< draft-ietf-pppext-posvcholo-05.txt		draft-ietf-pppext-posvcholo-06.txt >
			A new Request for Comments is now available in online RFC libraries.
	PPP Extensions Working Group N. Jones,		RFC 3255
	INTERNET DRAFT Agere Systems,
	Category: Standards Track C. Murton,
	Expires: June 2002 Nortel Networks
	December 2001
	Extending PPP over SONET/SDH
	with virtual concatenation, high order and low order payloads
	<draft-ietf-pppext-posvcholo-05.txt>
	Status of this Memo
	This document is an Internet-Draft and is in full conformance with
	all provisions of Section 10 of RFC 2026.
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	Abstract
	The RFC 1661 Point-to-Point Protocol (PPP) [1] provides a standard
	method for transporting multi-protocol datagrams over point-to-point
	links. The RFC 1662 PPP in HDLC-like Framing [2] and RFC 2615 PPP
	over SONET/SDH (POS) [3] documents describe the use of PPP over
	Synchronous Optical Network (SONET) and Synchronous Digital
	Hierarchy (SDH) circuits.
	This document describes an extension to the mapping of PPP into
	SONET/SDH defined in RFC 2615 PPP over SONET/SDH (POS) [3], to
	include use of SONET/SDH SPE/VC virtual concatenation and use of
	both high order and low order payloads.
	This document is the product of the Point-to-Point Protocol
	Extensions Working Group of the Internet Engineering Task Force
	(IETF). Comments should be submitted to the ietf-ppp@merit.edu
	mailing list.
	Table of Contents
	1. Introduction................................................3
	2. Rate Comparisons............................................4
	3. Physical Layer Requirements.................................5
	4. Standards Status............................................6
	5. Security Considerations.....................................6
	6. References..................................................7
	7. Acknowledgments.............................................7
	10. Author's Addresses..........................................7
	11. Copyright Notice............................................8
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	1. Introduction
	Current implementations of PPP over SONET/SDH are required to select
	transport structures from the relatively limited number of
	contiguously concatenated signals that are available
	The only currently supported SONET/SDH SPE/VCs in RFC 2615 [3] are
	the following:
	SONET SDH
	----------------------------------------
	STS-3c-SPE VC-4
	STS-12c-SPE VC-4-4c
	STS-48c-SPE VC-4-16c
	STS-192c-SPE VC-4-64c
	Note that VC-4-4c and above are not widely supported in SDH networks
	at present.
	The use of virtual concatenation means that the right size SONET/SDH
	bandwidth can be selected for PPP links.
	For the convenience of the reader, the equivalent terms are listed
	below:
	SONET SDH
	---------------------------------------------
	SPE VC
	VT (1.5/2/6) Low order VC (VC-11/12/2)
	STS SPE Higher Order VC (VC-3/4/4-Nc)
	STS-1 frame STM-0 frame (rarely used)
	STS-1 SPE VC-3
	STS-1-nv VC-3-nv (virtual concatenation)
	STS-1 payload C-3
	STS-3c frame STM-1 frame, AU-4
	STS-3c SPE VC-4
	STS-3c-nv VC-4-nv (virtual concatenation)
	STS-3c payload C-4
	STS-12c/48c/192c frame STM-4/16/64 frame, AU-4-4c/16c/64c
	STS-12c/48c/192c-SPE VC-4-4c/16c/64c
	STS-12c/48c/192c payload C-4-4c/16c/64c
	This table is an extended version of the equivalent table in RFC
	2615 [3]. Additional information on the above terms can be found in
	Bellcore GR-253-CORE [4], ANSI T1.105 [5], ANSI T1.105.02 [6] and
	ITU-T G.707 [7].
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	2. Rate Comparisons
	Currently supported WAN bandwidth links for PPP over SONET/SDH:
	ANSI ETSI
	-----------------------------------------------------
	STS-3c (150Mbit/s) STM-1 (150Mbit/s)
	STS-12c (620Mbit/s) STM-4 AU-4-4c (620Mbit/s)
	STS-48c (2.4Gbit/s) STM-16 AU-4-16c (2.4Gbit/s)
	STS-192c (9.6Gbit/s) STM-64 AU-4-64c (9.6Gbit/s)
	Note that AU-4-4c and AU-4-16c are not generally available in SDH
	networks at present.
