RFC7139
Internet Engineering Task Force (IETF) F. Zhang, Ed. Request for Comments: 7139 Huawei Updates: 4328 G. Zhang Category: Standards Track CATR ISSN: 2070-1721 S. Belotti
Alcatel-Lucent
D. Ceccarelli
Ericsson
K. Pithewan
Infinera
March 2014
GMPLS Signaling Extensions
for Control of Evolving G.709 Optical Transport Networks
Abstract
ITU-T Recommendation G.709 [G709-2012] introduced new Optical channel Data Unit (ODU) containers (ODU0, ODU4, ODU2e, and ODUflex) and enhanced Optical Transport Network (OTN) flexibility.
This document updates the ODU-related portions of RFC 4328 to provide extensions to GMPLS signaling to control the full set of OTN features, including ODU0, ODU4, ODU2e, and ODUflex.
Status of This Memo
This is an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community. It has received public review and has been approved for publication by the Internet Engineering Steering Group (IESG). Further information on Internet Standards is available in Section 2 of RFC 5741.
Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at http://www.rfc-editor.org/info/rfc7139.
Copyright Notice
Copyright (c) 2014 IETF Trust and the persons identified as the document authors. All rights reserved.
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8. Operations, Administration, and Maintenance (OAM)
Contents
- 1 Introduction
- 2 Terminology
- 3 GMPLS Extensions for the Evolving G.709 -- Overview
- 4 Generalized Label Request
- 5 Extensions for Traffic Parameters for Evolving G.709 OTNs
- 6 Generalized Label
- 7 Supporting Hitless Adjustment of ODUflex(GFP)
- 8 Operations, Administration, and Maintenance (OAM) Considerations
- 9 Control-Plane Backward-Compatibility Considerations
Introduction
With the evolution and deployment of Optical Transport Network (OTN) technology, it is necessary that appropriate enhanced control technology support be provided for [G709-2012].
RFC7062 provides a framework to allow the development of protocol extensions to support GMPLS and Path Computation Element (PCE) control of OTN as specified in [G709-2012]. Based on this framework, RFC7096 evaluates the information needed by the routing and signaling process in OTNs to support GMPLS control of OTN.
RFC4328 describes the control technology details that are specific to the 2001 revision of the G.709 specification. This document updates the ODU-related portions of RFC4328 to provide Resource Reservation Protocol - Traffic Engineering (RSVP-TE) extensions to support control for [G709-2012].
Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC2119.
GMPLS Extensions for the Evolving G.709 -- Overview
New features for the evolving OTN, for example, new ODU0, ODU2e, ODU4, and ODUflex containers, are specified in [G709-2012]. The corresponding new Signal Types are summarized below:
- Optical channel Transport Unit (OTUk):
o OTU4
- Optical channel Data Unit (ODUk):
o ODU0 o ODU2e o ODU4 o ODUflex
A new tributary slot granularity (i.e., 1.25 Gbps) is also described in [G709-2012]. Thus, there are now two tributary slot (TS) granularities for the foundation OTN ODU1, ODU2, and ODU3 containers. The TS granularity at 2.5 Gbps is used on the legacy interfaces while the new 1.25 Gbps is used on the new interfaces.
In addition to the support of ODUk mapping into OTUk (k = 1, 2, 3, 4), [G709-2012] encompasses the multiplexing of ODUj (j = 0, 1, 2, 2e, 3, flex) into an ODUk (k > j), as described in Section 3.1.2 of RFC7062.
Virtual Concatenation (VCAT) of Optical channel Payload Unit-k (OPUk) (OPUk-Xv, k = 1/2/3, X = 1...256) is also supported by [G709-2012]. Note that VCAT of OPU0 / OPU2e / OPU4 / OPUflex is not supported per [G709-2012].
RFC4328 describes GMPLS signaling extensions to support the control for the 2001 revision of the G.709 specification. However, RFC7096 does not provide the means to signal all the new Signal Types and related mapping and multiplexing functionalities. Moreover, it supports only the deprecated auto-MSI (Multiframe Structure Identifier) mode, which assumes that the Tributary Port Number (TPN) is automatically assigned in the transmit direction and not checked in the receive direction.
This document extends the G.709 Traffic Parameters described in RFC4328 and presents a new flexible and scalable OTN-TDM Generalized Label format. (Here, TDM refers to Time-Division Multiplexing.) Additionally, procedures about Tributary Port Number assignment through the control plane are also provided in this document.
Generalized Label Request
The GENERALIZED_LABEL_REQUEST object, as described in RFC3471, carries the Label Switched Path (LSP) Encoding Type, the Switching Type, and the Generalized Protocol Identifier (G-PID).
RFC4328 extends the GENERALIZED_LABEL_REQUEST object, introducing two new code-points for the LSP Encoding Type (i.e., G.709 ODUk (Digital Path) and G.709 Optical Channel) and adding a list of G-PID values in order to accommodate the 2001 revision of the G.709 specification.
