APR 26 '99 17:51 FR NT PATENTS 613 721 3017 TO 618199532476 P.05~34
MULTIPLEX IiIERARI~hIY FOR HIGH CAPACITY TRANSPORT
SYSTEMS
Field of the Invention
This invention is concerned with a method of extending the ITU-T
6.707 multiplex hierarchy for very high capacity transport systems,
through the creation of a new virtual container and its associated pointer.
SUMMARY OF THE INVENTION
Inherent with this method is the development of a new virtual
container, VC-5 and its associated pointer, AU-5. The method of the
invention has as an object to reduce the number of pointers on the high
capacity line. T'he present invention provides for a hierarchy based on
extrapolation of the SONET SPE and multiplex structure up to high
capacity. This would create an STS pointer density of, for example, 768
pointers on a 40Gbps channel.
This method also introduces the concept of nesting pointers, so
that a very high rate network ~VHRN) does not see the STS-1 / STM-1
pointer granularity. It is generally acknowledged there are significant
benefits associated in nesting pointers with respect to reduced
complexity and pointer proce,>sing.
A path overhead is necessarily added for monitoring purposes
within the network. For OAM of the constituent VIiRN payloads it rnay
be advantageous to provide a. VHRN path overhead for certain tributary
levels, i.e. for fault and performance management. This path overhead
has a minimum granularity of an STS-12 / STM-4 SPE. It is to be
understood that this granularity is by way of example only, and that the
present invention is not limited to this rate.
Synchronous multiplexing is also considered by the method
according to this invention.
CA 02270019 1999-04-26
APR 26 '99 17:52 FR NT PATENTS 613 721 3017 TO 618199532476 P.06i34
2
BRIEF DESCRIPTION OF THE DRAWINGS
The foregoing and other objects, features and advantages of the
invention will be apparent frorn the following more particular description
of the preferred embodiments, as illustrated in the appended drawings,
where:
Figure 1 shows the muntiplexing hierarchy as detailed in 6.707;
Figure 2 shows the relationship between various multiplexing
elements;
Figure 3 shows the multiplexing method directly from AU-3 using
TU-3;
Figure 4 is the translation of AU-3 to TUB;
Figure 5 is the translation of AU-3-3c/AU-4 to TU-4;
Figure 6 is the translation of AU-3-l2cl AU-4-4clAU-3-12 /AU4-4
to TU-5;
Figure 7 is the translation of AU-3-48c/AU-4-7 6c to TU-5-4c
Figure 8 is the translation of AU-3-192c/AU4-64c to TU-5-16c;
Figure 9 is the translati~~n of AU-3-768c/AU4-256c to TU-5-64c;
Figure 10 shows the mapping of a TUG-3 into a VC-4
Figure 11 shows the mapping .of a VC-4 into a TU-4;
Figure 12 shows the mapping of a TUG-4 into a TUG-5;
Figure 13 shows the mapping of a TUG-5 into a VC-5;
Figure 14 illustrates the mapping of a TUG-5-nc into a VC-5-nc;
Figure 15 shows thVC-5-nc concatenation;
Figure 16 illustrates the mapping of a C-5 into a VC-5;
Figure 17 illustrates the mapping of a C-5-nc into a VC-5-nc
Figure 18 illustrates the frame structure for the 40GBps VHRN;
Figure 19 is a block diagram of how the multiplex hierarchy may
be extended for a VC-6 granularity;
Figure 20 is a block diagram of how the multiplex hierarchy may
be extended for non-SDH/SONET formats and
Figure 21 show the frarne structure for Byte interleaved at AU-3
or AU-4.
CA 02270019 1999-04-26
APR 26 '99 17:52 FR NT PATENTS 613 721 3017 TO 618199532476 P.07i34
3
DESCRIPTION OF THE PREFERRED EMBODIMENT
The following assumptions are used in the ensuing
implementation, by way of ex<ample:
- The TDM line rate of the VHRN is assumed to be --40GBps.
- The frame size of the 40GBps is equivalent to the frame size for byte
interleaving 256 STM-1 s / 7613 STS-1 s.
The multiplex hierarchy will be considered from a functional
perspective. Consideration with respect to existing hardware is beyond
the scope of this invention.
Figure 1 shows the multiplex hierarchy as detailed in 6.707.
