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Re: Routing Question-- Maybe a hack
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Carl

I thought about this a bit last night and wanted to throw out a possible solution. The real goal I think you have is to make web client use the closest web server.

Here's my proposal:

On each worlds fair server, let's say two for now (call it www.worldsfair.org for now):

Create two interfaces for

1) Machine1 le0 --> 1.2.3.4 (the real address of the machine) vif0 --> 5.6.7.8 (the pseudo address of www.worldsfair.org) 2) Machine2 le0 --> 9.0.1.2 (the real address of the machine) vif0 --> 5.6.7.8 (the pseudo address of www.worldsfair.org)

In the DNS www.worldsfair.org would only map to 5.6.7.8

Then in the railroad infrastructure, import the host route 5.6.7.8 into the IGP (presumably OSPF or ISIS) pointing to both machine1[2].

With this, when a client resolves www.worldsfair.org, it will go to 5.6.7.8 which will be routed, once inside the railroad, to the *closest* 5.6.7.8 and get to the closest (IGP-wise) web server.

The trick will be to make the host route dynamic enough to remove its announcement for one of the machines[1 || 2] when that machine (or more specifically httpd) is not available. This should be pretty easy to do if you use gated on machine1[2]. A quick hack to remove the route from gated could be implemented to "watch" httpd and remove the announcement. Of course, gated will automatically remove the announcement if the machine becomes diconnected or dies.

This, I think, should accomplish what you are trying to do. Let me know what you think.

Thanks Jack

Note the second interface is a

At 11:13 AM 12/12/95 -0500, Carl Malamud [IMS] wrote:
>> if you're talking about multiple servers in different
>> locations with clients routing to them based on proximity
>> that's very different. perhaps possible.
>
>You bet, that is what we want to do. Different answers for
>different locations. I'll call Kim Claffy and see what she
>has to contribute.
>
>How hard is it to manually define some border AS's (e.g., the
>ones at the "edge" of Japan) and then ask the question: is this
>IP address "beyond" the border AS's? From a host, what would
>I do to ask that question?
>
>Carl
>
>
>

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