North American Network Operators Group Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical RE: jumbo frames
You are correct and my original answer stated such. The original question didn't differentiate. It simply asked who was using jumbo packets. > -----Original Message----- > From: Tony Hain [mailto:[email protected]] > Sent: Thursday, April 26, 2001 12:55 PM > To: Roeland Meyer; ALH-IETF; John Fraizer; Paul Lantinga > Cc: [email protected] > Subject: RE: jumbo frames > > > > Roeland you are talking about jumbo frames from the end > system lan, while > John is talking about only using the jumbo frames between the > routers. My > point was that in John's environment the packets will all be > 1500 since the > packets are restricted to that size just to get to the router > with the GE > interface. I understand that there are perf gains as long as > the entire path > supports the larger packets, but I don't understand the claim > that having a > bigger pipe in the middle helps. > > Tony > > -----Original Message----- > From: [email protected] [mailto:[email protected]]On Behalf Of > Roeland Meyer > Sent: Thursday, April 26, 2001 12:13 PM > To: '[email protected]'; John Fraizer; Paul Lantinga > Cc: [email protected] > Subject: RE: jumbo frames > > > > From: Tony Hain [mailto:[email protected]] > > Sent: Thursday, April 26, 2001 11:47 AM > > > > April 26, 2001 9:29 AM John Fraizer wrote: > > > We only have jumbo frames enabled on router<->router links. > > The GigE > > > ports facing the aggregation switches runs standard 1500 MTU. > > > > Hence my original question. Packets across the GE will be > > 1500 unless you > > are packing them. > > > > April 25, 2001 8:10 PM John Fraizer wrote: > > > Partially because I can. Partially because there seems to be a > > > performance increase when you start stuffing the pipe. > > > > Assuming you are just passing the packets as received from > > the aggregation > > switch, this would only happen if your router hardware was better at > > managing jumbo buffer allocations than 1500B ones. Clearly it > > will waste > > large chunks of memory, so do you have measurements to show > the actual > > performance increase? > > This depends on the type of traffic. We use it to enhance > performance of the > data tier. We've jiggered the TCP/IP stacks for ~4500 byte > packets and have > knee-capped the slow-start algorithm (which doesn't make > sense in a pure > switched environment anyway). What we then wind up with, is a > dedicated data > LAN between our application servers and the Oracle database > servers. It > comes out to about an order of magnitude increase in > performance and SQL > query responsiveness. At first we went to jumbo packets. We saw such a > radical improvement that we started investigating and found > the slow-start > issue. Jumbo packets are one way around the slow-start > problem if you can't > jigger the stack itself. Most of the queries are reasonably > short so we saw > some serious improvements by killing the slow-start. If you > can modify your > IP stack then it still pays to use jumbo packets because you > reduce the > overhead on the wire. > > We got sufficient performance improvement that we were able > to defer GigE > implementation, at some sites. Those sites are using switched > FDX 100baseTX. > >
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