NETWORK NOTES : BGP

Showing posts with label BGP. Show all posts

Sunday, August 16, 2015

BGP Best Path MED

R6
router bgp 1.301
bgp asnotation dot
bgp log-neighbor-changes
network 66.6.6.6 mask 255.255.255.255
aggregate-address 69.0.0.0 255.224.0.0
redistribute connected route-map conn
neighbor 16.0.0.1 remote-as 101
neighbor 16.0.0.1 next-hop-self
neighbor 56.0.0.5 remote-as 101
neighbor 56.0.0.5 route-map MED out

R6#

ip prefix-list dotsix seq 5 permit 69.1.1.0/24
ip prefix-list dotsix seq 10 permit 69.2.1.0/24
!

route-map MED permit 10

match ip address prefix-list dotsix

set metric 100

route-map MED permit 20

R4 MED is Non-Transitive attribute

* i 69.0.0.0/11 28.0.0.2 0 100 0 101 1.301 i

*> 3.3.3.3 0 101 1.301 i

* i 69.3.1.0/24 28.0.0.2 0 100 0 101 1.301 ?

*> 3.3.3.3 0 101 1.301 ?

* i 69.4.1.0/24 28.0.0.2 0 100 0 101 1.301 ?

*> 3.3.3.3 0 101 1.301 ?

Saturday, August 15, 2015

BGP - Best path origin

R2 Before

*>i 39.1.4.0/24 3.3.3.3 0 100 0 ?
* i 40.1.1.0/24 3.3.3.3 0 100 0 201 i
*> 28.0.0.8 0 201 i
* i 40.1.2.0/24 3.3.3.3 0 100 0 201 i
*> 28.0.0.8 0 201 i
* i 40.1.3.0/24 3.3.3.3 0 100 0 201 i
*> 28.0.0.8 0 201 i
* i 40.1.4.0/24 3.3.3.3 0 100 0 201 i
*> 28.0.0.8 0 201 i