6.707 multiplex hierarchy relies on multiplexing units at a granularity of
AU-3s or AU-4s. For an AU-~I multiplex hierarchy (analogous to the
GR.253, STS-1 multiplex hierarchy) extended to a 40GBps line this
results in 768 AU-3 pointers on the multiplex line. For AU-4 multiplexing
(STM-1 ) this results in 256 AU-4 pointers on the multiplex line. For very
high capacity transport systems, granularity of this order is not required
and indeed adds significant complexity to the VHRN product.
This invention is concerned with a method of extending the ITU-T
6.707 multiplex hierarchy for very high capacity transport systems,
through the creation of a new virtual container VC-5 and its associated
pointer, AU-5. The new virtual container has an effective payload area
equivalent to a STM-4/STS12 SPE. In addition, the novel hierarchy
provides translation of AU-3-ns and AU-4-ns into tributary units (TUs).
It is however to be undNrstood that the invention is applicable for
other rates. The conventions and terminology used in this document are
in line with 6.707.
Definitions
Synchronous Transaort Module STM
A STM is the information structure used to support section layer
connections in the SDH. It consists of information payload and section
overhead (SOH) information fields organized in a block frame structure
which repeats every 125 microseconds. The information is suitably
conditioned for serial transmi ssion on the selected media at a rate, which
CA 02270019 1999-04-26
RPR 26 '99 17:52 FR NT PATENTS 613 721 3017 TO 619199532476 P.08i34
4
is synchronized to the network. A basic STM is defined at 155 520
kbit/s. This is termed STM-1 and is analogous to the GR.253 SONET
STS-3. Higher capacity STMs are formed at rates equivalent to N times
multiples of this basic rate.
A STM-N as detailed in 6.707 can contain byte interleaved AU-3s
or AU-4s. For AU-3 byte interlleaving the STM-N will contain Nx3 AU-3s;
for AU-4 byte interleaving the STM-N will contain N AU-4s.
The STM-N described in this document contains N/4 AU-5s which
are byte interleaved together.
Virtual Container-n (VC-nl:
A virtual container is the information structure used to support path
layer connections in the SDH. It consists of information payload and
path overhead (POH) information fields organized in a block frame
structure which repeats every 125 microseconds. Alignment information
to identify VC-n frame start is provided by the server network layer.
Two types of virtual containers have been identified; higher order
and lower order virtual containers:
- Lower order virtual container-n: VC-n (n = 1, 2)
This element comprises a single container-n (n = 1, 2) plus the
lower order virtual container F'OH appropriate to that level.
- Higher order virtual Container-n: VC-n (n = 3, 4, 5)
6.707 describes virtual containers up to a VC-4. This document
describes a new higher order virtual container, VC-5. The higher order
containers comprise either a Single container-n (n = 3,.4, 5) or an
assembly of tributary unit groups (TUG-2s, TUG-3s, TUG-4s or TUG-5),
together with virtual container POH appropriate to that level,
VCs are equivalent to the SONET VT and STS SPEs. The lower
order virtual containers comprise VT1.5 SPE, VT2 SPE and VT6 SPE.
The higher order virtual containers comprise STS-1 SPE and STS-3c
SPE.
CA 02270019 1999-04-26
RPR 26 '99 17:53 FR NT PRTENTS 613 721 3017 TO 618199532476 P.09i34
Administrative Unit-n (AU-n):
An administrative unit is the information structure, which provides
adaptation between the higher order path layer and the multiplex section
layer. It consists of an information payload (the higher order virtual
container) and an administrative unit pointer, which indicates the offset of
the payload frame start relative to the multiplex section frame start.
Three administrative units are defined. The AU-5, which is
described in this document, consists of a VC-5 plus an administrative
unit pointer which indicates the phase alignment of the VC-5 with respect
to the STM-N frame. The AU-~4 and AU-3, which are detailed in 6.707,
consist of a VC-4 or VC-3, reCpectively, plus an administrative unit
pointer, which indicates the phas~ alignment of the VC with respect to
the STM-N frame.
In each case the administrative unit pointer location is fixed with
respect to the STM-N frame. One or more administrative units occupying
fixed, defined positions in an STM payload is termed an administrative
unit group (AUG).
An AUG 1 consists of a homogeneous assembly of AU-3s or an
AU-4.
An AUG-4 consists of a homogeneous assembly of AU-3s or AU-
4s or an AU-5.
AU-n is equivalent to the SONET STS. An AU-3 is equivalent to an
STS-1; an AU-4 is equivalent to an STS-3c.
