BGP help

[kartik.shah1]

hello,

i need some guidance regarding BGP.

i have taken public pool of /22. I have sub netted /22 pool in :  /24, /24, /24, /26, /26, /26, /27, /28, /28.

so if i advertise /22, will i able to ping or access any of devices with above sub netted network.

also guide regarding BGP configuration.

thankyou

[Support07]

Hi,

Maybe I didn't understand what do you want, but if you advertise your network/22 , your router have to know this network in his route table or it will be not advertise.

You could configure your BGP with "network X.X.X.X mask 255.255.252.0" and also "ip route X.X.X.X 255.255.252.0 null 0" with this you will advertise the /22 and you could reach the different subnet.

TkR07_9393

[kartik.shah1]

Hi,

thank you for support !!

can you explain use of route-map in/out command in BGP??

[aconticisco]

Hi,

route-maps can be used to filter/tag BGP network as traffic goes out (route-map NAME out) or comes in (route-map NAME in) on an interface. This can be used for example to create a preferred route in multi-homed networks or to limit the networks that are advertised out from an Autonomous System.

[kartik.shah1]

hi, 

thank you for support !!

i have 2 ISP. out of them i want to use ISP 1 as primary ie all traffic should go from ISP 1 and if ISP 1 fails then all traffic should go from ISP 2.

i have attached Nw diagram below.

here,

i have configured HSRP between 2 routers. with router 1 as higher priority than router 2.

i am new to BGP. i have configure external BGP between my router and ISP.

kindly guide internal BGP configuration between router 1 and router 2.

Regards,,

[aconticisco]

Assuming both routers reside in the same autonomous system I would:

On ROUTER 1 set a route-map that sets the local-preference with a higher value than the default of 100.

apply the route-map to the interface (inbound traffic from ISP1) of ROUTER 1.

ISP 1 routes will be preferred as they will have a higher local-preference.

[kartik.shah1]

hi, yes. both the routers are in same autonomous system. can you give the steps for configuration?? Also share configuration steps for internal BGP. Regards,,

[jarar_m01]

HI,

router bgp 45000
bgp log-neighbor-changes
neighbor 172.16.1.2 remote-as 45000
bgp default local-preference < 0 to 4294967295 >

please keep high local preference on the router you want to the primary exit or one with high priority. Keep it more than 100.

[Support07]

Hi,

Also you should configure a tracking who track internet for example and decrement your Master router HSRP if it's down.

TkR07_9393