[Ns-developers] Implementation of an IPv6 stack for NS-3

[Mathieu Lacage]

On Tue, 2008-06-17 at 10:03 +0200, Sébastien Vincent wrote:

> > Another issue I wonder about is what the socket API looks like. I have
> > to confess that I know next to nothing about ipv6 so, I would like to
> > know how OSes actually export ipv6 sockets ? How can I specify (in a
> > real OS) that I want an ipv6 tcp socket ? Can I specify that I want a
> > tcp socket to listen both on ipv4 and ipv6 on the same port ?
> >   
> Simply put AF_INET6 for the "domain" parameter of socket()
> i.e. for TCP : int sock=socket(AF_INET6, SOCK_STREAM, IPPROTO_TCP);
> other useful C function :
> - getaddrinfo : to retrieve IPv6 address from a DNS name (for bind(), 
> connect(), ...);
> - getnameinfo : to retriev name (hostname, ...) from IPv6 address;
> - inet_ntop / inet_pton (with AF_INET6 value for "af" parameter).
> 
> The IPv6 socket by default can receive both IPv4 and IPv6 if it is bind 
> with the unspecified address (::). The IPv4 address will be represented 
> as IPv4-mapped address (i.e. ::ffff:192.168.0.1). T**he setsockopt 
> option  IPV6_V6ONLY can disable this.

I see. Thanks for the explanation. 


> In IPv4 under GNU/Linux, when you want more than one address per 
> interface, you have to deals with alias (ifconfig eth0:1 10.0.0.1) and 
> it "creates" another interface.  So your way to have multipe 
> Ipv4Interface on same NetDevice is the same as Linux (for IPv4). But in 
> IPv6 you have all the addresses in the same interface name. So my first 
> impression was to do have a list of addresses as Linux and Unix do.
> 
> eth1      Link encap:Ethernet  HWaddr 00:xx:xx:xx:xx:xx
>           inet adr:192.168.0.1  Bcast:192.168.0.255  Masque:255.255.255.0
>           adr inet6: 2001:db80:aaaa::1234/64 Scope:Global
>           adr inet6:2001:db80:bbbb::1234/64 Scope:Global
>           adr inet6: fe80::1234/64 Scope:Lien
>           UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
>           RX packets:5382749 errors:0 dropped:0 overruns:0 frame:0
>           TX packets:917577 errors:0 dropped:0 overruns:0 carrier:0
>           collisions:0 lg file transmission:1000
>           RX bytes:1189822564 (1.1 GiB)  TX bytes:243898797 (232.6 MiB)
>           Interruption:22

Ok. I would be curious to know why they have taken these different
approaches in linux.

Mathieu