[c-nsp] BGP default vs BGP full

[Saku Ytti]

On 21 May 2016 at 00:14, Satish Patel <satish.txt at gmail.com> wrote:

Hey,

> Just wonder what would be the advantage and disadvantage of running
> BGP full vs default route.
>
> We have single ISP connection and ISP decided to just run default
> route over BGP instead full.

In my opinion one should never carry default route in any other
protocol than static route. In your case, with just single connection
to single ISP arguments are hard to present.
But the moment you have >1 connection to same or different ISP it
becomes more relevant.

If you accept default route from ISP and their edge router becomes
isolated from core, you're blackholing traffic. The way to avoid this,
is instead accept one of their PA prefixes, which is typically
originated in few core routers. If their edge loses connectivity to
core, the PA route is pulled. Now pointing recursive static default
route to this PA router means the static default becomes invalid if
the PA is pulled, and you've protected yourself from this failure
scenario.

-- 
  ++ytti