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sbuscemi

join:2012-06-23
Columbia, SC

[Business] SMCD3G and static addresses

I've got a smcd3g with a /28 block of ip addresses. I have three pieces of equipment that need to have static public addresses. I can't seem to make it work by just assigning them an IP out of my static range and plugging them directly into the modem. for instance the
comcast modem is 75.x.x.174/28
my dell server is set at 75.x.x.161/28
my terminal server is at 75.x.x.162/28
When I log in to the modem they don't show as connected.
I can get access by setting the server to a private address
and doing a static nat entry, but it doesn't make sense to do it that way. I requested that the modem be put in "bridge mode" but that didnt' help.
Is it possible to do it how I want? Or do I need to look at getting some other equipment or service from Comcast.



ropeguru
Premium
join:2001-01-25
Mechanicsville, VA

said by sbuscemi:

I've got a smcd3g with a /28 block of ip addresses. I have three pieces of equipment that need to have static public addresses. I can't seem to make it work by just assigning them an IP out of my static range and plugging them directly into the modem. for instance the
comcast modem is 75.x.x.174/28
my dell server is set at 75.x.x.161/28
my terminal server is at 75.x.x.162/28
When I log in to the modem they don't show as connected.
I can get access by setting the server to a private address
and doing a static nat entry, but it doesn't make sense to do it that way. I requested that the modem be put in "bridge mode" but that didnt' help.
Is it possible to do it how I want? Or do I need to look at getting some other equipment or service from Comcast.

Absolutely possible to do what you want.

What do you have set as your subnet mask and default gateway for those servers?

Subnet should be 255.255.255.240
GW should be 75.x.x.174

sbuscemi

join:2012-06-23
Columbia, SC

yeah, I've got the gw and mask set correctly.
So there definitely is no need to use private addresses for my equipment? Comcast support was not able to tell me, they said "they would not troubleshoot my equipment" which I understand, but I was trying to get a clear answer as to how to hook up to the equipment that I'm getting from them.



JohnInSJ
Premium
join:2003-09-22
San Jose, CA
reply to sbuscemi

You got static IPs

Make sure the SMC into 'true static' mode, so it doesn't do NAT.

Log into the smcd3, and under Firewall/Options check both

Disable Firewall for True Static IP Subnet Only
Disable Gateway Smart Packet Detection

Under Port Configuration Check

Disable all Port Forwarding rules

Under 1-to-1 NAT check

Disable all

Just for fun, make sure under LAN/Switch Controls

all ports are auto, the correct speed, duplex, active

Now the modem is more or less a dumb router, and you can assign static IPs to your devices behind it.

The only other possible problem is that you're assuming the GW is at the low end of your block - it could be at the other end.

With the /29 blocks at least, the gateway is the highest ip in the range
mine run from x.x.x.113-x.x.x.117, gatewaty is at x.x.x.118
--
My place : »www.schettino.us



NetFixer
From my cold dead hands
Premium
join:2004-06-24
The Boro
Reviews:
·Cingular Wireless
·Comcast Business..
·Vonage
·Comcast
reply to sbuscemi

I do exactly what you are doing (except of course for the actual IP addresses), and I have no problems with either internet visibility for my servers, and they definitely do show up in the SMCD3G network scan.

Here is the SMCD3G network scan screen shot:



The IP addresses 75.146.8.42 and 75.146.8.43 belong to my Windows and Linux servers respectively, and the IP address 75.146.8.41 is the WAN interface for my Netgear router. I also have a number of 192.168.10.x addressed devices, but those are irrelevant to the True Static IP assignments.

Here is my current network diagram for reference:




You will note that neither the servers nor the Netgear router are actually directly connected to the SMCD3G, but the SamKnows TP-WR1043ND functions as a simple layer 2 switch, so that has no effect on the results (the SamKnows box is a recent addition, and the network functioned the same with the mentioned devices attached directly to the SMCD3G).
--
History does not long entrust the care of freedom to the weak or the timid.
-- Dwight D. Eisenhower


NetFixer
From my cold dead hands
Premium
join:2004-06-24
The Boro
Reviews:
·Cingular Wireless
·Comcast Business..
·Vonage
·Comcast
reply to JohnInSJ

said by JohnInSJ:

You got static IPs

Make sure the SMC into 'true static' mode, so it doesn't do NAT.

Log into the smcd3, and under Firewall/Options check both

Disable Firewall for True Static IP Subnet Only
Disable Gateway Smart Packet Detection...

Actually it will work just fine with the True Static Firewall enabled. I use the firewall in my SMCD3G and it causes me no problems at all (in fact, I find it quite beneficial).






--
History does not long entrust the care of freedom to the weak or the timid.
-- Dwight D. Eisenhower

sbuscemi

join:2012-06-23
Columbia, SC

Ok. I'll have to check the modems settings myself. I sent the equipment out there preconfigured, and had a local tech install it, then had Comcast change settings in the modem. Maybe they have something set wrong. Comcast wouldnt really do any trouble shooting with me, or even tell me if what I wanted to do was possible, so I started getting paranoid.



NetFixer
From my cold dead hands
Premium
join:2004-06-24
The Boro
Reviews:
·Cingular Wireless
·Comcast Business..
·Vonage
·Comcast

said by sbuscemi:

Ok. I'll have to check the modems settings myself. I sent the equipment out there preconfigured, and had a local tech install it, then had Comcast change settings in the modem. Maybe they have something set wrong. Comcast wouldnt really do any trouble shooting with me, or even tell me if what I wanted to do was possible, so I started getting paranoid.

Comcast is supposed to be committed to remotely making any customer changes required since the SMCD3G does not allow direct remote access by the customer. All it should take is a telephone call to 800-391-3000 and explain to the tech what you want checked/changed.

»businesshelp.comcast.com/Pages/H···upport=1

Comcast does not provide remote access to the Gateway. Customers who are offsite will need to call Business Class Customer Support at 1-800-391-3000 to make changes for them.


--
History does not long entrust the care of freedom to the weak or the timid.
-- Dwight D. Eisenhower