nanog mailing list archives
Re: from the academic side of the house
From: Leigh Porter <leigh.porter () ukbroadband com>
Date: Tue, 24 Apr 2007 17:46:07 +0100
Jim Shankland wrote:
bmanning () karoshi com writes:The next day, the team used a modified version of TCP to achieve an even greater record. Using the same 30,000 km path, the network was able to achieve a throughput of 9.08 Gbps which is equal to 272,400 Tb-m/s for both the IPv6 multi and single stream categories. In doing so, the team surpassed the current IPv4 records, proving that IPv6 networks are able to provide the same, if not better, performance as IPv4.Good job. Two questions, though: (1) Do the throughput figures count only the data payload (i.e., anything above the TCP layer), or all the bits from the protocol stack? If the latter, it seems a little unreasonable to credit IPv6 with its own extra overhead -- though I'll concede that with jumbo datagrams, that's not all that much. (2) Getting this kind of throughput seems to depend on a fast physical layer, plus some link-layer help (jumbo packets), plus careful TCP tuning to deal with the large bandwidth-delay product. The IP layer sits between the second and third of those three items. Is there something about IPv6 vs. IPv4 that specifically improves perfomance on this kind of test? If so, what is it? Jim Shankland
Also, it's a "modified" TCP not just tuned. I wonder how modified it is? Will it talk to an un-modified TCP stack (whatever that really is) ?
-- Leigh Porter
Current thread:
- from the academic side of the house bmanning (Apr 24)
- Re: from the academic side of the house Adrian Chadd (Apr 24)
- Re: from the academic side of the house Leigh Porter (Apr 24)
- Re: from the academic side of the house Jim Shankland (Apr 24)
- Re: from the academic side of the house Leigh Porter (Apr 24)
- Re: from the academic side of the house Steven M. Bellovin (Apr 25)
- Re: from the academic side of the house Simon Leinen (Apr 25)
- Message not available
- Re: from the academic side of the house Simon Leinen (Apr 26)
- Re: from the academic side of the house JP Velders (Apr 29)
- Re: from the academic side of the house Adrian Chadd (Apr 24)
- Re: from the academic side of the house bmanning (Apr 29)