[j-nsp] Conditionally advertising default based on provider BGP status

[Saku Ytti]

On (2012-11-08 00:53 -0800), Morgan McLean wrote:

> I'd like to be able to do it based on BGP state...
> 
> Any tips?

You probably already generate your PA routes from some central core boxes.
Advertise one of these PA routes and have static default route point to it.

If edge loses connectivity to core, PA is withdrawn and static route
becomes invalid and next one can be considered.

http://blog.ip.fi/2011/08/when-should-you-advertise-default-route.html

Option Dennis describes is of course perfectly acceptable too. However not
all devices and vendors support conditional routes so it may or may not be
portable.

If you really want some practical reliability that Internet will work,
you'd need to look into RPM or IP SLA. In IP SLA you could have several
static defaults, where IP SLA is pinging 8.8.8.8 if packet loss or latency
is too high, you could make the route less preferable. If 8.8.8.8 itself is
suffering from all vantage points, each route becomes less preferable, i.e.
you're again using all of them.
-- 
  ++ytti