Re: filtering bridge

From: +Alan Hicks+ (alan_at_lizella.netWORK)
Date: 06/29/05 

Date: Wed, 29 Jun 2005 17:00:45 -0000

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

In comp.unix.bsd.openbsd.misc, Kernel Mustard dared to utter,
> The network configuration is ISP>cable modem>router/DHCP
> server providing non-routable addresses>bridge>switch>internal boxes.
>
> I read in one manual that a crossover cable was needed to connect the
> bridge to the internal machine. Is that true? If so, does the
> crossover cable go between the switch and the bridge or between the
> switch and each internal machine?

Yes it's true. Let me demonstrate this by showing the pin-out of a
regular 568B patch cable first.

1 = orange-white
2 = orange
3 = green-white
4 = blue
5 = blue-white
6 = green
7 = brown-white
8 = brown

1 2 3 4 5 6 7 8
| | | | | | | |
- ----------------------
       ||||||||
- ----------------------
| | | | | | | |
1 2 3 4 5 6 7 8

So you notice in a patch cable (a "regular" CAT-5 cable you might say)
that everything passes straight through. When you connect this to a
switch or hub, the switch or hub has receivers aligned somewhat like
this.

3 6 1 4 5 2 7 8

Basically the orange pair from the cable connects to the green pair on
the switch and vice-versa. Since you're using two NICs with no switch
between them, you need a cross-over cable made like this.

1 2 3 4 5 6 7 8
| | | | | | | |
- ----------------------
       ||||||||
- ----------------------
| | | | | | | |
3 6 1 4 5 2 7 8

With a cross-over cable, the cable itself connects the orange pair of
one NIC to the green pair of the other, and vice-versa. Make sense?
You need to connect the cross-over cable between the bridge and the
router so the connections look like this.

1 2 3 4 5 6 7 8
| | | | | | | |
1 2 3 4 5 6 7 8
| | | | | | | |
- ----------------------
       ||||||||
- ----------------------
| | | | | | | |
3 6 1 4 5 2 7 8
| | | | | | | |
1 2 3 4 5 6 7 8

If you've got it configured thusly and there are no problems with the
cable, you can be pretty sure the physical layer is alright, and you've
got some sort of software configuration problem.

- --
It is better to hear the rebuke of the wise,
Than for a man to hear the song of fools.
Ecclesiastes 7:5
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.2.4 (GNU/Linux)

iD8DBQFCwtN6zLTO1iU1uO4RAlIAAKDiEdxzqHj7Ah4RrV/T08MPRKC+NACeNN6R
a2ue2RxGuqI0NdvjeTAorkk=
=m6tN
-----END PGP SIGNATURE-----

Relevant Pages

  • cant get out of infinite while loop
    ... To get into the infinite loop, I write to a file the "on" status ... writing switch on ... ready to sleep for 10 seconds ... or die "Problem passing files to the bridge directory...$!"; ...
    (comp.lang.perl.misc)
  • Re: Is it possible to bridge three NIC on a Windows 2000 Server
    ... They could be referring specifically to a bridge type switch ... One uses Router methods (routing tables ... So if you join to broadcast domains with a Bridge, ...
    (microsoft.public.win2000.networking)
  • Re: Ethernet Bridging Question
    ... > construct a transparent firewall using an ethernet bridge (Nothing ... > ethernet traffic flow arrives at my device. ... The "learning" is automatic and, afaik, cannot be avoided in Linux. ... The switch does not generate any query or lookup ...
    (comp.os.linux.networking)
  • Re: DNS replication on 2 domain on 2 forests
    ... MAC switch ports. ... Routers work at the network protocol level to ... multi-port bridge, so, yes it does bridging functions, but on multiple ... based on source and destination MAC switch ports. ...
    (microsoft.public.win2000.dns)
  • Re: New Pickups installed
    ... I dropped a 59 in the neck and a JB in the bridge. ... and different sounds coming out of this guitar - oh man I'm in heaven. ... I am going to change out the switch, the jack and the other three ...
    (alt.guitar)