Fascinating history of transit-free tier 1 networks
I find the concept of transit-free / Tier 1 networks fascinating. These are networks which, by definition, are transit-free. They do not have any transit and can reach the entire routing table just through peering relationships. The importance of these networks has reduced over time as more and more peering happens directly between eyeball networks and content networks. But regardless, I always find it fascinating that these networks effectively define the full autonomy of the internet routing table. Together with the trust in 13 magical root DNS servers and these transit-free networks define what we call “the internet” today.
I was once chatting with my friend and guru Martin Levy (now happily retired) about which networks were possibly transit-free when the internet started. He suggested that Wikipedia history on Tier 1 networks has many of them. The challenge with the Wikipedia page on Tier 1 networks is that the list of transit-free networks appears on 14 Nov 2005. This leaves a gap around which networks were transit-free before Nov 2005.
Before Nov 2005, Nov 2005 and till now
I had an email exchange with Mr Randy Bush and he kindly replied with some hints. According to him AS701/702/703/704 (UUnet / now Verizon), AS174 (PSI / now Cogent), AS1 (BBN) and AS1239 (Sprint) were transit-free networks before this period. The oldest routing dump on RIPE RIS is from 1999 but those dumps are very small and contain too few routes to establish anything. RIPE RRC00 from September 1999 has “view” files, which are essentially a “sh ip bgp dump” and the following month they seem to have moved to the MRT format. On Oregon Route Views, the oldest I can find is this dump from 08 Nov 1997.
This brings me to a possible, although not perfect, method to document the history of transit-free networks.
| Timeline | Method |
|---|---|
| Before-Nov 1997 | Assume AS1, AS1239, AS701 and AS174 to be transit-free and find who else was adjacent to all of them along with BGP routing table dumps |
| Pre - Nov 2005 | Use Wikipedia’s first documented list of tier 1 networks |
| Nov 2005 - Aug 2006 & onwards | With some scripting, dump Wikipedia page history & parse who became tier 1 when along with the support of BGP routing table dumps to cross-validate it via public route collectors |
Limitations
There are some key limitations in my method:
- Ignore paid peering: Because it’s impossible to know about all paid peering agreements, I think, from a technical perspective, it makes sense to focus on “adjacencies” and finding whether a network is transiting via a transit-free network to another transit-free network or not. Take AS174 (earlier PSI and now Cogent) for example publicly states in this release on this release of possible paid peering outside of settlement-free terms with Level 3 in 2005. The Wikipedia article uses this as a reference, as it didn’t classify AS174 as transit-free until 2014. On technical grounds I am just ignoring that, as we never know who else in the list also had similar arrangements. If AS X transits via Y to reach Z", then X is not tier 1. If X has direct adjacency to Y and Z, I assume it is to be “transit-free” (with a mix of settlement-free and/or paid peerings).
- Unknown relation with last transit: If X transits via Y to reach Z and later establishes settlement-free peering with Z, X will appear to be directly adjacent to Y & Z, while X-Y is still a transit relation. Unless X negotiates with its last transit to become a peer as well. Take the case of AS7922 (Comcast) - which is adjacent to all networks but was transiting via AS6453 until recently. AS6453 still tags them as “6453:50 - Customer route”. It would be hard to state AS7922 as transit-free or not. Technically AS7922 is not transiting AS6453 to reach other transit-free networks but at the same time they are transiting AS6453 to reach AS6453 downstreams.
- Lack of data: The Internet itself was new back in the 1990s, BGP was new and so was the concept of route collectors. So what is visible did exist but there could be more that was not visible at the public collectors.
