Re: Centurylink having a bad morning?

[Martijn Schmidt via NANOG <nanog () nanog org>]

You're preaching to the choir here.. ;)

On 8/31/20 4:33 PM, Tomas Lynch wrote:
Maybe we are idealizing these so-called tier-1 carriers and we, tier-ns, should treat them as what they really are: 
another AS. Accept that they are going to fail and do our best to mitigate the impact on our own networks, i.e. more 
peering.

On Mon, Aug 31, 2020 at 9:54 AM Martijn Schmidt via NANOG <nanog () nanog org<mailto:nanog () nanog org>> wrote:
At this point you don't even know whether it's a human error (example: generating a flowspec rule for port TCP/179), a 
filtering issue (example: accepting a flowspec rule for port TCP/179), or a software issue (example: certain flowspec 
update crashes the BGP daemon). And in the third scenario I think that at least some portion of the blame shifts from 
the carrier to its vendors, assuming the thing that crashed was not a home-grown BGP implementation.

With the route optimizer incidents - because let's face it, Honest Networker is on the money as usual 
https://honestnetworker.net/2020/08/06/as10990-routing/ - there is really no excuse for any tier-1 carrier, they should 
at the very least have strict prefix-list based filtering in place for customer-facing EBGP sessions. In those cases 
it's much easier to state who's not taking care of their proverbial lawn.

Best regards,
Martijn

On 8/31/20 3:25 PM, Tom Beecher wrote:
https://blog.cloudflare.com/analysis-of-todays-centurylink-level-3-outage/

I definitely found Mr. Prince's writing about yesterday's events fascinating.

Verizon makes a mistake with BGP filters that allows a secondary mistake from leaked "optimizer" routes to propagate, 
and Mr. Prince takes every opportunity to lob large chunks of granite about how terrible they are.

L3 allows an erroneous flowspec announcement to cause massive global connectivity issues, and Mr. Prince shrugs and 
says "Incidents happen."





On Mon, Aug 31, 2020 at 1:15 AM Hank Nussbacher <hank () interall co il<mailto:hank () interall co il>> wrote:
On 30/08/2020 20:08, Baldur Norddahl wrote:

https://blog.cloudflare.com/analysis-of-todays-centurylink-level-3-outage/

Sounds like Flowspec possibly blocking tcp/179 might be the cause.

But that is Cloudflare speculation.

Regards,
Hank
Caveat: The views expressed above are solely my own and do not express the views or opinions of my employer

An outage is what it is. I am not worried about outages. We have multiple transits to deal with that.

It is the keep announcing prefixes after withdrawal from peers and customers that is the huge problem here. That is 
killing all the effort and money I put into having redundancy. It is sabotage of my network after I cut the ties. I do 
not want to be a customer at an outlet who has a system that will do that. Luckily we do not currently have a contract 
and now they will have to convince me it is safe for me to make a contract with them. If that is impossible I guess I 
won't be getting a contract with them.

But I disagree in that it would be impossible. They need to make a good report telling exactly what went wrong and how 
they changed the design, so something like this can not happen again. The basic design of BGP is such that this should 
not happen easily if at all. They did something unwise. Did they make a route reflector based on a database or 
something?

Regards,

Baldur

On Sun, Aug 30, 2020 at 5:13 PM Mike Bolitho <mikebolitho () gmail com<mailto:mikebolitho () gmail com>> wrote:
Exactly. And asking that they somehow prove this won't happen again is impossible.

- Mike Bolitho

On Sun, Aug 30, 2020, 8:10 AM Drew Weaver <drew.weaver () thenap com<mailto:drew.weaver () thenap com>> wrote:
I’m not defending them but I am sure it isn’t intentional.

From: NANOG <nanog-bounces+drew.weaver=thenap.com () nanog org<mailto:thenap.com () nanog org>> On Behalf Of Baldur 
Norddahl
Sent: Sunday, August 30, 2020 9:28 AM
To: nanog () nanog org<mailto:nanog () nanog org>
Subject: Re: Centurylink having a bad morning?

How is that acceptable behaviour? I shall remember never to make a contract with these guys until they can prove that 
they won't advertise my prefixes after I pull them. Under any circumstances.

søn. 30. aug. 2020 15.14 skrev Joseph Jenkins <joe () breathe-underwater com<mailto:joe () breathe-underwater com>>:
Finally got through on their support line and spoke to level1. The only thing the tech could say was it was an issue 
with BGP route reflectors and it started about 3am(pacific). They were still trying to isolate the issue. I've tried 
failing over my circuits and no go, the traffic just dies as L3 won't stop advertising my routes.

On Sun, Aug 30, 2020 at 5:21 AM Drew Weaver via NANOG <nanog () nanog org<mailto:nanog () nanog org>> wrote:
Hello,

Woke up this morning to a bunch of reports of issues with connectivity had to shut down some Level3/CTL connections to 
get it to return to normal.

As of right now their support portal won’t load: https://www.centurylink.com/business/login/

Just wondering what others are seeing.