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=33354&t=33256 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
