10/100 switches and NICs pretty much universally do not support jumbos. Joel's widget number 2
On Nov 26, 2010, at 8:02, Brandon Kim <brandon....@brandontek.com> wrote: > > Where would the world be if we weren't stuck at 1500 MTU? I've always kinda > thought, what if that was larger > from the start.... > > We keep getting faster switchports, but the MTU is still 1500 MTU! I'm sure > someone has done some testing with > a 10/100 switch with jumbo frames enables versus a 10/100/1000 switch using > regular 1500 MTU and compared > the performance..... > > > > >> Subject: RE: Jumbo frame Question >> Date: Thu, 25 Nov 2010 21:14:02 -0800 >> From: gbon...@seven.com >> To: harris....@hk1.ibm.com; nanog@nanog.org >> >>> Hi >>> >>> Does anyone have experience on design / implementing the Jumbo frame >>> enabled network? >>> >>> I am working on a project to better utilize a fiber link across east >>> coast >>> and west coast with the Juniper devices. >>> >>> Based on the default TCP windows in Linux / Windows and the latency >>> between >>> east coast and west coast (~80ms) and the default MTU size 1500, the >>> maximum throughput of a single TCP session is around ~3Mbps but it is >>> too >>> slow for us to backing-up the huge amount of data across 2 sites. >> >> There are a lot of stack tweaks you can make but the real answer is >> larger MTU sizes in addition to those tweaks. Our network is completely >> 9000 MTU internally. We don't deploy any servers anymore with MTU 1500. >> MTU 1500 is just plain stupid with any network >100mb ethernet. >> >>> The following is the topology that we are using right now. >>> >>> Host A NIC (MTU 9000) <--- GigLAN ---> (MTU 9216) Juniper EX4200 (MTU >>> 9216) >>> <---GigLAN ---> (MTU 9018) J-6350 cluster A (MTU 9018) <--- fiber link >>> across site ---> (MTU 9018) J-6350 cluster B (MTU 9018) <--- GigLAN >> --- >>>> >>> (MTU 9216) Juniper EX4200 (MTU 9216) <---GigLAN ---> (MTU 9000) NIC - >>> Host >>> B >>> >>> I was trying to test the connectivity from Host A to the J-6350 >> cluster >>> A >>> by using ICMP-Ping with size 8000 and DF bit set but it was failed to >>> ping. >>> >>> Does anyone have experience on it? please advise. >>> >>> Thanks :-) >> >> You might have some transport in the path (SONET?) that can't send 8000. >> I would try starting at 3000 and working up to find where your limit is. >> >> Your description of "fiber link across site" is vague. Who is the >> vendor, what kind of service? >> >> > >
