My Tractor Forum banner

1 - 15 of 15 Posts

·
Machinery enthusiast
Joined
·
4,257 Posts
Discussion Starter #1
Just changed ISP's and service from a 3.0 DSL to 10.0 cable and ran into several issues I wasn't prepared for, nor the installer for that matter.

My old DSL modem had builtin wireless and a 4 port switch so I pretty much used it for everything. I later installed another wireless router and set it up as an access point to extend the range but thats all it did.

When he cut me over to his cable modem I replaced the DSL modem w/a dumb switch and went to test my laptop in the shop and it would not aquire DHCP. He connected up his laptop at the modem and surfed. I then tried my laptop on the cable modem and after resetting it my laptop would surf, but not through the switch w/the other devices plugged in.
He left as his responsibility was complete since one device could surf but didn't know why I couldn't surf through the switch.
I was thinking that I needed a more powerful switch.
My PC server worked but thats it. After process of elimination I deterined as long as only one device was plugged into the switch & cable modem I could surf and that I must have plugged it in 1st and it got the IP.
A call to Comcast tech support verified that their modem would only issue one single DHCP IP and would not work more than 1 device period. Luckily I had a spare DSL/Cable router w/4 port switch in my stash and once I got it setup my little LAN was back to working as before.
Interesting to say the least.
Oh and they had to configure the cable modem for my email account too. Very unusual I rekon.
Dave
 

·
The Admin from... Nowhere!
Joined
·
13,935 Posts
That IS kinda "dark-ages" for them.... I THINK my ISP provides up to 8 IPs, I just haven't ever found out because the most I have in front of my router (on their modem) is 4-5 at a time.....
 

·
Administrator
Joined
·
21,252 Posts
I have Comcast and use my desktop and a laptop, but it goes thru a wireless router to do that. No problem there at all.
 

·
The Magnificent
Joined
·
20,952 Posts
Your cable modem will issue a single IP address via DHCP.

You need a separate router/wi-fi access point which will connect to the cable modem. It receives the cables companies single IP address, and allows you to connect wireless and other (my waireless access point has 4 outlets) devices to the single "front end" IP address via a process called Network Address Translation.

In short, you have to drop another $50.
 

·
Machinery enthusiast
Joined
·
4,257 Posts
Discussion Starter #6
No need to drop another $50, as I had an old DSL/cable router w/4port switch in my stash. I just find it unusual that the cable modem only issues 1 IP via it's built in DHCP server and it's way out of the normal 192.168.X.XXX realm...
They made me an offer for a router w/built in wireless and a 4 port switch for a 1 time fee of $10 and they'll cover it under their warranty just like the modem, I said ship it :D

As a side note I have some home automation going on and the controller uses a serial port for programming. I found this neat device, a StarTech ethernet remote serial interface and it works great. You give it a static IP thats in you subnet, load some drivers into the PC's you want to access it and it places a virtual serial port in the PC's hardware profile. It is then "nailed down" to that serial port on the PC. Pretty slick. It allowed me to move the controller back to my centrally located psuedo eqt room and I can access it from any PC on my Lan, hardwired and wireless.
Pretty slick :D
Dave
 

·
The Admin from... Nowhere!
Joined
·
13,935 Posts
No need to drop another $50, as I had an old DSL/cable router w/4port switch in my stash. I just find it unusual that the cable modem only issues 1 IP via it's built in DHCP server and it's way out of the normal 192.168.X.XXX realm...
They made me an offer for a router w/built in wireless and a 4 port switch for a 1 time fee of $10 and they'll cover it under their warranty just like the modem, I said ship it :D
I wonder if the provision of only one IP is a vendor's way of trying to deal with the upcoming world shortage of IP addresses (until we finally all get moved over to IP V6, of course).... Or perhaps its their way of preventing folks from doing a whole lot of semi-commercial hosting using THEIR residential IPs (not that I'VE ever done that :) ).
 

·
Resident John Deere Tech
Joined
·
1,372 Posts
Rule #1......a switch is garbage.........I would dare say if you stepped up to a router and hooked it up, you would have been working as well.....I have never had sucess with switches......so I only buy routers......
 

·
The Admin from... Nowhere!
Joined
·
13,935 Posts
Rule #1......a switch is garbage.........I would dare say if you stepped up to a router and hooked it up, you would have been working as well.....I have never had sucess with switches......so I only buy routers......
Depends.... What were you trying to use the switch FOR, and how much did you pay? I have DSL coming into my house, and have 1 switch in front of my router because the DSL feeds the boxes for my two televisions so those CANNOT be routed. THEN I have my wireless 4 port router, to provide my wireless connectivity and stream my music and videos throughout the house, THEN I have my 24 port Cisco switch for feeding the rest of the outlets in the house that don't need to be in front of my router (I'm about 2/3 full on that switch). It was a bit of work to get my ISP's 4 port DSL/wireless switch to play nicely with MY wireless router. I didn't want to USE their wireless, because it would not stream Airtunes for me, but I DID want it to be my DHCP provider for the rest of my devices... But after some messing about, I was able to get it all to work the way I want it to... But I have a good quality set of switches and routers to work with.... AND some years of experience working closely with network technicians (I'm NOT one, but its amazing what you can learn helping them rewire an entire 4 story building from thinwire to Cat5 twisted pair).
 