	With virtual concatenation the following additional WAN bandwidth
	links would be available for PPP over SONET/SDH:
	SONET
	VT-1.5-nv (n=3D1-64) 1.6Mbit/s-102Mbit/s
	STS-1-nv (n=3D1-64) 49Mbit/s-3.1Gbit/s
	STS-3c-nv (n=3D1-64) 150Mbit/s-10Gbit/s
	SDH
	VC-12-nv (n=3D1-64) 2.2Mbit/s-139Mbit/s
	VC-3-nv (n=3D1-64) 49Mbit/s-3.1Gbit/s
	VC-4-nv (n=3D1-64) 150Mbit/s-10Gbit/s
	Higher levels of virtual concatenation are possible, but not
	necessarily useful. Lower levels of virtual concatenation are
	defined in the telecommunications standards for use if needed.
	Table 1 and Table 2,respectively depict the SONET/SDH transport
	structures that are currently available to carry various popular bit
	rates. Each table contains three columns. The first column shows the
	bit rates of the service to be transported.
	The next column contains two values:
	a) the logical signals that are currently available to provide such
	transport and, b) in parenthesis, the percent efficiency of the
	given transport signal without the use of virtual concatenation.
	Likewise, the final column also contains two values:
	a) the logical signals that are currently available to provide such
	transport and, b) in parenthesis, the percent efficiency of the
	given transport signal with the use of virtual concatenation.
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	Note, that Table 1, contains SONET transport signals with the
	following effective payload capacity: VT-1.5 SPE =3D 1.600 Mbit/s,
	STS-1 SPE =3D 49.536 Mbit/s, STS-3c SPE =3D 149.760 Mbit/s, STS-12c =
	SPE
	=3D 599.040 Mbit/s, STS-48c SPE =3D 2,396.160 Mbit/s and STS-192c =
	SPE =3D
	9,584.640 Mbit/s.
	Table 1. SONET Virtual Concatenation
	Bit rate Without With
	--------------------------------------------
	10Mbit/s STS-1 (20%) VT-1.5-7v (89%)
	100Mbit/s STS-3c (67%) STS-1-2v (100%)
	200Mbit/s STS-12c(33%) STS-1-4v (100%)
	1Gbit/s STS-48c(42%) STS-3c-7v (95%)
	Similarly, Table 2, contains SDH transport signals with the
	following effective payload capacity: VC-12 =3D 2.176 Mbit/s,
	VC-3 =3D 48.960 Mbit/s, VC-4 =3D 149.760 Mbit/s, VC-4-4c =3D 599.040
	Mbit/s, VC-4-16c =3D 2,396.160 Mbit/s and VC-4-64c =3D 9,584.640 =
	Mbit/s.
	Table 2. SDH Virtual Concatenation
	Bit rate Without With
	-------------------------------------------
	10Mbit/s VC-3 (20%) VC-12-5v (92%)
	100Mbit/s VC-4 (67%) VC-3-2v (100%)
	200Mbit/s VC-4-4c(33%) VC-3-4v (100%)
	1Gbit/s VC-4-16c(42%) VC-4-7v (95%)
	3. Physical Layer Requirements
	There are two minor modifications to the physical layer requirements
	as defined in RFC 2615 when virtually concatenated SPEs/VCs are used
	to provide transport for PPP over SONET/SDH.
	First, the path signal label (C2 byte) value for SONET/SDH STS-1/VC-
	3 and above SPE/VCs is required to be the same for all constituent
	channels. This is in contrast to the use of a single C2 byte for PPP
	transport over contiguously concatenated SONET/SDH SPE/VCs. The
	values used for the C2 bytes should be in accordance with RFC 2615.
	For SONET VT-1.5/2/6 and SDH VC-11/12/2 the path signal label (V5
	byte bits 5-7) is required to be the same for all constituent
	channels per ITU-T G.707 [7] and ANSI T1.105.02 [6].
	Second, for SONET/SDH STS-1/VC-3 and above SPE/VCs the multi-frame
	indicator (H4) byte will be unused for transport links utilizing
	contiguously concatenated SONET/SDH SPE/VCs. When the concatenation
	scheme is virtual as opposed to contiguous the H4 byte must be
	populated as per ITU-T G.707 or T1.105.02. Similarly, for virtual
	concatenation based on SONET VT-1.5/2/6 and SDH VC-11/12/2 channels
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	bit 2 of the path overhead K4 byte will be set to the value
	indicated per ITU-T G.707 [7] and ANSI T1.105.02 [6].
