Re: [AVTCORE] Proposed text for draft-ietf-avtcore-ports-for-ucast-mcast-rtp-01

[Magnus Westerlund <[e-mail]>]

Hi,

I suggest the first paragraph is changed to:

Token Element (Variable size): Element that is used to carry the Token
generated by the server. This element is a 32-bit aligned Length-Value
element. The Length field, which is 16 bits, indicates the length (in
octets) of the Value field that follows the Length field. While a 16-bit
length allows for Tokens with a size of up to 65535 bytes, using Tokens
of sizes that make the RTCP compound packet larger than the MTU might
have a negative impact on functionality because of IP fragmentation.
Some NATs or other middleboxes do not pass IP fragments, thus a large
Token can cause the whole mechanism to fail. In addition, fragmentation
increases the risk for packet loss.

Cheers

Magnus

Ali C. Begen (abegen) skrev 2011-04-14 13:36:
> Based on a comment from IESG, we would like to propose the following
> change to the Token draft. It is about increasing the length of the
> Tokens. Currently, the length field is 1 byte, IESG recommends 2
> bytes with a warning sign.
> 
> Please let us know if you do not want this change. Link to the draft:
> https://datatracker.ietf.org/doc/draft-ietf-avtcore-ports-for-ucast-mcast-rtp/?include_text=1
>
>  -acbegen
> 
> New text for 4.2
> 
> Token Element (Variable size): Element that is used to carry the
> Token generated by the server. This element is a 32-bit aligned
> Length-Value element. The Length field, which is 16 bits, indicates
> the length (in octets) of the Value field that follows the Length
> field. While a 16-bit length allows for Tokens with a size of up to
> 65535 bytes, using Tokens larger than 1000 bytes is generally a bad
> idea since this can easily cause IP fragmentation. Note that a Token
> has to be transmitted in an RTCP compound packet within a UDP packet,
> which often has an MTU of 1500 bytes.
> 
> The length does not include any padding that is required for
> alignment. The Value field carries the Token (or more accurately, the
> output of the encoding process on the server). If the Token element
> does not fall on a 32-bit boundary, the last word MUST be padded to
> the boundary using further bits set to zero. 
> _______________________________________________ Audio/Video Transport
> Core Maintenance [e-mail] 
> https://www.ietf.org/mailman/listinfo/avt
> 


-- 

Magnus Westerlund

----------------------------------------------------------------------
Multimedia Technologies, Ericsson Research EAB/TVM
----------------------------------------------------------------------
Ericsson AB                | Phone  [phone]
Färögatan 6                | Mobile [phone]
SE-164 80 Stockholm, Sweden| mailto: [e-mail]
----------------------------------------------------------------------