R1- Before

*>i 40.1.1.0/24 3.3.3.3 0 100 0 201 i

* i 2.2.2.2 0 100 0 201 i

*>i 40.1.2.0/24 3.3.3.3 0 100 0 201 i

* i 2.2.2.2 0 100 0 201 i

*>i 40.1.3.0/24 3.3.3.3 0 100 0 201 i

* i 2.2.2.2 0 100 0 201 i

*>i 40.1.4.0/24 3.3.3.3 0 100 0 201 i

* i 2.2.2.2 0 100 0 201 i

*>i 44.4.4.4/32 3.3.3.3 0 100 0 201 i

* i 2.2.2.2 0 100 0 201 i

router bgp 101

bgp asnotation dot

bgp log-neighbor-changes

network 33.3.3.3 mask 255.255.255.255

neighbor 4.4.4.4 update-source Loopback0

neighbor 4.4.4.4 send-community

neighbor 4.4.4.4 route-map org in

ip prefix-list dottwo seq 5 permit 40.1.2.0/24

route-map org permit 10

match ip address prefix-list dottwo

set origin incomplete

route-map org permit 20

*> 40.1.1.0/24 4.4.4.4 0 0 201 i

* 40.1.2.0/24 4.4.4.4 0 0 201 ? { origin code changed to incomplete}

*>i 2.2.2.2 0 100 0 201 i

*> 40.1.3.0/24 4.4.4.4 0 0 201 i

*> 40.1.4.0/24 4.4.4.4 0 0 201 i

R1- After

*>i 40.1.1.0/24 3.3.3.3 0 100 0 201 i

* i 2.2.2.2 0 100 0 201 i

*>i 40.1.2.0/24 2.2.2.2 0 100 0 201 i { from R2 only}

*>i 40.1.3.0/24 3.3.3.3 0 100 0 201 i

* i 2.2.2.2 0 100 0 201 i

*>i 40.1.4.0/24 3.3.3.3 0 100 0 201 i

* i 2.2.2.2 0 100 0 201 i

*>i 44.4.4.4/32 3.3.3.3 0 100 0 201 i

* i 2.2.2.2 0 100 0 201 i

*> 40.1.1.0/24 28.0.0.8 0 201 i

* i 3.3.3.3 0 100 0 201 i

*> 40.1.2.0/24 28.0.0.8 0 201 i { No prefix from R3}

*> 40.1.3.0/24 28.0.0.8 0 201 i

* i 3.3.3.3 0 100 0 201 i

*> 40.1.4.0/24 28.0.0.8 0 201 i

* i 3.3.3.3 0 100 0 201 i

BGP Best Path - AS path

R1

* i 40.1.1.0/24 2.2.2.2 0 100 0 201 i
*>i 3.3.3.3 0 100 0 201 i
* i 40.1.2.0/24 2.2.2.2 0 100 0 201 i
*>i 3.3.3.3 0 100 0 201 i
* i 40.1.3.0/24 2.2.2.2 0 100 0 201 i
*>i 3.3.3.3 0 100 0 201 i
* i 40.1.4.0/24 2.2.2.2 0 100 0 201 i
*>i 3.3.3.3 0 100 0 201 i
* i 44.4.4.4/32 2.2.2.2 0 100 0 201 i
*>i 3.3.3.3 0 100 0 201 i

R2

* i 40.1.1.0/24 3.3.3.3 0 100 0 201 i
*> 28.0.0.8 0 201 i
* i 40.1.2.0/24 3.3.3.3 0 100 0 201 i
*> 28.0.0.8 0 201 i
* i 40.1.3.0/24 3.3.3.3 0 100 0 201 i
*> 28.0.0.8 0 201 i

*>i 40.1.1.0/24 28.0.0.8 0 100 0 201 i

* i 3.3.3.3 0 100 0 201 i

*>i 40.1.2.0/24 28.0.0.8 0 100 0 201 i

* i 3.3.3.3 0 100 0 201 i

*>i 40.1.3.0/24 28.0.0.8 0 100 0 201 i

* i 3.3.3.3 0 100 0 201 i

*>i 40.1.4.0/24 28.0.0.8 0 100 0 201 i

ip prefix-list dot seq 5 permit 40.1.2.0/24

ip prefix-list dot seq 10 permit 40.1.1.0/24

route-map ASPATH permit 10

match ip address prefix-list dot

set as-path prepend 201 201 201

route-map ASPATH permit 30

R8(config)#router bgp 201

R8(config-router)#neighbor 28.0.0.2 route-map ASPATH out

after applying the configuration

*>i 40.1.1.0/24 3.3.3.3 0 100 0 201 i

* 28.0.0.8 0 201 201 201 201 i

*>i 40.1.2.0/24 3.3.3.3 0 100 0 201 i

* 28.0.0.8 0 201 201 201 201 i

* i 40.1.3.0/24 3.3.3.3 0 100 0 201 i

*> 28.0.0.8 0 201 i

* i 40.1.4.0/24 3.3.3.3 0 100 0 201 i

*>i 40.1.1.0/24 3.3.3.3 0 100 0 201 i

*>i 40.1.2.0/24 3.3.3.3 0 100 0 201 i

* i 40.1.3.0/24 2.2.2.2 0 100 0 201 i

*>i 3.3.3.3 0 100 0 201 i

* i 40.1.4.0/24 2.2.2.2 0 100 0 201 i

*>i 3.3.3.3 0 100 0 201 i

*>i 40.1.1.0/24 3.3.3.3 0 100 0 201 i

*>i 40.1.2.0/24 3.3.3.3 0 100 0 201 i

*>i 40.1.3.0/24 28.0.0.8 0 100 0 201 i

* i 3.3.3.3 0 100 0 201 i

*>i 40.1.4.0/24 28.0.0.8 0 100 0 201 i

* i 3.3.3.3 0 100 0 201 i

Case-1 ...if Local-pref for 40.1.1.0/24 is increased then.......