Tributary Unit-n (AU-n):
A tributary unit is an information structure, which provides
adaptation between the lower and higher order path layer. It consists of
an information payload (the lower or higher order virtual container) and a
tributary unit pointer, which indicates the offset of the payload frame start
relative to the higher order virtual container frame start.
6.707 described tributary units up to TU-3. The present invention
extends the concept of the TU-n for n = 1, 2, 3, 4, 5. The TU-n consists
of a VC-n together with a tributary unit pointer. One or more tributary
CA 02270019 1999-04-26
APR 26 '99 17:53 FR NT PATENTS 613 721 3017 TO 618199532476 P.10i34
6
units, occupying fixed, defined positions in a higher order VC-n payload
is termed a tributary unit group (TUG). TUGs are defined in such a way
that mixed capacity payloads made up of different size tributary units can
be constructed to increase flexibility of the transport network.
A TUG-2 consists of a homogeneous assembly of identical TU-1s
or a TU-2.
A TUGS consists of a homogeneous assembly of TUG-2s or a TU-
3.
A TUG-4 consists of a homogeneous assembly of TUG-3s or a TU-
4.
A TUG-5 consists of a homogeneous assembly of TUG-4s or a TU-
5.
Container-n ~C-nl:
A container is the information structure, which forms the network
synchronous information payload for a virtual container. For each of the
defined virtual containers there is a corresponding container. Adaptation
functions have been defined for many common network rates into a
limited number of standard containers.
The capacity of each container is detailed in Table 1.
Table 1: Payloads for C-n
VHRN 6.707 Container-n
Container-n Payload (C-n) Payload (MBps)
(C-n) (MBps)
C-3' 48.384 C-3 48.384
C-4 ' 149.760 C-4. 149.760
C-5 603.648' C-4-4c 599.040
C-5-4c 2,414.592'C-4-16c 2,396.160
C-5-16c 9,658.368'C-4-64c 9,584.640
C-5-64c 38,633.472]C-4-256c I 38,338.560
)
CA 02270019 1999-04-26
APR 26 '99 17:53 FR NT PATENTS 613 721 3017 TO 618199532476 P.11i34
7
N otes:
1. C-3 and C-4 are defined in 6.707. Only C-5 and
concatenations thereof are nE>w containers for the VHRN multiplex
hierarchy.
2. For the VHRN hierarchy the payload for a C-n, where n >= 5, is
slightly larger than the corresponding 6.707 container. This is due to the
extra columns allocated for nesting pointers in an AU-n to TU-n
translation. For example for a C-5 these columns are unused and may
therefore be allocated for payload.
3. C-6, C-7 and C-8 map into a VC5-n. At this stage path
overhead is added. To maintain the AU-5 frame size columns of fixed
stuff are added. For a C-5-4c there will be one column of path ovefiead
and three columns of fixed stuff. Although it may seem advantageous to
remove these additional colurnns of fixed stuff for the G5-4c mapping
and assign them as payload; in the interests of scalability this should not
be performed. As the hierarchy scales and a VC-6 and AU-6 are created
the TUG-6 (TUG-5-4c, in this hierarchy) will map into a VC-6 instead of a
VC-5-4c. This mapping will add a column of path overhead but no fixed
stuff. If for the AU-5 hierarchy the C-5-4c container had been increased
to use the columns of fixed stuff it would now be too large to map into a
VC-6.
A op inter is an indicator whose value defines the frame offset of a
virtual container with respect to the frame reference of the transport
entity vn which it is supported.
Concatenation is a procedure by which tributaries are adapted into
Virtual Containers at the boundary of the synchronous network.
CA 02270019 1999-04-26
APR 26 '99 17:53 FR NT PATENTS 613 721 3017 TO 618199532476 P.12i34
8
SDH Multiplexing is a procedure by which lower multiple lower
order path layer signals are adapted into a higher order path or the
multiple higher order path layer signals are adapted into a multiplex
section.
SDH aliqnin4 is a procedure by which the frame offset information
is incorporated into the Tributary Unit or Administrative Unit when
adapting to the frame reference of the supporting layer.
TU pointer transformation is a procedure whereby the
Administrative Unit pointer is adapted to become a Tributary Unit pointer,
i.e. the AU pointer is removed from the overhead and placed in the
payload.
VHRN Multiplexing Structure_
Figure 2 shows the relationship between various multiplexing
elements. TUGs are defined in such a way that mixed capacity payloads
made up of different size tributary units can be constructed to increase
flexibility of the transport network.
