequence to abort.

Sending 3, 100-byte ICMP Echos to 5.5.5.5, timeout is 2 seconds:

Packet sent with a source address of 1.1.1.1

...

Success rate is 0 percent (0/3)

Type escape sequence to abort.

Sending 3, 100-byte ICMP Echos to 6.6.6.6, timeout is 2 seconds:

Packet sent with a source address of 1.1.1.1

...

Success rate is 0 percent (0/3)

Let's Try to fix the situation using Next-Hop-Self Option

===========================================

R2(config)#router bgp 200

R2(config-router)#nei 3.3.3.3 next-hop-self

R2(config-router)#nei 4.4.4.4 next-hop-self

R2(config-router)#end

R3(config)#router bgp 200

R3(config-router)#nei 2.2.2.2 next-hop-self

R3(config-router)#end

Let's Verify the solution

==================

R1#sh ip bgp | b N

Network Next Hop Metric LocPrf Weight Path

*> 1.1.1.1/32 0.0.0.0 0 32768 i

*> 2.2.2.2/32 12.12.12.2 0 0 200 i

*> 3.3.3.3/32 12.12.12.2 0 200 i

*> 4.4.4.4/32 12.12.12.2 0 200 i

*> 5.5.5.5/32 12.12.12.2 0 200 300 i

*> 6.6.6.6/32 12.12.12.2 0 200 i

R2#sh ip bgp | b N

Network Next Hop Metric LocPrf Weight Path

*> 1.1.1.1/32 12.12.12.1 0 0 100 i

*> 2.2.2.2/32 0.0.0.0 0 32768 i

r>i3.3.3.3/32 3.3.3.3 0 100 0 i

r>i4.4.4.4/32 4.4.4.4 0 100 0 i

*>i5.5.5.5/32 3.3.3.3 0 100 0 300 i

r>i6.6.6.6/32 6.6.6.6 0 100 0 i

R3#sh ip bgp | b N

Network Next Hop Metric LocPrf Weight Path

*>i1.1.1.1/32 2.2.2.2 0 100 0 100 i

r>i2.2.2.2/32 2.2.2.2 0 100 0 i

*> 3.3.3.3/32 0.0.0.0 0 32768 i

r>i4.4.4.4/32 4.4.4.4 0 100 0 i

*> 5.5.5.5/32 53.53.53.5 0 0 300 i

r>i6.6.6.6/32 6.6.6.6 0 100 0 i

R4#sh ip bgp | b N

Network Next Hop Metric LocPrf Weight Path

*>i1.1.1.1/32 2.2.2.2 0 100 0 100 i

r>i2.2.2.2/32 2.2.2.2 0 100 0 i

r>i3.3.3.3/32 3.3.3.3 0 100 0 i

*> 4.4.4.4/32 0.0.0.0 0 32768 i

*>i5.5.5.5/32 3.3.3.3 0 100 0 300 i

r>i6.6.6.6/32 6.6.6.6 0 100 0 i

R5#sh ip bgp | b N

Network Next Hop Metric LocPrf Weight Path

*> 1.1.1.1/32 53.53.53.3 0 200 100 i

*> 2.2.2.2/32 53.53.53.3 0 200 i

*> 3.3.3.3/32 53.53.53.3 0 0 200 i

*> 4.4.4.4/32 53.53.53.3 0 200 i

*> 5.5.5.5/32 0.0.0.0 0 32768 i

*> 6.6.6.6/32 53.53.53.3 0 200 i

R6#sh ip bgp | b N

Network Next Hop Metric LocPrf Weight Path

*>i1.1.1.1/32 2.2.2.2 0 100 0 100 i

r>i2.2.2.2/32 2.2.2.2 0 100 0 i

r>i3.3.3.3/32 3.3.3.3 0 100 0 i

r>i4.4.4.4/32 4.4.4.4 0 100 0 i

*>i5.5.5.5/32 3.3.3.3 0 100 0 300 i

*> 6.6.6.6/32 0.0.0.0 0 32768 i

Reachability Check Using TCL Scripting From R1

=====================================

tclsh

foreach address {

1.1.1.1

2.2.2.2

3.3.3.3

4.4.4.4

5.5.5.5

6.6.6.6

} {ping $address source lo0 repeat 3}

R1#foreach address {

+>(tcl)#1.1.1.1

+>(tcl)#2.2.2.2

+>(tcl)#3.3.3.3

+>(tcl)#4.4.4.4

+>(tcl)#5.5.5.5

+>(tcl)#6.6.6.6

+>(tcl)#} {ping $address source lo0 repeat 3}

Type escape sequence to abort.