History of transit-free / tier 1 networks
Based on BGP routing table data + Wikipedia Tier 1 history page + other publicly available data
| Month/Year | Data Source | Known transit-free networks | Comments |
|---|---|---|---|
| Before-Nov 1997 | Randy Bush | AS701 (UUnet), AS174 (PSI), AS1 (BBN) & AS1239 (Sprint) | Assumed to have been transit-free ASNs based on Randy’s information for further mapping. Full direct AS_PATHs between them are visible in the November 1997 Route Views dump. |
| Nov 1997 | rviews dump | AS701 (UUnet), AS174 (PSI), AS1 (BBN), AS1239 (Sprint) + (AS3561) C&W America | AT&T AS7018/6478 was likely not tier 1 at this point as routes visible with path “701 1 6478 7018” while some direct paths indicate that AT&T was transiting from BBN AS1 to UUnet AS701. Global Crossing was not a tier 1 at this point - AS3549 had transit via AS6196 (ISI) to reach AS1239 (Sprint) while direct adjacency to PSI AS174, AS701 (UUNET) etc. Unable to establish the situation with AS3356 as it had adjancency to AS701 but no (direct/indirect) routes visible to AS174/AS1/AS1239. Verio AS2914 was not tier 1 at this point as it had transit to via ISC AS1280 to reach UUNET AS701 but does have direct adjacency to AS1/174/1239. Qwest AS209 was not Tier 1, as it had transit to reach AS701 & others. Teleglobe AS6453 was not transit-free and was using UUNET AS701 to reach PSI AS174. Tiscali / Tinet AS3257 was not a tier 1 and was using AS6453 to reach UUNET AS701. TeliaSonera International Carrier AS1299 was not a tier 1 as it was many ASNs away from AS1239/AS3541 etc using AS4200 as transit. The situation with AboveNet AS6461 is unclear as it has adjacency with 701/1239/3561 but unclear with others. |
| June 1998 | rviews dump | AS701 (MCI UUNET), AS174 (PSI), AS1 (BBN), AS1239 (Sprint) + AS3561 (C&W America) + AS7018 (AT&T) + AS2914 (Verio) | AS7018 (AT&T ) got adjacency with AS701, AS1238, AS1, AS3561 etc and thus likely AS7018 became transit-free around this time |
| Sep 1998 | Wikipedia page on MCI | AS701 (MCI UUNET), AS174 (PSI), AS1 (BBN), AS1239 (Sprint) + (AS3561) C&W America | WorldCom (which acquired UUNET earlier) merged with MCI creating MCI WorldCom & thus AS701 becomes MCI UUNET |
| May 2000 | Lightreading | AS701 (MCI UUNET), AS174 (PSI), AS1 (BBN), AS1239 (Sprint) + AS3561 (C&W America) + AS7018 (AT&T) + AS2914 (NTT) | NTT buys Verio, and thus AS2914 becomes NTT from this point onwards |
| Jun 2000 | Verizon | AS701 (MCI UUNET), AS174 (PSI), AS1 (Genuity), AS1239 (Sprint) + AS3561 (C&W America) + AS7018 (AT&T) + AS2914 (NTT) | GTE Corp. merged with Bell Atlantic Corp to form Verizon. They barred Verizon from offering long-distance voice/data services in certain regions due to regulation & thus BBN IP assets including AS1 went to Genuity. |
| Aug 2000 | RIPE RIS RRC00 dump | AS701 (MCI UUNET), AS174 (PSI), AS1 (Genuity), AS1239 (Sprint) + AS3561 (C&W America) + AS7018 (AT&T) + AS2914 (NTT) + AS3539 (Global Crossing) + AS3356 (Level 3) + AS6461 (Metromedia) | AS3549 (Global Crossing) establishes direct adjacency to AS701 and AS3356 (Level 3) also establishes adjacency to AS1239 and seems to be directly adjacent to all known transit-free networks. Thus Both AS3549 and AS3356 likely became tier 1 around this point. Also, AS6461 (Metromedia) got adjacency to AS1239 and had the rest already by now. So AS6461 (Metromedia) became transit-free around this point |
