Re: [rohc] About Outer IP-ID field

[Klaus Warnke <klaus.warnke at acticom.de>]

Wukai,

> My question is how to use the IP-ID in Extension 3 Outer IP header
> fields?when to use the IP-ID in Extension 3 Outer IP header fields?

First, I think, that the sentence "carry the compressed IP-ID of the
innermost IPv4 header" applies to the IP-ID field in the base headers,
like UO-1-ID, not to the extension 3. In UO-1-ID there is no ip/ip2
flag that indicates for which IP header the IP-ID is, as in
extension-3. The problem here is, that if the outer IP-ID does not
jump +1 nbo/not nbo, you can not use the IP-ID field in UO-1-ID to
transmit such small change to the de-compressor, as for the inner
IP-ID. You must use an large extension-3, where you can tranmit the
IP-ID for inner and outer separate, because the IP-ID field in UO-1-ID
is reserved for the inner IP-ID.

br
Klaus Warnke
> hi £º
> I am having some difficulty about Outer IP-ID field¡£I need some help.
> http://www.ietf.org/mail-archive/web/rohc/current/msg02222.html
> >See page 75, "IP-ID":
> >"IP-ID fields in compressed base headers carry the compressed IP-ID
> >of the innermost IPv4 header whose corresponding RND flag is not 1."
> >This means for two IP headers (IP-ID field means the field in 
> compressed >headers):
> >IPv6/IPv6/UDP/RTP : No IP-ID field in compressed headers.
> >IPv6/IPv4(RND=1)/UDP/RTP : No IP-ID field in compressed headers.
> >IPv6/IPv4(RND=0)/UDP/RTP : The IP-ID field corresponds to the inner 
> >header.
> >IPv4(RND=1)/IPv6/UDP/RTP : No IP-ID field in compressed headers.
> >IPv4(RND=0)/IPv6/UDP/RTP : The IP-ID field corresponds to the outer 
> >header.
> >IPv4(RND=1)/IPv4(RND=1)/UDP/RTP: No IP-ID field in compressed headers.
> >IPv4(RND=1)/IPv4(RND=0)/UDP/RTP: The IP-ID field corresponds to the 
> >inner header.
> >IPv4(RND=0)/IPv4(RND=0)/UDP/RTP: The IP-ID field corresponds to the 
> >inner header.
> > This last case would only work if the >outer IP-ID
> > is totally sequential N, N+1, >N+2...etc.
> > (previous config should be used >instead)
> >Crystal clear from RFC3095...=)
> About Outer IP-ID field,it had clearly interpretation above¡£
> About last config :IPv4(RND=0)/IPv4(RND=0)/UDP/RTP: The IP-ID field 
> corresponds to the inner header.
> This last case would only work if the outer IP-ID is totally 
> sequential N, N+1, >N+2...etc.
> (previous config should be used instead,I.E: use config IPv4 
> (RND=1)/IPv4 (RND=0)/UDP/RTP: The IP-ID field corresponds to the inner 
> header.is it right?
> My question is how to use the IP-ID in Extension 3 Outer IP header 
> fields?when to use the IP-ID in Extension 3 Outer IP header fields?
>
> Outer IP header fields
> ..... ..... ..... ..... ..... ..... ..... .....
> | Type of Service/Traffic Class | if TOS2 = 1
> ..... ..... ..... ..... ..... ..... ..... .....
> | Time to Live/Hop Limit | if TTL2 = 1
> ..... ..... ..... ..... ..... ..... ..... .....
> | Protocol/Next Header | if PR2 = 1
> ..... ..... ..... ..... ..... ..... ..... .....
> / IP extension header(s) / variable,
> ..... ..... ..... ..... ..... ..... ..... ..... if IPX2 = 1
> | IP-ID | 2 octets,
> ..... ..... ..... ..... ..... ..... ..... ..... if I2 = 1
>
> br
> wukai
>
> ------------------------------------------------------------------------
>
> _______________________________________________
> Rohc mailing list
> Rohc at ietf.org
> https://www.ietf.org/mailman/listinfo/rohc