Sending 3, 100-byte ICMP Echos to 1.1.1.1, timeout is 2 seconds:

Packet sent with a source address of 1.1.1.1

!!!

Success rate is 100 percent (3/3), round-trip min/avg/max = 4/4/4 ms

Type escape sequence to abort.

Sending 3, 100-byte ICMP Echos to 2.2.2.2, timeout is 2 seconds:

Packet sent with a source address of 1.1.1.1

!!!

Success rate is 100 percent (3/3), round-trip min/avg/max = 24/53/96 ms

Type escape sequence to abort.

Sending 3, 100-byte ICMP Echos to 3.3.3.3, timeout is 2 seconds:

Packet sent with a source address of 1.1.1.1

!!!

Success rate is 100 percent (3/3), round-trip min/avg/max = 48/77/100 ms

Type escape sequence to abort.

Sending 3, 100-byte ICMP Echos to 4.4.4.4, timeout is 2 seconds:

Packet sent with a source address of 1.1.1.1

!!!

Success rate is 100 percent (3/3), round-trip min/avg/max = 36/74/132 ms

Type escape sequence to abort.

Sending 3, 100-byte ICMP Echos to 5.5.5.5, timeout is 2 seconds:

Packet sent with a source address of 1.1.1.1

!!!

Success rate is 100 percent (3/3), round-trip min/avg/max = 96/138/200 ms

Type escape sequence to abort.

Sending 3, 100-byte ICMP Echos to 6.6.6.6, timeout is 2 seconds:

Packet sent with a source address of 1.1.1.1

!!!