| Sept 2001 | route-views dump + RIPE RIS RRC03 | AS701 (MCI UUNET), AS174 (PSI), AS1 (Genuity), AS1239 (Sprint) + AS3561 (C&W America) + AS7018 (AT&T) + AS2914 (NTT) + AS3539 (Global Crossing) + AS3356 (Level 3) + AS6461 (Metromedia) + AS6453 (Teleglobe) | Teleglobe AS6453 connects to Savvis AS3561. Got other adjacencies also within this year and thus likely AS6453 becomes transit-free network |
| April 2002 | Cogent press release | AS701 (MCI UUNET), AS174 (Cogent), AS1 (Genuity), AS1239 (Sprint) + AS3561 (C&W America) + AS7018 (AT&T) + AS2914 (NTT) + AS3539 (Global Crossing) + AS3356 (Level 3) + AS6461 (Metromedia) + AS6453 (Teleglobe) | Cogent acquires PSI AS174 and thus AS174 becomes Cogent from this point onwards. Besides getting the network they also get C-root DNS server |
| Jan 2003 | Budapest University of Technology and Economics | AS701 (MCI UUNET), AS174 (Cogent), AS1 (Level 3), AS1239 (Sprint) + AS3561 (C&W America) + AS7018 (AT&T) + AS2914 (NTT) + AS3539 (Global Crossing) + AS3356 (Level 3) + AS6461 (Metromedia) + AS6453 (Teleglobe) | Level 3 acquires Genuity which had assets from previous spun off in 2000s when BBN merged with Bell Atlantic to form Verizon. AS1 was included in the assets and thus AS1 goes to Level 3 |
| May 2003 | RIPE RIS & RRC03 dumps | AS701 (MCI UUNET), AS174 (Cogent), AS1239 (Sprint) + AS3561 (C&W America) + AS7018 (AT&T) + AS2914 (NTT) + AS3539 (Global Crossing) + AS3356 (Level 3) + AS6461 (Metromedia) + AS6453 (Teleglobe) | AS1 loses adjacency with most of transit-free ASNs including AS701, AS6453 etc & losses its transit-free network status |
| Sep 2003 | The New York times | AS701 (MCI UUNET) + AS174 (Cogent) + AS1239 (Sprint) + AS3561 (C&W America) + AS7018 (AT&T) + AS2914 (NTT) + AS3539 (Global Crossing) + AS3356 (Level 3) + AS6461 (AboveNet) + AS6453 (Teleglobe) | AS6461 emerged from bankruptcy and becomes AboveNet |
| Jan 2004 | The New York times | AS701 (MCI UUNET) + AS174 (Cogent), AS1239 (Sprint) + AS3561 (Savvis) + AS7018 (AT&T) + AS2914 (NTT) + AS3539 (Global Crossing) + AS3356 (Level 3) + AS6461 (AboveNet) + AS6453 (Teleglobe) | Savvis buys C&W America, and thus AS3561 becomes Savvis |
| June 2004 | rviews dump | AS701 (MCI UUNET), AS174 (Cogent), AS1239 (Sprint) + AS3561 (Savvis) + AS7018 (AT&T) + AS2914 (NTT) + AS3539 (Global Crossing) + AS3356 (Level 3) + AS6461 (AboveNet) + AS6453 (Teleglobe) | AS1299 (TeliaSonera International Carrier) has adjacency to all known transit-free networks by this point although it was added to the Wikipedia list a few years later |
| Nov 2005 | Wikipedia | AS7018 (AT&T) + AS3539 (Global Crossing) + AS3356 (Level 3) + AS701 (MCI WorldCom) + AS2914 (NTT) + AS209 (Qwest) + AS3561 (Savvis) + AS1239 (Sprint) + AS6461 (AboveNet) + AS6453 (Teleglobe) | First list out on Wikipedia + existing known transit-free networks via BGP table guess work |
