Here’s a simple hack for getting the power out of a cat5 cable, then putting it right back.
It’s a pair of PoE injector/extractors, connected by a 3-way 9mm plug that I crimped together out of leftovers.
By connecting the plugs with a back-to-back cat5 cable, you can extract the power from a PoE cable. This is useful for ‘midspan’ repeaters.
It’s also useful for plugging directly into PoE wireless radios when you’re on the roof. More on that in the next post.
We switched recently from CEF (Cisco Express Forwarding) to MLPPP (multilink point-to-point protocol). Both are schemes for sharing bandwidth across multiple fixed-bandwidth channels: in this case, T1s.
We went from 2 T1s in CEF to 3 T1s in MLPPP. Some observations.
We now have a couple of subscribers who are inaccessible using wireless, so they connect via a personal T1. Somebody else inquired by email, and here’s my reply:
Yes, we have a bunch of people in a
similar situation to you, and there are
a couple of options.First, as background, T1s here are
cheap by national standards, about
$288/month for a 3 year contract. Top
end T1 equipment - Cisco routers - are
now also very cheap: $244 each, so $688
for the pair to drive a point-to-point
T1. What this gives you is a personal
T1: a 1.5 megabit link to your house.Now the financing. What we have done
for a couple of people recently is this.
They order and sign contract with AT&T
for the point-to-point T1. One end of
the link (and one Cisco) is at their
house. The other end of the T1 is here:
we plug it into our giant connection and
bingo, they have regular internet
service.Then they can either:
1. Pay $90/month to us for regular
subscription for business-class service.or:
2. If they are in a place where we can
feasibly beam service to their
neighbors, then we waive their $90
subscription, put up a transmitter
antenna and start a new cluster of
acelere subscribers. Obviously, this
isn’t for everyone: being part of your
ISP’s infrastructure means that we need
access to the equipment. On the other
hand, most transmitter sites go for 12
months+ without any kind of servicing.So to summarize in a single sentence:
you get a T1 and you pay $288 to the
phone company for the pipe, and either
$90 or nothing to the ISP for internet.
It is suprisingly tricky to enable telnet access on a Cisco box. Here’s how:
Router#config t
Enter configuration commands, one per line. End with CNTL/Z.
Router(config)#enable secret mysecretpassword
Router(config)#line vty 0 4
Router(config-line)#password mysecretpassword
Router(config-line)#login
Router(config-line)#^Z
Nice list of FreeBSD-related links
I often find myself on some roof, configuring wireless clients using a laptop. Very often this involves changing the IP address of the laptop. This is a fiddly process involving tabs, scroll lists and dialog boxes.
As an alternative, here are some handy scripts to do this from the command-line:
In November 2004 we upgraded to 2 T1s - which they call 2XT1. This 3-megabit connection has worked well enough, but with the number of people rising steady (today we have 121 subscribers) there is continuous bandwidth shortage. When I talked with the AT&T reps I deal with, they gave me a good deal on 3XT1 connection, but also mentioned that there is a better bonding scheme available.
We had been using CEF (Cisco Express Forwarding), but the new option is MLPPP (Multilink PPP). The big difference is that the packet order is preserved - good for VoIP. Our current VoIP works well enough when the load is light, but above 50% loading, becomes very choppy indeed. So I hope that MLPPP will improve that, at least.
A couple of years ago we needed a Cisco router to run a T1. It cost about $450, refurbished. Last week we needed two more, and the price was an amazing $288 each, including shipping.
These units are Cisco 2610s, with a WIC 1DSU T1 cards.
I’m adding a subscriber using a point-to-point T1 circuit. For this we bought a pair of Cisco 2600s. I’m setting up the Ciscos to bridge the interfaces - instead of routing - so the remote end just looks like part of the main network. Here’s how:
enable
configure
bridge-group 1 protocol ieee
interface Serial 0/0
ip address 192.168.0.X 255.255.255.0
encapsulation ppp
no shutdown
bridge-group 1
exit
interface Ethernet 0/0
no shutdown
bridge-group 1
exit
no ip routing
exit
copy system:running-config nvram:startup-config
Doing this on each end (with different addresses for 192.168.0.X) makes a bridged link across the T1.
From email:
What would I do to setup a WISP for a neighborhood within a 2-5 mile radius?
I am having excellent results with Deliberant products. In particular
the DLB2700 is a really powerful radio. It can run as either an
access point or a client, and in client mode can work as a bridge
or a NATting firewall.
The DLB2714 has an integrated 14dBi antenna, and is intended for
clients. The DLB2700 has an external antenna connector, so you can
use it with a panel for clients (I use 19dBi panels and 24dBi grids
with it). When using the DLB2700 as an access point, you can just
plug in an omni antenna.
Easy enough.