Success rate is 100 percent (3/3), round-trip min/avg/max = 80/102/128 ms

Method 4 => Using Default Route For BGP Next-Hop Reachability

##############################################################

Let's Rollback Method 3

===================

R2(config)#router bgp 200

R2(config-router)#no neighbor 3.3.3.3 next-hop-self

R2(config-router)#no neighbor 4.4.4.4 next-hop-self

R2(config-router)#end

R3(config)#router bgp 200

R3(config-router)#no neighbor 2.2.2.2 next-hop-self

R3(config-router)#end

Now Let's try our Final Method 4

=========================

R2(config)#ip route 0.0.0.0 0.0.0.0 null 0

R2(config)#router eigrp 200

R2(config-router)#redistribute static metric 1 1 1 1 1

R2(config-router)#end

R2#sh ip route 53.53.53.5

% Network not in table

R2#sh ip route | b ^G

Gateway of last resort is 0.0.0.0 to network 0.0.0.0

S* 0.0.0.0/0 is directly connected, Null0

1.0.0.0/32 is subnetted, 1 subnets

B 1.1.1.1 [20/0] via 12.12.12.1, 00:03:36

2.0.0.0/32 is subnetted, 1 subnets

C 2.2.2.2 is directly connected, Loopback0

3.0.0.0/32 is subnetted, 1 subnets

D 3.3.3.3 [90/156160] via 23.23.23.3, 00:03:32, FastEthernet1/1

4.0.0.0/32 is subnetted, 1 subnets

D 4.4.4.4 [90/156160] via 24.24.24.4, 00:03:32, FastEthernet2/0

5.0.0.0/32 is subnetted, 1 subnets

B 5.5.5.5 [200/0] via 53.53.53.5, 00:02:47

6.0.0.0/32 is subnetted, 1 subnets

D 6.6.6.6 [90/412160] via 24.24.24.4, 00:03:32, FastEthernet2/0

12.0.0.0/8 is variably subnetted, 2 subnets, 2 masks

C 12.12.12.0/24 is directly connected, FastEthernet1/0

L 12.12.12.2/32 is directly connected, FastEthernet1/0

23.0.0.0/8 is variably subnetted, 2 subnets, 2 masks

C 23.23.23.0/24 is directly connected, FastEthernet1/1

L 23.23.23.2/32 is directly connected, FastEthernet1/1

24.0.0.0/8 is variably subnetted, 2 subnets, 2 masks

C 24.24.24.0/24 is directly connected, FastEthernet2/0

L 24.24.24.2/32 is directly connected, FastEthernet2/0

46.0.0.0/24 is subnetted, 1 subnets

D 46.46.46.0 [90/284160] via 24.24.24.4, 00:03:34, FastEthernet2/0

R3(config)#ip route 0.0.0.0 0.0.0.0 null0

R3(config)#router eigrp 200

R3(config-router)#redistribute static metric 1 1 1 1 1

R3(config-router)#end

R2#sh ip route | b ^G

Gateway of last resort is 0.0.0.0 to network 0.0.0.0

S* 0.0.0.0/0 is directly connected, Null0

1.0.0.0/32 is subnetted, 1 subnets

B 1.1.1.1 [20/0] via 12.12.12.1, 00:09:18

2.0.0.0/32 is subnetted, 1 subnets

C 2.2.2.2 is directly connected, Loopback0

3.0.0.0/32 is subnetted, 1 subnets

D 3.3.3.3 [90/156160] via 23.23.23.3, 00:09:14, FastEthernet1/1

4.0.0.0/32 is subnetted, 1 subnets

D 4.4.4.4 [90/156160] via 24.24.24.4, 00:09:14, FastEthernet2/0

5.0.0.0/32 is subnetted, 1 subnets

B 5.5.5.5 [200/0] via 53.53.53.5, 00:08:29

6.0.0.0/32 is subnetted, 1 subnets

D 6.6.6.6 [90/412160] via 24.24.24.4, 00:09:14, FastEthernet2/0

12.0.0.0/8 is variably subnetted, 2 subnets, 2 masks

C 12.12.12.0/24 is directly connected, FastEthernet1/0

L 12.12.12.2/32 is directly connected, FastEthernet1/0

23.0.0.0/8 is variably subnetted, 2 subnets, 2 masks

C 23.23.23.0/24 is directly connected, FastEthernet1/1

L 23.23.23.2/32 is directly connected, FastEthernet1/1

24.0.0.0/8 is variably subnetted, 2 subnets, 2 masks

C 24.24.24.0/24 is directly connected, FastEthernet2/0

L 24.24.24.2/32 is directly connected, FastEthernet2/0

46.0.0.0/24 is subnetted, 1 subnets

D 46.46.46.0 [90/284160] via 24.24.24.4, 00:09:16, FastEthernet2/0

R2(config)#no ip route 0.0.0.0 0.0.0.0 null 0

R2(config)#do sh ip route | b ^G

Gateway of last resort is 23.23.23.3 to network 0.0.0.0

D*EX 0.0.0.0/0 [170/2560002816] via 23.23.23.3, 00:00:18, FastEthernet1/1

1.0.0.0/32 is subnetted, 1 subnets

B 1.1.1.1 [20/0] via 12.12.12.1, 00:10:43

2.0.0.0/32 is subnetted, 1 subnets

C 2.2.2.2 is directly connected, Loopback0

3.0.0.0/32 is subnetted, 1 subnets

D 3.3.3.3 [90/156160] via 23.23.23.3, 00:10:39, FastEthernet1/1

4.0.0.0/32 is subnetted, 1 subnets

D 4.4.4.4 [90/156160] via 24.24.24.4, 00:10:39, FastEthernet2/0

5.0.0.0/32 is subnetted, 1 subnets

B 5.5.5.5 [200/0] via 53.53.53.5, 00:09:54

6.0.0.0/32 is subnetted, 1 subnets

D 6.6.6.6 [90/412160] via 24.24.24.4, 00:10:39, FastEthernet2/0

12.0.0.0/8 is variably subnetted, 2 subnets, 2 masks

C 12.12.12.0/24 is directly connected, FastEthernet1/0

L 12.12.12.2/32 is directly connected, FastEthernet1/0

23.0.0.0/8 is variably subnetted, 2 subnets, 2 masks

C 23.23.23.0/24 is directly connected, FastEthernet1/1

L 23.23.23.2/32 is directly connected, FastEthernet1/1

24.0.0.0/8 is variably subnetted, 2 subnets, 2 masks

C 24.24.24.0/24 is directly connected, FastEthernet2/0

L 24.24.24.2/32 is directly connected, FastEthernet2/0

46.0.0.0/24 is subnetted, 1 subnets

D 46.46.46.0 [90/284160] via 24.24.24.4, 00:10:41, FastEthernet2/0

R1#ping 5.5.5.5

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 5.5.5.5, timeout is 2 seconds:

.....

Success rate is 0 percent (0/5)

R1#sh ip route 53.53.53.0

% Network not in table

R2(config)#do ping 5.5.5.5

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 5.5.5.5, timeout is 2 seconds:

.....

