Issues with 4-octet BGP AS and Akamai?

Greg Gombas -X (grgombas) grgombas at cisco.com
Tue Nov 14 17:36:04 CST 2017


Thank you all for your assistance thus far. I wanted to confirm with my customer that it was okay to share more details and they said it was okay. We did just send an email to Akamai net support and awaiting their reply.

The customer is NYULH (AS 394666). They currently use NYU (AS 12) for internet connectivity. They advertise the following prefixes to NYU:

216.165.124.0/24
216.165.125.0/24
216.165.126.0/24
216.165.127.0/24

NYU aggregates the above prefixes, strips NYULH's AS number, and replaces it with their own AS number (AS 12).
The aggregates are as follows:

216.165.124.0/23
216.165.126.0/23

Below is a sample /23 route seen from one of the looking glass servers with origin AS 12:

216.165.124.0/23  
[DIGITALOCEAN3 2017-11-11 from 162.243.188.2] * (100/-) [AS12i]
	Type: BGP unicast univ
	BGP.origin: IGP
	BGP.as_path: 393406 3630 12
	BGP.next_hop: 162.243.188.2
	BGP.local_pref: 100
	BGP.atomic_aggr: 
	BGP.aggregator: 192.168.255.3 AS12
	BGP.community: (14061,2000) (14061,2002) (14061,3000) (14061,3001) (65363,714) (65363,2906) (65363,13335) (65363,13414) (65363,14061) (65363,20940) (65363,32934) (65363,41690) (65363,46489) (65363,65340)
	BGP.ext_community: (RPKI Origin Validation State: not-found)

With their routes originating from AS 12, all their internet connectivity works fine.

However when they failover to their secondary path which is F5 Silverline DDOS protection over Optimimum Lightpath, they are unable to connect to any Akamai hosted websites.
The difference between their primary path and secondary path is that the secondary path does not strip their origin AS 394666.

To answer Job's question, yes the originating router is AS4 capable. I checked the looking glass link you provided and see the correct origin AS 394666. See below:

216.165.124.0/24  
[DIGITALOCEAN5 14:14:44 from 5.101.111.2] * (100/-) [AS394666i]
	Type: BGP unicast univ
	BGP.origin: IGP
	BGP.as_path: 202109 2914 55002 394666
	BGP.next_hop: 5.101.111.2
	BGP.local_pref: 100
	BGP.community: (2914,410) (2914,1203) (2914,2201) (2914,3200) (14061,2100) (14061,2101) (14061,4000) (14061,4001)
	BGP.ext_community: (RPKI Origin Validation State: not-found)

However we noticed some of Level 3's looking glass routers only see the AS_Trans 23456 as shown in the output below. I'm assuming that means some of Level3's routers are not AS4 capable, but does that mean they will drop the routes?

Report generated from: car1.jan1

Route results for 216.165.124.0/24 from Jackson, MS

BGP routing table entry for 216.165.124.0/24
Paths: (2 available, best #2)
  1299 55002 23456
  AS-path translation: { TELIANET DEFENSENET-1 AS23456 }
    ear3.Dallas1 (metric 43807)
      Origin IGP, metric 100000, localpref 86, valid, internal
      Community: North_America Lclprf_86 United_States Level3_Peer Dallas Level3:10497
      Originator: ear3.Dallas1
  1299 55002 23456
  AS-path translation: { TELIANET DEFENSENET-1 AS23456 }
    ear3.Dallas1 (metric 43807)
      Origin IGP, metric 100000, localpref 86, valid, internal, best
      Community: North_America Lclprf_86 United_States Level3_Peer Dallas Level3:10497
      Originator: ear3.Dallas1

Thanks,
Greg

Gregory Gombas
CCIE# 19649 - R&S
Network Consulting Engineer
Advanced Services
grgombas at cisco.com
Office: +1-212-714-4497
Mobile: +1-201-675-9457
Cisco Systems Limited
One Penn Plaza
6th & 9th Floors
New York, NY 10119
United States
Cisco.com





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-----Original Message-----
From: Job Snijders [mailto:job at ntt.net] 
Sent: Tuesday, November 14, 2017 11:36 AM
To: Greg Gombas -X (grgombas) <grgombas at cisco.com>
Cc: nanog at nanog.org
Subject: Re: Issues with 4-octet BGP AS and Akamai?

Hi,

What prefix and ASN is this about?

Are you sure you are advertising from an AS4 capable router?

Do you see the expected 4-byte ASN as origin in a aggregator looking glass like http://lg.ring.nlnog.net/prefix_detail/lg01/ipv4?q=www.nlnog.net ?

Kind regards,

Job


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