[RndTbl] shaw 2nd ip

Hartmut W Sager hwsager at marityme.net
Wed Dec 1 08:23:12 CST 2021

Oh, I forgot to add:  Yes, the multiple IP addresses would come in on the single Shaw coax RG-6 cable and into/thru the same single Shaw modem-router.

From: Hartmut W Sager <hwsager at live.ca>
Sent: December 1, 2021 07:59
To: Continuation of Round Table discussion <roundtable at muug.ca>
Cc: Trevor Cordes <trevor at tecnopolis.ca>
Subject: Re: [RndTbl] shaw 2nd ip

I can answer the first part of your questions, up to the NIC, but not beyond.

On my residential Shaw, I have had 3 IP addresses (all 3 dynamic, but they rarely change) for several years now.  The first one was of course included in the service, the second one was available for free just for the asking (subject to availability in the area, they said), and the third one is costing $10 per month.

I wish you had told us which model of Shaw modem-router you have.  Here's the 4 common ones they've issued over the last number of years:

1.  Cisco DPC3825.
2.  Hitron CGNM-2250.
3.  Cisco/Motorola DPC3848V.
4.  That funny-looking new contraption that promises to reach every corner of your house and your cranium with deep penetration.


1.  Cisco DPC3825.  A complete piece of junk, designed by a company that Cisco then bought so that they had something to sell to carriers for their lowest-priced plans.  It does support "bridge" mode, but only on an all-or-nothing basis for the whole box, not per RJ-45 socket (4 of them).  "Bridge" mode is the only way people get this junk to work somewhat reasonably.

4.  That funny-looking new contraption.  I have no idea about this one, but I wouldn't want my remaining brain cells to be destroyed this way.

3.  Cisco/Motorola DPC3848V.  Well-regarded, and I THINK it works the same way as #2 below.

2.  Hitron CGNM-2250.  A top-notch gem, which I've been using for several years now.  It does support "bridge" mode, aka IP pass-thru, on a per RJ-45 socket (4 of them) basis.  Its (Web) config lets you configure that, along with loads of other parameters (most of which don't apply to IP pass-thru sockets).  The raw (non-NAT'ed, non-firewalled) IP addresses coming out of the chosen pass-thru RJ-45 sockets are fit to send into SEPARATE routers or SEPARATE NIC's, and the non-pass-thru RJ-45 sockets (if any) remain as NAT'ed/firewalled sockets, along with the Hitron's own Wi-Fi output.

Now, back to Shaw.  You need to request the second (and beyond) IP's explicitly, otherwise #2 above will NOT work as described.  Once you do have the second (and beyond) IP's, the Hitron nicely distributes them as above.  Even if all 4 RJ-45 sockets are configured as IP pass-thru, though, the Hitron might still retain one IP to service its own Wi-Fi, perhaps even if you turn off Wi-Fi in its config - I'm not sure about this part.

As for two IP's to one NIC, I have no idea.  Hence my comment right at the beginning, along with my emphasis on "SEPARATE routers or SEPARATE NIC's".

Hmmm, now all I have to do is remember why I need 3 IP addresses at Shaw.  🙂

Hartmut W Sager - Tel +1-204-339-8331

From: Roundtable <roundtable-bounces at muug.ca> on behalf of Trevor Cordes <trevor at tecnopolis.ca>
Sent: November 30, 2021 22:42
To: MUUG RndTbl <roundtable at muug.ca>
Subject: [RndTbl] shaw 2nd ip

I think with Shaw residential I can get 2 dynamic IPs?

I'm using my modem in "bridge mode" or "wired mode" or whatever the shaw
techs want to call it this week.  In other words, the builtin router is
disabled and it acts just like an old-style cable modem direct into my

Obviously, I'm getting 1 dynamic.  That's great.

Can I get the 2nd too, but using just the one cable to the modem, and just
the one NIC?

I'm guessing I'll have to assign a 2nd IP, 2nd fake MAC, and/or "fake"
interface to the existing interface?  Then setup dhcpclient to use it
(too)?  (All in linux, of course.)

Is what I'm describing doable or am I missing something here?  Any tips on
the sequence of events here?

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