This document follows these extensions and introduces a new Switching Type to indicate the ODUk Switching Capability [G709-2012] in order to support backward compatibility with RFC4328, as described in RFC7062. The new Switching Type (OTN-TDM Switching Type) is defined in RFC7138.
This document also updates the G-PID values defined in RFC4328:
Value G-PID Type
----------
47 Type field updated from "G.709 ODUj" to "ODU-2.5G" to
indicate transport of Digital Paths (e.g., at 2.5, 10, and
40 Gbps) via 2.5 Gbps TS granularity.
56 Type field updated from "ESCON" to "SBCON/ESCON" to align
with [G709-2012] payload type 0x1A.
Note: Value 47 includes mapping of Synchronous Digital Hierarchy (SDH).
In the case of ODU multiplexing, the Lower Order ODU (LO ODU) (i.e., the client signal) may be multiplexed into a Higher Order ODU (HO ODU) via 1.25G TS granularity, 2.5G TS granularity, or ODU-any. Since the G-PID type "ODUk" defined in RFC4328 is only used for 2.5 Gbps TS granularity, two new G-PID types are defined as follows:
- ODU-1.25G: Transport of Digital Paths at 1.25, 2.5, 10, 40, and
100 Gbps via 1.25 Gbps TS granularity.
- ODU-any: Transport of Digital Paths at 1.25, 2.5, 10, 40, and
100 Gbps via 1.25 or 2.5 Gbps TS granularity (i.e.,
the fallback procedure is enabled and the default
value of 1.25 Gbps TS granularity can fall back to 2.5
Gbps if needed).
The full list of payload types defined in [G709-2012] and their mapping to existing and new G-PID types are as follows:
G.709
Payload
Type G-PID Type/Comment LSP Encoding
==== ===== ===================== ===================
0x01 No standard value
0x02 49 CBRa G.709 ODUk
0x03 50 CBRb G.709 ODUk
0x04 32 ATM G.709 ODUk
0x05 59 Framed GFP G.709 ODUk
54 Ethernet MAC (framed GFP) G.709 ODUk
70 64B/66B GFP-F Ethernet G.709 ODUk (k=2)
0x06 Not signaled
0x07 55 Ethernet PHY G.709 ODUk (k=0,3,4)
(transparent GFP)
0x08 58 Fiber Channel G.709 ODUk (k=2e)
0x09 59 Framed GFP G.709 ODUk (k=2)
70 64B/66B GFP-F Ethernet G.709 ODUk (k=2)
0x0A 60 STM-1 G.709 ODUk (k=0)
0x0B 61 STM-4 G.709 ODUk (k=0)
0x0C 58 Fiber Channel G.709 ODUk (k=0)
0x0D 58 Fiber Channel G.709 ODUk (k=1)
0x0E 58 Fiber Channel G.709 ODUflex
0x0F 58 Fiber Channel G.709 ODUflex
0x10 51 BSOT G.709 ODUk
0x11 52 BSNT G.709 ODUk
0x12 62 InfiniBand G.709 ODUflex
0x13 62 InfiniBand G.709 ODUflex
0x14 62 InfiniBand G.709 ODUflex
0x15 63 Serial Digital Interface G.709 ODUk (k=0)
0x16 64 SDI/1.001 G.709 ODUk (k=1)
0x17 63 Serial Digital Interface G.709 ODUk (k=1)
0x18 64 SDI/1.001 G.709 ODUflex
0x19 63 Serial Digital Interface G.709 ODUflex
0x1A 56 SBCON/ESCON G.709 ODUk (k=0)
0x1B 65 DVB_ASI G.709 ODUk (k=0)
0x1C 58 Fiber Channel G.709 ODUk
0x20 47 G.709 ODU-2.5G G.709 ODUk (k=2,3)
66 G.709 ODU-1.25G G.709 ODUk (k=1)
0x21 66 G.709 ODU-1.25G G.709 ODUk (k=2,3,4)
67 G.709 ODU-any G.709 ODUk (k=2,3)
0x55 No standard value
0x66 No standard value
0x80-0x8F No standard value
0xFD 68 Null Test G.709 ODUk
0xFE 69 Random Test G.709 ODUk
0xFF No standard value
Note: Values 59 and 70 include mapping of SDH.
Note that the mapping types for ODUj into OPUk are unambiguously per Table 7-10 of [G709-2012], so there is no need to carry mapping type information in the signaling.
Note also that additional information on G.709 client mapping can be found in [G7041].
