Subject: [rohc] ROHC-v2 packet formats

From: "Mallikarjuna.H.B" <[email-masked]>
Date: Tue, 25 Sep 2007 23:57:55 -0700 (PDT)

Hi,

1)

 For the ROHC RTP profile packet formats CO_common and CO_repair almost
same.(all the flags in CO_common are same as CO_repair, but in the draft it
is written like this:

co_repair: This format is very similar to the co_common format described
above. The difference is that this packet is intended to be used when
context damage has been assumed, and therefore
changing fields are transmit uncompressed when present in this format. This
format also contains some options to transmit semistatic fields from
extension headers which cannot be transmit with
the co_common format. This packet format should be considered a replacement
for the IR-DYN packet format which is not defined for the profiles defined
in this document.

other than the SN every thing is same. In Co_repair SN shall be sent
completely. 
Repair flag also there in CO_common . can we send the outer ip and ip_ext
header information using CO_common packet as in CO_repair packet?

2)

if ipv4_ipv4 packets to be compressed , the ip_id, TOS, TTL of the outer
header has to sent to the decompressor. if the inner ip_id is random then
even that also need to sent to the decompressor but i found no flag bits
indicating that the inner ip_id is present or not how the decompressor could
decompress the packet.

3)

if ipv6_extension headers are supported then even if there is a change in
one extension header, i might have to send all the extension header
information in the order following the actual packet or is there any other
way to convey this?

plz plz reply anybody knew this.

Regards,
Mallikarjuna

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From: "Mallikarjuna.H.B" <[email-masked]>
Date: Wed, 26 Sep 2007 03:52:53 -0700 (PDT)

Hi all,
 
 After studying the ROHC-v2 profiles 01 draft  i tried to define the
irregular chain in the format given below.
If there is any misconception in this then any body could reply to this

Ipv4 :

IF repair flag and ip_outer flag are 1 then df and ip_id behave control
fields shall be sent in the first octet. ----------------------1

If outer header is present and also it’s ip_id field is random then the
first field in the irregular chain could be the outer ip_id
field.(implied)---------------2

If ip_outer flag is also 1 then TOS, TTL wll also be present next to outer
ip_id.----2

If inner ip_id field is random then that follows the above
fields.-----------2

If udp checksum is not zero then even the udp checksum could also follow
these 
fields.----------------2

Ipv6:
 
If the outer header is present and also the ip_outer flag is 1 then TC and
HL wll be the first and the second fields respectively in the irregular
chain.-----2

If repair flag is present and ip_extension headers are also the part of the
IR packet then option fields of the ip_extension headers shall follow these
fields in the order they are sent in the IR packet.
------------------variable

If udp checksum is not zero then even the udp checksum could also follow
these 
fields.----------------2

conclusion:  Irregular chain could also be present even for the other
packets. The order in which the irregular chain to be defined may follow the
above order.

regards,
Mallikarjuna
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