CenturyLink/Level 3 combined AS

Hey all,

Are there plans for CL and Level3 to combine AS’s into one network?

If not, do they actively peer and route traffic through each other’s networks at least?

Basically we’re looking at picking up 1G of CL and wondering if it’s near the same quality as Level3 in terms of latency and packet loss.


I wouldn’t expect them to be integrated for at least another decade. Global Crossing AS3549 still exists with over 2,000 peer ASNs, yet Level 3 acquired them in 2011. Time Warner Telecom was acquired in 2014 and it still has 89 peer ASNs.

Centurylink bought Digital Teleport in 2003 and their ASN is still out there.

Once upon a time, Darin Steffl <darin.steffl@mnwifi.com> said:

Are there plans for CL and Level3 to combine AS's into one network?

We have CenturyLink transit from old Qwest (AS 209) and old Level3 (AS
3356) in Chicago... when we ordered the more recent circuit, both sales
and tech said that there's no plan to merge the ASes together at this
time. They already had peering, so I assume that just expanded. We
haven't had any issues with either.

And BTW: when you say "CL" - those are just two of the large family of
ASes that CL has bought. There's also old Savvis AS 6347, and other old
Savvis (aka Cable & Wireless aka InternetMCI) AS 3561, and untold more
Internet history... :slight_smile:

That ‘2000 peer ASN’s’ value is likely very, very inflated. I have prefixes that would look like I am peering with 3549 directly in many places that I do not.

L3 has for some time had a partial as-merge community that you can set so that if you announce a prefix to 3356, they’ll mirror it over to 3549 in the same location and strip 3356 from the as-path. The reverse also works for an announcement to 3549 mirrored over to 3356. They’re doing some inter-as option c juju to make all that work.

Doesn’t change the point that 3549 is still around 8 years later and likely will be for 8 more, but yeah. :slight_smile: I’m sure efforts to make that happen have a plethora of roadblocks such that it would cost 10x more to get rid of it than it would to just leave it as is and just shrink it when possible.

All new CL Internet get's provisioned on AS3356
You would need a strong case for them to put you on AS209

At this time they are not merging the two AS's
And also define "quality" :wink:


That isn’t true in my recent experience. We just replaced an older L3 transit with a new CL one on different floors of the same building, and doing so involved moving from 3356 to 209.

Interestingly, the CFA for the new circuit’s attachment suggests it came out of the “L3” suite, not the “Qwest” suite (both on the same floor); so it seems that 209 is provision-able at former L3 facilities.

Other recent entirely new CL turn-ups with us, out of rural COs belonging to Frontier, have also been with 209.


Got provisioned last year on AS209 when they turned up my ent Fiber with BGP.

Could depend heavily on what services and where.

Ok just so simplify things.

Is Cogent or CenturyLink/L3 better for transit?

As usual, that depends. Gotta give us a lot more information than that.

-Mike Bolitho

Cogent is great, or worthless, depending on whether you like talking to Google via IPv6.

Cogent is great, or worthless, depending on whether you like talking to Google via IPv6.

bps pricing is rarely apples to apples, Cogent will happily tell you
that. However, you may want more than just apples. I've seen at least
three serious providers offer as good or better deals in the last year
or so. At one time they were unbeatable from a sheer price perspective,
but in my more recent experience, this is no longer true.


Generally, I'd say hook up to more than one "transit-free" provider if
you must use any of them.


Price is so low right now (especially if you are willing to settle on
the large providers) that it's six and half-a-dozen if you want to use
that as a decision factor.