Extensions for Traffic Parameters for Evolving G.709 OTNs
The Traffic Parameters for the OTN-TDM-capable Switching Type are carried in the OTN-TDM SENDER_TSPEC object in the Path message and the OTN-TDM FLOWSPEC object in the Resv message. The objects have the following class and type:
- OTN-TDM SENDER_TSPEC object: Class = 12, C-Type = 7 - OTN-TDM FLOWSPEC object: Class = 9, C-Type = 7
The format of Traffic Parameters in these two objects is defined as follows:
0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Signal Type | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | NVC | Multiplier (MT) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Bit_Rate | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Signal Type: 8 bits
As defined in Section 3.2.1 of RFC4328, with the following additional values:
Value Type ----- ---- 4 ODU4 (i.e., 100 Gbps) 9 OCh at 100 Gbps 10 ODU0 (i.e., 1.25 Gbps) 11 ODU2e (i.e., 10 Gbps for FC1200 and GE LAN) 12-19 Reserved (for future use) 20 ODUflex(CBR) (i.e., 1.25*N Gbps) 21 ODUflex(GFP-F), resizable (i.e., 1.25*N Gbps) 22 ODUflex(GFP-F), non-resizable (i.e., 1.25*N Gbps) 23-255 Reserved (for future use)
Note: Above, CBR stands for Constant Bit Rate, and GFP-F stands for Generic Framing Procedure - Framed.
NVC (Number of Virtual Components): 16 bits
As defined in Section 3.2.3 of RFC4328. This field MUST be set to 0 for ODUflex Signal Types.
Multiplier (MT): 16 bits
As defined in Section 3.2.4 of RFC4328. This field MUST be set to 1 for ODUflex Signal Types.
Bit_Rate: 32 bits
In the case of ODUflex, including ODUflex(CBR) and ODUflex(GFP) Signal Types, this field indicates the nominal bit rate of ODUflex expressed in bytes per second, encoded as a 32-bit IEEE single- precision floating-point number (referring to RFC4506 and [IEEE]). For other Signal Types, this field MUST be set to zero on transmission, MUST be ignored on receipt, and SHOULD be passed unmodified by transit nodes.
Usage of ODUflex(CBR) Traffic Parameters
In the case of ODUflex(CBR), the Bit_Rate information carried in the ODUflex Traffic Parameters MUST be used to determine the actual bandwidth of ODUflex(CBR) (i.e., Bit_Rate * (1 +/- Tolerance)). Therefore, the total number of tributary slots N in the HO ODUk link can be reserved correctly. Where:
N = Ceiling of
ODUflex(CBR) nominal bit rate * (1 + ODUflex(CBR) bit rate tolerance)
ODTUk.ts nominal bit rate * (1 - HO OPUk bit rate tolerance)
In this formula, the ODUflex(CBR) nominal bit rate is the bit rate of the ODUflex(CBR) on the line side, i.e., the client signal bit rate after applying the 239/238 factor (according to Clause 7.3, Table 7-2 of [G709-2012]) and the transcoding factor T (if needed) on the CBR client. According to Clauses 17.7.3, 17.7.4, and 17.7.5 of [G709-2012]:
ODUflex(CBR) nominal bit rate = CBR client bit rate * (239/238) / T
The ODTUk.ts (Optical channel Data Tributary Unit k with ts tributary slots) nominal bit rate is the nominal bit rate of the tributary slot of ODUk, as shown in Table 1 (referring to Table 7-7 of [G709-2012]).
ODUk.ts Minimum Nominal Maximum ----------------------------------------------------------- ODU2.ts 1,249,384.632 1,249,409.620 1,249,434.608 ODU3.ts 1,254,678.635 1,254,703.729 1,254,728.823 ODU4.ts 1,301,683.217 1,301,709.251 1,301,735.285
Table 1: Actual TS Bit Rate of ODUk (in Kbps)
Note that:
Minimum bit rate of ODUTk.ts =
ODTUk.ts nominal bit rate * (1 - HO OPUk bit rate tolerance)
Maximum bit rate of ODTUk.ts =
ODTUk.ts nominal bit rate * (1 + HO OPUk bit rate tolerance)
Where: HO OPUk bit rate tolerance = 20 ppm (parts per million)
Note that the bit rate tolerance is implicit in Signal Type and the ODUflex(CBR) bit rate tolerance is fixed and it is equal to 100 ppm as described in Table 7-2 of [G709-2012].
Therefore, a node receiving a Path message containing an ODUflex(CBR) nominal bit rate can allocate a precise number of tributary slots and set up the cross-connection for the ODUflex service.
Note that for different ODUk, the bit rates of the tributary slots are different, so the total number of tributary slots to be reserved for the ODUflex(CBR) may not be the same on different HO ODUk links.
An example is given below to illustrate the usage of ODUflex(CBR) Traffic Parameters.
+-----+ +---------+ +-----+ | +-------------+ +-----+ +-------------+ | | +=============+\| ODU |/+=============+ | | +=============+/| flex+-+=============+ | | +-------------+ | |\+=============+ | | +-------------+ +-----+ +-------------+ | | | | | | |
| A +-------------+ B +-------------+ C | +-----+ HO ODU4 +---------+ HO ODU2 +-----+
=========: TSs occupied by ODUflex
---------: available TSs
Figure 1: Example of ODUflex(CBR) Traffic Parameters
As shown in Figure 1, assume there is an ODUflex(CBR) service requesting a bandwidth of 2.5 Gbps from node A to node C.
