[78226] in North American Network Operators' Group
RE: E1 - RJ45 pinout with ethernet crossover cable
daemon@ATHENA.MIT.EDU (Hannigan, Martin)
Fri Feb 25 09:49:13 2005
Date: Fri, 25 Feb 2005 09:43:53 -0500
From: "Hannigan, Martin" <hannigan@verisign.com>
To: "Sam Stickland" <sam_ml@spacething.org>, <nanog@nanog.org>
Errors-To: owner-nanog@merit.edu
> -----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
>=20
>=20
>=20
> Hi,
>=20
> Quick question: If I have two E1 ports (RJ45), then will running a=20
> straight ethernet cable between the two ports have the same affect as=20
> plugging a ballan into each port and using a pair of coax (over a v.=20
> 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 =20
RX Tip RX Ring n/c TX Tip TX Ring n/c n/c n/c =20
Just for reference, here's ether xover:
Crossover Cable (EIA/TIA 568A)
RJ-45 PIN RJ-45 PIN=20
1 Rx+ 3 Tx+ =20
2 Rc- 6 Tx-=20
3 Tx+ 1 Rc+=20
6 Tx- 2 Rc-=20
> Likewise would using an ethernet crossover cable have the=20
> same affect as=20
> swapping the pairs round on one balland.
Not that I know of, but I've never attempted what you=20
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<
