North American Network Operators Group Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical Re: E1 - RJ45 pinout with ethernet crossover cable
On Fri, 25 Feb 2005, Per Gregers Bilse wrote: > You generally need a router or something else acting as store-and-forward. > E1/T1 and other plesiochronous circuits are just that, near synchronous, > and certainly not asynchronous. Things cannot be transmitted or received > without clocks on both sides being in synch, which may or may not be the > case if you try to hook up two arbitrary lines. Moreover, assuming both > are terminated towards you, both will be driving clock for your router > ("terminal equipment") to pick up, and they are not going to be in phase. > Then there's the issue of different options for framing and various > control bits, etc. You might get lucky if you could convince one of the > circuit providers to take clock from you (which would then come from the > other circuit), but you would probably still need to deal with signal > level, framing, and other issues (ie, have a box of sorts). All in all, > an old cisco 2500 is probably the cheapest and most troublefree solution. In every case I've dealt with when setting up a back-to-back connection of T1 or E1 circuits, the appropriate crossover connection between transmit and receive (1,2 - 4,5 on 8-pin jacks, swap Tx and Rx on co-ax) and setting one side to supply internal clock and the other side to recover clock from line works just fine. -- Jay Hennigan - CCIE #7880 - Network Administration - [email protected] WestNet: Connecting you to the planet. 805 884-6323 WB6RDV NetLojix Communications, Inc. - http://www.netlojix.com/
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