Related to the subject of ethernet utilization, the following paper, while dated, provides some interesting insight.
http://www-2.cs.cmu.edu/~srini/current_class/readings/B+88.pdf At 09:06 AM 1/27/2002 -0500, you wrote: >Priscilla is absolutely right, its a fuzzy question. I have just two >things to add. > >If the network is "mainly LAN" that suggests that there are some wide >area links. Because wide area links are usually slower than local area >media and are used by lots of users, congestion on them is definitely >worth checking. Also, if there are complaints about response to a >distant resource, you should also look at delay (which you could check >with ping). If people are complaining about the time required for a >complex interaction (one requiring many packets in both directions), its >possible that a moderate amount of delay can be a problem. > >Second, ethernet is different from most media. Because of the way >ethernet works utilization numbers require some interpretation, at least >for half duplex operation. This necessarily includes segments used by >more than two hosts, if you have any. There are no definite definitions >of what ok and whats too much, but utilization above 40% (and maybe >less), IMHO, should be considered congested. > >HTH, > >Jason > >Priscilla Oppenheimer wrote: > > > At 06:36 PM 1/25/02, Doug Korell wrote: > > > >>I have checked individual switches and routers for utilization before but > >>when asked what the average utilization of an entire network (mainly LAN) > >>is, what exactly makes up this figure? I am working on getting a packet > >>sniffer which I know will help take all the variables and give me an answer > >>but is there a way to do it without one? How about SNMP queries? If anyone > >>can help explain this or knows of a good website, please let me know. > >> > > Thanks. > > > > That's a rather old-fashioned question. It used to make sense on a shared > > LAN. You could put a Sniffer or RMON Probe in a shared hub and get a > > measurement of how much of the overall, shared 10-Mbps capacity was in use > > on the LAN. > > > > In these days of microsegmented, switched networks, you can't do that > > easily. You can only monitor the switch ports that you mirror. > > > > Each switch port provides full capacity, usually 100-Mbps full duplex. >(You > > would have to know if that's true for your network.) Overall capacity is > > the number of ports times the speed. Overall utilization would be the > > aggregate of each port utilization divided by the overall capacity, I > > guess. (But people don't actually tend to make that calculation.) > > > > Another capacity issue is the backplane speed of the switches and routers > > in use. That could actually be more of a bottleneck than overall LAN > > capacity. > > > > Did a pointy-haired boss type ask you to make this measurement? I'm afraid > > you might have to explain that it doesn't make sense. Work with them to > > specify which individual LAN ports need monitoring, rather than trying to > > find an overall number. The ports that you should monitor are any ones >that > > aggregate traffic. Check the utilization on trunk lines and links that go > > to mission-critical servers. Also, check utilization on an end-user port > > while doing some typical processes, including logging into the network. It > > might also make sense to check other performance metrics such as response > > time. > > > > Hopefully others will respond too in case I have a blind spot with regards > > to this, but my initial thought is that this is not the right performance > > measurement to be considering for a modern LAN. > > > > Priscilla > > ________________________ > > > > Priscilla Oppenheimer > > http://www.priscilla.com Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=33418&t=33256 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
