Solved: Trace BGP peering interface

anitachoi3 · ‎07-02-2010

Hi expert,

I would like to announce "ip address 10" to ISP B when the interface EF0/0 is down. Grateful if you could advise how to do it. The trace commands are in the configuration file as below.

Thank you

--- configuration ------

track 1 interface FE0/0 line-protocol

! track 2 interface serial1/1 line-protocol

! track 3 interface serial1/2 line-protocol

track 100 list threshold percentage

object 1

! object 2

! object 3

! object 4

threshold percentage up 80

!

interface FE 0/0

description IPS A (AS1)

ip address 10.10.10.2 255.255.255.0

!

interface FE 0/1

description IPS B (AS3)

ip address 10.10.20.2 255.255.255.0

!

router bgp 10

bgp log-neighbor-changes

network 192.168.16.0 255.255.240.0

neighbor 10.10.10.1 remote-as 1

neighbor 10.10.10.1 route-map ROUTES_TO_ISP_A out

!

neighbor 10.10.20.3 remote-as 3

neighbor 10.10.20.3 route-map ROUTES_TO_ISP_B out

neighbor 10.10.20.3 advertise-map ADVERTISE non-exist-map NON-EXIST

!--- Advertises the routes matched in the route-map ADVERTISE (192.168.16, 192.168.24 and 192.168.28)

!--- only if the routes matched in route-map NON-EXIST (192.168.50.0/24)

!--- do not exist in the BGP table.

!

ip route 192.168.16.0 255.255.240.0 Null0

!

! Route Condition

access-list 65 permit 192.168.50.0 0.0.0.255

!

! announce routes to ISP A only

access-list 10 permit 192.168.16.0 0.0.7.255

access-list 10 permit 192.168.24.0 0.0.3.255

access-list 10 permit 192.168.28.0 0.0.1.255

!

! announce routes to ISP B only

access-list 15 permit 192.168.30.0 0.0.1.255

!

ip as-path access-list 400 deny .*

!

route-map NON-EXIST permit 10

match ip address 65

!

route-map ADVERTISE permit 10

match ip address 10

!

route-map ROUTES_TO_ISP_A permit 10

match ip address 10

!

route-map ROUTES_TO_ISP_A permit 20

match as-path 400

!

route-map ROUTES_TO_ISP_B permit 10

match ip address 15

!

route-map ROUTES_TO_ISP_B permit 20

match as-path 400

!

---- end -----

Chetan Kumar Ress · ‎07-02-2010

Hi Anita

Try this one ........

interface FE 0/0

description ISP A (AS1)

ip address 10.10.10.2 255.255.255.0

!

interface FE 0/1

description ISP B (AS3)

ip address 10.10.20.2 255.255.255.0

router bgp 10

bgp log-neighbor-changes

neighbor 10.10.10.1 remote-as 1

neighbor 10.10.10.1 route-map ROUTES_TO_ISP_A out

!

neighbor 10.10.20.3 remote-as 3

neighbor 10.10.20.3 route-map ROUTES_TO_ISP_B out

neighbor 10.10.20.3 advertise-map ROUTES_TO_ISP_A non-exist-map NO_ROUTE

-----Advertise to ISP A -------

access-list 10 permit 192.168.16.0 0.0.7.255

access-list 10 permit 192.168.24.0 0.0.3.255

access-list 10 permit 192.168.28.0 0.0.1.255

-----Advertise to ISP B -------

access-list 15 permit 192.168.30.0 0.0.1.255

access-list 20 permit 10.10.10.0 0.0.0.255

route-map ROUTES_TO_ISP_A

match address 10

route-map ROUTES_TO_ISP_B

match address 15

route-map NO_ROUTE

match address 20

Regards

Chetan Kumar

View solution in original post

Mohamed Sobair · ‎07-02-2010

Hi,

Your configuration should look lik this:

interface FE 0/0

description IPS A (AS1)

ip address 10.10.10.2 255.255.255.0

!

interface FE 0/1

description IPS B (AS3)

ip address 10.10.20.2 255.255.255.0

!

router bgp 10

bgp log-neighbor-changes

network 192.168.16.0 255.255.240.0

network 10.10.20.0 mask 255.255.255.0

neighbor 10.10.10.1 remote-as 1

neighbor 10.10.10.1 route-map ROUTES_TO_ISP_A out

!

neighbor 10.10.20.3 remote-as 3

neighbor 10.10.20.3 route-map ROUTES_TO_ISP_B out

neighbor 10.10.20.3 advertise-map ADVERTISE non-exist-map NON-EXIST

ip prefix-list advertise permit 10.10.20.0/24

Note:

your route-map (ROUTES_TO_ISP_B) should include Network 10.10.2.0

ip perefix-list NON-EXIST permit 10.10.10.2/24

route-map ADVERTISE

match ip address prefix-list ADVERTISE

route-map NON-EXIST

match ip address prefix-list NON-EXIST

Note:

Your route-map (ROUTES_TO_ISP_B) should include Network 10.10.20.0/24 in another sequence number in order for this network not to be filtered when its being advertised to ISP-B by the route-map.

