[j-nsp] Policy option for advertising full routes

[Erdem Sener]

 Hi Ihsan,

 The question 'how to announce the full table' is a bit tricky,
because you are probably computing this full table using multiple
upstream bgp neighborships, and maybe some other protocols such as
static routes. (I've seen some cases with that)

 So, while building your export policy, you need to make sure to
include all your 'sources' that help you build your full table. This
might be a protocol (eg. bgp), ASN's or such..

 IMHO, a typical export policy should also take into account some
mistakes that could harm your peer's network, or maintain your company
perception, if you prefer :)

 I'll assume you're peering with AS1, AS2 and AS3 as upstream
providers and peer with your local (other) service providers AS4 and
AS5. Of course, you may have your customers with different ip/as
configurations as well.

 Also assuming that your import policies from these peers are correct,
your export policy for the customer might look something like below:

lab at lab1> show configuration policy-options policy-statement bgp-customer-full
term Small-Subnets-Reject {
    from {
        route-filter 0.0.0.0/0 prefix-length-range /25-/32;
    }
    then reject;
}
term remove_rfc1918 {
    from {
        route-filter 10.0.0.0/8 orlonger;
        route-filter 172.16.0.0/12 orlonger;
        route-filter 192.168.0.0/16 orlonger;
    }
    then reject;
}
term My-Upstreams {
    from as-path-group Upstreams;
    then accept;
}
term My-Peers {
    from as-path-group Peerings;
    then accept;
}
term My-Customers {
    from as-path-group Customers;
    then accept;
}
term anything_else {
    then reject;
}

lab at lab1> show configuration policy-options as-path-group Upstreams
as-path up1 "1 .*";
as-path up2 "2 .*";
as-path up3 "3 .*";

lab at lab1> show configuration policy-options as-path-group Customers
as-path cus1 "10 .*";
as-path cus2 "11 .*";
as-path cus3 "12 .*";

lab at lab1> show configuration policy-options as-path-group Peerings
as-path per1 "20 .*";
as-path per2 "21 .*";
as-path per3 "22 .*";



HTH
Erdem

 If your customer is multihomed (eg. connected to different service
providers), it'll require to get <as possible> identical routing
tables, so it may choose between prefixes/as's by prioritizing using
various methods.

 In

On 10/22/05, Ihsan Junaidi Ibrahim <ihsan at synthexp.net> wrote:
> Hi all,
>
> I have a customer who is going to utilize us as a transit and requires
> full internet routes via BGP. Please excuse myself for posing an
> elementary question but how do I define the export policy for advertising
> full routes. FYI, Our router has full routes.
>
> Another question what is the advantage from the customer's view to have
> full routes than simply injecting a default route to us?
>
> --
> Thank you for your time,
> Ihsan Junaidi Ibrahim
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