| Jan 2006 | Wikipedia page on MCI | AS7018 (AT&T) + AS3539 (Global Crossing) + AS3356 (Level 3) + AS701 (Verizon) + AS2914 (NTT) + AS209 (Qwest) + AS3561 (Savvis) + AS1239 (Sprint) + AS6461 (AboveNet) + AS6453 (Teleglobe) + AS1299 (Telia) | Verizon acquires MCI and thus AS701 becomes Verizon along with other AS702, 703, 704 etc |
| Feb 2006 | SEC filing | AS7018 (AT&T) + AS3539 (Global Crossing) + AS3356 (Level 3) + AS701 (Verizon) + AS2914 (NTT) + AS209 (Qwest) + AS3561 (Savvis) + AS1239 (Sprint) + AS6461 (AboveNet) + AS6453 (VSNL) | VSNL acquires AS6453 (Teleglobe) and thus from this point onwards AS6453 becomes VSNL |
| May 2006 | Wikipedia | AS7018 (AT&T) + AS3539 (Global Crossing) + AS3356 (Level 3) + AS701 (Verizon) + AS2914 (NTT) + AS209 (Qwest) + AS3561 (Savvis) + AS1239 (Sprint) + AS6461 (AboveNet) + AS6453 (VSNL) + AS174 (Cogent) + AS1668 (AOL/ATDN) | AS174 (Cogent) reappears in here as it’s there in the Wikipedia list + AS1668 (AOL / ATDN) appears in the list |
| Dec 2007 | Economic Times, India | AS7018 (AT&T) + AS3539 (Global Crossing) + AS3356 (Level 3) + AS701 (Verizon) + AS2914 (NTT) + AS209 (Qwest) + AS3561 (Savvis) + AS1239 (Sprint) + AS6461 (AboveNet) + AS6453 (Tata Comm) + AS174 (Cogent) | Tata Group renames VSNL to Tata Communications and thus AS6453 becomes Tata Communications from this point onwards. This single entity gets assets of VSNL + Teleglobe + Tyco etc under the brand name Tata Comm |
| May 2008 | Wikipedia | AS7018 (AT&T) + AS3539 (Global Crossing) + AS3356 (Level 3) + AS701 (Verizon) + AS2914 (NTT) + AS209 (Qwest) + AS3561 (Savvis) + AS1239 (Sprint) + AS6461 (AboveNet) + AS6453 (Tata Comm) + AS174 (Cogent) + AS1668 (AOL/ATDN) + AS1299 (Telia) | AS1299 (Telia) added to the list as per Wikipedia |
| Apr 2010 | Wikipedia | AS7018 (AT&T) + AS3539 (Global Crossing) + AS3356 (Level 3) + AS701 (Verizon) + AS2914 (NTT) + AS209 (Qwest) + AS3561 (Savvis) + AS1239 (Sprint) + AS6461 (AboveNet) + AS6453 (Tata Comm) + AS174 (Cogent) + AS1668 (AOL/ATDN) + AS1299 (Telia) + AS3257 (Tinet) | AS3257 (Tinet) added to Wikipedia list |
| Nov 2010 | CenturyLink press release | AS7018 (AT&T) + AS3539 (Global Crossing) + AS3356 (Level 3) + AS701 (Verizon) + AS2914 (NTT) + AS209 (CenturyLink) + AS3561 (Savvis) + AS1239 (Sprint) + AS6461 (AboveNet) + AS6453 (Tata Comm) + AS174 (Cogent) + AS1668 (AOL/ATDN) + AS1299 (Telia) + AS3257 (Tinet) | CenturyLink merges with Qwest & AS209 becomes CenturyLink |
| Feb 2011 | Wikipedia | AS7018 (AT&T) + AS3539 (Global Crossing) + AS3356 (Level 3) + AS701 (Verizon) + AS2914 (NTT) + AS209 (CenturyLink) + AS3561 (Savvis) + AS1239 (Sprint) + AS6461 (AboveNet) + AS6453 (Tata Comm) + AS174 (Cogent) + AS1668 (AOL/ATDN) + AS1299 (Telia) + AS3257 (Tinet) + AS3320 (DTAG) | AS3320 (DTAG) added to the Wikipedia list |
| Apr 2011 | Techcrunch | AS7018 (AT&T) + AS3356/AS3539 (Level 3) + AS701 (Verizon) + AS2914 (NTT) + AS209 (CenturyLink) + AS3561 (Savvis) + AS1239 (Sprint) + AS6461 (AboveNet) + AS6453 (Tata Comm) + AS174 (Cogent) + AS1668 (AOL/ATDN) + AS1299 (Telia) + AS3257 (Tinet) + AS3320 (DTAG) | Level 3 acquires Global Crossing and thus AS3549 starts fading behind AS3356 from this point onwards |
