[c-nsp] /18 and multihomed BGP

[Heath Jones]

Hi

If you advertise the /18 to one ISP (a) and the /24 to another ISP (b), you
will find that all your traffic will enter via the 2nd ISP (b) as it will be
the more specific routes in global BGP tables.
Is there a reason you wanted to use 64x /24's in the first place?

Cheers
Heath



On 12 August 2010 13:21, RAZAFINDRATSIFA Rivo Tahina <r.tahina at moov.mg>wrote:

> Hi all,
>
> I'm BGP multihomed with 2 ISPs and have a /18 subnet.
> I declared the /18 block in RIPE database as 64 /24.
> I'm adding a new ISP and he asked me to modify the 64 /24 in RIPE to a
> unique /18.
> How does this change affect the existing routing with 2 former ISPs?
> How can I announce a /24 prefix from one ISP to another? He is talking
> about "no export", what is the purpose of this attribute?
>
> BR
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