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kwazywabbit
join:2000-09-06
Chandler, AZ

kwazywabbit

Member

[Connectivity] How can I force Comcast to issue a different IP?

I need to get a new IP address from Comcast.

I'm using a SMCD3GNV modem/router combo supplied by Comcast. There is no option to change a MAC in the modem/router itself, and changing the MAC of any attached PCs or external router has any effect, even when completely resetting the router back to factory settings and starting over.

Leaving everything turned off for three days had no effect.

Suggestions?

tshirt
Premium Member
join:2004-07-11
Snohomish, WA

3 recommendations

tshirt

Premium Member

[Connectivity] Re: How can I force Comcast to issue a different IP?

Why do you need a new IP?
Are you paying for a "static" (business class) IP?
Have you called and ask them to help?
You will NEVER be able to change the modem's MAC, you could have them place that gateway in "bridge mode" (disable the router function) and attach a different router, which the CMTS SHOULD see (After a powercycle) as a different MAC and issue a new IP.
None of this can happen without contacting Comcast.

NetFixer
From My Cold Dead Hands
Premium Member
join:2004-06-24
The Boro
Netgear CM500
Pace 5268AC
TRENDnet TEW-829DRU

1 recommendation

NetFixer to kwazywabbit

Premium Member

to kwazywabbit
With a rented cable gateway with no way to change the WAN CPE MAC address, the only option you really have is to go to the Comcast office and try to get an exchange (but if your only reason is to get a new public IPv4 address, you may find that Comcast will not be inclined to cooperate).

If you find yourself frequently in need of changing your public IPv4 address, it would be simpler to have the gateway put into bridge mode (or purchase a standard cable modem/eMTA) and use a real router over which you have more control. If you are using this particular gateway device because you need its voice ports, you should be able to have it put into bridge mode, and still use the CDV service.

My experience when I have occasionally found myself with a public IPv4 address that had routing problems, was that it would often take about two weeks (and sometimes longer) before their DHCP server would release an old lease and allow me to return to using the original factory MAC address instead of a cloned MAC address.

B4Knight
Premium Member
join:2014-03-20
Colon, MI

B4Knight to kwazywabbit

Premium Member

to kwazywabbit
I can change my IP easily, however I am using a Moto SB6121 not a gateway device. All I have to do is power cycle the modem and switch between direct connection to my laptop or just power cycle again and connect my Netgear router to my modem.

In your case though you its sounds like you have business class and you most likely have a Static IP which you will need to call Comcast in order to have it changed.

Good luck!

NetFixer
From My Cold Dead Hands
Premium Member
join:2004-06-24
The Boro
Netgear CM500
Pace 5268AC
TRENDnet TEW-829DRU

NetFixer

Premium Member

said by B4Knight:

In your case though you its sounds like you have business class and you most likely have a Static IP which you will need to call Comcast in order to have it changed.

The SMCD3GNV is not an officially approved static IP business class gateway; you are thinking of the SMCD3G-CCR, which is an entirely different device. While it is possible the the OP is using a SMCD3GNV residential gateway box for a business class account (unapproved modems have been known to be allowed for some customers), it would not (to my knowledge) support Comcast's authenticated RIP method of routing their business class static IP blocks.

B4Knight
Premium Member
join:2014-03-20
Colon, MI

B4Knight

Premium Member

I just thought that might be the case.. I'm not a Comcast customer so I don't know what they use. Thanks for the info though

Coelispex
join:2013-06-03
Howell, MI

Coelispex to kwazywabbit

Member

to kwazywabbit
I don't know why people don't give straight answers. If you want to change your IP address given you have a dynamic one, the only requirement is if you router has/supports a MAC Clone feature.

It's that simple.

Just generate a random MAC address. Restart your modem. Restart your router and you will be assigned a new one.

If your router doesn't come with one, you're out of luck.
rody_44
Premium Member
join:2004-02-20
Quakertown, PA

rody_44

Premium Member

He is using a modem router combo that doesnt have the ability to clone the mac address.