This multiplexing hierarchy provides a single pointer at the STM-
4/STS-12 level and path ovefieads at SPEs>= STM-4/STS-12.
Figure 3 shows how an AU-3 is multiplexed using this hierarchy.
Translation of AU-n to TU-n
The possible SDH/SONET tributary interfaces to the VHRN are
defined in Table 2. Upon recEaipt of these signals at the VHRN the
section overhead will be terminated. This leaves either an AU-3-n or an
AU-4-n or concatenations thereof. The relationship between the
tributaries and their corresponding AU-n is shown in Table 2.
The primary requirement of the high capacity multiplex hierarchy is
to reduce the number of point~ars on the high capacity line. For AU-3 and
AU-4 byte interleaved system:; the pointers are presented to the line at a
granularity of STS-1 or STM-1, respectively. For a 40GBps (STM-
256/STS-768) this will result in potentially 768 pointers on the line.
In order for synchronous traffic which has been created using byte
interleaved AU-3s and AU-4s to be carried on the VHRN the pointers of
CA 02270019 1999-04-26
APR 26 '99 17:54 FR NT PATENTS 613 721 3017 TO 618199532476 P.13~34
9
the traffic signals must be hidden from the line, i.e. through nesting
pointers. 6.707 has already standardized a method for nesting pointers
for lower order containers, see Figure 1. This is achieved through the
use of TUs (Tributary Units).
In order to "hide" the tributary pointers from the high capacity line
the tributary AU ns are translated to TU-ns. The translation from AU-n to
corresponding TU-n is detailed in Table 2. The information content and
pointers of both structures area identical; it is only the position of the
pointers with respect to the payload which has changed. The TU-ns will
then be packaged into TUG-5~s and an AU-5 pointer assigned.
CA 02270019 1999-04-26
RPR 26 '99 17:54 FR NT PATENTS 613 721 3017 TO 618199532476 P.14i34
x0
Table 2 Relationship between Synchronous Module, AU-n and TU-n
Tributary Section OH Translation for
Interface
to the
VHRN Termination processing in
of VHRN
tributaries Multiplex Hierarchy
SDH SONET AU-n TU-n
STM-0 STS-1 AU-3 TU-3'
STS-3c AU-3-3c TU-4
STS-12c AU-3-12c TU-5
STS-48c AU-3-48c TU-5-4c
STS-192c AU-&y 92c TU-5-16c
STS-768c AU-3-768c TU-5-64c
~' : M~~
w: '~. N
M. .
STM-1 AU-4 TU-4
STM-4-4c AU-4-4c TU-5
a
7
~. e
STM16-16c fdi. R AU-4-16c TU-5-4c
9.I~A
~ ' "~"
"
K~;a,
STM-64-64c AU-4-64c TU-5-16c
. ,~.
STM-256-256c ~ ~~ . AU-4-256c TU-5-64c
"
~~ ~ "'' ' STS-3 AU-3-3 TU-4
~
.~,.~"~.-
.
STS-12 AU-3-12 TU-5
.:~~.--~.
~.
STS-48 AU-3-48 TU-5-4
-
~~
''~ ~'~'~py',STS-192 AU-3-192 TU-5-16
,~
~'
'~~
,
M
Y4
~~
'~, ~ STS-768 AU-3-768 TU-5-64
;"
~
,.
. 1
STM-4 , AU-4-4 TU-5
STM-16 AU-4r16 TU-5-4
STM-64 i . AU-4-64 TU-5-16
STM-256 ~ , AU-4-256 TU-5-64
. ',
~
We note that the tributary interfaces described are SDHISONET in
nature. Other interfaces (1G Ethemet) may also be supported, an
investigation of optimization of the hierarchy for other tributary interfaces
is for further study. (i.e. 1 G Ethernet may be mapped into a TU-5-2c).
The TU-3 is defined in ta.707, all other tributary units which are
described, i.e. TU-4 and TU-5, are an extension to the 6.707 hierarchy.
CA 02270019 1999-04-26
RPR 26 '99 17:54 FR NT PATENTS 613 721 3017 TO 618199532476 P.15~34
11
Translation of AU-3 to TU-3
The TU-3, as defined in 6.707, consists of a VC-3 with a 9-byte
VC-3 POH and the TU-3 pointer. The first column of the 9-row by 86-
column TU-3 is allocated to the TU-3 pointer (bytes H1, H2, H3) and
fixed stuff. The phase of the'VC~ with respect to the TU-3 in indicated
by the TU-3 pointer. The translation from AU-3 to TU-3 relies on
removing the columns of fixed stuff within the AU-3 payload.