R2:-

R2#sh run | sec bgp
router bgp 101
bgp log-neighbor-changes
neighbor 28.0.0.8 remote-as 201
neighbor 28.0.0.8 route-map localp in

ip prefix-list dotone seq 5 permit 40.1.1.0/24

route-map localp permit 10

match ip address prefix-list dotone

set local-preference 200

route-map localp permit 20

!

Network Next Hop Metric LocPrf Weight Path

*> 40.1.1.0/24 28.0.0.8 200 0 201 201 201 201 i
{ preferred over R3 even As-path is long}
*>i 40.1.2.0/24 3.3.3.3 0 100 0 201 i
* 28.0.0.8 0 201 201 201 201 i
* i 40.1.3.0/24 3.3.3.3 0 100 0 201 i
*> 28.0.0.8 0 201 i
* i 40.1.4.0/24 3.3.3.3 0 100 0 201 i
*> 28.0.0.8 0 201 i
--More--

R1

*>i 40.1.1.0/24 2.2.2.2 0 200 0 201 201 201 201 i
*>i 40.1.2.0/24 3.3.3.3 0 100 0 201 i
*>i 40.1.3.0/24 3.3.3.3 0 100 0 201 i
* i 2.2.2.2 0 100 0 201 i
*>i 40.1.4.0/24 3.3.3.3 0 100 0 201 i
* i 2.2.2.2 0 100 0 201 i

*> 40.1.1.0/24 1.1.1.1 0 101 201 201 201 201 i

* 5.5.5.5 0 101 201 201 201 201 i

*> 40.1.2.0/24 1.1.1.1 0 101 201 i

* 5.5.5.5 0 101 201 i

* 40.1.3.0/24 1.1.1.1 0 101 201 i

AS-PATH is well known mandatory attribute.

Case 3- if we want to ignore AS-PATH attribute in best selection

R2(config)#router bgp 101

R2(config-router)#bgp bestpath as-path ignore

{ This command is is hidden command in cisco IOS , but it is accepted}

Network Next Hop Metric LocPrf Weight Path

*> 40.1.1.0/24 28.0.0.8 200 0 201 201 201 201 i
* i 40.1.2.0/24 3.3.3.3 0 100 0 201 i
*> 28.0.0.8 0 201 201 201 201 i
* i 40.1.3.0/24 3.3.3.3 0 100 0 201 i
*> 28.0.0.8 0 201 i
* i 40.1.4.0/24 3.3.3.3 0 100 0 201 i
*> 28.0.0.8 0 201 i
* i 44.4.4.4/32 3.3.3.3 0 100 0 201 i

R1

*>i 40.1.1.0/24 3.3.3.3 0 100 0 201 i
* i 2.2.2.2 0 100 0 201 201 201 201 i
*>i 40.1.2.0/24 3.3.3.3 0 100 0 201 i
* i 2.2.2.2 0 100 0 201 201 201 201 i
*>i 40.1.3.0/24 3.3.3.3 0 100 0 201 i
* i 2.2.2.2 0 100 0 201 i
*>i 40.1.4.0/24 3.3.3.3 0 100 0 201 i
* i 2.2.2.2 0 100 0 201 i
*>i 44.4.4.4/32 3.3.3.3 0 100 0 201 i
* i 2.2.2.2 0 100 0 201

*>i 40.1.1.0/24 3.3.3.3 0 100 0 201 i
* i 28.0.0.8 0 100 0 201 201 201 201 i
*>i 40.1.2.0/24 3.3.3.3 0 100 0 201 i
* i 28.0.0.8 0 100 0 201 201 201 201 i
* i 40.1.3.0/24 3.3.3.3 0 100 0 201 i
*>i 28.0.0.8 0 100 0 201 i
* i 40.1.4.0/24 3.3.3.3 0 100 0 201 i
*>i 28.0.0.8 0 100 0 201 i
* i 44.4.4.4/32 3.3.3.3 0 100 0 201 i