In other words, the ODUflex Traffic Parameters indicate that Signal Type is 20 (ODUflex(CBR)) and Bit_Rate is 2.5 Gbps (note that the tolerance is not signaled as explained above).
- On the HO ODU4 link between node A and B:
The maximum bit rate of the ODUflex(CBR) equals 2.5 Gbps * (1 + 100 ppm), and the minimum bit rate of the tributary slot of ODU4 equals 1,301,683.217 Kbps, so the total number of tributary slots N1 to be reserved on this link is:
N1 = ceiling (2.5 Gbps * (1 + 100 ppm) / 1,301,683.217 Kbps) = 2
- On the HO ODU2 link between node B and C:
The maximum bit rate of the ODUflex equals 2.5 Gbps * (1 + 100 ppm), and the minimum bit rate of the tributary slot of ODU2 equals 1,249,384.632 Kbps, so the total number of tributary slots N2 to be reserved on this link is:
N2 = ceiling (2.5 Gbps * (1 + 100 ppm) / 1,249,384.632 Kbps) = 3
Usage of ODUflex(GFP) Traffic Parameters
[G709-2012] recommends that the ODUflex(GFP) fill an integral number of tributary slots of the smallest HO ODUk path over which the ODUflex(GFP) may be carried, as shown in Table 2.
ODU Type | Nominal Bit Rate | Tolerance ---------------------------------+------------------+----------- ODUflex(GFP) of n TSs, 1<=n<=8 | n * ODU2.ts | +/-100 ppm ODUflex(GFP) of n TSs, 9<=n<=32 | n * ODU3.ts | +/-100 ppm ODUflex(GFP) of n TSs, 33<=n<=80 | n * ODU4.ts | +/-100 ppm
Table 2: Recommended ODUflex(GFP) Bit Rates and Tolerance
According to this table, the Bit_Rate field for ODUflex(GFP) MUST be equal to one of the 80 values listed below:
1 * ODU2.ts; 2 * ODU2.ts; ...; 8 * ODU2.ts;
9 * ODU3.ts; 10 * ODU3.ts, ...; 32 * ODU3.ts;
33 * ODU4.ts; 34 * ODU4.ts; ...; 80 * ODU4.ts.
In this way, the number of required tributary slots for the ODUflex(GFP) (i.e., the value of "n" in Table 2) can be deduced from the Bit_Rate field.
Notification on Errors of OTN-TDM Traffic Parameters
There is no Adspec associated with the OTN-TDM SENDER_TSPEC object. Either the Adspec is omitted or an Int-serv Adspec with the Default General Characterization Parameters and Guaranteed Service fragment is used (see RFC2210).
For a particular sender in a session, the contents of the OTN-TDM FLOWSPEC object received in a Resv message SHOULD be identical to the contents of the OTN-TDM SENDER_TSPEC object received in the corresponding Path message. If the objects do not match, a ResvErr message with a "Traffic Control Error/Bad Flowspec value" error MUST be generated.
Intermediate and egress nodes MUST verify that the node itself, and the interfaces on which the LSP will be established, can support the requested Signal Type, NVC, and Bit_Rate values. If the requested value(s) cannot be supported, the receiver node MUST generate a PathErr message with a "Traffic Control Error/Service unsupported" indication (see RFC2205).
In addition, if the MT field is received with a zero value, the node MUST generate a PathErr message with a "Traffic Control Error/Bad Tspec value" indication (see RFC2205).
Further, if the Signal Type is not ODU1, ODU2, or ODU3, and the NVC field is not 0, the node MUST generate a PathErr message with a "Traffic Control Error/Bad Tspec value" indication (see RFC2205).
Generalized Label
This section defines the format of the OTN-TDM Generalized Label.
OTN-TDM Switching Type Generalized Label
The following is the GENERALIZED_LABEL object format that MUST be used with the OTN-TDM Switching Type:
0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | TPN | Reserved | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The OTN-TDM GENERALIZED_LABEL object is used to indicate how the LO ODUj signal is multiplexed into the HO ODUk link. Note that the LO OUDj Signal Type is indicated by Traffic Parameters, while the type of HO ODUk link is identified by the selected interface carried in the IF_ID RSVP_HOP object.
TPN: 12 bits
Indicates the TPN for the assigned tributary slot(s).
- In the case of an LO ODUj multiplexed into an HO
ODU1/ODU2/ODU3, only the lower 6 bits of the TPN field are
significant; the other bits of the TPN field MUST be set to 0.
- In the case of an LO ODUj multiplexed into an HO ODU4, only the
lower 7 bits of the TPN field are significant; the other bits
of the TPN field MUST be set to 0.