| Jul 2011 | CenturyLink press release | AS7018 (AT&T) + AS3356/AS3539/AS3561 (Level 3) + AS701 (Verizon) + AS2914 (NTT) + AS209 (CenturyLink) + AS1239 (Sprint) + AS6461 (AboveNet) + AS6453 (Tata Comm) + AS174 (Cogent) + AS1668 (AOL/ATDN) + AS1299 (Telia) + AS3257 (Tinet) + AS3320 (DTAG) | CenturyLink merges with Savvis & thus AS3561 moves to CenturyLink |
| Mar 2012 | SEC filing | AS7018 (AT&T) + AS3356/AS3539/AS3561 (Level 3) + AS701 (Verizon) + AS2914 (NTT) + AS209 (CenturyLink) + AS1239 (Sprint) + AS6461 (Zayo) + AS6453 (Tata Comm) + AS174 (Cogent) + AS1668 (AOL/ATDN) + AS1299 (Telia) + AS3257 (Tinet) + AS3320 (DTAG) | Zayo acquires Abovenet and thus AS6461 moves to Zayo |
| May 2012 | Wikipedia | AS7018 (AT&T) + AS3356/AS3539/AS3561 (Level 3) + AS701 (Verizon) + AS2914 (NTT) + AS209 (CenturyLink) + AS1239 (Sprint) + AS6461 (Zayo) + AS6453 (Tata Comm) + AS174 (Cogent) + AS1668 (AOL/ATDN) + AS1299 (Telia) + AS3257 (Tinet) + AS3320 (DTAG) + AS6762 (Telecom Italia) | AS6762 (Telecom Italia added to Wikipedia list) |
| Jun 2012 | Wikipedia | AS7018 (AT&T) + AS3356/AS3539/AS3561 (Level 3) + AS701 (Verizon) + AS2914 (NTT) + AS209 (CenturyLink) + AS1239 (Sprint) + AS6461 (Zayo) + AS6453 (Tata Comm) + AS174 (Cogent) + AS1668 (AOL/ATDN) + AS1299 (Telia) + AS3257 (Tinet) + AS3320 (DTAG) + AS6762 (Telecom Italia) + AS2828 (XO Comm) | AS2828 (XO Communications) is listed as tier 1 network this time onwards |
| Aug 2012 | Wikipedia | AS7018 (AT&T) + AS3356/AS3539/AS3561 (Level 3) + AS701 (Verizon) + AS2914 (NTT) + AS209 (CenturyLink) + AS1239 (Sprint) + AS6461 (Zayo) + AS6453 (Tata Comm) + AS174 (Cogent) + AS1668 (AOL/ATDN) + AS1299 (Telia) + AS3257 (Tinet) + AS3320 (DTAG) + AS6762 (Telecom Italia) + AS2828 (XO Comm) + AS5511 (France Telecom) | Wikipedia reports AS5511 (France Telecom) became transit-free around this time based on Renesys & CAIDA |
| Sept 2012 | RIPE RIS RRC00 + Wikipedia | AS7018 (AT&T) + AS3356/AS3539/AS3561 (Level 3) + AS701 (Verizon) + AS2914 (NTT) + AS209 (CenturyLink) + AS1239 (Sprint) + AS6461 (Zayo) + AS6453 (Tata Comm) + AS174 (Cogent) + AS1668 (AOL/ATDN) + AS1299 (Telia) + AS3257 (Tinet) + AS3320 (DTAG) + AS6762 (Telecom Italia) + AS2828 (XO Comm) + AS5511 (France Telecom) + AS12956 (Telefonia) | AS12956 (Telefonia) got adjacency to all known transit-free networks earlier in the year around Feb 2012 & by Sep 2012 it is listed in Wikipedia list as transit-free network |
| Apr 2013 | Telecom Ramblings | AS7018 (AT&T) + AS3356/AS3539/AS3561 (Level 3) + AS701 (Verizon) + AS2914 (NTT) + AS209 (CenturyLink) + AS1239 (Sprint) + AS6461 (Zayo) + AS6453 (Tata Comm) + AS174 (Cogent) + AS1668 (AOL/ATDN) + AS1299 (Telia) + AS3257 (GTT) + AS3320 (DTAG) + AS6762 (Telecom Italia) + AS2828 (XO Comm) + AS5511 (France Telecom) + AS12956 (Telefonia) | GTT Buys Inteliquent’s Data Network and thus AS3257 moves to GTT |
| Jul 2013 | Lightreading | AS7018 (AT&T) + AS3356/AS3539/AS3561 (Level 3) + AS701 (Verizon) + AS2914 (NTT) + AS209 (CenturyLink) + AS1239 (Sprint) + AS6461 (Zayo) + AS6453 (Tata Comm) + AS174 (Cogent) + AS1668 (AOL/ATDN) + AS1299 (Telia) + AS3257 (GTT) + AS3320 (DTAG) + AS6762 (Telecom Italia) + AS2828 (XO Comm) + AS5511 (Orange) + AS12956 (Telefonia) | France telecom renames to Orange and thus AS5511 becomes Orange from this point onwards |