Success rate is 0 percent (0/5)

R2(config)#do ping 5.5.5.5 so lo0

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 5.5.5.5, timeout is 2 seconds:

Packet sent with a source address of 2.2.2.2

!!!!!

Success rate is 100 percent (5/5), round-trip min/avg/max = 60/85/116 ms

Let's try to combine two solutions

=========================

R2(config)#ip route 0.0.0.0 0.0.0.0 null 0 254

R2(config)#router eigrp 200

R2(config-router)#redistribute static metric 1 1 1 1 1

R3(config)#router bgp 200

R3(config-router)# neighbor 2.2.2.2 next-hop-self

R3(config-router)#end

Final Reachability Check Using TCL Scripting From R1-R6

============================================

tclsh

foreach address {

1.1.1.1

2.2.2.2

3.3.3.3

4.4.4.4

5.5.5.5

6.6.6.6

} {ping $address source lo0 repeat 3}

R1#tclsh

R1#foreach address {

+>(tcl)#1.1.1.1

+>(tcl)#2.2.2.2

+>(tcl)#3.3.3.3

+>(tcl)#4.4.4.4

+>(tcl)#5.5.5.5

+>(tcl)#6.6.6.6

+>(tcl)#} {ping $address source lo0 repeat 3}

Type escape sequence to abort.

Sending 3, 100-byte ICMP Echos to 1.1.1.1, timeout is 2 seconds:

Packet sent with a source address of 1.1.1.1

!!!

Success rate is 100 percent (3/3), round-trip min/avg/max = 1/3/4 ms

Type escape sequence to abort.

Sending 3, 100-byte ICMP Echos to 2.2.2.2, timeout is 2 seconds:

Packet sent with a source address of 1.1.1.1

!!!

Success rate is 100 percent (3/3), round-trip min/avg/max = 12/32/60 ms

Type escape sequence to abort.

Sending 3, 100-byte ICMP Echos to 3.3.3.3, timeout is 2 seconds:

Packet sent with a source address of 1.1.1.1

!!!

Success rate is 100 percent (3/3), round-trip min/avg/max = 48/68/100 ms

Type escape sequence to abort.

Sending 3, 100-byte ICMP Echos to 4.4.4.4, timeout is 2 seconds:

Packet sent with a source address of 1.1.1.1

!!!

Success rate is 100 percent (3/3), round-trip min/avg/max = 36/77/104 ms

Type escape sequence to abort.

Sending 3, 100-byte ICMP Echos to 5.5.5.5, timeout is 2 seconds:

Packet sent with a source address of 1.1.1.1

!!!

Success rate is 100 percent (3/3), round-trip min/avg/max = 84/112/152 ms

Type escape sequence to abort.

Sending 3, 100-byte ICMP Echos to 6.6.6.6, timeout is 2 seconds:

Packet sent with a source address of 1.1.1.1

!!!

Success rate is 100 percent (3/3), round-trip min/avg/max = 80/90/112 ms

R2#foreach address {

+>(tcl)#1.1.1.1

+>(tcl)#2.2.2.2

+>(tcl)#3.3.3.3

+>(tcl)#4.4.4.4

+>(tcl)#5.5.5.5

+>(tcl)#6.6.6.6

+>(tcl)#} {ping $address source lo0 repeat 3}

Type escape sequence to abort.

Sending 3, 100-byte ICMP Echos to 1.1.1.1, timeout is 2 seconds:

Packet sent with a source address of 2.2.2.2

!!!

Success rate is 100 percent (3/3), round-trip min/avg/max = 72/73/76 ms

Type escape sequence to abort.

Sending 3, 100-byte ICMP Echos to 2.2.2.2, timeout is 2 seconds:

Packet sent with a source address of 2.2.2.2

!!!

Success rate is 100 percent (3/3), round-trip min/avg/max = 4/5/8 ms

Type escape sequence to abort.

Sending 3, 100-byte ICMP Echos to 3.3.3.3, timeout is 2 seconds:

Packet sent with a source address of 2.2.2.2

!!!

Success rate is 100 percent (3/3), round-trip min/avg/max = 48/64/80 ms

Type escape sequence to abort.

Sending 3, 100-byte ICMP Echos to 4.4.4.4, timeout is 2 seconds:

Packet sent with a source address of 2.2.2.2

!!!

Success rate is 100 percent (3/3), round-trip min/avg/max = 44/65/104 ms

Type escape sequence to abort.

