Re: Dual-homing

[Philip Smith <]

Hi Edgar,

If you are using Cisco routers, check out the conditional advertisement 
feature. It's not perfect, but at least subprefixes are only leaked to the 
Internet when there is a failure situation (which usually are few and far 
between). Also, the multihomed customer doesn't need a public AS, and can 
use address space from both upstreams. It's documented in IOS Essentials 
(http://www.cisco.com/public/cons/isp/documents/IOSEssentialsPDF.zip), if 
it helps.

Also I've put some examples of multihoming (including conditional 
advertisement) in one of the BGP presentations I use for ISP workshops 
(http://www.cisco.com/public/cons/workshops/bgp/4-Multihoming-6up.pdf).

At 16:51 04/10/00 +0200, Edgar Reinke wrote:
> Dear Madame,
>      dear Sir!
>
> Are there any RIPE documents available which describe address assignment 
> strategies for Multi-homed customer (multi-homed to different ISPs):
> - Does those customers require PI address space?
> - Does RIPE assign the PI address space (is it a /19 CIDR block)?
> - If the customer has to use PA address space from ISP A, must ISP B 
> announce prefixes in addition to his CIDR blocks (or is it optional for 
> ISP B to comply with the wishes of his customer with respect to the 
> stability of the global routing system)
This third question is causing many folks more and more concern. Routing 
table is undergoing an explosion in growth at the moment, and from what I 
can tell, most of it is through multihoming. BGP is an excellent tool, but 
ill thought out multihoming solutions are becoming our undoing too...

philip
--


> Regards
>
>  Edgar Reinke
>
> ____________________________________________
>
> Edgar Reinke
> ExperTeach GmbH
> Waldstrasse 92
> 63128 Dietzenbach
>
> E-Mail: edgar.reinke@localhost
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Philip Smith                         ph: +61 7 3238 8200
Consulting Engineering, Office of the CTO, Cisco Systems
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