Generally, CenturyLink will install two pieces of equipment, and ONT and a "modem/router". The ONT is the optical network termination, and converts the fiber to ethernet. The "modem/router" is really just a specially configured router. You can use your own router instead (I do), primarily because I don't like the idea of the ISP having visibility into my local network. You can also just hang your router off of their router, although then you are going to have a double NAT situation.
The first issue you will have is that in order to talk to the ONT, you need to use VLAN 201. Packets leaving your WAN port need to be tagged with that VLAN. That is often as easy as using "eth0.201" where you would ordinarily use "eth0". The second issue is that historically they have used PPPoE to do the access control and IP address provisioning. I did recently encounter someone for whom the gear in their building provisioned them with DHCP instead. If you want to use your own router in place of theirs, that means you will need your credentials. You can ask your installer to provide them (they will call someone to get them), or you can ask CenturyLink and they will give them to you without too much hassle). The second issue is that PPPoE eats some of your MTU. I recall trying to configure jumbo packets on the gateway router I use and I could never get it working (although it's long enough ago I don't recall the details). It might have been a problem with the hardware I was using or it might be a limitation of the ONT. I needed a configuration that does "TCPMSS clamp to PMTU" on ingress and egress on the pppoe wan interface and I lose 32 bytes of MTU (1468 instead of 1500). You mileage may vary. I got the service in 2015 and *every time* the pppd restarted I got a new IP address. Back then, for whatever reason, it was happening a few times a day, which made my IP address very unstable. I requested a static IP. They charged me a $75 setup fee and $10/month. About a year ago, they decided that the $10/month was not enough, so despite the "price for life" guarantee, the static IP fee was not included in the price stability. As a joke, I complained to the FCC about that, and they just laughed at my joke and kept charging me $15/month. My bill is currently $100/month. I do have a stable IPv4 address, and can also configure IPv6 provisioning using 6rd, which uses your IPv4 address as part of the IPv6 allocation, so it's stable also. The pppd restarts (which were caused by the upstream provisioning server bouncing) have occurred less frequently in the last few years. If you are really curious, I can dredge through my syslogs to say how often and the outage durations. On Wed, Dec 29, 2021 at 3:18 PM Robert Munro <[email protected]> wrote: > > I've avoided using the phone company as my ISP for decades, but alas GTT > is going out of business in terms of serving me as an ISP customer, so a > CenturyLink installer will visit me here tomorrow. I suspect this means > that I won't have a static IP address. > > Can anyone confirm the change I need to make in my Linux system network > to use a CenturyLink Gigabit fiber connection? > > At present, my (Fedora derived) Mageia Linux 8 system is using a static > IP address that is set up as follows: > > The file /etc/sysconfig/network-scripts/ifcfg-enp0s16 contains: > > DEVICE=enp0s16 > BOOTPROTO=static > IPADDR=68.167.251.142 > NETMASK=255.255.255.252 > GATEWAY=68.167.251.141 > ONBOOT=yes > METRIC=10 > MTU=9000 > MII_NOT_SUPPORTED=no > USERCTL=no > DNS1=64.105.163.106 > DNS2=64.105.172.26 > RESOLV_MODS=no > LINK_DETECTION_DELAY=6 > IPV6INIT=no > IPV6TO4INIT=no > ACCOUNTING=no > NOZEROCONF=yes > > In order to use a CenturyLink DHCP provided IP address, I suspect that > I'll have to change this file to contain: > > DEVICE=enp0s16 > BOOTPROTO=dhcp > IPADDR= > NETMASK=255.255.255.0 > GATEWAY= > ONBOOT=yes > METRIC=10 > MII_NOT_SUPPORTED=no > USERCTL=no > MTU=9000 > DNS1=8.8.8.8 > DNS2=8.8.4.4 > RESOLV_MODS=no > LINK_DETECTION_DELAY=6 > IPV6INIT=no > IPV6TO4INIT=no > ACCOUNTING=no > NOZEROCONF=yes > > What does everyone else use to run Linux with CenturyLink as their ISP? > > Thanks in advance. >
