All,

The list of concepts/terms  proposed by Sue and Margo are very useful and I 
have attempted to answer some of them,  unfortunately, quite few of the terms 
are complicated and may need further explanation. Please feel free to add or 
improve upon my answers.

1.  Legacy is anything that has been existence for a long time and handed 
down from previous generations.  In the world of telecom, there are many 
different legacies,  including legacy application, legacy card, legacy data, 
legacy LAN and legacy equipment  There is no precise category of legacy 
items, in short, legacy is anything that is outdated but too expensive to 
replace.  See 3) for an example.

2.  Enterprise are companies, or retail customers.  Contrast with wholesale 
customers, which are mainly capacity carriers like Level 3, Global Crossing, 
RBOCS, IXCS, etc.
 
3.  I am not sure what is meant by recommended standard.  Single-mode fiber 
(SMF) is an optical fiber with diameter of  7 to 9 microns (about 1/3000th of 
an inch), used for high speed transmission over long distances.  It provides 
greater bandwidth and lower dispersion than multi-mode fiber(diameter of  50 
to100 microns).  The next generation of SMF are high-speed data optimized 
fibers like Corning's LEAF and Lucent's TrueWave.  These new fibers have 
wider core and better dispersion/attenuation characteristics to allow more 
traffic to travel over longer distances with out having to be amplified.  The 
fiber core is the part of the fiber that actually carries the light signal 
transmission.  Existing fiber networks of incumbents such as AT&T, MCI 
Worldcom and Sprint are largely made up of the older SMF (legacy fibers) 
while the new bandwidth barons such as Level 3, Global Crossing. Qwest and 
EBS have deployed the latest SMF. 

4.  IRU-  Indefeasible Right of Use is a term used in the underseas cable and 
fiber optic business.  An IRU is mainly composed of the following elements

a) Basis of offer -- transfer of asset ownership of fiber to the buyer. In 
some respects, IRUs is similar to real estate acquisition, in which ownership 
of a physical entity passes from seller to buyer by the execution of a 
contract.  

b) Ownership period -- usually for the planned life of a cable and is 
determined by the seller.  
Typically, a cable life span would be 15, 20 or 25 years.  However, cable 
life cycles will probably shorten in the near future due to the more rapid 
pace of the innovation in fiber and photonic engineering.

c) Deposits
It is usual for a non-refundable deposit to be requested by the seller at the 
time of executing contracts, in most cases this is 10% of the purchase price.

d) O&M costs
O&M charges are normally a recurring annual charge payable to the seller (or 
third party O&M contractor) to cover both costs of daily and emergency 
maintenance.  The charges are usually escalated to inflation and to the 
additional costs associated with cable aging.

5.  The information transmitted along the various capacities are 1s and 0s, 
the digitalized equivalent of voice, data or video.  It is common to express 
the capacity of a digital transmission medium by the speed or rate at which 
it is able to transmit digital information. A single voice transmission 
normally operates at 64 kb/s, a T-1 or a DS-0, the consequent digital signals 
are all based on the number of DS-0 channels.  DS standards was developed in 
North American  and is mainly used for copper lines.  A fiber optics became 
mainstream, SONET (Synchronous Optical Network)  was adopted as a  standard 
for connecting fiber-optic transmission systems

6. SONET is the lowest level of the OSI protocol model-- the physical layer, 
it is a method of providing a roadway, or path that can be used by a variety 
of traffic sources and protocols. In many ways, SONET is completely neutral 
to the content or higher level protocols in the traffic stream itself.  Basic 
foundation of SONET consist of DS-0 signal that are multiplexed to create 
51.84 kbps, known as STS-1 (Synchronous transport signal), STS-1 is an 
electrical signal rate that corresponds to optical carrier line rate of OC-1 
(building blocks).   With the older DS systems, signals can't jump from DS-1 
to DS-3, instead a 2 steps process must be taken, which involves adding 
overhead to the transmission.  With Sonet, higher capacities can be created 
by interleaving STS-1 signals to create a concatenated, or linked, signal. 
For example, three STS-1 frames can form an STS-3 frame (155Mbits/sec). Rates 
above STS-3 can be created by either directly multiplexing STS-1 signals or 
by byte-interleaving STS-3 signals. SONET can also handle signals below 
51Mbits/sec. A structure called VT (virtual tributary) accommodates DS-1, 
DS-2 and E1 (European equivalent of T1 at 2 Mbit/s)

7. ATM is Short for Asynchronous Transfer Mode, a network technology based on 
transferring data in cells or packets of a fixed size. The cell used with ATM 
is relatively small compared to units used with older technologies. ATM 
creates a fixed channel, or route, between two points whenever data transfer 
begins. This differs from TCP/IP, in which messages are divided into packets 
and each packet can take a different route from source to destination. This 
difference makes it easier to track and bill data usage across an ATM 
network, but it makes it less adaptable to sudden surges in network 
traffic.   ATM is designed specifically to operates with  SONET as the 
transport.  While new entrants such as Level 3 built its network based on 
pure IP technology, it is still using ATM to link up its core locations.  The 
trouble with IP currently is the QoS and delay issues. In the future, 
however, with advanced protocols such as MPLS, routers are expected to 
eliminate ATM in the network.  MPLS is an extension of IP and it provides QoS 
similar to ATM.   For new entrants, the long term goal is to replace the 
legacy system  (SONET and ATM) with IP over DWDM, which is more efficient and 
lower cost transport. 

