using ipv6 router alert option for manipulating packets at routers

[ns.u...@gmail.com]

Hi all,
I'm working on manipulating specific packets at routers for my Ms.c thesis. I want to overwrite value of some packet fields at routers. For simulating network conditions I read related parts of ns3 source code. I realized that router alert option only used for dropping packets or stopping packet processing in ns3. so should I change Ipv6OptionRouterAlert::process function? Furthermore according to link below some router alert options are defined till now. How to apply these options in ns3?

http://www.iana.org/assignments/ipv6-routeralert-values/ipv6-routeralert-values.xhtml

Regards,

[Tommaso Pecorella]

Hi,

sorry, but this is wrong on many levels. I avoid to post the meme, because I used it too much.

First and foremost, I understand that you didn't understand at all what's a router alert option. Please study it a bit more.

In particular you should read (and understand) RFC 2711 and 6398.

Second, the Router Alert options in ns-3 are not used right now. They are decoded, but they're not used.

Why ? Because. Read the RFCs and you'll find out why. Hint: there's no need to "use" them (yet).

Third, I'm happy you want to use IPv6 and forget about IPv4. Because that's what you're doing, right ?

Have fun,

T.

[ns user]

Is it mean that there is no way for manipulating packets at routers with IPv6?!

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[Tommaso Pecorella]

You can manipulate IPv6 packet just like you can do it for IPv4 packets. It's just that there's no need to use RouterAlert options.

Again, study the rationale behind RouterAlert options.

Quoting RFC 2711 (I didn't point to it for nothing):

   This document defines a new option within the IPv6 Hop-by-Hop Header.
   The presence of this option in an IPv6 datagram informs the router
   that the contents of this datagram is of interest to the router and
   to handle any control data accordingly.  The absence of this option
   in an IPv6 datagram informs the router that the datagram does not
   contain information needed by the router and hence can be safely
   routed without further datagram parsing.  Hosts originating IPv6
   datagrams are required to include this option in certain
   circumstances.

"can be safely routed  without further datagram parsing" doesn't means that they MUST be routed without further datagram parsing.

I understand that English is not your native language, but you should exercise in understanding the differences. Otherwise you'll just not understand the standards.

Cheers,

T.