- In the case of ODUj mapped into OTUk (j=k), the TPN is not
needed, and this field MUST be set to 0.
Per [G709-2012], the TPN is used to allow for correct demultiplexing in the data plane. When an LO ODUj is multiplexed into an HO ODUk occupying one or more TSs, a new TPN value is configured at the two ends of the HO ODUk link and is put into the related MSI byte(s) in the OPUk overhead at the (traffic) ingress end of the link, so that the other end of the link can learn which TS(s) is/are used by the LO ODUj in the data plane.
According to [G709-2012], the TPN field MUST be set according to the following tables:
+-------+-------+----+-------------------------------------------+ |HO ODUk|LO ODUj|TPN | TPN Assignment Rules | +-------+-------+----+-------------------------------------------+ | ODU2 | ODU1 |1-4 |Fixed, = TS# occupied by ODU1 | +-------+-------+----+-------------------------------------------+ | | ODU1 |1-16|Fixed, = TS# occupied by ODU1 | | ODU3 +-------+----+-------------------------------------------+ | | ODU2 |1-4 |Flexible, != other existing LO ODU2s' TPNs | +-------+-------+----+-------------------------------------------+
Table 3: TPN Assignment Rules (2.5 Gbps TS Granularity)
+-------+-------+----+-------------------------------------------+ |HO ODUk|LO ODUj|TPN | TPN Assignment Rules | +-------+-------+----+-------------------------------------------+ | ODU1 | ODU0 |1-2 |Fixed, = TS# occupied by ODU0 | +-------+-------+----+-------------------------------------------+ | | ODU1 |1-4 |Flexible, != other existing LO ODU1s' TPNs | | ODU2 +-------+----+-------------------------------------------+ | |ODU0 & |1-8 |Flexible, != other existing LO ODU0s and | | |ODUflex| |ODUflexes' TPNs | +-------+-------+----+-------------------------------------------+ | | ODU1 |1-16|Flexible, != other existing LO ODU1s' TPNs | | +-------+----+-------------------------------------------+ | | ODU2 |1-4 |Flexible, != other existing LO ODU2s' TPNs | | ODU3 +-------+----+-------------------------------------------+ | |ODU0 & | |Flexible, != other existing LO ODU0s and | | |ODU2e &|1-32|ODU2s and ODUflexes' TPNs | | |ODUflex| | | +-------+-------+----+-------------------------------------------+ | ODU4 |Any ODU|1-80|Flexible, != ANY other existing LO ODUs' | | | | |TPNs | +-------+-------+----+-------------------------------------------+
Table 4: TPN Assignment Rules (1.25 Gbps TS Granularity)
Note that in the case of "Flexible", the value of TPN MAY not correspond to the TS number as per [G709-2012].
Length: 12 bits
Indicates the number of bits of the Bit Map field, i.e., the total number of TSs in the HO ODUk link. The TS granularity, 1.25 Gbps or 2.5 Gbps, may be derived by dividing the HO ODUk link's rate by
the value of the Length field. In the context of [G709-2012], the values of 4 and 16 indicate a TS granularity of 2.5 Gbps, and the values 2, 8, 32, and 80 indicate a TS granularity of 1.25 Gbps.
In the case of an ODUk mapped into OTUk, there is no need to indicate which tributary slots will be used, so the Length field MUST be set to 0.
Bit Map: variable
Indicates which tributary slots in the HO ODUk that the LO ODUj will be multiplexed into. The sequence of the Bit Map is consistent with the sequence of the tributary slots in the HO ODUk. Each bit in the bit map represents the corresponding tributary slot in the HO ODUk with a value of 1 or 0 indicating whether the tributary slot will be used by the LO ODUj or not.
Padding Bits
Are added after the Bit Map to make the whole label a multiple of four bytes if necessary. Padding bits MUST be set to 0 and MUST be ignored on receipt.
Procedures
The ingress node MUST generate a Path message and specify the OTN-TDM Switching Type and corresponding G-PID in the GENERALIZED_LABEL_REQUEST object, which MUST be processed as defined in RFC3473.
The ingress node of an LSP MAY include a Label ERO (Explicit Route Object) subobject to indicate the label in each hop along the path. Note that the TPN in the Label ERO subobject need not be assigned by the ingress node. When the TPN is assigned by a node, the node MUST assign a valid TPN value and then put this value into the TPN field of the GENERALIZED_LABEL object when receiving a Path message.
In order to create bidirectional LSP, the ingress node and upstream node MUST generate an UPSTREAM_LABEL object on the outgoing interface to indicate the reserved TSs of ODUk and the assigned TPN value in the upstream direction. This UPSTREAM_LABEL object is sent to the downstream node via a Path massage for upstream resource reservation.
The ingress node or upstream node MAY generate a LABEL_SET object to indicate which labels on the outgoing interface in the downstream direction are acceptable. The downstream node will restrict its choice of labels, i.e., TS resource and TPN value, to one that is in the LABEL_SET object.