8. SDH is European equivalent of SONET

9. bi-directional line switched ring (BLSR)- SONET operates in several 
different modes. A major distinction in operation is whether the service is 
deployed in a linear fashion or as one of several ring types.  There are two 
types of SONET ring. One switches individual paths (path switched) and the 
other switches the entire optical line capacity (line switched).  A key 
difference is the number of fibers used. Path switched rings use only two 
fibers while line switching can use either two or four fibers. Four fiber 
bi-directional line switching sends traffic only in the required direction 
during normal operation. Each direction has a working fiber and a protect 
fiber in each direction. During a fiber interruption, the traffic is routed 
around the break in the opposite direction, hence the name bi-directional.
 
10. Throughput capacity is the actual amount of useful information which is 
transmitted.  It is used to measure the efficiency of a network.
11. Long haul - means long distance, long haul implies traversing states or 
countries, as oppose to short haul.
12.  10% rule -  A accounting rule in a case in which 10% of the traffic is 
intrastate, and the other 90% interstate, then the traffic is deemed to be 
interstate.




	Susan M Landwehr@ENRON
	12/27/00 02:59 PM
		
		 To: Margo Reyna/NA/Enron@Enron
		 cc: Barbara A Hueter/NA/Enron@Enron, Donald Lassere/Enron 
Communications@Enron Communications, Jeff Dasovich/NA/Enron@Enron, Lara 
Leibman/Enron Communications@Enron Communications, Marchris 
Robinson/NA/Enron@Enron, Mona L Petrochko/NA/Enron@Enron, Ricardo 
Charvel/NA/Enron@Enron, Scott Bolton/Enron Communications@Enron 
Communications, Stephen D Burns/Corp/Enron@ENRON, Sue Nord/NA/Enron@Enron, 
Susan M Landwehr/NA/Enron@Enron, Tracy Cooper/Enron Communications@Enron 
Communications, Xi Xi/Enron Communications@Enron Communications
		 Subject: Re: My list of concepts/terms

I'll add two to the list:

1  Why is the term "Legacy" often used and does it mean something other than 
"old way of doing things"


2.  Why is a business customer called an "Enterprise" customer?  Does it have 
something to do with the size of the customer?  The type of customer?  Or is 
it just a fancy name for a customer.



	Margo Reyna
	12/19/2000 10:37 AM
		 
		 To: Sue Nord/NA/Enron@Enron, Scott Bolton/Enron Communications@Enron 
Communications, Tracy Cooper/Enron Communications@Enron Communications, Lara 
Leibman/Enron Communications@Enron Communications, Donald Lassere/Enron 
Communications@Enron Communications, Mona L Petrochko/NA/Enron@Enron, Barbara 
A Hueter/NA/Enron@Enron, Jeff Dasovich/NA/Enron@Enron, Susan M 
Landwehr/NA/Enron@Enron, Marchris Robinson/NA/Enron@Enron, Ricardo 
Charvel/NA/Enron@Enron, Stephen D Burns/Corp/Enron@ENRON, Xi Xi/Enron 
Communications@Enron Communications
		 cc: 
		 Subject: My list of concepts/terms

Here's my list of some things that I would like to learn more about:

1.  The difference between recommended standard (RS) and single-mode fiber 
(SMF) cable?

2.  What is an indefeasible right of use (IRU)?  It is like a right-of-way?

3.  What are the differences in the various capacities of cable (DS-3, 
OC-192, etc.).  Not just the amount of capacity each has, but what types of 
information are transmitted along each.

4.  What is a synchronous optical network (SONET)?

5.  What is asynchronous transfer mode (ATM)? 

6.  What is synchronous digital hierarchy (SDH)?  I think this is used in 
Europe, but I'm not sure.

7.  What is a bi-directional line switched ring (BLSR)?

8.  What is throughput capacity?

9.  What does the term "long haul" mean?

10.  I still don't have a grasp of the 10% rule.  Unfortunately, I think I 
need this one spelled out in the most basic terms.

I have many more questions, but I think this is a good start.

Thanks.

Margo Reyna
Regulatory Analyst
Enron Corp., Government Affairs
Phone:  713-853-9191