EIA-TIA Cabling Specifications

rj45

Crossover Cable
RJ-45 PIN RJ-45 PIN
1 Rx+ 3 Tx+
2 Rc- 6 Tx-
3 Tx+ 1 Rc+
6 Tx- 2 Rc-
wirea
wire
Straight Through Cable
RJ-45 PIN RJ-45 PIN
1 Tx+ 1 Rc+
2 Tx- 2 Rc-
3 Rc+ 3 Tx+
6 Rc- 6 Tx-

Use a straight thru cable assembly,568B on both ends when connecting Hub to Xcvr or NIC Card. When connecting hub to hub, Xcvr to Xcvr, or NIC to NIC, the wires must crossover at the opposite end of the cable assembly,use the 568B on one end, 568A on the other end.

Interconnecting Your Hubs, Transceivers, and NIC Cards

A crossover cable is required when connecting a Hub to a Hub, or a Transceiver to Transceiver, or NIC to NIC card, or Transceiver to NIC card. When connecting a Hub to a transceiver or NIC card, a straight through cable is always used. Please Note: Some products are equipped with internal switches that can internally cross the twisted pairs.

 

10BASE-T Crossover Wiring


When connecting two twisted-pair MAUs together over a segment, the transmit data pins of one eight-pin connector must be wired to the receive data pins of the other, and vice versa. The crossover wiring may be accomplished in two ways: with a special cable or inside the hub.

For a single segment connecting only two computers you can provide the signal crossover by building a crossover cable, with the transmit pins on the eight-pin plug at one end of the cable wired to the receive data pins on the eight-pin plug at the other end of the crossover cable and vice versa.
crossover

FIGURE 5.2 10BASE-T crossover cable

However, when you are wiring multiple segments in a building it’s much easier to wire the cable connectors “straight through,” and not worry about whether the wires in the jumper cables or other twisted-pair cables in your building have been correctly crossed over. The way to accomplish this is to do all the crossover wiring at one point in the system: inside the multiport hub.

The standard recommends that the signal crossover be done internally in each hub port. If the crossover function is done inside a hub port, then the standard notes that the port should be marked with an “X.”

Avaya/Lucent/Orinoco RG-1000 Residential Gateway notes

rg1000I have a wireless network segment at home using the Lucent RG-1000 residential gateway. The RG-1000 has been passed around from WaveLAN to Proxim to Lucent to Avaya to Agere and back to Proxim, and so finding documentation and drivers can be a problem. Here are my notes, should anyone else be looking for information about this little router/gateway/access point.

The documentation that came with the gateway covered little more than running the basic setup, and didn’t cover important issues like how to reset the firmware, how to configure the firewall, how to limit access to the RG by MAC address and so on. I was able to learn more about the router on the web, and programs. The routers are quite popular, and googling “RG-1000” came up with a lot of hits.

1. Finding drivers is a little complicated. Proxim originally sold the router and card as a part of the WaveLAN line. Lucent either bought the line or Proxim and re-named it Orinoco. Lucent then spun off the company to become Agere and/or Avaya. Proxim re-appeared somewhere along the line, and now has drivers available at http://www.proxim.com. Because of this lineage, finding the right driver is difficult. I’m using the card drivers from http://www.proxim.com, the basic setup utility from http://www.avaya.com and the AP configuration utility from http://www.agere.com.

2. The Lucent/Orinoco RG-1000 is a residential gateway with bridging mode, full NAT router mode, and has a feature-set resembling many appliance routers. The Avaya RG-1 appears to be a re-branded RG-1000, and may have an ethernet port. The AP-500/1000 is an access point without the NAT router features and with more advanced bridging reporting/diagnostics. The Apple Airport resembles the RG-1000/RG-1. Oddly enough, the firmware is interchangeable between all the models, so you can convert a bridging only AP-500/1000 into a RG-1/RG-1000 by uploading a different firmware set.

The model I own has no ethernet ports, making it a little useless as a router if you have wired machines. It does have a V.90 modem, and can be configured as a dial-on-demand router. I’m going to use my PPP account as a dial backup.

3. There are two “official” configuration utilities – the RG setup tool, which is basic and lacks several important configuration tools, like MAC address security. The other utility is the Access Point configuration tool, which despite the name, can configure any of the compatible models. Once you make changes with the AP configuration utility, however, if you run the RG setup tool, it complains about non-RG values and resets the router to defaults. There is a freeware configuration utility called freebase at http://freebase.sourceforge.net that also looks promising, but it seems like some features are only available with AP manager.

A summary of features available with each of the tools:

RG Setup Utility : Basic network configuration, will also update router firmware to the latest version seamlessly.

AP Configuration tool: Allows you to set NAT parameters, virtual server ports, access passwords, MAC Address security, PPPoE information, SNMP information, and DHCP server configuration. From the monitor page, you can check on ethernet, IP, wireless, ICMP and bridging information.

