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OTT and  the  future  of  the  PSTN   Henning  Schulzrinne   FCC  

PSTN: The  good  &  the  ugly   The  good  

The ugly  

Global Connectivity  (across  devices  and   providers)  

Minimalist service  

High reliability   (engineering,  power)  

Limited quality  (4  kHz)  

Ease of  use  

Hard to  control  reachability   (ring  at  2  am)  

Emergency usage  

Operator trunks!  

Universal access   (HAC,  TTY,  VRS)  

No universal  text  &  video  

Mostly private   (protected  content  &  CPNI)  

Limited authentication   Security  more  legal  than  technical   (“trust  us,  we’re  a  carrier”)  

Relatively cheap   (c/minute)  

Relatively expensive   ($/MB)   2  

The OTT  to  “traditional”  spectrum    

Non-­‐interconnected VoIP   • Not   interconnected  

Interconnected VoIP   • Bidirectional   connectivity  to  E. 164  numbers   • 911   • CALEA   • USF  

Video relay  service   • Multimedia  for   Deaf  &  HoH   • Can  reach  any  E. 164  number  via   relay  

QoS-­‐enabled VoIP   • [technical   possibility]   • Can  reach  any   telephone  number   • QoS  as  commercial   service  

Facilities-­‐based VoIP   • “specialized   service”   • often,  logical,  not   physical  separation   (“service  flow”)   • e.g.,  MVPD  service  

user-­‐initiated resource  reservation   (RSVP,  NSIS,  DOCSIS   3)    

Traditional Analog/ TDM  POTS   • needs  no   explanation  

What are  key  attributes?   *  Universality  

*  reachability à  global  numbering  &  interconnection   *  media  à  HD  audio,  video,  text   *  availability  à  universal  service  regardless  of   *  geography   *  income   *  disability  

*  affordability à  service  competition  +  affordable  standalone  broadband  

*  Public safety   *  *  *  * 

citizen-­‐to-­‐authority: emergency  services  (911)   authority-­‐to-­‐citizen:  alerting   law  enforcement   survivable  (facilities  redundancy,  power  outages)  

*  Quality *  *  *  * 

media (voice  +  …)  quality   assured  identity   assured  privacy  (CPNI)   accountable  reliability   4  

What is  less  important?   *  Technology   *  wired  vs.  wireless   *  but:  maintain  quality  if  substitute  rather  than   supplement  

*  packet vs.  circuit   *  “facilities-­‐based”  vs.  “over-­‐the-­‐top”   *  distinction  may  blur  if  QoS  as  a  separable   service  

*  Economic organization   *  “telecommunication  carrier”  





circuit (A)  

circuit (A)  


circuit (D)  

circuit (D)  


packet (SS7)  

circuit (D)  


packet (SIP)  

packet (RTP)  

OTT: access  to  broadband   Chart  1 Households  With  Access  to  the   Fixed  B roadband  Speed  Benchmark  by  Technology Any Fi xed Cable DSL Fixed Wireless Other Copper Fi ber 0%




Eighth Broadband  Progress  Report,  August  2012  




Measuring Broadband America

Advertised vs.  actual  2012  

Chart 1: Average Peak Period and 24-Hour Sustained Download Speeds as a Percentage of Advertised, by Provider—April 2012 Test Data 24 hr Mon Sun

7pm 11pm Mon Fri


Actual/ Advertised speed (%)

120% 100% 80% 60% 40% 20%

ht M ed iac om Qw es Ti m eW t ar Ve ne riz r on Fib Ve er riz on DS W L in ds tre am


r In

Fr on tie

Co x

AT &T Ca bl ev isi on Ce nt ur yL in k Ch ar te Co r m ca st


As shown in Chart 2, upload performance in 7 the April 2012 test data is much less affected than download Bperformance peak periods. Measuring   roadband  Aduring merica,   July   2012   While in 2011 almost all ISPs reached 90 percent or above of their advertised upload rate, in 2012 most ISPs improved to deliver above 100 percent of their advertised rate, even during peak periods.

Significantly better  than  2011  

Measuring Broadband  America,  July  2012  

Measuring Broadband America

Latency by  technology   Chart 10: Average Peak Period Latency in Milliseconds, by Technology—April 2012 Test Data

Average Latency (Milliseconds)




70 60 50 40 30 20 10

M bp s


M bp s


M bp s


M bp s


M bp s


M bp s


M bp s


M bp s 8

M bp s 6

M bp s 4

M bp s 2

M bp s 1

0. 51


M bp s


Advertised Speed (Mbit/s)


Measuring Broadband  America,  July  2012  

Charts 11.1-11.5 displays average web page loading 39 time by speed tier for the April 2012 test data period. Web pages load much faster as broadband speed increases, but beyond 10 Mbps,

(a) Download throughput is mostly consistent, with some exceptions.