The ingress node or upstream node MAY also generate a SUGGESTED_LABEL object to indicate the preference of TS resource and TPN value on the outgoing interface in the downstream direction. The downstream node is not required to use the suggested labels; it may use another label based on local decision and send it to the upstream node, as described in RFC3473.
When an upstream node receives a Resv message containing a GENERALIZED_LABEL object with an OTN-TDM label, it MUST first identify which ODU Signal Type is multiplexed or mapped into which ODU Signal Type according to the Traffic Parameters and the IF_ID RSVP_HOP object in the received message.
- In the case of ODUj-to-ODUk multiplexing, the node MUST retrieve
the reserved tributary slots in the ODUk by its downstream neighbor node according to the position of the bits that are set to 1 in the Bit Map field. The node determines the TS granularity (according to the total TS number of the ODUk or pre-configured TS granularity), so that the node can multiplex the ODUj into the ODUk based on the TS granularity. The node MUST also retrieve the TPN value assigned by its downstream neighbor node from the label and fill the TPN into the related MSI byte(s) in the OPUk overhead in the data plane, so that the downstream neighbor node can check whether the TPN received from the data plane is consistent with the Expected MSI (ExMSI) and determine whether there is any mismatch defect.
- In the case of ODUk-to-OTUk mapping, the size of the Bit Map field
MUST be 0, and no additional procedure is needed.
When a downstream node or egress node receives a Path message containing a GENERALIZED_LABEL_REQUEST object for setting up an ODUj LSP from its upstream neighbor node, the node MUST generate an OTN- TDM label according to the Signal Type of the requested LSP and the available resources (i.e., available tributary slots of ODUk) that will be reserved for the LSP and send the label to its upstream neighbor node.
- In the case of ODUj-to-ODUk multiplexing, the node MUST first
determine the size of the Bit Map field according to the Signal Type and the tributary slot type of ODUk and then set the bits to 1 in the Bit Map field corresponding to the reserved tributary slots. The node MUST also assign a valid TPN, which MUST NOT collide with other TPN values used by existing LO ODU connections in the selected HO ODU link, and configure the Expected MSI (ExMSI) using this TPN. Then, the assigned TPN MUST be filled into the label.
- In the case of ODUk-to-OTUk mapping, the TPN field MUST be set to
0. Bit Map information is not required and MUST NOT be included, so the Length field MUST be set to 0 as well.
Notification on Label Error
When an upstream node receives a Resv message containing a GENERALIZED_LABEL object with an OTN-TDM label, the node MUST verify if the label is acceptable. If the label is not acceptable, the node MUST generate a ResvErr message with a "Routing problem/Unacceptable label value" indication. Per RFC3473, the generated ResvErr message MAY include an ACCEPTABLE_LABEL_SET object. With the exception of label semantics, a downstream node processing a received ResvErr message and ACCEPTABLE_LABEL_SET object is not modified by this document.
Similarly, when a downstream node receives a Path message containing an UPSTREAM_LABEL object with an OTN-TDM label, the node MUST verify if the label is acceptable. If the label is not acceptable, the node MUST generate a PathErr message with a "Routing problem/Unacceptable label value" indication. Per RFC3473, the generated PathErr message MAY include an ACCEPTABLE_LABEL_SET object. With the exception of label semantics, the upstream nodes processing a received PathErr message and ACCEPTABLE_LABEL_SET object are not modified by this document.
A received label SHALL be considered unacceptable when one of the following cases occurs:
- The received label doesn't conform to local policy;
- An invalid value appears in the Length field;
- The selected link only supports 2.5 Gbps TS granularity while the
Length field in the label along with ODUk Signal Type indicates the 1.25 Gbps TS granularity;
- The label includes an invalid TPN value that breaks the TPN
assignment rules; and
- The indicated resources (i.e., the number of "1"s in the Bit Map
field) are inconsistent with the Traffic Parameters.
Supporting Virtual Concatenation and Multiplication
Per RFC6344, the Virtual Concatenation Groups (VCGs) can be created using the One LSP approach or the Multiple LSPs approach.
In the case of the One LSP approach, the explicit ordered list of all labels MUST reflect the order of VCG members, which is similar to RFC4328. In the case of multiplexed virtually concatenated signals (NVC > 1), the first label MUST indicate the components of the first virtually concatenated signal; the second label MUST indicate the components of the second virtually concatenated signal; and so on. In the case of multiplication of multiplexed virtually concatenated signals (MT > 1), the first label MUST indicate the components of the first multiplexed virtually concatenated signal; the second label MUST indicate components of the second multiplexed virtually concatenated signal; and so on.
Support for Virtual Concatenation of ODU1, ODU2, and ODU3 Signal Types, as defined by RFC6344, is not modified by this document. Virtual Concatenation of other Signal Types is not supported by [G709-2012].
Multiplier (MT) usage is as defined in RFC6344 and RFC4328.
