[c-nsp] bgp & static default route?

[Michael Smith]

On Aug 25, 2005, at 8:36 PM, matthew zeier wrote:

>
> I work at a medium sized ISP with one data center.  Network isn't too
> large - three upstream providers, ~400Mbps at peak.  There are a pair
> of routers that connect to the Internet and a pair of routers that
> customers hang off of directly.
>
> Management is of the opinion that the best way to run this network is
> with full BGP routes and static defaults out uplink interfaces
> redistributed into OSPF.  The thinking process is that if a external
> peer stops sending me all routes, I still need a way to get out.
>
> I content that if an external peer stops sending me full routes, why
> should I send them traffic they don't think they know how to get to?
> And if all routers are running bgp, I don't see how the static default
> will ever help unless I lose all external bgp routes at which point
> there's probably a bigger problem and I'm probably offline.
>
> When I raise my objections, I'm told "we're not MCI - we need a  
> default
> route".
>
> Any comments?  Is this how anyone else runs a network?
>

Hello Matthew:

The default route works pretty well if you are receiving address  
space from one of your upstream providers; the assumption being your  
block is part of a greater aggregate that will still be reachable.   
However,  it would be advisable for them to have a static route  
pointed back to you for the assigned netblock(s).

However, that aside, I tend to agree with you.  A gateway of last  
resort is probably fine and if it makes your management team happy  
it's probably not something worth arguing about.  I don't think the  
static route will do much if you've had some sort of issue that  
knocks BGP out.  I mean, I'm sure there are instances where it's just  
the BGP process, but for it to fail simultaneously across both your  
eBGP routers, my guess is you will have a default to nowhere.

Then again, you will also have a smart-ass response for your  
Management Team, to the tune of "Thank god we had that default  
route."  Of course, that might also be the last thing you get to say  
to your <now former> employer.  :-)

Mike