RE: E1 - RJ45 pinout with ethernet crossover cable
-----Original Message----- From: owner-nanog@merit.edu [mailto:owner-nanog@merit.edu]On Behalf Of Sam Stickland Sent: Friday, February 25, 2005 6:26 AM To: nanog@nanog.org Subject: E1 - RJ45 pinout with ethernet crossover cable
Hi,
Quick question: If I have two E1 ports (RJ45), then will running a straight ethernet cable between the two ports have the same affect as plugging a ballan into each port and using a pair of coax (over a v. short distance).
If I understand you correctly, you can eliminate the coax altogether with a standard t1/e1 cable betweem the dsu's: 1 2 3 4 5 6 7 8 RX Tip RX Ring n/c TX Tip TX Ring n/c n/c n/c Just for reference, here's ether xover: Crossover Cable (EIA/TIA 568A) RJ-45 PIN RJ-45 PIN 1 Rx+ 3 Tx+ 2 Rc- 6 Tx- 3 Tx+ 1 Rc+ 6 Tx- 2 Rc-
Likewise would using an ethernet crossover cable have the same affect as swapping the pairs round on one balland.
Not that I know of, but I've never attempted what you describe. Putting the baluns in the loop will destroy the framing i.e. it's going to try and convert b8zs/ami to 802.x. [ SNIP ] -M<
--On 25 February 2005 09:43 -0500 "Hannigan, Martin" <hannigan@verisign.com> wrote:
Not that I know of, but I've never attempted what you describe. Putting the baluns in the loop will destroy the framing i.e. it's going to try and convert b8zs/ami to 802.x.
How does a balun destroy the framing (or rather line coding)? It's just a pair of transformers, and hence AC characteristics pass through intact. All you've done is converted impedance (and, IIRC, line voltage). Alex
Not that I know of, but I've never attempted what you describe. Putting the baluns in the loop will destroy the framing i.e. it's going to try and convert b8zs/ami to 802.x.
A Balun (BALanced to UNbalanced) is simply an impledence matching mechanism. Crossover is still required. -- -Steve
participants (3)
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Alex Bligh -
Hannigan, Martin -
Steve Meuse