Examples
The following examples are given in order to illustrate the label format described in Section 6.1 of this document.
(1) ODUk-to-OTUk Mapping:
In this scenario, the downstream node along an LSP returns a label indicating that the ODUk (k=1, 2, 3, 4) is directly mapped into the corresponding OTUk. The following example label indicates an ODU1 mapped into OTU1.
0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | TPN = 0 | Reserved | Length = 0 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
(2) ODUj-to-ODUk Multiplexing:
In this scenario, this label indicates that an ODUj is multiplexed into several tributary slots of OPUk and then mapped into OTUk. Some instances are shown as follows:
- ODU0-to-ODU2 Multiplexing:
0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | TPN = 2 | Reserved | Length = 8 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0 1 0 0 0 0 0 0| Padding Bits (0) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The label above indicates an ODU0 multiplexed into the second tributary slot of ODU2, wherein there are 8 TSs in ODU2 (i.e., the type of the tributary slot is 1.25 Gbps), and the TPN value is 2.
- ODU1-to-ODU2 Multiplexing with 1.25 Gbps TS Granularity:
0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | TPN = 1 | Reserved | Length = 8 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0 1 0 1 0 0 0 0| Padding Bits (0) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The label above indicates an ODU1 multiplexed into the 2nd and the 4th tributary slots of ODU2, wherein there are 8 TSs in ODU2 (i.e., the type of the tributary slot is 1.25 Gbps), and the TPN value is 1.
- ODU2 into ODU3 Multiplexing with 2.5 Gbps TS Granularity:
0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | TPN = 1 | Reserved | Length = 16 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0 1 1 0 1 0 1 0 0 0 0 0 0 0 0 0| Padding Bits (0) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The label above indicates an ODU2 multiplexed into the 2nd, 3rd, 5th, and 7th tributary slots of ODU3, wherein there are 16 TSs in ODU3 (i.e., the type of the tributary slot is 2.5 Gbps), and the TPN value is 1.
Supporting Hitless Adjustment of ODUflex(GFP)
[G7044] describes the procedure of ODUflex(GFP) hitless resizing using the Link Connection Resize (LCR) and Bandwidth Resize (BWR) protocols in the OTN data plane.
For the control plane, signaling messages are REQUIRED to initiate the adjustment procedure. Sections 2.5 and 4.6.4 of RFC3209 describe how the Shared Explicit (SE) style is used in the Traffic Engineering (TE) network for bandwidth increasing and decreasing, which is still applicable for triggering the ODUflex(GFP) adjustment procedure in the data plane.
Note that the SE style MUST be used at the beginning when creating a resizable ODUflex connection (Signal Type = 21). Otherwise an error with Error Code "Conflicting reservation style" MUST be generated when performing bandwidth adjustment.
- Bandwidth Increasing
For the ingress node, in order to increase the bandwidth of an ODUflex(GFP) connection, a Path message with SE style (keeping Tunnel ID unchanged and assigning a new LSP ID) MUST be sent along the path.
The ingress node will trigger the BWR protocol when successful completion of LCR protocols on every hop after the Resv message is processed. On success of BWR, the ingress node SHOULD send a PathTear message to delete the old control state (i.e., the control state of the ODUflex(GFP) before resizing) on the control plane.
A downstream node receiving a Path message with SE style compares the old Traffic Parameters (stored locally) with the new one carried in the Path message to determine the number of TSs to be added. After choosing and reserving new available TS(s), the downstream node MUST send back a Resv message carrying both the old and new GENERALIZED_LABEL objects in the SE flow descriptor.
An upstream neighbor receiving a Resv message with an SE flow descriptor MUST determine which TS(s) is/are added and trigger the LCR protocol between itself and its downstream neighbor node.
- Bandwidth Decreasing
For the ingress node, a Path message with SE style SHOULD also be sent for decreasing the ODUflex bandwidth.
The ingress node will trigger the BWR protocol when successful completion of LCR handshake on every hop after Resv message is processed. On success of BWR, the second step of LCR, i.e., link connection decrease procedure will be started on every hop of the connection. After decreasing the bandwidth, the ingress node SHOULD send a ResvErr message to tear down the old control state.
A downstream node receiving a Path message with SE style compares the old Traffic Parameters with the new one carried in the Path message to determine the number of TSs to be decreased. After choosing TSs to be decreased, the downstream node MUST send back a Resv message carrying both the old and new GENERALIZED_LABEL objects in the SE flow descriptor.
An upstream neighbor receiving a Resv message with an SE flow descriptor MUST determine which TS(s) is/are decreased and trigger the first step of the LCR protocol (i.e., LCR handshake) between itself and its downstream neighbor node.
Operations, Administration, and Maintenance (OAM) Considerations
OTN OAM configuration could be done through either Network Management Systems (NMSs) or the GMPLS control plane as defined in [TDM-OAM]. RFC4783 SHOULD be used for communication of alarm information in GMPLS-based OTN.
