RE: Issues with 4-octet BGP AS and Akamai?

["Greg Gombas -X (grgombas)" <grgombas () cisco com>]

Hi Tyler,

Unfortunately we had a limited window to test so could not check the reverse path.

During our failover testing we stopped advertising out the primary path and only advertised out the secondary path. 
Routes are advertised out the secondary path through a DDOS prevention company called F5 Silverline which is reached 
via a GRE tunnel running over the Optimum Lightpath network.

So outgoing traffic would go from NYULH going out the Optimum Lightpath circuit and return traffic coming in on F5 
Silverline’s network then tunneled over Optimum Lightpath back to NYULH.
So traffic was definitely routing asymmetrically.

However F5 Silverline assured us they have many customers using a similar setup but have no issues with Akamai.

I would think that many customers using similar DDOS prevention services such as F5 Silverline and Prolexic are routing 
asymmetrically as well, wouldn’t uRPF be affecting them all?

Thanks,
Greg
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Gregory Gombas
CCIE# 19649 – R&S
Network Consulting Engineer
Advanced Services
grgombas () cisco com<mailto:grgombas () cisco com>
Office: +1-212-714-4497
Mobile: +1-201-675-9457

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From: Tyler Conrad [mailto:tyler () tgconrad com]
Sent: Tuesday, November 14, 2017 1:30 PM
To: james machado <hvgeekwtrvl () gmail com>
Cc: Greg Gombas -X (grgombas) <grgombas () cisco com>; nanog () nanog org
Subject: Re: Issues with 4-octet BGP AS and Akamai?

Are you advertising out multiple circuits? Check the pathing both directions if you can. A lot of CDNs enforce uRPF 
strict.

On Tuesday, November 14, 2017, james machado <hvgeekwtrvl () gmail com<mailto:hvgeekwtrvl () gmail com>> wrote:
Greg,

I have a 4 byte ASN and have not had any issues with reach ability,
including the 2 websites you have linked.

James