(a) The biggest difference between peak and worst performance is about 40%.

Other QoS  impairments   (b) Upload throughput is consistent across ISPs. Figure 7: Consistency of throughput performance: The average throughput of each user is normalized by the 95th percentile value obtained by that user. (SamKnows)

(b) The standard deviation of throughput measurements increases during peak hours, most significantly for ISPs that see lower throughputs at peak hours.

*  Packet loss  

*  VoIP: <  1-­‐5%  acceptable   *  Video:  loss  à  lower   throughput  

“speed test” measurement taken at the wrong time could likely report misleading numbers that do not have much bearing on the long-term performance.


Effect of Traffic Shaping on Throughput

*  Home networks   *  “Buffer  bloat”  in  gateways  

ISPs shape traffic in different ways, which makes it difficult to compare measurements across ISPs, and sometimes even across users within the same ISP. We study the effect of PowerBoost 3 across different ISPs, time, and users. We also explore how Comcast implements PowerBoost.

(c) Loss increases during peak hours for Cox. Other ISPs do not see this effect as much.

*  “don’t download  that  video,   Figure 8: Time of day is significant: The average download throughput for Cablevision and Cox users drops significantly durWhich ISPs useI’m   PowerBoost, and how does it vary across ISPs? o n   t he   p hone!”   ing the evening peak time. Throughput is also significantly more The SamKnows deployment performs throughput measurements

*  Reliability?

once every two hours; each measurement lasts 30 seconds, and each report is divided into six snapshots at roughly 5-second intervals for the duration of the 30-second test (Section 4). This measurement approach allows us to see the progress of each throughput measurement over time; if PowerBoost is applied, then the throughput during the last snapshot will be less than the throughput during the first. For each report, we normalize the throughput in each period by the throughput reported for the first period. Without PowerBoost, we would expect that the normalized ratio would be close

variable during peak time. (SamKnows)

gradual decrease, rather than an abrupt decrease, could be because PowerBoost durations vary across users or that the ISP changes S. Sundaresan  et  al,    Broadband  Internet  Performance:  A  View   PowerBoost parameters basedACM   on Snetwork From  the  Gateway,   IGCOMM  state. 2011   From a similar analysis for uploads (not shown), we saw that only Comcast and Cox seem to provide PowerBoost for uploads; we observed a decrease in throughput of about 20%. Dischinger et al. [12] also re-

Broadband virtuous  cycle   adoption  

fixed broadband   investment  

(relevance, value)  

applications (incl.  OTT)  

OI principles  

cellular broadband   (backhaul)  

broadband availability  

Open Internet  Principles   Transparency.  Fixed  and  mobile  broadband  providers  must   disclose  the  network  management  practices,  performance   characteristics,  and  terms  and  conditions  of  their  broadband   services;   No  blocking.  Fixed  broadband  providers  may  not  block  lawful   content,  applications,  services,  or  non-­‐harmful  devices;  mobile   broadband  providers  may  not  block  lawful  websites,  or  block   applications  that  compete  with  their  voice  or  video  telephony   services  

No unreasonable  discrimination.  Fixed  broadband  providers   may  not  unreasonably  discriminate  in  transmitting  lawful   network  traffic.   12  

Going forward   *  Interconnected  VoIP:  done   *  CALEA,  USF,  E911   *  Part  4  outage  reporting  

*  In progress  

*  Intercarrier compensation:  IP  interconnection   expectation  +  transition  to  bill-­‐and-­‐keep   *  NG911,  better  location   *  video  relay  services,  CVAA  

*  To do  

*  numbering &  databases   *  security  model  (robocalls,  text  spam,  vishing)   *  VoIP  interconnection  model  

… ,  we  expect  all  carriers  to   negotiate  in  good  faith  in  response   to  requests  for  IP-­‐to-­‐IP   interconnection  for  the  exchange   of  voice  traffic.  The  duty  to   negotiate  in  good  faith  has  been  a   longstanding  element  of   interconnection  requirements   under  the  Communications  Act  and   does  not  depend  upon  the  network   technology  underlying  the   interconnection,   whether  TDM,  IP,  or  otherwise.   Moreover,  we  expect  such  good   faith  negotiations  to  result  in   interconnection  arrangements   between  IP  networks  for  the   purpose  of  exchanging  voice  traffic.  

Henning Schulzrinne Presentation  

Henning Schulzrinne Presentation

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