Thursday, August 13, 2015

BGP :- Route filtering

Filtering with Prefix-list

R4

ip prefix-list Filter seq 5 deny 40.1.2.0/24
ip prefix-list Filter seq 10 permit 0.0.0.0/0 le 32

!

router bgp 201

bgp log-neighbor-changes

network 40.1.1.0 mask 255.255.255.0

network 40.1.2.0 mask 255.255.255.0

network 40.1.3.0 mask 255.255.255.0

network 40.1.4.0 mask 255.255.255.0

neighbor 3.3.3.3 prefix-list Filter out

R3

R3#sh ip bgp | in 40|44
*> 40.1.1.0/24 4.4.4.4 0 0 201 i
* i 40.1.2.0/24 28.0.0.8 0 100 0 201 i
*> 40.1.3.0/24 4.4.4.4 0 0 201 i
*> 40.1.4.0/24 4.4.4.4 0 0 201 i

*> 44.4.4.4/32 4.4.4.4 0 0 201 i

Standard Access-Lists

R4

router bgp 201

bgp log-neighbor-changes

neighbor 3.3.3.3 update-source Loopback0

neighbor 3.3.3.3 distribute-list 20 out

access-list 20 deny 40.1.2.0 0.0.0.255

access-list 20 permit any

R3#sh ip bgp | in 40|44
* 40.1.1.0/24 4.4.4.4 0 0 201 i
* i 40.1.2.0/24 28.0.0.8 0 100 0 201 i
* 40.1.3.0/24 4.4.4.4 0 0 201 i
* 40.1.4.0/24 4.4.4.4 0 0 201 i
* 44.4.4.4/32 4.4.4.4 0 0 201 i

R3#

Extended Access-Lists

R4

access-list 101 deny ip host 40.1.2.0 host 255.255.255.0

access-list 101 permit ip any any

router bgp 201

bgp log-neighbor-changes

network 40.1.1.0 mask 255.255.255.0

network 40.1.2.0 mask 255.255.255.0

network 40.1.3.0 mask 255.255.255.0

network 40.1.4.0 mask 255.255.255.0

network 44.4.4.4 mask 255.255.255.255

neighbor 3.3.3.3 remote-as 101

neighbor 3.3.3.3 ebgp-multihop 255

neighbor 3.3.3.3 update-source Loopback0

neighbor 3.3.3.3 distribute-list 101 out

R3

R3#sh ip bgp | in 40|44
* 40.1.1.0/24 4.4.4.4 0 0 201 i
* i 40.1.2.0/24 28.0.0.8 0 100 0 201 i
* 40.1.3.0/24 4.4.4.4 0 0 201 i
* 40.1.4.0/24 4.4.4.4 0 0 201 i
* 44.4.4.4/32 4.4.4.4 0 0 201 i

R3#

Path Filtering with BGP Regular Expressions

Objective- 1:- Filter out prefixes originated from 1.301 in R4

R4

R4 Before Applying Filter list

R4#sh ip bgp regexp _1.301$
BGP table version is 17, local router ID is 44.4.4.4

Network Next Hop Metric LocPrf Weight Path
*> 69.0.0.0/11 3.3.3.3 0 101 1.301 i
R4#

