NETWORK NOTES

Wednesday, August 12, 2015

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

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

Wednesday, August 5, 2015

Route- Summarization -Part 2

With Community attribute

Monday, August 3, 2015

BGP - Summerization

Method 1

Method 2

Summary only

R6#sh ip bgp 69.1.1.1

BGP routing table entry for 69.1.1.0/24, version 89

Paths: (1 available, best #1, table default, Advertisements suppressed by an aggregate.)

Not advertised to any peer

R6#sh ip bgp 69.0.0.0
BGP routing table entry for 69.0.0.0/11, version 40
Paths: (1 available, best #1, table default)
Advertised to update-groups:
3
Refresh Epoch 1
Local, (aggregated by 1.301 69.4.1.1)
0.0.0.0 from 0.0.0.0 (69.4.1.1)
Origin IGP, localpref 100, weight 32768, valid, aggregated, local, atomic-aggregate, best
rx pathid: 0, tx pathid: 0x0
R6#

R4#sh ip bgp 69.0.0.0

BGP routing table entry for 69.0.0.0/11, version 694

Paths: (1 available, best #1, table default)

Not advertised to any peer

Refresh Epoch 1

101 1.301, (aggregated by 1.301 69.4.1.1)

3.3.3.3 from 3.3.3.3 (39.1.4.1)

Origin IGP, localpref 100, valid, external, atomic-aggregate, best

rx pathid: 0, tx pathid: 0x0

*> 69.0.0.0/11 3.3.3.3 0 101 1.301 i

R4#sh ip bgp 69.0.0.0

BGP routing table entry for 69.0.0.0/11, version 726

Paths: (1 available, best #1, table default)

Not advertised to any peer

Refresh Epoch 1

101, (aggregated by 101 39.1.4.1)

3.3.3.3 from 3.3.3.3 (39.1.4.1)

Origin IGP, metric 0, localpref 100, valid, external, atomic-aggregate, best

rx pathid: 0, tx pathid: 0x0

R4#

continue
wi

Sunday, August 2, 2015

BGP Best Path Selection - Weight

Saturday, August 1, 2015

BGP - AutoSummary

Case 1...

Config in R3

router bgp 101

bgp log-neighbor-changes

network 33.0.0.0

neighbor 1.1.1.1 remote-as 101

neighbor 1.1.1.1 update-source Loopback0

..........

R3#

No auto-summary is configured so BGP will require exact Network mask which is present in the routing table.

So in this case 33.0.0.0/8 will not be advertise in the BGP update.

R1#sh ip bgp

BGP table version is 21, local router ID is 1.1.1.1

!!!!!!!

Network Next Hop Metric LocPrf Weight Path

* i 4.4.4.4/32 4.4.4.4 0 100 0 201 i

* i 44.4.4.4/32 4.4.4.4 0 100 0 201 i

*>i 55.5.5.5/32 5.5.5.5 0 100 0 i

* i 66.6.6.6/32 6.6.6.6 0 100 0 1.301 i

*> 6.6.6.6 0 0 1.301 i

R1#

Now Auto-summary will be configured.

Config in R3....

R3#sh run | sec bgp

router bgp 101

bgp log-neighbor-changes

network 33.0.0.0

neighbor 1.1.1.1 remote-as 101

neighbor 1.1.1.1 update-source Loopback0

............

auto-summary

Network 33.0.0.0/8 classfull advertised . Auto-summary will do

this .

see in R1

R1#sh ip bgp

Network Next Hop Metric LocPrf Weight Path

* i 4.4.4.4/32 4.4.4.4 0 100 0 201 i

*>i 33.0.0.0 3.3.3.3 0 100 0 i Classful network for 33.0.0.0/8 will be advertised.

* i 44.4.4.4/32 4.4.4.4 0 100 0 201 i

*>i 55.5.5.5/32 5.5.5.5 0 100 0 i

*> 66.6.6.6/32 6.6.6.6 0 0 1.301 i

* i 6.6.6.6 0 100 0 1.301 i

R1#

Case 2

if any individual network is advertised , in Auto-summary case it will be advertised too.

R3(config)#router bgp 101

R3(config-router)#net 39.1.1.0 mask 255.255.255.0

in R1

Sh ip bgp

*>i 39.0.0.0 3.3.3.3 0 100 0 ?

*>i 39.1.1.0/24 3.3.3.3 0 100 0 i