	4. Standards Status
	ITU-T (SG13/SG15), ANSI T1X1 and ETSI TM1/WP3 have developed a
	global standard for SONET/SDH High Order and Low Order payload
	Virtual Concatenation. This standard is defined in the following
	documents:
	ITU-T G.803 Architecture of transport networks based on the
	synchronous digital hierarchy (SDH)
	ITU-T G.707 Network Node Interface for the Synchronous Digital
	Hierarchy (SDH)
	ITU-T G.783 Characteristics of Synchronous Digital Hierarchy
	(SDH) Equipment Functional Blocks
	ANSI T1.105 Synchronous Optical Network (SONET) - Basic
	Description including Multiplex Structure, Rates and Formats
	ANSI T1.105.02 Synchronous Optical Network (SONET) - Payload
	Mappings
	ETSI EN 300 417-9-1 Transmission and Multiplexing (TM) Generic
	requirements of transport functionality of equipment Part 9:
	Synchronous Digital Hierarchy (SDH) concatenated path layer
	functions. Subpart 1: Requirements
	Work in ITU-T, ANSI T1X1 and ETSI TM1/WP3 has ensured global
	standards alignment.
	With the completion of a standard for SONET/SDH SPE/VC virtual
	concatenation it is appropriate to document the use of this standard
	for PPP transport over SONET/SDH, which is the intent of this
	document.
	5. Security Considerations
	The security discussion in RFC 2615 also applies to this document.
	No new security features have been explicitly introduced or removed
	compared to RFC 2615.
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	6. References
	[1] Simpson, W., Editor, "The Point-to-Point Protocol (PPP)", RFC
	1661, Daydreamer, July 1994.
	[2] Simpson, W., Editor, "PPP in HDLC-like Framing, "RFC 1662,
	Daydreamer, July 1994.
	[3] Malis, A. & Simpson, W., "PPP over SONET/SDH, "RFC 2615, June
	1999.
	[4] Bellcore Publication GR-253-Core "Synchronous Optical Network
	(SONET) Transport Systems: Common Generic Criteria" January 1999
	[5] American National Standards Institute, "Synchronous Optical
	Network (SONET) - Basic Description including Multiplex Structure,
	Rates and Formats" ANSI T1.105-1995
	[6] American National Standards Institute, "Synchronous Optical
	Network (SONET) - Payload Mappings" ANSI T1.105.02-1998
	[7] ITU-T Recommendation G.707 "Network Node Interface for the		Title: Extending Point-to-Point Protocol (PPP) over
	Synchronous Digital Hierarchy" 1996		Synchronous Optical NETwork/Synchronous Digital
			Hierarchy (SONET/SDH) with virtual concatenation,
			high order and low order payloads
			Author(s): N. Jones, C. Murton
			Status: Standards Track
			Date: April 2002
			Mailbox: nrjones@agere.com, murton@nortelnetworks.com
			Pages: 8
			Characters: 14192
			Updates/Obsoletes/SeeAlso: None
	7. Acknowledgments		I-D Tag: draft-ietf-pppext-posvcholo-06.txt
	Huub van Helvoort, Maarten Vissers (Lucent Technologies), Paul		URL: ftp://ftp.rfc-editor.org/in-notes/rfc3255.txt
	Langner (Lucent Microelectronics), Trevor Wilson (Nortel Networks),
	Mark Carson (Nortel Networks) and James McKee (Nortel Networks) for
	their contribution to the development of virtual concatenation of
	SONET/SDH payloads.
	8. Author's Addresses		This document describes an extension to the mapping of Point-to-Point
			Protocol (PPP) into Synchronous Optical NETwork/Synchronous Digital
			Hierarchy (SONET/SDH) to include the use of SONET/SDH SPE/VC virtual
			concatenation and the use of both high order and low order payloads.
	Nevin Jones		This document is a product of the Point-to-Point Protocol Extensions
	Agere Systems		Working Group of the IETF.
	Broadband IC Systems Architecture
	Rm. 7E-321
	600 Mountain Avenue
	Murray Hill, NJ 07974
	Email: nrjones@agere.com
	Chris Murton		This is now a Proposed Standard Protocol.
	Nortel Networks Harlow Laboratories
	London Road, Harlow,
	Essex, CM17 9NA UK
	Email: murton@nortelnetworks.com
	Jones Expires June 2002 7		This document specifies an Internet standards track protocol for
	=0C		the Internet community, and requests discussion and suggestions
	9. Copyright Notice		for improvements. Please refer to the current edition of the
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