Now As-Path filter list

ip as-path access-list 1 deny _1.301$ Prefix originated from 1.301

ip as-path access-list 1 permit .*

route-map ASPATH permit 10

match as-path 1

R4(config)#router bgp 201

R4(config-router)# nei 3.3.3.3 route-map ASPATH in

Objective- 2:- Filter out prefixes originated from 201 in R3

R3

Before Applying rules,

R3#sh ip bgp
BGP table version is 141, local router ID is 39.1.4.1

Network Next Hop Metric LocPrf Weight Path
* i 8.8.8.8/32 28.0.0.8 0 100 0 201 i
*> 4.4.4.4 0 201 i
*> 33.3.3.3/32 0.0.0.0 0 32768 i
*> 39.1.0.0/19 0.0.0.0 32768 i
*> 39.1.1.0/24 0.0.0.0 0 32768 ?
*> 39.1.2.0/24 0.0.0.0 0 32768 ?
*> 39.1.3.0/24 0.0.0.0 0 32768 ?
*> 39.1.4.0/24 0.0.0.0 0 32768 ?
* i 40.1.1.0/24 28.0.0.8 0 100 0 201 i
*> 4.4.4.4 0 0 201 i
* i 40.1.2.0/24 28.0.0.8 0 100 0 201 i
*> 4.4.4.4 0 0 201 i
* i 40.1.3.0/24 28.0.0.8 0 100 0 201 i
*> 4.4.4.4 0 0 201 i
* i 40.1.4.0/24 28.0.0.8 0 100 0 201 i
Network Next Hop Metric LocPrf Weight Path
*> 4.4.4.4 0 0 201 i
* i 44.4.4.4/32 28.0.0.8 0 100 0 201 i
*> 4.4.4.4 0 0 201 i
*>i 55.5.5.5/32 5.5.5.5 0 100 0 i
*>i 69.0.0.0/11 1.1.1.1 0 100 0 1.301 i
*>i 69.1.1.0/24 1.1.1.1 0 100 0 ?
*>i 111.111.111.111/32
1.1.1.1 0 100 0 i

R3

ip as-path access-list 1 deny ^201_

ip as-path access-list 1 permit .*

route-map ASPATH permit 10

match as-path 1

router bgp 101

neighbor 4.4.4.4 ebgp-multihop 255
neighbor 4.4.4.4 update-source Loopback0
neighbor 4.4.4.4 send-community
neighbor 4.4.4.4 route-map ASPATH inneighbor 4.4.4.4 ebgp-multihop 255
neighbor 4.4.4.4 update-source Loopback0
neighbor 4.4.4.4 send-community
neighbor 4.4.4.4 route-map ASPATH in

*******************************
All prefix from As 201 from nei 4.4.4.4 are not in BGP table

R3#sh ip bgp regexp ^201_
BGP table version is 11, local router ID is 39.1.4.1
Network Next Hop Metric LocPrf Weight Path
* i 8.8.8.8/32 28.0.0.8 0 100 0 201 i
* i 40.1.1.0/24 28.0.0.8 0 100 0 201 i
* i 40.1.2.0/24 28.0.0.8 0 100 0 201 i
* i 40.1.3.0/24 28.0.0.8 0 100 0 201 i
* i 40.1.4.0/24 28.0.0.8 0 100 0 201 i
* i 44.4.4.4/32 28.0.0.8 0 100 0 201 i

R3

router bgp 101

bgp asnotation dot
bgp log-neighbor-changes
neighbor 2.2.2.2 remote-as 101
neighbor 2.2.2.2 update-source Loopback0
neighbor 2.2.2.2 route-map ASPATH in

No prefix from AS 201

Filtering With Maximum Prefix

R6

Before applying the Rule R6 have prefix from R1 and R5

R6

R6(config-router)# nei 1.1.1.1 maximum-prefix 9

%BGP-4-MAXPFX: Number of prefixes received from 1.1.1.1 (afi 0) reaches 9, max 9

R6(config-router)#^Z

R6(config-router)# nei 1.1.1.1 maximum-prefix 8
%BGP-3-MAXPFXEXCEED: Number of prefixes received from 1.1.1.1 (afi 0): 9 exceeds limit 8
R6(config-router)#^Z
R6#
%BGP-5-ADJCHANGE: neighbor 1.1.1.1 Down Peer over prefix limit

Sh ip bgp

Network Next Hop Metric LocPrf Weight Path

*> 11.11.11.11/32 5.5.5.5 0 101 i

*> 33.3.3.3/32 5.5.5.5 0 101 i

*> 39.1.0.0/19 5.5.5.5 0 101 i

*> 39.1.1.0/24 5.5.5.5 0 101 ?

