Path: utzoo!attcan!uunet!husc6!bu-cs!kwe From: kwe@bu-cs.BU.EDU (kwe@bu-it.bu.edu (Kent W. England)) Newsgroups: comp.dcom.lans Subject: Re: Does anyone rent TDR's? Message-ID: <24956@bu-cs.BU.EDU> Date: 19 Sep 88 16:41:04 GMT References: <425@aoa.UUCP>Reply-To: kwe@buit13.bu.edu (Kent England) Followup-To: comp.dcom.lans Organization: Boston Univ. Information Tech. Dept. Lines: 43 In article ron@topaz.rutgers.edu (Ron Natalie) writes: >The Ethernet TDR's are generally cheaper. [...] > >I actually have a Cabletron unit. We've had it out a couple >of times, but we haven't actually found a problem that it >would have solved. Usually just serves to point out that >the physical cable is NOT what is causing the failure. > >-Ron Just a follow-up to this: You should have a cable TDR'ed before installation when it is still spooled and TDR'ed after installation. The first test is the "cable acceptance" test and the second is the "installation acceptance" test. You can have the installer do both TDRs as part of his contract. Any contractor with Ethernet experience can do that. You usually won't need to TDR a cable again, unless you let just anybody install stuff on it. :-) You might be able to do without one, unless you have miles and miles of cable. However, another trick we use is strategically placed barrel connectors. We usually have floor cables run into a closet to access a riser. There are barrel connectors placed in the closets that let us physically partition a segment for diagnostics. It's actually easier and less disruptive than a TDR, for to TDR a cable you have to disrupt traffic on it. Ideally you want the cable completely shutdown to traffic, which may be impractical. We do all the transceiver installs ourselves and rarely find the need for a TDR beyond acceptance testing, but we do have one because they are relatively cheap. If you don't have an Ethernet analyzer, buy that first, then buy a LAN-MD (or other), buy the TDR last. Hope this helps. Upon further reflection [pardon that pun], a TDR would be nice when some other contractor damages your cable, but again we usually find it faster by inspection and by asking questions. The bright yellow color we use saves a lot of damage. I guess contractors will waste anything black or aluminum/steel colored (like broadband coax) before they'll touch that funny yellow stuff. (Anybody know a vendor that sells orange broadband coax?)