Ah, this is one of those cases where I wasn't really answering the question you were asking. :-) Sorry about that! I know I have some information like that around here but I can't find it at the moment. Perhaps some of the listmembers that are more versed in network analysis than I could provide some links. If I can find the links that I've used in the past for this type of information, I'll let you know. Regards, John >>> [EMAIL PROTECTED] 6/26/01 2:04:07 PM >>> You're comparing apples to oranges. A 10BaseT LAN is a shared medium, which explains the oft-quoted-but-not-quite-accurate 40% max usage figure. The theory is that with CSMA/CD, as traffic increases so do collisions, which forces retransmits. This is exacerbated in a half duplex environment. Dana's Comment - I realize that LAN and WAN environments are different. I was just using the 10Mb quote as an example. WAN links, such as a T-1, are synchronous (or isochronous or pleisochronous or some other x-ochronous word that I don't understand) full duplex connections. This means that frames are travelling boths directions over the link at the same speed regardless of the amount of traffic to be carried. In the case of a T-1, if you have 1.536 Mb/s of data to send, then go for it. The bandwidth is there if you need it. For you hair-splitters, I'm purposefully not getting overly detailed. Of course, you have to factor in packet headers in your calculations. Any data you have to send has to be encapsulated first. If you're using IP, then any data packets must be encapsulated with a UDP or TCP header and then with an IP header. This packet then must be placed inside whichever datalink frame you're using, whether it's Ethernet, HDLC, PPP, or whatever. All of this creates overhead that you have to take into account when calculating how much bandwidth you actually have available. Dana's Comment - On WAN links, I just was wondering how what percentage I should give to headers, framing, signaling, etc. One Cisco SE told me that I should calculate 25% to cover those issues. I.E. On a 512K link I could only expect 384K of usable bandwidth. I figured that different technologies should have different percentages - ATM vs. ISDN vs. Frame Relay etc. That is what I am looking for is specifics per technology as opposed to a general WAN figure. I hope these notes clarify my question. But the moral of the story is that point-to-point WAN links suffer from different issues than CSMA/CD networks. Dana's comment - John, thanks for your comments. Regards, Dana CCNP, CCDP Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=10001&t=10001 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
