:Re:Help with element design...(drwaings DID messed up)

[Jean-Francois Dive]

Largely better.. :)

On Wed, 14 Nov 2001, Juan Luis Baptiste wrote:

> I send it again, hope this time the drawing are ok:
>
> Hi,
>
> As I said before, I'm going to do some elements to complement the IPv6/IPv4
> translator elements
> of
> Click's GT64, they are two ALG's, one for handling FTP packages and the other
> one for DNS
> requests.
> I have in this moment two approaches for this, but I don't know wich of them
> would be better to do in
> click.
>
> First of all, let me explain a little how GT64 works:
>            (IPv4)                                              (IPv6)
>
>           ---------                    -------------------
> --------->| pt46  | ---------------->  |                 | ------------->
>           ---------                    |                 |
>                                        |                 |
>           ---------                    |       APT       |
> <---------| pt64  | <----------------  |                 | <-------------
>           ---------                    |                 |
>                                        -------------------
>
> APT is the Address and Port Translator, it receives ipv6 packages and changes
> it addresses
> based
> in some mappings defined in the configuration (static or dynamic), like a NAT.
> pt46 is the protocol translator from ipv4 to ipv6, it translates the
> ipv4/tcp/udp headers to ipv6
> equivalents.
> pt64 does the same thing but in the opposite direction.
>
> The two approaches for the alg's are as follows:
>
>          (IPv4)                                                     (IPv6)
>
>           ---------                    -------------------
> --------->| pt46  | ---------------->  |
> |------------------->
>           ---------                    |                  |                /\
>                                        |                  |                 |
>           ---------                    |        APT       |                 |
> <---------| pt64  | <----------------  |                  | <-------------- |
> ---
>           ---------        /\          |                  |                 |
>                             |          --------------------                 |
>                             |               |        |                      |
>                             |               v        v                      |
>                             |              -------------                    |
>                             ---------------|    ALG    |---------------------
>                                            -------------
>
> With this approach, I would have to modify APT elements to distinguish for
> FTP/DNS (based in the
> source/destination
> port), and distinguish if a packet is heading to a IPv6 or IPv4 network so it
> can send the packet thru
> the
> right output, so when the alg gets it it can know to wich routing elements push
> it. What I don't like
> from
> this one is that I got to modify APT element, and I think that is not the best
> way, as the idea is to
> leave
> the elements unchanged.
>
> The other approach is this:
>
> (IPv4)
> (IPv6)
>
> ---------                -------------------
>
> -------______>
> ------->| pt46   | ----------->  |                 |
> ----------->| ALG
> |______>
>                         ---------                |                 |
>                                                  |                 |
>   <___ -------          ---------                |       APT       |
> <___ | ALG | <--------| pt64   | <----------   |                 |
> <-------------
>         ------          ---------                |                 |
>                                                  -------------------
>
> Here, the alg's are connected after the packet translation has been done. In
> the same way the ALG element
> has
> two push inputs and outputs that work in the same way as in the other case. I
> like this one
> more,
> but what I don't like is that every packet has to be checked by the ALG
> independently if it is a
> FTP/DNS
> packet or not, so I don't know if the performance would be dramatically
> affected.
>
> Well, what do you guys think?
>
> Juan Luis
> http://www.merlinux.org
>
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