On Mon, 19 June 2000, "Bora Akyol" wrote:
As long as most end users are running Ethernet, Fast Ethernet, DSL or Cable Modems, what is the point of jumbo frames/packets other than transferring BGP tables really fast. Did any one look into how many packets are moved through an OC-48 in 1 seconds. (approx. 6 million 40 byte packets). I think even without jumbo frames, this bandwidth will saturate most CPUs.
Jumbo frames are pointless until most of the Internet end users switch to a jumbo frame based media.
Yes, they look cool on the feature list (we support it as well). Yes they are marginally more efficient than 1500 byte MTUs ( 40/1500 vs 40/9000). But in reality, 99% or more of the traffic out there is less than 1500 bytes. In terms of packet counts, last time I looked at one, 50% of the packets were around 40 byte packets (ACKs) with another 40% or so at approx 576 bytes or so.
What is the big, clear advantage of supporting jumbo frames?
When 1500 byte frames from the customer's LAN enter the customer's router and enter some form of IP tunnel, then a core fabric which supports larger than 1500 byte frames will not cause fragmentation. It's not necessary to do the full jumbo size frames. I suspect that supporting two levels of encapsulation will be enough in 99.9% of the cases. For the sake of argument, what would be the downside of using a 2000 byte MTU as the minimum MTU in your core? --- Michael Dillon Phone: +44 (20) 7769 8489 Mobile: +44 (79) 7099 2658 Director of Product Engineering, GTS IP Services 151 Shaftesbury Ave. London WC2H 8AL UK