nanog mailing list archives
Re: IPv4 address length technical design
From: Masataka Ohta <mohta () necom830 hpcl titech ac jp>
Date: Thu, 04 Oct 2012 17:10:00 +0900
Eugen Leitl wrote:
Except that these will be pure photonic networks, and apart from optical delay lines for your packet buffer you'd better be able to make a routing (switching) decision
Seriously speaking, that is the likely future as 1T Ethernet will be impractical. The point is to use 1Tbps packet by encoding a packet simultaneously over, for example, 100 wavelengths each encoded at 10Gbps.
while few bits of the header have streamed by your photonic router circuit. There is no time for any table look-ups, obviously.
At 1Tbps, 500B packet is 4ns long, which is long enough for full /24 (with limited support for /32) look up. While wavelengths containing header information are used for table look up and rewritten, rest of the wavelengths are delayed. What you can't use with fiber delay lines is hash table, which means large number (beyond CAM capacity) of Ethernet MAC addresses is unusable and IPv6 with current allocation scheme is bad.
And optical gates are *really* expensive, so better use few of them. And don't add too many gate delays, too.
That's one reason why we should use 1Tbps packets. A gate should switch not 10Gbps but 1Tbps or faster data. Another reason is that 1Tbps packet needs 100 times shorter delay lines to buffer than 10Gbps ones.
Above describes your setting for the next protocol. There is not a lot of leeway in design space, I'm afraid.
Just keep using IPv4. Masataka Ohta PS See ftp://chacha.hpcl.titech.ac.jp/IEEE-ST.ppt presented at a summer topical of IEEE photonic society.
Current thread:
- RE: IPv4 address length technical design, (continued)
- RE: IPv4 address length technical design Tony Hain (Oct 03)
- Re: IPv4 address length technical design George Herbert (Oct 03)
- RE: IPv4 address length technical design Tony Patti (Oct 03)
- Re: IPv4 address length technical design Valdis . Kletnieks (Oct 03)
- RE: IPv4 address length technical design Tony Hain (Oct 03)
- Re: IPv4 address length technical design Dave Crocker (Oct 03)
- Re: IPv4 address length technical design Jay Ashworth (Oct 03)
- Re: IPv4 address length technical design Jimmy Hess (Oct 03)
- Re: IPv4 address length technical design Valdis . Kletnieks (Oct 03)
- Re: IPv4 address length technical design David Conrad (Oct 03)
- Re: IPv4 address length technical design Eugen Leitl (Oct 03)
- Re: IPv4 address length technical design Masataka Ohta (Oct 04)
- Re: [tt] IPv4 address length technical design Eugen Leitl (Oct 04)
- Re: [tt] IPv4 address length technical design Masataka Ohta (Oct 04)
- Re: IPv4 address length technical design Barry Shein (Oct 04)
- Re: IPv4 address length technical design Mark Andrews (Oct 04)
- Re: IPv4 address length technical design George Herbert (Oct 04)
- Re: IPv4 address length technical design Jay Ashworth (Oct 04)
- Re: IPv4 address length technical design Barry Shein (Oct 05)
- Re: IPv4 address length technical design Jay Ashworth (Oct 05)
- RE: IPv4 address length technical design nanog (Oct 06)
- Re: IPv4 address length technical design William Herrin (Oct 05)