Framework for GMPLS and PCE Control of
G.709 Optical Transport Networks
CCAMP WG, IETF 76th, Hiroshima, Japan
draft-zhang-ccamp-gmpls-g709-framework-00.txt
Fatai Zhang
(zhangfatai@huawei.com)
Dan Li (danli@huawei.com)
Jianrui Han (hanjianrui@huawei.com)
Han Li (lihan@chinamobile.com)
Background: Overview of G.709 (1)
OTN Layer Network
• Analogue Layer: OCh, OMS, OTS
• Digital layer: OTUk, ODUk, OPUk
Mapping/Multiplexing
• TDM: Client signal →LO OPU → LO ODU → (HO OPU → HO ODU →) OTU
‐ODU0 into ODU1 multiplexing (with 1.25Gbps TS granularity)
‐ODU0, ODU1, ODUflex into ODU2 multiplexing (with 1.25Gbps TS granularity)
‐ODU1 into ODU2 multiplexing (with 2.5Gbps TS granularity)
‐ODU0, ODU1, ODU2, ODU2e and ODUflex into ODU3 multiplexing
(with 1.25Gbps TS granularity)
‐ODU1, ODU2 into ODU3 multiplexing (with 2.5Gbps TS granularity)
‐ODU0, ODU1, ODU2, ODU2e, ODU3 and ODUflex into ODU4 multiplexing
(with 1.25Gbps TS granularity)
• WDM:OCh[r] → OCC[r] → OCG-n[r] → OTM-n[r].m → OTM-n.m
Note that we would only focus on the control of the normative things for G.709, other
things like ODU3e1 and ODU3e2 in G.sup43 will be moved to an appendix.
Background: Overview of G.709 (2)
•
Tributary Slot allocation: important for Control Plane
– ODU0 into ODU1, ODU2, ODU3 or ODU4 multiplexing (TS =1.25Gbps)
•
ODU0 occupies 1 of the 2, 8, 32or 80 TS for ODU1, ODU2, ODU3 or ODU4
– ODU1 into ODU2, ODU3 or ODU4 multiplexing (TS =1.25Gbps)
•
ODU1 occupies 2 of the 8, 32 or 80 TS for ODU2, ODU3 or ODU4
– ODU1 into ODU2, ODU3 multiplexing (TS =2.5Gbps)
•
ODU1 occupies 1 of the 4 or 16 TS for ODU2 or ODU3
– ODU2 into ODU3 or ODU4 multiplexing (TS =1.25Gbps)
•
ODU2 occupies 8 of the 32 or 80 TS for ODU3 or ODU4
– ODU2 into ODU3 multiplexing (TS =2.5Gbps)
•
ODU2 occupies 4 of the 16 TS for ODU3
– ODU3 into ODU4 multiplexing (TS =1.25Gbps)
•
ODU3 occupies 31 of the 80 TS for ODU4
– ODUflex into ODU2, ODU3 or ODU4 multiplexing (TS =1.25Gbps)
•
ODUflex occupies n of the 8, 32 or 80 TS for ODU2, ODU3 or ODU4 (n <= Total TS
numbers of ODUk)
– ODU2e into ODU3 or ODU4 multiplexing (TS =1.25Gbps)
•
ODU2e occupies 9 of the 32 TS for ODU3 or 8 of the 32 TS for ODU4
Connection Management in OTN
(Typical Cases)
LO ODUj
OCh/OTUk
 LO ODU connection can be created
based on the link resource provided
by OTUk/OCh
OCh/OTUk
 The LO ODU can be switched at the
intermediate ODXC node
ODXC
PXC
Node A
ODXC
PXC
Node B
ODXC
 LO ODU is mapped into OTU directly
Node C
Case 1:Connection of LO ODUk (1)
LO ODUj
OCh/OTUk/HO ODUk
OCh/OTUk/HO ODUk
 LO ODU connection can be created
based on the link resource provided
by HO ODU
 The LO ODU can be switched at the
intermediate ODXC node
ODXC
Node A
PXC
ODXC
Node B
PXC
ODXC
Node C
Case 2:Connection of LO ODUk (1)
 LO ODU is multiplexed into HO ODU
Connection Management in OTN
(Topology Representation)
LO ODU2
LO ODU1
OCh/OTU1
ODXC
Node A
PXC
OCh/OTU3/HO ODU3
ODXC
Node B
PXC
ODXC
Node C
OCh/OTU2
PXC
ODXC
Node D
Different LO ODUk (e.g., ODUflex, ODU0, ODU1, ODU2, ODU3, etc.) may share
the same server Higher ODUk.