NetFixer
From My Cold Dead Hands
Premium Member
join:2004-06-24
The Boro
Netgear CM500
Pace 5268AC
TRENDnet TEW-829DRU

NetFixer to Coelispex

Premium Member

to Coelispex
said by Coelispex:

I don't know why people don't give straight answers. If you want to change your IP address given you have a dynamic one, the only requirement is if you router has/supports a MAC Clone feature.

It's that simple.

Just generate a random MAC address. Restart your modem. Restart your router and you will be assigned a new one.

And I don't know why people don't pay attention and/or do a bit of research before making irrelevant replies. The OP has a rented Comcast gateway, not a standard modem with a standalone router. The option you present is not available to the OP in that configuration (which has already been explained by the OP and by multiple posters who "don't give straight answers").

And yes, it really is that simple.

modem change
@comcast.net

1 edit

modem change

Anon

I rebooted my modem and noticed my settings; modem ip mode changed to IPv6 only. Has anybody else noticed this change?

Model Name: SB6141
Vendor Name: Motorola
Firmware Name: SB_KOMODO-1.0.6.10-SCM00-NOSH
Hardware Version: 7.0
Firmware Build Time: Oct 29 2012 18:07:13

Edit: This post is off topic. Please start a new topic when you wish to change the subject. Sunny See Profile

Mike Wolf
join:2009-05-24
Tuckerton, NJ

Mike Wolf

Member

Yup that's been like that on my SB6121 for about a year of two when that SB_KOMODO-1.0.6.10-SCM00-NOSH firmware was rolled out nationwide.
Model Name: SB6121
Vendor Name: Motorola
Firmware Name: SB_KOMODO-1.0.6.10-SCM00-NOSH
Boot Version: PSPU-Boot(25CLK) 1.0.12.18m3
Hardware Version: 5.0
Mike Wolf

Mike Wolf to rody_44

Member

to rody_44
said by rody_44:

He is using a modem router combo that doesnt have the ability to clone the mac address.

Just another reason why I hate combo units

tshirt
Premium Member
join:2004-07-11
Snohomish, WA

1 recommendation

tshirt to modem change

Premium Member

to modem change
said by modem change :

...modem ip mode changed to IPv6 only.

That is normal...in more and more areas every week.
Be aware the v6 address they are mentioning is just the link they use to remotely address your modem and SHOULD change nothing you will notice other then that note in the modems pages.
Comcast is moving to v6 as rapidly as possible but you'll still see IPv4 and v6 pages as equally usable for some time to come.

EG
The wings of love
Premium Member
join:2006-11-18
Union, NJ

EG to Coelispex

Premium Member

to Coelispex
said by Coelispex:

Just generate a random MAC address. Restart your modem. Restart your router and you will be assigned a new one.

FWIW, and IMO, a better idea is to use MAC addresses of devices that you actually own. Less potential for issues that way.
EG

1 recommendation

EG to modem change

Premium Member

to modem change
said by modem change :

I rebooted my modem and noticed my settings; modem ip mode changed to IPv6 only.

FWIW, that is for the DOCSIS WAN / ISP's management side of the modem and has nothing to do with what the modem bridges to the LAN side.

Kasoah
join:2013-08-20
Merced, CA

Kasoah

Member

You can't on combos, just get a real modem and buy a router. Your ip will change because of the router's wan mac address is different.

TheTechGuru
join:2004-03-25
TEXAS

TheTechGuru to kwazywabbit

Member

to kwazywabbit
This is another example of why one should not use combo modem router junk.

Your only option is to put it in bridge mode and connect a different router to it, even then that may not work if it don't pass that router's MAC though.

I would suggest getting a separate modem and router, then you can change your IP all you want by changing the virtual WAN MAC in the router.

B4Knight
Premium Member
join:2014-03-20
Colon, MI

1 recommendation

B4Knight

Premium Member

Totally agree! You have more control over your network when you have them separate. Plus its easier to diagnose problems
Expand your moderator at work

Mike Wolf
join:2009-05-24
Tuckerton, NJ

1 recommendation

Mike Wolf to B4Knight

Member

to B4Knight

Re: [Connectivity] Re: How can I force Comcast to issue a different IP?

And better quality of service by being able to use new high quality gear (and firmware) instead of whatever Comcast decides to give you that could be refurbished or in poor condition or old.