Thomas wrote:
> Hi all,
>
> Simple question - I'm looking into running BGP for a set of servers
> for a company. There are 5 servers now, and the network has been
> allocated a /29 by the upstream cable provider (isolated from any
> other machines). The company also has a DSL connection which is
> allocated a /29, and handles connections from employee workstations,
> etc. I'd like to make the servers fault-tolerant through BGP, and have
> been researching Zebra for this task. However, my research has
> indicated that we need provider-indepdendent IP address (PI-Space) for
> this task, and when looking online at ARIN I see the smallest space
> they allocate for multi-homed sites is a /22, far too large. Are
> smaller organizations out of luck when it comes to announcing their
> own routes?
If your cable provider is the same company as your DSL provider, it's easy -
as long as they're willing to do the BGP peering with you.
Use one of the "private" AS numbers - your ISP can allocate you one to use
and then you can advertise those subnets back to the provider over both
links, with a prefix on the least-preferred link. Get the provider to
advertise the default route to you, which you can set a preference on to
select your preferred return path.
If the DSL and cable providers are different, then you'll have to have a
larger address space to advertise it past the interconnect filters.
Obviously it would be preferable if it's your own address space. You'd also
require your own AS number.
(you may be able to work around these requirements by getting the cable
and DSL companies to cooperate on peering one of the companies address
spaces, but it's unlikely).
Another way to get around this is to co-locate a router at the provider that
owns the IP address space, create a tunnel though the other server and do
the route control there (OSPF would probably be easier at that point).
Bruce
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