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I was about to go on Amazon to buy my own CenturyLink branded fiber modem (Arris C2100T) to replace the one I am renting from the ISP (Arris C3000T), but then I read here on SuperUser that I might not even need their modem at all. My whole objective here is to save money, so obviously it'd be ideal if I could simply not replace the modem, but rather just stop renting it from CenturyLink. After all, I have the ISP rented modem in bridge-mode, so (as I understand it) it's essentially doing nothing. Here is my current setup:

  • ISP fiber-to-ethernet handoff/converter (Calix 716GE-i R2 ONT)
  • CenturyLink fiber modem (Arris C3000T) in bridge mode
  • My Cisco ASA 5505 router (full support for 802.1q VLAN tagging)

I already know my PPPoE credentials and am using them on the WAN port of the Cisco ASA. However, I am not doing any VLAN tagging. Do I just need to setupu VLAN tagging (ID 201) on the WAN port of my Cisco ASA, as the aforementioned SU post suggests? Of course I can (and will) simply try this out, but I want to get ahead of any potential pitfalls before I go attempting changes on my WAN link.

Update 1: Tried setting VLAN 201 on the WAN link (Eth0/0) of my ASA: no joy, could not obtain an IP. PPPoE did seem to authenticate fine, however. I am missing something, but not sure what as of yet.

SamAndrew81
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  • Well sure, but it _is_ a router. The original post makes it sound like any router that supports VLAN tagging (which the ASA does) will suffice...? – SamAndrew81 Feb 24 '19 at 20:39
  • There is a difference between a router and a gateway modem. I am guessing you are connecting the modem to the device with a CAT5'ish cable? – Ramhound Feb 24 '19 at 20:42
  • Yes, that is correct, CAT6. I see what you mean about router vs modem, yes. I suppose I will have to buy one, but was hopeful after reading that original SU post. – SamAndrew81 Feb 24 '19 at 20:43
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    If you want to simplify your network, the Cisco isn't required, but I understand the reason you have it :-) – Ramhound Feb 24 '19 at 20:45
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    What exactly is a "fiber modem"? It would make sense if the fiber-to-ethernet converter was built into it, but you list that as a separate item – so what sort of device is the Arris C3000T? What's "fiber" about it" and what's "modem" about it? – u1686_grawity Feb 24 '19 at 21:02
  • @grawity The fiber-ethernet media converter is a separate box, yes (Calix 716GE-i R2). The fiber is hardwired into the box and it has an ethernet output jack. The Arris C3000T is a Century Link provided modem/router and it only has ethernet ports on it. – SamAndrew81 Feb 24 '19 at 22:44
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    @grawity, Verizon does the same thing. You usually have the ONT (fiber to Ethernet converter) in the basement or garage. Then have the VZ "Fiber router" which is essentially no different than a regular router minus the moca port which feeds set-top boxes. Most likely they have locked the account to the mac-address of the Arris wan interface. – Tim_Stewart Feb 25 '19 at 17:41
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    Try duplicating the WAN Mac address of the Arris WAN interface to the Cisco ASA WAN interface. (MAC cloning) if that fails, you may have to call them and ask them to release the DHCP binding on their end. – Tim_Stewart Feb 25 '19 at 17:44
  • Thank you, @Tim_Stewart. I'm expecting the least amount of cooperation possible from CenturyLink, so asking them for help will be last resort (their support is horrible). – SamAndrew81 Feb 25 '19 at 17:47
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    Unless you have some sort of totalitarian agreement with CenturyLink... This is usually a straight forward kinda thing, most ISPs don't **force** you to use their equipment. If they implied that **at all** I would escalate the request to **customer retention**. – Tim_Stewart Feb 25 '19 at 17:56
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    @Tim_Stewart, I called and spoke with CenturyLink tech support today. The "technician" (using that term loosely) I spoke with did not know cloning the MAC is obligatory or not. So you see, even if they wanted to help (they don't) actually *getting* the help is a different matter. – SamAndrew81 Mar 01 '19 at 21:41
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    Lol I haven't had the pleasure of dealing with them yet... Did you ask them to release the DHCP binding? I know that's a Longshot when the technicians sound like they were cherry picked from Walmart. – Tim_Stewart Mar 01 '19 at 22:12
  • I was able to successfully use my pfSense router to bypass the CenturyLink modem. I could not get the ASA 5505 working, but I am fairly certain it was just a config issue on my part (not a shortcoming of the ASA itself). – SamAndrew81 Mar 04 '19 at 01:21

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The answer is YES - this is possible! However, I could not figure out how to configure the ASA properly, so I just used my pfSense router instead, which I prefer because it's more full-featured and easier to use.

SamAndrew81
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