HTH

Mohamed

anitachoi3 · ‎07-02-2010

Dear Mohamed,

My preceding email may be vague. Following is the user requirements:

- 192.168.16.0/21, 192.168.24.0/22, 192.168.28/23 are down stream network behind AS 2. They will be announced to ISP A only

- 192.168.30.0/23 is down stream network behind AS 2. They will be announced to ISP B only

- If ISP A down, the routes 192.168.16.0/21, 192.168.24.0/22, 192.168.28/23 will be announced to ISP B. If ISP A is up again, the routes 192.168.16.0/21, 192.168.24.0/22, 192.168.28/23 will be withdrawn from ISP B and announced to ISP A.

I have revised the config for your comments

Thank you

------ config ------

interface FE 0/0

description ISP A (AS1)

ip address 10.10.10.2 255.255.255.0

!

interface FE 0/1

description ISP B (AS3)

ip address 10.10.20.2 255.255.255.0

!

router bgp 10

bgp log-neighbor-changes

network 192.168.16.0 mask 255.255.240.0

network 10.10.20.0 mask 255.255.255.0

neighbor 10.10.10.1 remote-as 1

neighbor 10.10.10.1 route-map ROUTES_TO_ISP_A out

!

neighbor 10.10.20.3 remote-as 3

neighbor 10.10.20.3 route-map ROUTES_TO_ISP_B out

neighbor 10.10.20.3 advertise-map ADVERTISE non-exist-map NON-EXIST

!--- Advertises the routes matched in the route-map ADVERTISE (192.168.16, 192.168.24 and 192.168.28)

!--- only if the routes matched in route-map NON-EXIST (10.10.10.0/24)

!--- do not exist in the BGP table.

!

ip route 192.168.16.0 255.255.240.0 Null0

!

! Route Condition

ip perefix-list NON-EXIST permit 10.10.10.0/24

! ~~ip prefix-list ADVERTISE permit 10.10.20.0/24~~

!

! announce routes to ISP A only

access-list 10 permit 192.168.16.0 0.0.7.255

access-list 10 permit 192.168.24.0 0.0.3.255

access-list 10 permit 192.168.28.0 0.0.1.255

!

access-list 20 permit 10.10.10.0 0.0.0.255

!

! announce routes to ISP B only

access-list 15 permit 192.168.30.0 0.0.1.255

!

access-list 25 permit 10.10.20.0 0.0.0.255

!

ip as-path access-list 400 deny .*

!

route-map ADVERTISE

! ~~match ip address prefix-list ADVERTISE~~

match ip address 10

!

route-map NON-EXIST

match ip address prefix-list NON-EXIST

!

route-map ROUTES_TO_ISP_A permit 10

match ip address 10 20

!

route-map ROUTES_TO_ISP_A permit 20

match as-path 400

!

route-map ROUTES_TO_ISP_B permit 10

match ip address 15 25

!

route-map ROUTES_TO_ISP_B permit 20

match as-path 400

!

---- end -----

Chetan Kumar Ress · ‎07-02-2010

Hi Anita

Try this one ........

interface FE 0/0

description ISP A (AS1)

ip address 10.10.10.2 255.255.255.0

!

interface FE 0/1

description ISP B (AS3)

ip address 10.10.20.2 255.255.255.0

router bgp 10

bgp log-neighbor-changes

neighbor 10.10.10.1 remote-as 1

neighbor 10.10.10.1 route-map ROUTES_TO_ISP_A out

!

neighbor 10.10.20.3 remote-as 3

neighbor 10.10.20.3 route-map ROUTES_TO_ISP_B out

neighbor 10.10.20.3 advertise-map ROUTES_TO_ISP_A non-exist-map NO_ROUTE

-----Advertise to ISP A -------

access-list 10 permit 192.168.16.0 0.0.7.255

access-list 10 permit 192.168.24.0 0.0.3.255

access-list 10 permit 192.168.28.0 0.0.1.255

-----Advertise to ISP B -------

access-list 15 permit 192.168.30.0 0.0.1.255

access-list 20 permit 10.10.10.0 0.0.0.255

route-map ROUTES_TO_ISP_A

match address 10

route-map ROUTES_TO_ISP_B

match address 15

route-map NO_ROUTE

match address 20

Regards

Chetan Kumar

anitachoi3 · ‎07-02-2010

Hi Chetan Kumar,

One more question, if the FE 0/0 is down, the route (direct connect) 10.10.10.0/24 will be withdrawn from the routing table. Is it correct?

rdgs

Chetan Kumar Ress · ‎07-06-2010

Hi Anita

Yes , If you physical interface goes down then you won't see the route in routing table.

Regards

Chetan Kumar