Translation of AU-3,3c I AU-4 to TU-4
Figure 5 shows a translation from an AU-4 to an TU-4. The AU-4
could contain a VC-4 or a STS3c. The TU-4 consists of a VC-4 with a 9-
byte VC-4 POH and the TU-4 pointer. The first column of the 9-row by
262-column TU-4 is allocated to the TU-4 pointer. The phase of the VC-
4 with respect to the TU-4 in indicated by the TU-4. pointer.
Translation of AU-3-12c / AIU-4-4c to TU-5
Figure 6 shows a mapping from an AU-3-12 (AU-3-12-c) or an AU-
4-4 (AU-4-4c) signal into a TU-5. Non-concatenated STM-N signals
where n>4 shall also be processed as AU-5s. 6.707 requires such
signal to be demultiplexed to the STM-1 level and byte interleaved as
AU-4s. Using the AU-5 method it is now only necessary to demultiplex
the signals to AU-5 granularity. The first 4-columns of the 9-row by 1048-
column TU-5 is allocated to the TU-5 pointer. The phase of the VC-5 with
respect to the TU-5 in indicat~ad by the TU-5 pointer.
Translation of AU-3-48c / AI~-4-16c to TU-5-4c
Figure 7 shows a mapping from an AU-3-48c or an AU-4-16c
signal into a TU-5-4c. The first 4x4-columns of the 9-row by 1048x4-
column TU-5-4c is allocated to the TU-5-4c pointer. The phase of the
VC-5-4c with respect to the TU-5-4c in indicated by the TU-5-4c pointer.
CA 02270019 1999-04-26
APR 26 '99 17:54 FR NT PATENTS 613 721 3017 TO 618199532476 P.16i34
12
Translation of AU-3-192c / AU-4-64c to TU-5-16c
Figure 8 shows a mapping from an AU-3-192c or an AU-4-64c
signal into a TU-5-16c. The first 4x16-columns of the 9-row by
1048x16-column TU-5-16c is allocated to the TU-5-16c pointer. The
phase of the VC-5-16c with respect to the TU-5-16c in indicated by the
TU-5-16c pointer.
Translation of AU-3-768c / AU-4-256c to TU-5-64c
Figure 9 shows a mapping from an AU-3-768c or an AU-4-256c
signal into a TU-5-64c. The first 4x64-columns of the 9-row by 1048x64-
column TU-5-64c is allocated to the TU-5~64c pointer. The phase of the
VC-5-64c with respect to the 'fU-5-64c in indicated by the TU-5-64c
pointer.
Figures 10 to 15 show mappings and multiplexing the tributary
groups which have been defined in the hierarchy.
Mapping TUG-3s into a VC-4
The arrangement of three TUG-3s multiplexed into a VC-4 is
shown in Figure 10. The TUG-3 is a 9-row by 86-column structure. The
VC-4 consists of one column of VC-4 POH, two columns of fixed stuff
and a 258 column payload structure. The three TUG-3s are single byte
interleaved into the 9-row by ~?58-column VC-4 payload structure and
have a fixed phase with respect to the VC-4.
Mapping a VC-4 into a TU-4
The mapping of a VC-4 into a TU-4 is shown in Figure 11. The
TU-4 consists of the VC-4 and the TU-4 pointer. The phase of the VC-4
with respect to the TU-4 is indicated by the TU-4 pointer (H1, N1, H1,
H2, H2, H2, H3, H3, H3).
CA 02270019 1999-04-26
APR 26 '99 17:55 FR NT PATENTS 613 721 3017 TO 618199532476 P.17i34
13
Multiplexing a TUG-4 into a TUG-5
The multiplexing structure for the TUG-4 via the TUG-5 is depicted
in Figure 12. The TUG-5 is a 9-row by 1048-column structure, which is
created by single byte interleaving the TUG-4s.
Mapping a TUG-5 into a VC-5
The mapping of a TUG-5 into a VC-5 is shown in Figure 13. The
TUG-5 is a 9-row by 1048-column structure. The VC-5 consists of one
column of VC-5 POH and a 1048 column payload structure. Note that
the VC-5 path overhead has not yet been defined, this is for further
study.
