The IP over ATM Mailing List Archive by date

[Hiroshi Esaki <hiroshi@ctr.columbia.edu>]

Hi Jon, 

 jc> we were talking about expierences with IP on ATM and decided we would
 jc> like to start some kind of discussion on alternate protocol wrappers
 jc> for IP around AAL5
 jc> 
 jc> 2 examples why we need it

 jc> 1/ Video on RTP on UDP/IP on AAL5
 jc> 
 jc> we'd like to propoe peopel think about deliverying partial IP packets,
 jc> and think hard about a siognal being propogated thru AAL5, IP and UDP
 jc> to say "I know the CRC and UDP checksums fail, but i don't care"

This seems to be actually happened both at ATM Forum and ITU-T. 
By the liasion report provided at ATM Forum meeting, ITU-T clearly
mentiones in the spec to use collaped data delivery for AAL 5, in 
Annex (or Appendix ?). 
The meaning of collaped data delivery is that the data with some 
error (detected by CRC-32 and/or payload length) can be delivered 
to the application with error indication. 
Yes, though, it does not seem no vender support this collaped 
data delivery option, at this time. 
# When there are some vendors, I am very sorry to say wrong thing. 

Also, AAL0 (without any header nor trailer) is seriously considered, 
by my understanding. 
In this case, there is CRC error check sequence. 

I really support these two direction. 
I guess you also. 


# Through, it is not solved the fatal issue for ATM due to 
  fragment packet into cells...... 



 jc> 2/ TCP on IP on AAL5 on an ABR service
 jc> we'd like an explicit congestion bit (even if ATT don';t let us get
 jc> the explicit rate,they'll still pass the congestion signal back sooner
 jc> than packet loss in traditional TCP congestion detection) signal from
 jc> AAL up thu IP....

This will be true. 
Also, I think this kind of interface may be applied to the other 
services (i.e., UBR, VBR), as well as ABR. 


Best Regards, 

Hiroshi Esaki