Blair, Philip S wrote: > > If you attached the Fluke to a switched port then it will only > see network > traffic destined to the device on that port and > multicast/broadcast traffic.
Very good point. If at all possible, all traffic should be analyzed. More below... > > It would seem than that your broadcast traffic is 0.8% of your > available > bandwidth, 80% of your 1% utilization. That seems reasonable, > I'd look > elsewhere for the problem. Broadcasts aren't using a lot of bandwidth, but they could still be a problem. On 100 Mbps Ethernet, you can have a maximum of 148,800 packets per second. Let's say we're using 1% of that (round up from 0.8%). Then we could have 1,488 broadcasts per second and still be using only 1% of the available bandwidth! That's a lot. Note the math requires that the packets be only 64 bytes each, and includes the FCS, preamble, and interframe-gap. If the packets were bigger, then there would be fewer per second, but broadcasts often are small. If you have slow PCs and/or NICs, they will indeed slow down with this level of broadcasts. A lot of networks still have the rather dangerous combination of 100 Mbps, chatty software, and PCs that are a few years old. The easiest and least expensive thing to fix, if there are problems, is probably the software or configuration of the software. Recently I saw a Windows 2000 server completely stop all its services when it got overwhelmed by broadcasts, and in this case it was only one station broadcasting. It was a station sending more frequently than once per second trying to find the non-existent server that was supposed to have the newest anti-virus updates. We were able to tell the client to stop this bad behavior, and, last I heard, the server had stopped having problems. What is this RCS software? It may have been written by software developers who have never considered the effects of their code on a network. You wouldn't believe how common that is! ;-) _______________________________ Priscilla Oppenheimer www.troubleshootingnetworks.com www.priscilla.com > > One option if your equipment supports it would be to span the > vlan traffic > to a port and plug the fluke into the spanned port. Depending > on you > network design you still may only see a subset of your traffic. > > Philip > > -----Original Message----- > From: Sim, CT (Chee Tong) [mailto:[EMAIL PROTECTED]] > Sent: Friday, October 04, 2002 6:35 AM > To: [EMAIL PROTECTED] > Subject: Fluke one touch Network assistant and RCS SafeNet > software > [7:54860] > > > Hi... > > > > Recently we found that LAN is getting slower and I used Fluke > One Touch > Network Assistant to check the health of network. And it gave > me the > following. > > > > Utilization 1% > > Error 0 % > > Collision 0% > > Broadcast 80 % > > IP 48% > > Station >250 % > > > > Do you think the fluke output indicate that our network got > problem? The > broadcast portion is quite high and I tried to find out which > pc contribute > to the broadcast, it gave me > > > > PC-A 6% > > PC-B 6& > > PC-C 6% > > PC-D 6% > > PC-E 6% > > PC-F 6% > > PC-G 6% > > PC-H 6% > > PC-I 6% > > > > All the PC that listed are installed with RCS software, when we > uninstalled > RCS from the PC, the PC's broadcast will be gone. Why RCS > caused the > broadcast, I am not sure whether it is the cause of our network > slowness or > not. Any idea? > > > > Thanks in advanced > > > > Sim > > > > > > > > > ================================================================== > De informatie opgenomen in dit bericht kan vertrouwelijk zijn > en > is uitsluitend bestemd voor de geadresseerde. Indien u dit > bericht > onterecht ontvangt wordt u verzocht de inhoud niet te gebruiken > en > de afzender direct te informeren door het bericht te > retourneren. > ================================================================== > The information contained in this message may be confidential > and is intended to be exclusively for the addressee. Should you > receive this message unintentionally, please do not use the > contents > herein and notify the sender immediately by return e-mail. > > > ================================================================== > > Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=54900&t=54887 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