From the viewpoint of layer connection, a simpler representation is to describe the
LO ODU as a single layer network, in which the bit rate of a client is a parameter.
This representation shows a single topology containing ODU links and subnetworks
(i.e. resources) that is shared by all client ODU signals.
Connection Management in OTN
(Example)
Link #5
LO ODU0 Connection
ODXC
Link #4
Node E
ODXC
Node A
Link #1
ODXC
Node B
Link #2
ODXC
Node C
Link #3
ODXC
Node D
The above topology containing links and matrices:
Link #1: HO ODU2/OTU2, support transport of either LO ODU0 and LO ODU1 via HO ODU2/OTU2,
or LO ODU2 via OTU2;
Link #2: HO ODU3/OTU3, support transport of either LO ODU0, LO ODU1, LO ODU2 via HO
ODU3/OTU3, or LO ODU3 via OTU3;
Link #3: HO ODU2/OTU2, support transport of either LO ODU0, LO ODU1 via HO ODU2/OTU2,
or LO ODU2 via OTU2;
Link #4: HO ODU1/OTU1, support transport of either LO ODU0 via HO ODU1/OTU1,
or LO ODU1 via OTU1;
Link #5: HO ODU1/OTU1, support transport of either LO ODU0 via HO ODU1/OTU1,
or LO ODU1 via OTU1;
LO ODU Matrix A, LO ODU Matrix B, LO ODU Matrix C, LO ODU Matrix D, LO ODU Matrix E
Therefore, there are two possible pathes (in red) for the LO ODU0 connection request
(from Node A to Node D)
Implications for LSP Hierarchy
with GMPLS TE
 The path computation for LO ODU connection request is based on the
topology of ODU layer, including OCh layer visibility.
 Connection request in OTN can be divided into two layers. One layer is
OCh/OTUk/HO ODUk, the other is LO ODU. [RFC4206] defines the
mechanisms to accomplish creating the hierarchy of LSPs. The LSP
management of multiple layers in OTN can follow the procedures
defined in [RFC4206] and related MLN drafts.
 The route path computation for WSON is in the scope of [WSON-Frame].
 This document only considers ODU layer for LO ODU connection
request.
Implications for GMPLS Signaling
Some new features for the evolutive OTN has been introduced since
[RFC4328] released. [RFC4328] can not support these new features:
 New traffic parameters may need to be extended in signaling
message to support:
(1)New signal types of digital wrapper layer
Optical Channel Transport Unit (OTUk):
Optical Channel Data Unit (ODUk):
OTU4
ODU0, ODU2e, ODU4, ODUflex
(2)ODUflex traffic parameter:
How many tributary slots need for an ODUflex connection along each link
depends on Bit Rate and Bit Rate Tolerance (BR, BRT)
Therefore, (BR, BRT) information of an ODUflex conn should be included in the
signaling End-to-End
 New label should be defined to carry the exact label allocation
information to support:
(1)A new Tributary Slot (TS) granularity (i.e., 1.25 Gbps)
(2)New multiplexing hierarchy (e.g., ODU0 into ODU1 multiplexing, ODUj into ODU4
(with 1,25Gbps TS granularity).)
Implications for GMPLS Routing
 One ODU link may support one or more types of ODU signals
multiplexing.
--->The routing protocol should be extended to carry this multiplexing
capability.
 One type of ODUj can be multiplexed to one ODUk by different
tributary slots.
---> The routing protocol should be extended to carry which TS
granularity supported by the ODU interface
 Total bandwidth of the TE link, Unreserved Bandwidth of the TE link,
Maximum LSP Bandwidth are dependent on total number of the
Tributary Slots, the unallocated Tributary Slots and the maximum
Tributary Slots in OTN
---> The routing protocol should be extended to carry this link
bandwidth information in OTN networks
Implications for Auto-discovery
 The two ends of an ODU link may support different TS
structure.
--->Correlate the Granularity of the TS (two ends of the one
link should correlate TS type)
 The switching capability of two ends of the link may be
different, so the link capability of two ends should be correlate.
--->Correlate the Supported LO ODU Signal Types (which
types of LO ODU can be supported by the HO ODU link)
Implications for PCE
 PCECP also has a desire to be extended to carry the
new signal type and related variable bandwidth
information when a PCC requests a path computation.
Next Steps
• Move the content of G.sup43 in an appendix
• Put reference to G.709
• Continue discussion with ITU-T
• Liaison to ITU-T SG15 when/if this work is
adopted by CCAMP
• Refine it according to the feedback from the
meeting or mailing list