| Feb 2014 | Wikipedia | AS7018 (AT&T) + AS3356/AS3539/AS3561 (Level 3) + AS701 (Verizon) + AS2914 (NTT) + AS209 (CenturyLink) + AS1239 (Sprint) + AS6461 (Zayo) + AS6453 (Tata Comm) + AS174 (Cogent) + AS1299 (Telia) + AS3257 (GTT) + AS3320 (DTAG) + AS6762 (Telecom Italia) + AS2828 (XO Comm) + AS5511 (Orange) + AS12956 (Telefonia) | AS1668 (AOL/ATDN) was removed from the list as it started taking transit via AS3356 (Level 3) and AS1273 (Sprint) |
| Apr 2016 | Wikipedia | AS7018 (AT&T) + AS3356/AS3539/AS3561 (Level 3) + AS701 (Verizon) + AS2914 (NTT) + AS209 (CenturyLink) + AS1239 (Sprint) + AS6461 (Zayo) + AS6453 (Tata Comm) + AS174 (Cogent) + AS1299 (Telia) + AS3257 (GTT) + AS3320 (DTAG) + AS6762 (Telecom Italia) + AS2828 (XO Comm) + AS5511 (Orange) + AS12956 (Telefonia) + AS286 (KPN) | AS286 (KPN) appears in the Wikipedia list as tier 1 network |
| October 2016 | CenturyLink press release | AS7018 (AT&T) + AS701 (Verizon) + AS2914 (NTT) + AS209/AS3356/AS3539/AS3561 (CenturyLink) + AS1239 (Sprint) + AS6461 (Zayo) + AS6453 (Tata Comm) + AS174 (Cogent) + AS1299 (Telia) + AS3257 (GTT) + AS3320 (DTAG) + AS6762 (Telecom Italia) + AS2828 (XO Comm) + AS5511 (Orange) + AS12956 (Telefonia) + AS286 (KPN) | CenturyLink acquires Level 3 and thus AS3356 moves to CenturyLink. While CenturyLink acquired it, the Level 3 IP network was huge and over time AS3356 remained, while the other ASNs went behind it |
| Nov 2016 | Wikipedia | AS7018 (AT&T) + AS701 (Verizon) + AS2914 (NTT) + AS209/AS3356/AS3539/AS3561 (CenturyLink) + AS1239 (Sprint) + AS6461 (Zayo) + AS6453 (Tata Comm) + AS174 (Cogent) + AS1299 (Telia) + AS3257 (GTT) + AS3320 (DTAG) + AS6762 (Telecom Italia) + AS2828 (XO Comm) + AS5511 (Orange) + AS12956 (Telefonia) + AS286 (KPN) + AS6830 (Liberty Global) | AS6830 (Liberty Global) gets added to the list on Wikipedia |
| Feb 2017 | Lightreading | AS7018 (AT&T) + AS701/AS2828 (Verizon) + AS2914 (NTT) + AS209/AS3356/AS3539/AS3561 (CenturyLink) + AS1239 (Sprint) + AS6461 (Zayo) + AS6453 (Tata Comm) + AS174 (Cogent) + AS1299 (Telia) + AS3257 (GTT) + AS3320 (DTAG) + AS6762 (Telecom Italia) + AS5511 (Orange) + AS12956 (Telefonia) + AS286 (KPN) + AS6830 (Liberty Global) | AS701 (Verizon) buys XO Communications and slowly integrates it in it’s backbone. Thus AS2828 is no longer transit-free. |
| April 2017 | Wikipedia | AS7018 (AT&T) + AS701 (Verizon) + AS2914 (NTT) + AS209/AS3356/AS3539/AS3561 (CenturyLink) + AS1239 (Sprint) + AS6461 (Zayo) + AS6453 (Tata Comm) + AS1299 (Telia) + AS3257 (GTT) + AS3320 (DTAG) + AS6762 (Telecom Italia) + AS5511 (Orange) + AS12956 (Telefonia) + AS286 (KPN) + AS6830 (Liberty Global) | AS174 (Cogent) is removed from the Wikipedia tier 1 list due to a lack of IPv6 routes with AS6939 (HE) |