·
Resident John Deere Tech
Joined
·
1,372 Posts
True Littletractorguy.....

I only use the network for gaming and internet........and I run a gigabit ethernet......LOL I need constant 2 way communication........
 

·
Registered
Joined
·
5,609 Posts
No need to drop another $50, as I had an old DSL/cable router w/4port switch in my stash. I just find it unusual that the cable modem only issues 1 IP via it's built in DHCP server and it's way out of the normal 192.168.X.XXX realm...
My guess is that you were being assigned a public IP, not a private RFC1918 IP and that the cable modem was just that, a modem, not a firewall/router/NAT/PAT device.

I'm a firm believer of placing a firewall at the edge.
 

·
The Magnificent
Joined
·
20,952 Posts
My guess is that you were being assigned a public IP, not a private RFC1918 IP and that the cable modem was just that, a modem, not a firewall/router/NAT/PAT device.

I'm a firm believer of placing a firewall at the edge.
Yes, that is how my setup works. The ethernet port of the cable modem assigns a public IP address to whatever device is connected. In my case it is my router/firewall/WAP/Switch uplink port. The router's DCHP server then assigns private IP addresses.

Your old DSL modem sounds like it has all the curcuitry in the one box.
 

·
Machinery enthusiast
Joined
·
4,257 Posts
Discussion Starter #13
Your old DSL modem sounds like it has all the curcuitry in the one box.
It did.
I was able to access it to turn on the wireless and change the IP range the builtin DHCP server issued to a more desireable range 192.168.0.XXX to match my other devices. It was an Actiontech DSL modem. It had NAT, IP routing etc. and worked great until lightning ruined it's day (and mine). And which of course was the reason for the ISP change.

This is what the ipconfig /all told me when my laptop was directly connected to the cable modem (which btw my laptop was setup to recieve it's IP from the DHCP server).

Laptop IP: 68: 68.47.2XX.51
Laptop subnet: 255.255.255.0
Gateway: 68.47.2XX.1
DHCP server: 68.8X.XX.10
1st DNS: 68.8X.XX.1XX
2nd DNS: 68.8X.XX.1XX

I'm pretty sure that I don't have an actual static IP as they charge extra for it. I believe their DHCP server issues the IP's and probably assigns a different one on every reset of the modem, but I'm just guessing on that as thats what my old ISP did with the DSL modem. I know as I tried to use that IP for other purposes :D
Now my cheap little cable modem/router is issueing my desired IP range and is also providing the ports for my other hardwired devices (PC server, LAN serial adapter and another wireless router setup as an access point to provide coverage to my den).

Dave
I put X's in so as to protect the innocent, me :D
 

·
Tractor Nut
Joined
·
550 Posts
Your DSL modem was a modem/router combo, while your Cable modem is only a modem obviously. They make Cable modem/router combos also, but my experience with them is that overall among all the brands I had worked with, they had a higher failure rate. My preference is the route you opted, and that's to use your modem with a stand alone router.

On a cable operator's network, your modem is actually considered a transparent bridge. The modem has an IP address that you can't see on it's RF side. Typically, it's in the 10.x.x.x range. The cable company uses this to manage the modem. Through TFTP, using that IP address, they can send configuration files to the modem that control what download and upload speeds you receive, how many public IP addresses to hand out, as well as firmware updates. The IP address that your router receives is given to it by DHCP based on it's MAC address. While you don't have a static IP, chances are good that you'll maintain the same IP for long periods of time as long as you have the same router always hooked up to your modem. You'll notice that if you power cycle the modem and plug another device in, you'll probably get a different IP address. The same goes for if you configured MAC Cloning in your router to change the MAC address.

If Comcast is giving you 1 IP address, it may be based simply because they consider their residential connection to support 1 IP device outside of their network. They could give out more, but it gets costly for them. They, as well as other ISPs purchase IP addresses in "blocks". Comcast, as the US's largest ISP having over 20 million internet customers, probably wants to keep unnecessary IPs to a minimum.

Anyway, that's a look into my world. Haha. I don't work for Comcast, so some of what I stated is just an educated guess based on my work in the same industry.
 

·
Machinery enthusiast
Joined
·
4,257 Posts
Discussion Starter #15
Good info CableGei.
I'm in a related sort of business but we deliver voice & internet via T1's. We also use a 10.XXX IP to remote manage our IAD's. Like cable you have to be on the VPN inorder to manage/access it.
Our IAD's (made by Adtran) can be setup to deliver static IP's (most customers get 5 consecutive) or we can set them up as a std router w/NAT, DHCP etc,. We usually don't recommend useing the IAD as their primary router since it has no firewall functionality, just NAT but if they don't have a router we'll set it up to do that function for them and just use a dumb switch behind it.
This industry changes daily. Now I don't get involved unless we also maintain/install a PBX with it.
We're fairly large in the southeast. We have fiber strung everywhere. We even lease bandwidth to our local competitors between large metropolitan areas, go figure that :D
Dave
 
1 - 15 of 15 Posts
Top