Subject: RE: [manet] Re: Default Routes (WAS: Request of Comments on the i-d ietf-cha-manet-aodv-internet-00.txt)

From: "Sheena Lizen Barbosa" <[email-masked]>
Date: Fri, 5 Mar 2004 01:49:21 +0800

Hi Anders,

I just wanted to know if the implementation Nico Bayer presented at EW2004 was with AODV6 or DSR? It's because we are working on a similar implementation for DSR.

Thanks and Regards,
Sheena
Final Year Student (B.Eng. Computer Engineering)
National University of Singapore

-----Original Message-----
From: [email-masked] [mailto:[email-masked]] On Behalf Of Anders Nilsson
Sent: Wednesday, March 03, 2004 6:05 PM
To: [email-masked]; manet; [email-masked]
Subject: [manet] Re: Default Routes (WAS: Request of Comments on the i-d ietf-cha-manet-aodv-internet-00.txt)

Hello,

I must say that I agree with all the comments about trying to coordinate 
our efforts. (I am a co-author with Ryuji).
It doesn't make any sense at all to have several drafts that say 
basically the same thing, with some minor modifications. This is really 
the case right now. But the fact that we have so similiar drafts tells 
us that we are close to consensus, so making a common requirement 
document shouldn't be too hard. Having several drafts is really bad, and 
makes things bad for the implementors. There are implementors out there 
trying to implement these features, and they are clearly confused by all 
the different drafts. Nico Bayer have an implementation that he 
presented last week at EW2004, that closely follows the globalv6 draft. 
This is great, and although the imp. seems to follow the draft closely, 
there are some major differences to the draft. This could be explained 
by the confusion created by the different drafts, but may also 
implementation choices. Either way, a consensus is needed.

>Although I admit that I was inspired and motivated by your draft, I do 
>not think that your draft does address all related issues and propose 
>all possilbe solutions. If you are interested in my suggestion, we can 
>have good chance to share ideas and make productive work in this topic.
>  
>
Please point out what you think is wrong.

>   
>As for your comment on my draft, please take it easy.
>
>[The draft says]
>one including [1 globalv6], [2], [3] which use next hop forwarding for 
>default routes and the other including [1 globalv6] which do not use 
>next hop forwarding and require that a sender specifies a gateway in 
>routing header.
>
>  
>
What do you mean here?

This is from Paals mail:

> If you have two gateways announcing the same default route, the
> MANET node has no control of which gateway the packet is routed 
> out through. You might get problems with:
> - Stateless firewalls: E.g. The first packet of your (TCP-) session 
> might go out through another gateway than the one corresponding to 
> the selected source IP address. Thus, the return inbound packets will 
> not reach the gateway corresponding to the MANET node's source IP address 
> if the gateway is behind i firewall because no state is set in the firewall.
> - Ingress filtering: Outbound packets escaping out through "wrong" gateways 
> are filtered out.

As pointed out earlier, this problem can solved by letting intermediate 
forwarding nodes search their gateway list for the source prefix. If the 
source prefix matches an entry in the gateway list, the packet is 
forwarded to the indicated gateway. I think this solves the problem 
stated above. However, there is an other problem here. If the node is 
moving inside the network, it will probably want to switch to different 
gateways as they become closer. The only way for this to work in the 
mentioned solution is to onfigure a new address, which is not really a 
good solution. If the different gateways belong to the same domain, it 
might not even be possible, and routing header might be to prefer in 
that case. I discuss this problem among other things in a paper to be 
presented at WWC04, the main focus of the paper is performance though.

regards,

Anders

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