*> 39.1.2.0/24 5.5.5.5 0 101 ?

*> 39.1.3.0/24 5.5.5.5 0 101 ?

*> 39.1.4.0/24 5.5.5.5 0 101 ?

*> 55.5.5.5/32 5.5.5.5 0 0 101 i

By default it will drop the connection

R6(config-router)# nei 1.1.1.1 maximum-prefix 20 50

NO warning message

R6(config-router)# nei 1.1.1.1 maximum-prefix 20 40

R6(config-router)#

%BGP-4-MAXPFX: Number of prefixes received from 1.1.1.1 (afi 0) reaches 9, max 20

at 40% of max , it will show a message,

R6(config-router)# nei 1.1.1.1 maximum-prefix 8 warning-only

R6(config-router)#

%BGP-3-MAXPFXEXCEED: Number of prefixes received from 1.1.1.1 (afi 0): 9 exceeds limit 8

Now it is showing only warning no neighborship down.

with Community

Community

Wednesday, August 12, 2015

BGP - Conditional Route Advertisement

Case -1 ADVRTISE-MAP with EXIST-MAP

R1

router bgp 101
bgp asnotation dot
bgp log-neighbor-changes
network 11.11.11.11 mask 255.255.255.255
neighbor 3.3.3.3 remote-as 101
neighbor 3.3.3.3 update-source Loopback0
neighbor 3.3.3.3 route-reflector-client
neighbor 3.3.3.3 next-hop-self
neighbor 3.3.3.3 advertise-map ADVERTISE exist-map NON

{ if 69.0.0.0/11 is present in BGP table , we will advertise 11.11.11.11/32 to neighbor, otherwise will drop}

int lo10
ip add 11.11.11.11 255.255.255.255

ip prefix-list ADD seq 5 permit 11.11.11.11/32
!
ip prefix-list NON seq 5 permit 69.0.0.0/11
!
route-map ADVERTISE permit 10
match ip address prefix-list ADD
!
route-map NON permit 10
match ip address prefix-list NON

R6

router bgp 1.301
bgp asnotation dot
bgp log-neighbor-changes
network 66.6.6.6 mask 255.255.255.255
aggregate-address 69.0.0.0 255.224.0.0 {Advertising summary route }

we can see status is advertise as 69.0.0.0/11 is in bgp table.

R1#sh ip bgp nei 3.3.3.3 | in Condition-map

Condition-map NON, Advertise-map ADVERTISE, status: Advertise

R3#sh ip bgp | in 11

*>i 11.11.11.11/32 1.1.1.1 0 100 0 i

*>i 69.0.0.0/11 1.1.1.1 0 100 0 1.301 i

*>i 111.111.111.111/32

Now we are removing aggregate address from R6

R6(config)#router bgp 1.301

R6(config-router)#no aggregate-address 69.0.0.0 255.224.0.0

R1#sh ip bgp | in 69

* i 69.1.1.0/24 6.6.6.6 0 100 0 1.301 ?

* i 69.2.1.0/24 6.6.6.6 0 100 0 1.301 ?

* i 69.3.1.0/24 6.6.6.6 0 100 0 1.301 ?

* i 69.4.1.0/24 6.6.6.6 0 100 0 1.301 ?

R1#

We can see now it is withdraw status as 69.0.0.0/11 is not present in bgp table.

R1#sh ip bgp nei 3.3.3.3 | in Condition-map

Condition-map NON, Advertise-map ADVERTISE, status: Withdraw

R3#sh ip bgp | in 11

*>i 111.111.111.111/32 No BGP prefix for 69.0.0.0/11 and 11.11.11.11/32

Case 2-ADVRTISE-MAP with NON-EXIST-MAP

router bgp 101

neighbor 3.3.3.3 remote-as 101

neighbor 3.3.3.3 update-source Loopback0

neighbor 3.3.3.3 route-reflector-client

neighbor 3.3.3.3 next-hop-self

neighbor 3.3.3.3 advertise-map ADVERTISE non-exist-map NON

{ if 69.0.0.0/11 is not present in BGP table , we will advertise 11.11.11.11/32 to neighbor, otherwise will drop}

R1
we can see status is advertise as 69.0.0.0/11 is not in bgp table.

