Re: active networking in ns

[Guillermo Rodriguez Garcia <guille@iies.es>]

At 10:55 19/10/99 +0200, you wrote:

>> There is one thing that is not entirely clear for me yet. With
>> your solution, if you need to have custom fields in the active
>> packet header, how/where do yo carry them? In other words, how
>> do you store state information associated with each active
>> packet? Just imagine a simple, stupid active packets that
>> records routes from source to destination. Implementation
>> should be straightforward with PANAMA's approach because
>> you have a new packet format for each new active protocol,
>> so you can just carry a list of node addresses and append
>> each node that you visit as you travel the network. How
>> would you do this with your approach?
>
>State is carried in the procedure's parameters. Here is an example traceroute
>capsule evaluated at each "$ee" on the path to the destination:
>
># "traceroute", method "record path"
>proc traceroute2 {return path srcee dstee ee} {
>    if {$return} {
>        if {$ee == $dstee} {
>            $ee debug "path to [[$srcee set node_] id] is: $path"
>        } else {
>            set capsule "traceroute2 $return $path $srcee $dstee"
>            $ee forward $capsule $dstee
>        }
>    } else {
>        set newpath "${path}_[[$ee set node_] id]"
>        if {$ee == $dstee} {
>            set capsule "traceroute2 1 $newpath $dstee $srcee"
>            $ee forward $capsule $srcee
>        } else {
>            set capsule "traceroute2 0 $newpath $srcee $dstee"
>            $ee forward $capsule $dstee
>        }
>    }
>}

This looks nice !

>> I would like to have an eye at it when it is ready anway,
>> even when I won't probably be able to use it for this project.
>
>I'll prepare a neat version as soon as I can... I'll probably include the
>possibility to use "router alert" as well, you've convinced me :-)

I like your ideas as well :-) I'm now thinking about some 'hybrid'
solution combining the best from your approach and PANAMA's ...

Regards,
G.

--
Guillermo Rodriguez Garcia
<guille@iies.es>