Sending 3, 100-byte ICMP Echos to 5.5.5.5, timeout is 2 seconds:

Packet sent with a source address of 2.2.2.2

!!!

Success rate is 100 percent (3/3), round-trip min/avg/max = 92/104/124 ms

Type escape sequence to abort.

Sending 3, 100-byte ICMP Echos to 6.6.6.6, timeout is 2 seconds:

Packet sent with a source address of 2.2.2.2

!!!

Success rate is 100 percent (3/3), round-trip min/avg/max = 92/108/124 ms

R3(tcl)#foreach address {

+>(tcl)#1.1.1.1

+>(tcl)#2.2.2.2

+>(tcl)#3.3.3.3

+>(tcl)#4.4.4.4

+>(tcl)#5.5.5.5

+>(tcl)#6.6.6.6

+>(tcl)#} {ping $address source lo0 repeat 3}

Type escape sequence to abort.

Sending 3, 100-byte ICMP Echos to 1.1.1.1, timeout is 2 seconds:

Packet sent with a source address of 3.3.3.3

!!!

Success rate is 100 percent (3/3), round-trip min/avg/max = 64/70/80 ms

Type escape sequence to abort.

Sending 3, 100-byte ICMP Echos to 2.2.2.2, timeout is 2 seconds:

Packet sent with a source address of 3.3.3.3

!!!

Success rate is 100 percent (3/3), round-trip min/avg/max = 24/66/104 ms

Type escape sequence to abort.

Sending 3, 100-byte ICMP Echos to 3.3.3.3, timeout is 2 seconds:

Packet sent with a source address of 3.3.3.3

!!!

Success rate is 100 percent (3/3), round-trip min/avg/max = 1/3/4 ms

Type escape sequence to abort.

Sending 3, 100-byte ICMP Echos to 4.4.4.4, timeout is 2 seconds:

Packet sent with a source address of 3.3.3.3

!!!

Success rate is 100 percent (3/3), round-trip min/avg/max = 72/84/92 ms

Type escape sequence to abort.

Sending 3, 100-byte ICMP Echos to 5.5.5.5, timeout is 2 seconds:

Packet sent with a source address of 3.3.3.3

!!!

Success rate is 100 percent (3/3), round-trip min/avg/max = 32/70/116 ms

Type escape sequence to abort.

Sending 3, 100-byte ICMP Echos to 6.6.6.6, timeout is 2 seconds:

Packet sent with a source address of 3.3.3.3

!!!

Success rate is 100 percent (3/3), round-trip min/avg/max = 92/113/140 ms

R4(tcl)#foreach address {

+>(tcl)#1.1.1.1

+>(tcl)#2.2.2.2

+>(tcl)#3.3.3.3

+>(tcl)#4.4.4.4

+>(tcl)#5.5.5.5

+>(tcl)#6.6.6.6

+>(tcl)#} {ping $address source lo0 repeat 3}

Type escape sequence to abort.

Sending 3, 100-byte ICMP Echos to 1.1.1.1, timeout is 2 seconds:

Packet sent with a source address of 4.4.4.4

!!!

Success rate is 100 percent (3/3), round-trip min/avg/max = 56/80/96 ms

Type escape sequence to abort.

Sending 3, 100-byte ICMP Echos to 2.2.2.2, timeout is 2 seconds:

Packet sent with a source address of 4.4.4.4

!!!

Success rate is 100 percent (3/3), round-trip min/avg/max = 36/48/64 ms

Type escape sequence to abort.

Sending 3, 100-byte ICMP Echos to 3.3.3.3, timeout is 2 seconds:

Packet sent with a source address of 4.4.4.4

!!!

Success rate is 100 percent (3/3), round-trip min/avg/max = 72/82/96 ms

Type escape sequence to abort.

Sending 3, 100-byte ICMP Echos to 4.4.4.4, timeout is 2 seconds:

Packet sent with a source address of 4.4.4.4

!!!

Success rate is 100 percent (3/3), round-trip min/avg/max = 4/4/4 ms

Type escape sequence to abort.

Sending 3, 100-byte ICMP Echos to 5.5.5.5, timeout is 2 seconds:

Packet sent with a source address of 4.4.4.4

!!!

Success rate is 100 percent (3/3), round-trip min/avg/max = 68/109/136 ms

Type escape sequence to abort.

Sending 3, 100-byte ICMP Echos to 6.6.6.6, timeout is 2 seconds:

Packet sent with a source address of 4.4.4.4

!!!