| Sep 2017 | Wikipedia + route-views2 + rrc03 dump | AS7018 (AT&T) + AS701 (Verizon) + AS2914 (NTT) + AS209/AS3356/AS3539/AS3561 (CenturyLink) + AS1239 (Sprint) + AS6461 (Zayo) + AS6453 (Tata Comm) + AS1299 (Telia) + AS3257 (GTT) + AS3320 (DTAG) + AS6762 (Telecom Italia) + AS5511 (Orange) + AS12956 (Telefonia) + AS286 (KPN) + AS6830 (Liberty Global) + AS3491 (PCCW) | AS3491 (PCCW) established direct adjacency to AS1299 (TeliaSonera International) earlier in the year. Was already connected to others by now. By Sep 2017 it was added to the list of transit-free networks by Wikipedia |
| Dec 2019 | KPN AS286 website | AS7018 (AT&T) + AS701 (Verizon) + AS2914 (NTT) + AS209/AS3356/AS3539/AS3561 (CenturyLink) + AS1239 (Sprint) + AS6461 (Zayo) + AS6453 (Tata Comm) + AS1299 (Telia) + AS3257 (GTT) + AS3320 (DTAG) + AS6762 (Telecom Italia) + AS5511 (Orange) + AS12956 (Telefonia) + AS6830 (Liberty Global) + AS3491 (PCCW) | (AS286) KPN was taken over by AS3257 (GTT), and thus AS286 was integrated into it and is removed from the list of tier 1 networks |
| Sep 2020 | CenturyLink press release | AS7018 (AT&T) + AS701 (Verizon) + AS2914 (NTT) + AS3356 (Lumen) + AS1239 (Sprint) + AS6461 (Zayo) + AS6453 (Tata Comm) + AS1299 (Telia) + AS3257 (GTT) + AS3320 (DTAG) + AS6762 (Telecom Italia) + AS5511 (Orange) + AS12956 (Telefonia) + AS6830 (Liberty Global) + AS3491 (PCCW) | CenturyLink rebranded as Lumen and thus AS3356 becomes Lumen from this point onwards and most of its other ASNs had slowly moved behind AS3356 by this time. |
| Jan 2022 | Telecom TV | AS7018 (AT&T) + AS701 (Verizon) + AS2914 (NTT) + AS3356 (Lumen) + AS1239 (Sprint) + AS6461 (Zayo) + AS6453 (Tata Comm) + AS1299 (Arelion) + AS3257 (GTT) + AS3320 (DTAG) + AS6762 (Telecom Italia) + AS5511 (Orange) + AS12956 (Telefonia) + AS6830 (Liberty Global) + AS3491 (PCCW) | Telia becomes Arelion and thus AS1299 becomes Arelion |
| May 2023 | SEC filing | AS7018 (AT&T) + AS701 (Verizon) + AS2914 (NTT) + AS3356 (Lumen) + AS6461 (Zayo) + AS6453 (Tata Comm) + AS1299 (Arelion) + AS3257 (GTT) + AS3320 (DTAG) + AS6762 (Telecom Italia) + AS5511 (Orange) + AS12956 (Telefonia) + AS6830 (Liberty Global) + AS3491 (PCCW) | Cogent acquires Sprint’s IP network as Sprint’s mobile network goes to T-Mobile and and shortly afterwards AS1239 goes behind AS174 |
| Nov 2023 | Colt press release | AS7018 (AT&T) + AS701 (Verizon) + AS2914 (NTT) + AS3356 (Lumen + Colt jointly maintaining it) + AS6461 (Zayo) + AS6453 (Tata Comm) + AS1299 (Arelion) + AS3257 (GTT) + AS3320 (DTAG) + AS6762 (Telecom Italia) + AS5511 (Orange) + AS12956 (Telefonia) + AS6830 (Liberty Global) + AS3491 (PCCW) | Colt buys Lumen’s EMEA network and from this point onwards AS3356 becomes a split network jointly owned by Lumen (in North America, Singapore etc) and Colt in Europe, the Middle East and Africa |
| Aug 2026 | Wikipedia page on Tier 1 networks | AS7018 (AT&T) + AS701 (Verizon) + AS2914 (NTT), AS3356 (Lumen + Colt) + AS6461 (Zayo) + AS6453 (Tata Comm) + AS1299 (Arelion) + AS3257 (GTT) + AS3320 (DTAG) + AS6762 (Telecom Italia) + AS5511 (Orange) + AS12956 (Telefonia/Telxius) + AS6830 (Liberty Global) + AS3491 (PCCW) | Current situation! :-) |
Notes on AS174 / Cogent / PSI
- While Randy’s email listed PSI (AS174) which later became Cogent as transit-free from the early days, I do not see that from Wikipedia’s first list in 2005.