R1#sh ip bgp nei 3.3.3.3 | in Condition-map

Condition-map NON, Advertise-map ADVERTISE, status: Advertise

R1#

As we don't have 69.0.0.0/11 in bgp table status is advertise

R1#sh ip bgp | in 69

* i 69.1.1.0/24 6.6.6.6 0 100 0 1.301 ?

* i 69.2.1.0/24 6.6.6.6 0 100 0 1.301 ?

* i 69.3.1.0/24 6.6.6.6 0 100 0 1.301 ?

* i 69.4.1.0/24 6.6.6.6 0 100 0 1.301 ?

R1#

R3#sh ip bgp | in 11

*>i 11.11.11.11/32 1.1.1.1 0 100 0 i

*>i 111.111.111.111/32

Now 69.0.0.0/11 will be advertise in R6 so it would be in R1 bgp table

R6

R6(config-router)#router bgp 1.301

R6(config-router)# aggregate-address 69.0.0.0 255.224.0.0

R1#sh ip bgp | in 69

* i 69.0.0.0/11 6.6.6.6 0 100 0 1.301 i

R1#sh ip bgp nei 3.3.3.3 | in Condition-map

Condition-map NON, Advertise-map ADVERTISE, status: Withdraw

R3

We can see no 11.11.11.11/32 in bgp table

R3#sh ip bgp | in 11

*>i 69.0.0.0/11 1.1.1.1 0 100 0 1.301 i

*>i 111.111.111.111/32

R3#

BGP- Route Injection

R1

router bgp 101
bgp asnotation dot
bgp log-neighbor-changes
bgp inject-map ORIGIN exist-map LEARNED

ip prefix-list ORIG seq 5 permit 69.1.1.0/24

route-map ORIGIN permit 10

set ip address prefix-list ORIG

ip prefix-list ROUTE seq 5 permit 69.0.0.0/11

ip prefix-list ROUTE-SOURCE seq 5 permit 6.6.6.6/32

route-map LEARNED permit 10

match ip address prefix-list ROUTE

match ip route-source prefix-list ROUTE-SOURCE

R1#sh ip bgp | sec 69

* i 69.0.0.0/11 6.6.6.6 0 100 0 1.301 i

*> 69.1.1.0/24 6.6.6.6 0 ?

R1#

R1#sh ip bgp injected-paths

BGP table version is 16, local router ID is 11.11.11.11

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

*> 69.1.1.0/24 6.6.6.6 0 ?

R1#

R3#sh ip bgp | in 69

*>i 69.0.0.0/11 1.1.1.1 0 100 0 1.301 i

*>i 69.1.1.0/24 1.1.1.1 0 100 0 ?

R3#

Monday, August 10, 2015

BGP- Community -2

R6
route-map commun permit 10
match ip address 1
set community no-export
!
route-map commun permit 20
match ip address 4
set community no-advertise
!
route-map commun permit 30
match ip address 5
set community 200:100
!
route-map commun permit 59
set community none
!
!
access-list 1 permit 69.1.0.0 0.0.255.255
access-list 4 permit 69.3.0.0 0.0.255.255
access-list 5 permit 69.2.0.0 0.0.255.255

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

router bgp 1.301
bgp asnotation dot
bgp log-neighbor-changes
network 66.6.6.6 mask 255.255.255.255
redistribute connected route-map permit
neighbor 1.1.1.1 remote-as 101
neighbor 1.1.1.1 ebgp-multihop 2
neighbor 1.1.1.1 update-source Loopback0
neighbor 1.1.1.1 send-community
neighbor 1.1.1.1 route-map commun out