Mapping a TUG-5 nc into a VC-5-nc
6.707 defines concatenated payloads at the VC-4 level. As a
larger AU pointer and virtual container have been defined it is now
possible to perform concatenation at the VC-5 level. Figure 14 shows
the mapping from a TUG-5-nc into a VC-5-nc, where N defines the level
of concatenation, N = 4, 16, 64. Figure 15 shows the frame size for a
concatenated VC-5.
Concatenated tributary units are a new concept from 6.707. To
indicate the concatenated nature of the payload there must be a
concatenation indicator assigned in the VC-5 path overhead. This is
required to prevent misconnection of the concatenated VC-5 payload.
Mapping a C-5 info a VC-5
The mapping of a C-5 into a VC-5 is shown in Figure 16_ The C-5
is a 9-row by 1048-column structure. The VC-5 consists of one column
of VC-5 POH and a 1048 column payload structure.
Mapping a C-5-nc into a VC-5-nc
The mapping of a C-5-nc into a VC-5-nc is shown in Figure 17.
The C-5-nc is a 9-row by 1048xN-column structure. The VC-5 consists of
one column of VC-5 POH, N 1 columns of fixed stuff and a 1048xN
column payload structure.
CA 02270019 1999-04-26
RPR 26 '99 17:55 FR NT PATENTS 613 721 3017 TO 618199532476 P.18i34
14
AU-5 Pointer Definition
The AU-5 pointer can be optimised for system performance. H3
may vary from one to twelve bytes. One H1 byte and one H2 byte are
required.
AU-5 Path Overhead
The path overhead will be align with the VC-4 path ovefiead
detailed in 6.707. In addition, a concatenation indicator is required in the
overhead.
TUG-n Numbering Scheme
A numbering scheme is required to locate the TUG-ns within the
VHRN. 6.707 defines a three figure address (K, L, M) where K
represents the TUG-3 number, L the TUG-2 number and M the TU-1
number. This can logically be extended to include TUG-4. and TUG-5.
Table 1 TUG-n Numbering Scheme
TUG-n Address Range of values
TUG-5 I 1,2,3,4
TUG-4 J 1,2,3,4
TUG-3 K 1,2,3
AU-5 Numbering Scheme
A numbering scheme is required to locate the AU-5s within the
VHRN line. 6.707 defines a two figure address (A, B) where A
represents the AU-3 number and B the AU-4 number. This can logically
be extended to include the AU-5.
CA 02270019 1999-04-26
RPR 26 '99 17:55 FR NT PATENTS 613 721 3017 TO 618199532476 P.19i34
Table 2 AU-» Numbering Scheme
AU-n Address Range of values
AU-5 C 1,2,3,4
AU-4 B 1,2,3,4
AU-3 A I 1,2,3
Frame Structure of the VHRN
The STM-256/STS-768 frame structure for a VHRN is shown
Figure 18. The three main areas of the frame are indicated:
~ SOH
~ Administrative unit (AU-5) pointers
~ Information payload
Figure 21 details the frame structure for a STM-256 signal which
has been created by byte interleaving AU-3s or AU-4s In order to retain
the 40GBps bit rate the frame size for the VHRN must be kept the same
as the AU-3IAU-4 byte interleaving. Figure 20 shows the frame size and
OH allocation for a 40GBps line signal which has been created by byte
interleaving 768 AU-3s or 256 AU-4s.
As the payload is larger due to the nested pointers of the
constituent payloads it is therefore necessary to reduce the byte
allocation for the section and line overheadaintain a line rate in even
multiples of the existing SONE:T/SDH line rates.
This approach has assumed scaling the 6.707 frame. It may be
optimal to define embed the FEC and OH within the frame..
Scalability to VC-6 and AU-6~
The multiplex hierarchy in this invention is designed to be scalable
to higher order virtual containE~rs, i.e. VC-6. Figure 19 shows how this
multiplex hierarchy may be extended for a VC-6 and its associated AU-6.
CA 02270019 1999-04-26
RPR 26 '99 17:55 FR NT PATENTS 613 721 3017 TO 618199532476 P.20i34
16
The same principles as defined here can be applied to scale the
granularity of the hierarchy as the network demands increase.
Optimization for non-SONETISDti Tributaries
(t is possible to optimize this hierarchy for transport of non-
SDH/SONET formats. An example of how this can be implemented is
shown in Figure 20, where a 1 Gbps ethemet signal is mapped into a C-
5-2c which represents a STM-8. This principle can be extended to other
non-SONET/SDH rates as currently defined.
CA 02270019 1999-04-26
