redundancy between two links with BGP on same ISP

[Mukund M Deshpande]

Hi ,

I want to know how can I achive redundancy between two links from same ISP .

I m using bgp here , we can consider both senario where both links will be having same AS no and diffrent AS nos .

Thanks for reply

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[Marwan ALshawi]

If you receive same routes from both ISPs or at least the default route you can use some bgp attribute to let your router prefer one link over the other and the other one can be used as fallback or back pun

You Can use any if the bellow in the inbound direction withna route map

Local preference

Bgp wight

See the bellow link you may find a useful example

http://www.cisco.com/en/US/tech/tk365/technologies_configuration_example09186a00800945bf.shtml#conf2

Hope this help

If helpful rate

[Mukund M Deshpande]

Hi marwanshawi ,

Thanks for the reply , but here I want to know how can I achive redundancy between two links from same ISP having same AS no .

Thanks

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[cadet alain]

Hi,

If you want redundancy for the BGP TCP session not going down when 1 link fails then:

do your eBGP peering with loopbacks on both sides, don't forget to use eBGP-multihop as by default eBGP TTL=1.

Here is an example: suppose R1 is your router and R2 the ISP and you're connected with s1/0 and s1/1

R1:

int lo0

ip add 1.1.1.1 255.255.255.0

int s1/0

ip add 10.1.1.1 255.255.255.0

int s1/1

ip add 10.2.2.1 255.255.255.0

ip route 1.1.1.0 255.255.255.0 10.1.1.2

ip route 1.1.1.0 255.255.255.0 10.2.2.2

router bgp 100

neigh 2.2.2.2 remote-as 200

neigh 2.2.2.2 update-source lo0

neigh 2.2.2.2 ebgp-multihop 2

R2:

int lo0

ip add 2.2.2.2 255.255.255.0

int s1/0

ip add 10.1.1.2 255.255.255.0

int s1/1

ip add 10.2.2.2 255.255.255.0

ip route 2.2.2.0 255.255.255.0 10.1.1.1

ip route 2.2.2.0 255.255.255.0 10.2.2.1

router bgp 200

neigh 1.1.1.1 remote-as 100

neigh 1.1.1.1 update-source lo0

neigh 1.1.1.1 ebgp-multihop 2

Regards.

Alain