----------------------------------------
R1

'R1#sh ip bgp | in 69
*> 69.1.0.0/16      6.6.6.6                  0             0 1.301 ?
*> 69.2.0.0/16      6.6.6.6                  0             0 1.301 ?
*> 69.3.0.0/16      6.6.6.6                  0             0 1.301 ?
*> 69.4.0.0/16      6.6.6.6                  0             0 1.301 ?
R1#
R1(config)#ip bgp-community new-format

R1#sh ip bgp 69.1.1.1 | in Community
      Community: no-export
R1#sh ip bgp 69.2.1.1 | in Community
      Community: 200:100
R1#sh ip bgp 69.3.1.1 | in Community
      Community: no-advertise
R1#sh ip bgp 69.4.1.1 | in Community
R1#
----------------------------------------

router bgp 101
neighbor 3.3.3.3 route-reflector-client
neighbor 3.3.3.3 next-hop-self
neighbor 3.3.3.3 send-community

R3
R3#sh ip bgp | in 69
*>i 69.1.0.0/16      1.1.1.1                  0    100      0 1.301 ?
*>i 69.2.0.0/16      1.1.1.1                  0    100      0 1.301 ?
*>i 69.4.0.0/16      1.1.1.1                  0    100      0 1.301 ?
R3#
R3#sh ip bgp 69.1.0.0 | in Community
      Community: no-export
R3#sh ip bgp 69.2.0.0 | in Community
      Community: 200:100
R3#sh ip bgp 69.4.0.0 | in Community
R4

R4#sh ip bgp | in 69
*> 69.2.0.0/16      3.3.3.3                                0 101 65837 ?
*> 69.4.0.0/16      3.3.3.3                                0 101 65837 ?
R4#

R3#sh ip bgp 69.2.0.0 | in Community
      Community: 200:100

Case 2:-

Now we want to advertise 69.1.0.0 to R4 and change community of 69.2.0.0 from 200:100 to 300:400

R3

****To match community , Community list is must**
ip community-list 10 permit 200:100

access-list 10 permit 69.1.0.0 0.0.255.255

route-map Commchange permit 10
match community 10
set community 300:400

!
route-map Commchange permit 20
match ip address 10
set community none
!
route-map Commchange permit 30
router bgp 101
neighbor 1.1.1.1 route-map Commchange in

R3#sh ip bgp | in 69
*>i 69.1.0.0/16      1.1.1.1                  0    100      0 1.301 ?
*>i 69.2.0.0/16      1.1.1.1                  0    100      0 1.301 ?
*>i 69.4.0.0/16      1.1.1.1                  0    100      0 1.301 ?
R3#
R3#sh ip bgp 69.1.1.0 | in Community
    No community attached now with 69.1.0.0
R3#sh ip bgp 69.2.1.0 | in Community
      Community: 300:400
R3#sh ip bgp 69.4.1.0 | in Community
R3#

R4

We can see 69.1.0.0 in R4

R4#sh ip bgp | in 69
*> 69.1.0.0/16      3.3.3.3                                0 101 65837 ?
*> 69.2.0.0/16      3.3.3.3                                0 101 65837 ?
*> 69.4.0.0/16      3.3.3.3                                0 101 65837 ?
R4#
R4#sh ip bgp 69.1.0.0
BGP routing table entry for 69.1.0.0/16, version 39
Paths: (1 available, best #1, table default)
Not advertised to any peer
Refresh Epoch 1
101 65837
    3.3.3.3 from 3.3.3.3 (39.1.4.1)
      Origin incomplete, localpref 100, valid, external, best
      rx pathid: 0, tx pathid: 0x0

R4#sh ip bgp 69.2.0.0
BGP routing table entry for 69.2.0.0/16, version 41
Paths: (1 available, best #1, table default)
Not advertised to any peer
Refresh Epoch 1
101 65837
    3.3.3.3 from 3.3.3.3 (39.1.4.1)
      Origin incomplete, localpref 100, valid, external, best
      Community: 300:400
      rx pathid: 0, tx pathid: 0x0