Success rate is 100 percent (3/3), round-trip min/avg/max = 12/49/100 ms

R5(tcl)#foreach address {

+>(tcl)#1.1.1.1

+>(tcl)#2.2.2.2

+>(tcl)#3.3.3.3

+>(tcl)#4.4.4.4

+>(tcl)#5.5.5.5

+>(tcl)#6.6.6.6

+>(tcl)#} {ping $address source lo0 repeat 3}

Type escape sequence to abort.

Sending 3, 100-byte ICMP Echos to 1.1.1.1, timeout is 2 seconds:

Packet sent with a source address of 5.5.5.5

!!!

Success rate is 100 percent (3/3), round-trip min/avg/max = 96/102/112 ms

Type escape sequence to abort.

Sending 3, 100-byte ICMP Echos to 2.2.2.2, timeout is 2 seconds:

Packet sent with a source address of 5.5.5.5

!!!

Success rate is 100 percent (3/3), round-trip min/avg/max = 40/82/108 ms

Type escape sequence to abort.

Sending 3, 100-byte ICMP Echos to 3.3.3.3, timeout is 2 seconds:

Packet sent with a source address of 5.5.5.5

!!!

Success rate is 100 percent (3/3), round-trip min/avg/max = 40/52/68 ms

Type escape sequence to abort.

Sending 3, 100-byte ICMP Echos to 4.4.4.4, timeout is 2 seconds:

Packet sent with a source address of 5.5.5.5

!!!

Success rate is 100 percent (3/3), round-trip min/avg/max = 64/106/132 ms

Type escape sequence to abort.

Sending 3, 100-byte ICMP Echos to 5.5.5.5, timeout is 2 seconds:

Packet sent with a source address of 5.5.5.5

!!!

Success rate is 100 percent (3/3), round-trip min/avg/max = 4/4/4 ms

Type escape sequence to abort.

Sending 3, 100-byte ICMP Echos to 6.6.6.6, timeout is 2 seconds:

Packet sent with a source address of 5.5.5.5

!!!

Success rate is 100 percent (3/3), round-trip min/avg/max = 132/168/240 ms

R6(tcl)#foreach address {

+>(tcl)#1.1.1.1

+>(tcl)#2.2.2.2

+>(tcl)#3.3.3.3

+>(tcl)#4.4.4.4

+>(tcl)#5.5.5.5

+>(tcl)#6.6.6.6

+>(tcl)#} {ping $address source lo0 repeat 3}

Type escape sequence to abort.

Sending 3, 100-byte ICMP Echos to 1.1.1.1, timeout is 2 seconds:

Packet sent with a source address of 6.6.6.6

!!!

Success rate is 100 percent (3/3), round-trip min/avg/max = 76/101/128 ms

Type escape sequence to abort.

Sending 3, 100-byte ICMP Echos to 2.2.2.2, timeout is 2 seconds:

Packet sent with a source address of 6.6.6.6

!!!

Success rate is 100 percent (3/3), round-trip min/avg/max = 56/81/116 ms

Type escape sequence to abort.

Sending 3, 100-byte ICMP Echos to 3.3.3.3, timeout is 2 seconds:

Packet sent with a source address of 6.6.6.6

!!!

Success rate is 100 percent (3/3), round-trip min/avg/max = 100/129/156 ms

Type escape sequence to abort.

Sending 3, 100-byte ICMP Echos to 4.4.4.4, timeout is 2 seconds:

Packet sent with a source address of 6.6.6.6

!!!

Success rate is 100 percent (3/3), round-trip min/avg/max = 36/54/84 ms

Type escape sequence to abort.

Sending 3, 100-byte ICMP Echos to 5.5.5.5, timeout is 2 seconds:

Packet sent with a source address of 6.6.6.6

!!!

Success rate is 100 percent (3/3), round-trip min/avg/max = 80/133/168 ms

Type escape sequence to abort.

Sending 3, 100-byte ICMP Echos to 6.6.6.6, timeout is 2 seconds:

Packet sent with a source address of 6.6.6.6

!!!

Success rate is 100 percent (3/3), round-trip min/avg/max = 4/4/4 ms

HTH...
Deepak Arora
Evil CCIE

A Network Artist

Wednesday, August 8, 2012

BGP Next Hop Issues & How Do We Fix It Using Different Ways .... With Some Troubleshooting Along The Way (Not For Soft Heart People ;-p)

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