This post is a summary of some difficulties I worked through to set up Comcast's SMC four port modem/router device for a small business network -- with no static IP's. Hopefully, if there are better, more secure adaptations, more knowledgeable people will chime in, but, if you face setting up CC's SMC device for your network and you're not an expert or even well-versed in networking (my case), the following account may be helpful to you.
Previously, we had the cat5 wire from the Frontier DLS modem connected to the Internet port of a Netgear FSV318v3 Prosafe router and that 8-port unit connected to 7 PC's and a LAN port of another 8-port switch. The remaining seven ports on the switch fed more devices. The Netgear LAN was set up on the 192.168.0.1... addressing scheme and we had specified or reserved IP addresses for a printer, the timeclock and security camera system, haphazardly choosing 100, 4, and 11 as the fourth set of digits for these three devices' addresses, as they came into the system. With the Netgear unit, we could and did reserve the IP addresses related to the MAC addresses of these different devices.
On the day of the Frontier DSL to Comcast cable triple-play switch-over, basically, on the Internet side, the SMC modem replaced the DSL modem and after a few minor tweaks by the installer to shut off DHCP in the SMC (leaving DHCP still to be served by the Netgear), all our network was running, even faster than before. The Netgear continued to shut Internet access off on the graveyard shift by scheduled rules.
After the dust settled and the phone lines and everything else was settled in, running speed test on the workstations gave results of 8-9 Mbps download and 2-3 Mbps upload, which was well below the 22/5 expected. Speed test's on a port of the SMC unit ran a smooth 30+/ 6.5 Mbps dn/up. An initial call to CC tech support resulted in the tech doing something from their side which I understood was putting the SMC unit in "bridge" or "pass-thru" mode which made the device interface inaccessible to us via the 10.0.10.0 address link. Speed may have improved just slightly, but not above 9.5 Mbps -- still very slow speed.. Some research on the web indicated that our Netgear units (or, the way I might have had them mis-configured) was the likely cause of the slow-down.
Presently, after one harrowing afternoon of quite unproductive calls with Comcast tech support, and thankfully avoiding the pitch that we needed to purchase static IP's to get our network printer and other two devices working while staying with the SMC's 10.0.10.0 default addressing scheme, what we have now, getting the wonderful 30+/8 Mbps dn/up speeds, is the cat5 cable from the SMC modem, plus all our cat5 lines from our other ~12-14 devices now plug into a Netgear JFS524 ProSafe 24-port 10/100 Fast Ethernet Switch. ($85 purchased from Amazon in preparation for the change-over.) This switch is rated to convey 200 Mbps to each port and our system continues, now, to run on the 192.168.0.1... IP addressing scheme, such that our three network devices which need an assigned, consistent IP address still have them.
Once the wiring is set and the network (except for network printing, etc.) are running on the SMC's 10.0.10.0 scheme, how does a networking novice get the system to actually WORK??
It turns out this is very simple. And, it turns out that one certainly does not need to buy a bank of static IP addresses from Comcast as they suggested to get network printing, a time clock or security camera back in operation.
What we did, which should have been during slack times on the network was, from the browser, access the interface of the SMC modem/router/four-port switch via its default 10.1.10.1 IP address. And then log in with the username and password.
In the LAN Setup Section:
1. Set the IP Address: 192.168.0.1 (was 10.1.10.1)
2. Set DHCP start: 192.168.0.101
3. Set DHCP end: 192.168.0.199
This leaves 101 - 199 to be dynamically assigned to workstations as they join the network but leaves 192.168.0.2 to .100 outside of DHCP space and thus available for assigned IP addresses like, in our case, 192.168.0.4 or 192.168.0.11 or 192.168.0.100 which had already been assigned previously in hardware setups and/or specified as ports to print to, and/or for software to read from or write to.
4. Save these changes in the SMC setup -- which disrupts all LAN connections (devices were on 10.1.10.1...)
5. Reset the dynamically assigned IP's of workstations and devices by re-booting or, at Windows
workstations --> Start/Run/cmd to get to a DOS prompt and then
type: ipconfig /release <Enter>
and then: ipconfig /renew <Enter>
If all is well, network printing will resume, the timeclock and security cameras and what-not will all continue to work as before, and when you run speedtest.comcast.net you'll at least get 22 Mbps download and 5 Mbps upload, or maybe even better!
In my recent learning episode on "how to setup a Comcast SMC cable modem/router", I was very, very fortunate to have gotten some last-minute onsite help from a very capable young man named Craig who currently provides tech support for and through Copiers Plus in Lafayette, Indiana. Thanks, Craig. You are the man!