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RE: A telephony carrier industry perspective


Some excellent comments and observations.

One comment I would make is that many carriers are moving away from SONET
for restoral and protection for IP traffic.  CANARIE, Enron, Sprint,
Frontier, Teleglobe and many others are building IP/DWDM networks where
restoral is done at layer 3.  MPLS (multi Protocol Label Switching) is the
most common implementation of supporting restoral and protection at layer 3.
The vendors claim that we will be able to do restoral at the same speed as
SONET - 50 msec for up to 14 nodes.

With layer 3 restoral, the type of transport protocol becomes less critical.
Thus a simple and cost effective data protocol like GbE may be all that is

For more detailed information on layer 3 restoral please see the white
papers on our web site at


Bill St Arnaud
Director Network Projects



> -----Original Message-----
> From: owner-stds-802-3-hssg@xxxxxxxxxxxxxxxxxx
> [mailto:owner-stds-802-3-hssg@xxxxxxxxxxxxxxxxxx]On Behalf Of Roy Bynum
> Sent: Sunday, May 16, 1999 10:55 AM
> Cc: Roy A. Bynum
> Subject: A telephony carrier industry perspective
> All,
> As an introduction, my name is Roy Bynum. I work for MCI WorldCom in
> the Data and Optical Network Technology Development organization. I am
> late coming to this discussion because of a failure by the telephony
> industry to recognize GbE as a defacto optical networking technology.
> My charter was to work on a native optical networking standard for IP
> services over carrier systems. I came across GbE by accident and
> friends that work for data systems vendors.
> Over the last several months, I have been involved in evaluating
> Gigabit Ethernet (GbE) as a viable data service. The outcome of that
> is the following observations (I apologize for the length of this
> memo.):
> 1. Depending on whom you talk to, 80% to 85% of all data
> communications traffic in the world originates on "Ethernet" (802.3).
> The reason for this is a combination of almost commodity prices on the
> interfaces and very simple operational support requirements, which
> translates into very low cost of ownership for the return on investment.
> 2. Internet Protocol (IP) can operate on most any layer two protocol,
> and does. However, (again depending on whom you talk to) up to 95% of
> all IP communications traffic originates on Ethernet. This makes
> Ethernet the defacto native data communications protocol for IP. The
> reason for this is economics, as stated above.
> 3. GbE is following the precedence of Ethernet in that it is very cost
> effective to deploy compared to other high bandwidth technologies. The
> cost for GbE, per bandwidth, is anywhere from one forth to one tenth
> of that of ATM or Packet Over SONET (POS).
> 4. Dense Wavelength Division Multiplexing (DWDM) is being developed
> and deployed in the Metropolitan carrier and other fiber optic
> systems. These DWDM systems have up to 32 wavelengths, with path
> protection for each. Metro DWDM uses single mode fiber (SMF) over
> "short" distances, 200km or less. The economics for these systems is
> turning out to be very favorable as well.
> 5. Another technology standard is being proposed in the telephony
> industry that provides for transportation of native data, such as
> Ethernet, directly over SONET facilities. Data Aware Transmission over
> SONET (DATS) is the name of that proposal. DATS comes in two types,
> transparent data, and Native data. The transparent data technology
> puts ATM SAR switches directly on SONET transport nodes. Native data
> technology puts Ethernet switches directly on SONET nodes. Native data
> over SONET was demonstrated last year at Interopt and is also turning
> out to have some economic benefits.
> 6. Telephony carrier data communications standards (WAN) today are
> very different from Information Technology (IT) data communications
> (LAN/MAN) standards. Telephony standards are circuit based and are
> concerned with maintaining traffic connection path integrity and
> quality. IT standards are based on connectionless data with a major
> emphasis on cost of ownership. Telephony standards have been based on
> Time Division Multiplexing (TDM) of voice rate (modulo 64kbs)
> circuits. IT Ethernet standards have developed independently and are
> based on native data requirements (modulo 10Mbs). Up until recently,
> the two standards only came together at a router/gateway device that
> removed the different standards at layer two, leaving the upper layer
> (layer three and above) data to be communicated. It also means that
> data traffic path restoration has been dealt with differently by the
> two industries and standards. This is changing.
> 7. Telephony carriers have recognized that in a few years the massive
> bulk of the traffic on their systems will be connectionless oriented
> native data, not connection oriented voice. Some have also recognized
> that the services on this traffic are abstracted from software on the
> end systems, not the facilities based services that provides the
> profits of today. This means that telephony carriers are looking for a
> very cost-effective alternative to the TDM systems that they have been
> using. Many are working, along with vendors on what they refer to as
> "Optical Networking". This is a combination of very high DWDM
> wavelength systems (up to 160 wavelengths) and optical switching which
> provides for direct optical transport of data. I will not go into the
> economics of what has been developed so far, but it is sufficient to
> know that this work is being done.
> 8. SONET/SDH is a very resilient communications standard. It provides
> for very tightly coupled traffic path restoration, which prevents the
> unnecessary loss of data traffic connectivity. It provides for very
> high bandwidth of channelized and concatenated traffic. It provides
> for operational and maintenance support for 365 day x 24 hour
> communications services. It is also very expensive, but justified in
> the many customers, much circuit oriented, bulk traffic services
> provided by the telephony carrier industry.
> 9. The loss of traffic path connectivity for high bandwidth, bulk data
> communications has a much more massive impact than it does with lower
> or moderate bandwidth communications. As more and more applications
> utilize more and more data communications bandwidth, the loss of
> traffic path connectivity will have a business, economic, and personal
> impact that it did not have on lower or moderate bandwidth data
> communications.
> 10. The nature of wide area networking protocols such as IP's OSPF
> changes when you move from a telephony circuit based WAN to a common
> virtual circuit based, layer two switching/bridging WAN. The
> implications of traffic restoration timers and timing requirements
> change when moved from a non-broadcast, multiple circuit path
> architecture to a broadcast domain, single segment architecture. This
> is not very well understood at the present time. It will take a while
> for WAN data communications engineers to work out these changes. This
> will delay, for a short while, the deployment of GbE or 10GbE for
> enterprise WAN systems.
> These observations should help provide some insight into the some of
> the issues being discussed by the HSSG. Whatever is developed must be
> economical for it to survive. 10GbE is approaching the bandwidth and
> functionality requirements of the telephony carrier systems. Where it
> is deployed will have a major impact on what the requirements for it
> will be. Depending on where it is deployed, it needs to be traffic
> path resilient and have operational and maintenance support
> functionality directly within 10GbE. This does not mean that 10GbE
> could not defined with two standards, one for LAN/MAN, and another
> that encapsulates the LAN/MAN framing in a WAN transport standard. A
> LAN standard does not have the requirements of a WAN standard. Many of
> the WAN requirements can be incorporated in the Metro DWDM systems for
> MAN services. This could simplify many of the issues of wavelength,
> power, distance, synchronous or block coding, fiber type, and others.
> I hope that I can be of some help with the development of this or
> these standards. It is very critical to the future economics of the
> carrier data communications industry.
> Thank you,
> Roy Bynum   roy.bynum@xxxxxxx
> Sr. Engineer, Data and Optical Networking Technology Development
> MCI WorldCom
> (972) 729-7249