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Re: ipv6 plans for ns-3
by Fabian Mauchle
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Hi all
-----Ursprüngliche Nachricht-----
Von: ns-developers-bounces@... [mailto:ns-developers-bounces@...] Im Auftrag von Sébastien Vincent
Gesendet: Freitag, 24. Juli 2009 10:19
An: Tom Henderson
Cc: ns-developers@...
Betreff: Re: [Ns-developers] ipv6 plans for ns-3
In old ns-3-ipv6 repository, we made an application (radvd) to send
router advertisements (RA). We did it to mimic Linux, but it could be
also interresting if somebody wants to put extension to RA like for
example DNS servers information (RFC 5006) => no changes to IPv6 stack
itself just the application. What do you think ?
>
>>
>> As you see many files have been copy/paste/adapt, but for the routing
>> part I think it will have some changes.
>>
>> Next steps are :
>> - handle link-local multicast in routing part;
>> - handle Router Advertisement (receive, parse, extract prefix and
>> autoconfigured global address with it + timer);
> > - radvd application like;
>
> - I am guessing that the DAD stuff commented out in
> icmpv6-l4-protocol.cc can be enabled once the router advertisements
> are enabled? Maybe we can avoid to merge these commented out code
> blocks until then.
DAD is working and router solicitation (RS) is also sent after DAD is
completed. But like all nodes start at the same time, they do their DAD
and sent RS at approximately 1 second of simulation time, so a lot of
messages at the beginning of the simulation. We think about this last
year and solution was to temporary disable sending RS. As radvd
application can be configured to sent periodically RA the problem is not
very important for static nodes but for Mobile IPv6 ones it is critical
to have an address quickly and not wait for next period of RA sending.
--------------
During my study and simulation (based on the old ns-3-ipv6) of Mobile IPv6 (RFC 3775) I found the following:
- The DAD and RS messages at the beginning was no problem. I usually start the applications some seconds into the simulation, and give the network time to 'organize' itself (do the DAD stuff...).
- When thinking about Mobile Nodes, it is basically important that there is a configurable radvd application. For Mobile IPv6, it is recommended to send RA's every 30-70ms to help Mobile Nodes get an address quickly. The radvd application in the old repo did this job perfectly. Nevertheless, Mobile IPv6 is not defined to be fast or fulfill any QoS requirements. So it's not that critical.
- For fast moving Mobile Nodes which eg. have a running VoIP session, other methods like Media Independent Handover are needed to be fast enough. Basically, for this scenario, the address configuration is not the basic problem, but updating the Mobile Node's location and redirecting its traffic.
So, from My point of view, I would keep the DAD behavior as it was in the old repo. I would also keep the radvd application. Maybe it's configuration could be simplified.
Regards
Fabian
-----Ursprüngliche Nachricht-----
Von: ns-developers-bounces@... [mailto:ns-developers-bounces@...] Im Auftrag von Sébastien Vincent
Gesendet: Freitag, 24. Juli 2009 10:19
An: Tom Henderson
Cc: ns-developers@...
Betreff: Re: [Ns-developers] ipv6 plans for ns-3
In old ns-3-ipv6 repository, we made an application (radvd) to send
router advertisements (RA). We did it to mimic Linux, but it could be
also interresting if somebody wants to put extension to RA like for
example DNS servers information (RFC 5006) => no changes to IPv6 stack
itself just the application. What do you think ?
>
>>
>> As you see many files have been copy/paste/adapt, but for the routing
>> part I think it will have some changes.
>>
>> Next steps are :
>> - handle link-local multicast in routing part;
>> - handle Router Advertisement (receive, parse, extract prefix and
>> autoconfigured global address with it + timer);
> > - radvd application like;
>
> - I am guessing that the DAD stuff commented out in
> icmpv6-l4-protocol.cc can be enabled once the router advertisements
> are enabled? Maybe we can avoid to merge these commented out code
> blocks until then.
DAD is working and router solicitation (RS) is also sent after DAD is
completed. But like all nodes start at the same time, they do their DAD
and sent RS at approximately 1 second of simulation time, so a lot of
messages at the beginning of the simulation. We think about this last
year and solution was to temporary disable sending RS. As radvd
application can be configured to sent periodically RA the problem is not
very important for static nodes but for Mobile IPv6 ones it is critical
to have an address quickly and not wait for next period of RA sending.
--------------
During my study and simulation (based on the old ns-3-ipv6) of Mobile IPv6 (RFC 3775) I found the following:
- The DAD and RS messages at the beginning was no problem. I usually start the applications some seconds into the simulation, and give the network time to 'organize' itself (do the DAD stuff...).
- When thinking about Mobile Nodes, it is basically important that there is a configurable radvd application. For Mobile IPv6, it is recommended to send RA's every 30-70ms to help Mobile Nodes get an address quickly. The radvd application in the old repo did this job perfectly. Nevertheless, Mobile IPv6 is not defined to be fast or fulfill any QoS requirements. So it's not that critical.
- For fast moving Mobile Nodes which eg. have a running VoIP session, other methods like Media Independent Handover are needed to be fast enough. Basically, for this scenario, the address configuration is not the basic problem, but updating the Mobile Node's location and redirecting its traffic.
So, from My point of view, I would keep the DAD behavior as it was in the old repo. I would also keep the radvd application. Maybe it's configuration could be simplified.
Regards
Fabian
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