- It was added as Tier 1 in the May 2006 list and was repeatedly added and removed due to their declared paid peering agreement with AS3356 (Level 3). I considered it transit-free until the 2017 change because I am excluding “paid peering” logic for any given ASN. (Just looking at whether transit exists or not).
- There is a genuine possibility of AS174 being transit-free earlier and not later for a few years as they expanded to Asia. This slide from Gaurab Upadhaya (PCH) shows AS_PATH: 1239 2914 174 on slide 7 showing that there was a transit via AS2914 (NTT).
- Since its status is not clear, I will just follow the Wikipedia list. It might be worth exploring through each available collector, including those in Asia, if this situation changed at some other time.
- It was removed from the list in April 2017 due to a lack of IPv6 peering with AS6939 (Hurricane Electric). My table is reflecting the same. Since I am not a neutral person on this, I will avoid any further comment and simply follow what others have documented on the Wikipedia page.
Interesting history Verio -> NTT
Verio had an interesting history of being a web hosting provider in 1996 & was acquired by NTT in 2000. Wikipedia has a fascinating history of the transaction and it is worth reading:
By the year 2000, Verio had purchased 55 ISP/Hosting companies, most in the U.S. but some in Europe. During this time Verio went public on the NASDAQ, trading under the symbol VRIO, with a market value exceeding $1 billion. Shortly after the IPO, in early 2000, Verio was sold to NTT at a per-share price of $73, a total cost slightly exceeding $5 billion. Because NTT was a 53% Japanese government-owned company, foreigners were not allowed to own NTT stock, according to Japanese law at the time,[2] and therefore the buy-out was a 100% cash deal, making it one of the highest grossing deals of the dotcom era. The United States Congress held hearings over the transaction to ensure it did not violate national security concerns. The Justice Department and the Federal Bureau of Investigation expressed concern that the Japanese government, which owned 53 percent of NTT at the time, could gain access to classified information should the U.S. government use Verio’s network to tap Internet communications during an investigation. To placate these concerns, NTT agreed to form a separate division within the company staffed only by U.S. citizens to handle any work in support of government investigations. As a result, the Committee on Foreign Investment in the United States recommended that President Clinton allow the $5.5 billion purchase to proceed. The deal also prompted scrutiny of Japan’s openness to foreign telecom competitors.
Shortly after the announced deal, the NASDAQ stock market crashed in the spring of 2000 in the dot-com bubble burst. The agreed price of $73 remained and NTT and Verio completed the transaction by the fall of 2000.
Eventually, it became NTT AS2914 as we know it today and the hosting part was sold off to Endurance in 2015.
Transit but cannot transit!
Another important thing to mention here is that - there are cases of large networks that have transit but are not completely open to receiving any traffic from transit. When Wikipedia states that “X buys transit from Y” - one may or may not be able to reach X via Y due to the way they control the announcements.
Here’s an example:
Let’s look for a random IP (1.71.103.0/24) from AS4809 (China Telecom) in AS1299 (Arelion) looking glass:
Notice the use of:
- 1299:2009 (Do NOT announce to ANY peer in Europe)
- 1299:5009 (Do NOT announce to ANY peer in North America)
- 1299:7009 (Do NOT announce to ANY peer in Asia)
Thus even though it’s tagged as 1299:37000 (APAC customer) - most of the peers of AS1299 will not get this route because AS4809 is maintaining a direct relationship with those networks & seems to be using AS1299 for very selective announcements. It’s hard to locate all these historical cases but in the present scenario consider these networks to not have full transit. They have their own peerings with many other transit-free networks, along with AS_PATH filters dropping those tier1s from other paths (i.e peer lock).
Feedback & updates
I have very likely missed some data here. Feedback via the comments below or through the direct contact page is welcome. I will update the page accordingly.