Freebase: Network configuration, DHCP and NAT, Port forwarding, access control, login scripting (?) and modem control.

4. The Lucent/Orinoco documentation is not very helpful on some points – resetting the router, for example. To reset the router, if you have an ethernet port, plug into it and run the RG setup. If you have a wireless only model, you need to use the Forced Reload feature. Power the router down, and while it’s booting, press and hold the “Forced Reload” button. The power light will glow amber. When this happens, the router WEP encryption password and access password is disabled. Log in using the RG setup utility, and configure the router within 5 minutes or the router will revert to standard operation.

5. The Windows 2000 drivers shipped with the operating system identify the card as a WaveLan/IEEE card, and do not work. Instead, use the newest drivers from http://www.proxim.com, which as of today are the version 7.4, winter 2002 drivers. The gold cards support their own 128-bit RC4-based encryption scheme, as well as WEP+.

6. Lucent/Avaya/Agere/Proxim/whoever claim that you can’t plug an external antenna into the unit. Inside the unit is an Orinoco wireless card, which has an antenna port. If you drill a hole in the case, you can use the AP-1000 external antenna for extended range. I can reach the upstairs portions of my house, so I’ll probably hold off on upgrading the antenna.

I’m going to use the freebase tools to configure it. Since I’m using it as an access point, once the dust settles I’m going to use the AP-500/1000 firmware to get the enhanced bridging reporting.

Apparently, there’s a way to get this thing to run Linux! The router is an underclocked 486. An enterprising network admin could design a huge centrally-managed wireless network that booted and got configuration information via bootp on the cheap. Apparently at one time, Lucent closed these things out at $60 each with a client PC card!

Some sites of interest:

Google Posterity Post — flashing DD-WRT onto a Belkin FD4230-4 router

I’ve had this little router for years, bought it for $20 with a $20 rebate, and since upgrading the OS to DD-WRT it’s performed flawlessly.

I have a Belkin wireless router (model number: F5D7230-4 v1444). For some reason, the “Virtual Server” (or “Port Forwarding”) did not work correctly. It’s obviously a firmware problem. I checked the firmware version and my router had the latest firmware from Belkin. I wrote to Belkin Customer Service but who knows how long I have to wait to a response from them.

Thus I tried to find a custom firmware for my router on the Internet and I came across a firmware project called “DD-WRT“. The project was targeted at making custom firmwares for Linksys WRT54G/GS routers. However, there is a micro version which can be used on Belkin F5D7230-4 v1444. I decided to give it a try.

Read More

Spamassassin settings for bayesian filtering

SPAM fighting (A talking to myself, want to get this in google post…)
I’ve been getting a HUGE number of SPAMs slipping through my SPAMASSASSIN filter, and have been trying to figure out how to combat it. SPAMs are getting flagged as BAYES_00, which gives them a negative score.

I was moving them into the SPAM folder, then running sa-learn nightly to train.
I’ve started moving those SPAMs into a separate folder, then running sa-learn—forget to forget the scoring, then moving them back into the SPAM folder and re-running sa-learn.

I’ve also tried changing the score for BAYES_00 from negative to 0 by adding the following line to my user_prefs file:

score BAYES_00 0.1

I should look at getting my addresses out of Outlook and into a whitelist format for Spamassassin.
So, the process looks like:

Move mis-filed HAM from SPAM to SPAM-moved

/usr/bin/sa-learn—forget—dir /home/kweiske/Maildir/.SPAM-moved/cur
/usr/bin/sa-learn—spam—dir /home/kweiske/Maildir/.SPAM/cur

Move the mis-files HAM from SPAM-moved to Inbox

/usr/bin/sa-learn—ham—dir /home/kweiske/Maildir/cur

Fingers are crossed.

There’s a good online resource regarding Bayesian filtering at http://spamassassinbook.packtpub.com/chapter9.htm, a free chapter in an online book.

Weird networking knockoff

This is one of the strangest knock-offs I’ve seen; they’ve totally borrowed the Linksys case design, but use a one-antenna board:

 

WR214E-unit

I’m pretty sure that even the B Linksys routers had two antennae.

In another project, I have my FON router operational. It’s in a DMZ and allows access to other FON users for free. Check out the web page, it’s a great idea.

The FON router is a WRT54GL, apparently it’s a Linux version of the WRT54G series. Older G series routers ran Linux, newer ones run VXworks. Mine is the router equivalent of putting “Classic” at the name of anything. :)

I’m going to hook one up as the FON point, another as a router to handle PPTP services, featureful firewalling, and act as a border host.

Having a router running embedded Linux changes the way I think of appliance routers. Instead of a box with limited functionality, a finite development path and obscure featureset, linux routers are functional, expandable, can be extended beyond the manufacturer’s end-of-life, and are easy to understand if you know Linux.

The Netopia R- and 3500-series routers and SMC barricades I’ve loved over the years seem crippled by comparison.