Decius wrote:

Decius wrote:
Five months later and it happens again... my internet is down. The router (an SMC Barricade) that I hooked up during the previous debacle is now unable to obtain a DHCP lease from Comcast's network....

So, I replaced the SMC with my Belkin. This is the exact same Belkin that Comcast's first and second level technical support insisted MUST be malfunctioning last December because it was unable to obtain a DHCP lease from their network at that time. It works just fine. I'm back up.

And then three weeks later I'm down again. I was out of town on Sunday so its possible this occurred on the weekend as well. Tried to get a new lease with the Belkin and couldn't, even after resetting both the router and the cable modem. I replaced the Belkin with the SMC, and now I can get a lease just fine.

The last time I had to do this, I was up for 6 months. This time, I was only up for three weeks. Thats not a good sign...

Comcast and most ISPs will tie a profile to your particular MAC address and the DOCSIS device used to terminate the line. This is how your line is provisioned and how your traffic patterns are monitored. These profiles are all automatically generated and the tech on the phone's ability to do anything with it is severely limited. If anything changes (ie power outage, upstream router reboot, etc) and there's any discrepancy in the profile tied to that MAC address, then you will see this behavior. It could be one of two things:

1) the MAC address of the device on your end has changed or was not the same as the one in the original profile. Connectivity can sometimes work once if this is the case, but not again if something burps the line. I see this whenever someone gets a new router or modem and doesn't call the ISP to have their profile updated or changed. This can sometime happen when an upstream policy has also changed, which will force a more "stringent" matching of device to provisioning profile thus fixing something that was previously working but considered "broken".

2) the profile itself is munged or the server hosting it has been borked. This is FAR more common, because these networks are constantly being upgraded, extended, and gear swapped. Policies change, and so do configs, which means that stuff gets hosed. And with 10's of millions of profiles network wide, something will inevitably fail. But good luck getting even Tier 3 support to a) check this and/or b) admit it.

On the DOCSIS side of the house, there's not a lot you can do here because of the way that profiles are stored and managed. On the DSL side of the house, you can sometimes jigger things with your modem to cause it to resync with whatever mechanism is managing the profiles (usually some form of RADIUS) depending on the modem itself. Older modems are ironically, more configurable. This is why simply changing the modem itself will usually solve things because it likely forces the provisioning infrastructure to "start over". However, changing back to your previous gear will usually cause more problems. It just depends on how that provisioning infrastructure is managed.

Another alternative I'd suggest is pay for multiple IP addresses for your line. Even temporarily. This will force a reconfig of your profile and likely will put you in a different queue for addresses, which might be enough to solve this problem permanently. Some providers offer static addressing, which would eliminate this problem altogether, but I don't think Komkast does.

One final thing to look at is the firmware of your modem. They do have bugs and they do get updated. Especially the DOCSIS junk. Updating it might help. It's a hassle but this is what you get for no competition in telecom.

RE: Comcast's DHCP is STILL broken