[nsp] Typical Prefix filters - greater than /24's dropped?
michael at lyngbol.dk
Sat Nov 22 14:10:34 EST 2003
On 20.11.2003 22:29:36 +0000, Gert Doering wrote:
> On Thu, Nov 20, 2003 at 10:58:48AM -0000, Sam Stickland wrote:
> > I'm trying to get a feel for the sort of prefix filters that are typically
> > in use on the backbones and transit providers. Are prefixes longer than
> > /24's typically filtered out?
> We do not accept anything more-specific than a /24.
That's the basic standard.
> I'd really appreciate if people would stick to aggregation: announce your
> network block in *one* piece. Don't try to impose the costs for your
> broken business models ("this upstream must only be used for backup, so
> I'll announce more-specific over the other upstream") onto the whole
Prepending mixed with community support (if existing) from your upstream
provider is more doable.
Philip Smith, Cisco gave a nice presentation at NANOG in Salt Lake City
> *Everybody* pays for every additional prefix, and it sums up. When we hit
> 200.000 routes (or so), the next round of "junk all your backbone ciscos
> because they can't take more than 256 Mb of RAM" is due, and then you'll
> *feel* the cost. Stop it before that happens.
It's a lost cause.
Inspired by Verio's BGP filter policy filtering a full view yelds
~107K accpted routes and ~20K rejected:
Peer AS InPkt OutPkt OutQ Flaps Last Up/Dwn State|#Active/Received/Damped...
22.214.171.124 3292 4374165 115848 0 3 5w5d5h Establ
Michael Lyngbøl -- michael at lyngbol dot dk
Network Architect, AS3292 TDC, IP·backbone
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