Management Information Bases (MIBs) may need be extended to read new information (e.g., OTN-TDM Generalized Label and OTN-TDM SENDER_TSPEC / FLOWSPEC) from the OTN devices. This is outside the scope of this document.
More information about the management aspects for GMPLS-based OTN, refer to Section 5.7 of RFC7062.
Control-Plane Backward-Compatibility Considerations
As described in RFC7062, since RFC4328 has been deployed in the network for the nodes that support the 2001 revision of the G.709 specification, control-plane backward compatibility SHOULD be taken into consideration. More specifically:
o Nodes supporting this document SHOULD support RFC7138.
o Nodes supporting this document MAY support RFC4328 signaling.
o A node supporting both sets of procedures (i.e., RFC4328 and
this document) is not required to signal an LSP using both procedures, i.e., to act as a signaling version translator.
o Ingress nodes that support both sets of procedures MAY select
which set of procedures to follow based on routing information or local policy.
o Per RFC3473, nodes that do not support this document will
generate a PathErr message, with a "Routing problem/Switching Type" indication.
10. Security Considerations
This document is a modification to RFC3473 and RFC4328; it only differs in specific information communicated. As such, this document introduces no new security considerations to the existing GMPLS signaling protocols. Refer to RFC3473 and RFC4328 for further details of the specific security measures. Additionally, RFC5920 provides an overview of security vulnerabilities and protection mechanisms for the GMPLS control plane.
11. IANA Considerations
IANA has made the following assignments in the "Class Types or C- Types - 9 FLOWSPEC" and "Class Types or C-Types - 12 SENDER_TSPEC" section of the "Resource Reservation Protocol (RSVP) Parameters" registry located at <http://www.iana.org/assignments/ rsvp-parameters>.
Value Description Reference 7 OTN-TDM RFC7139
IANA maintains the "Generalized Multi-Protocol Label Switching (GMPLS) Signaling Parameters" registry (see <http://www.iana.org/assignments/gmpls-sig-parameters>). The "Generalized PIDs (G-PID)" subregistry is included in this registry, which is extended and updated by this document as detailed below.
Value Type Technology Reference ===== ====================== ========== ========= 47 G.709 ODU-2.5G G.709 ODUk RFC4328 (IANA updated the Type field) RFC7139 56 SBCON/ESCON G.709 ODUk, RFC4328 (IANA updated the Type field) Lambda, Fiber RFC7139 59 Framed GFP G.709 ODUk RFC7139 60 STM-1 G.709 ODUk RFC7139 61 STM-4 G.709 ODUk RFC7139 62 InfiniBand G.709 ODUflex RFC7139 63 SDI (Serial Digital Interface) G.709 ODUk RFC7139 64 SDI/1.001 G.709 ODUk RFC7139 65 DVB_ASI G.709 ODUk RFC7139 66 G.709 ODU-1.25G G.709 ODUk RFC7139 67 G.709 ODU-any G.709 ODUk RFC7139 68 Null Test G.709 ODUk RFC7139 69 Random Test G.709 ODUk RFC7139 70 64B/66B GFP-F Ethernet G.709 ODUk RFC7139
The new G-PIDs are shown in the TC MIB managed by IANA at <https://www.iana.org/assignments/ianagmplstc-mib> as follows:
g709FramedGFP(59), g709STM1(60), g709STM4(61), g709InfiniBand(62), g709SDI(63), g709SDI1point001(64), g709DVBASI(65), g709ODU1point25G(66), g709ODUAny(67), g709NullTest(68), g709RandomTest(69), g709GFPFEthernet(70)
Note that IANA has not changed the names of the objects in this MIB module with the values 47 and 56.
IANA has defined an "OTN Signal Type" subregistry to the "Generalized Multi-Protocol Label Switching (GMPLS) Signaling Parameters" registry:
Value Signal Type Reference ----- ----------- --------- 0 Not significant RFC4328 1 ODU1 (i.e., 2.5 Gbps) RFC4328 2 ODU2 (i.e., 10 Gbps) RFC4328 3 ODU3 (i.e., 40 Gbps) RFC4328 4 ODU4 (i.e., 100 Gbps) RFC7139 5 Unassigned RFC4328 6 Och at 2.5 Gbps RFC4328 7 OCh at 10 Gbps RFC4328 8 OCh at 40 Gbps RFC4328 9 OCh at 100 Gbps RFC7139 10 ODU0 (i.e., 1.25 Gbps) RFC7139 11 ODU2e (i.e., 10 Gbps for FC1200 RFC7139 and GE LAN) 12-19 Unassigned RFC7139 20 ODUflex(CBR) (i.e., 1.25*N Gbps) RFC7139 21 ODUflex(GFP-F), resizable RFC7139 (i.e., 1.25*N Gbps) 22 ODUflex(GFP-F), non-resizable RFC7139 (i.e., 1.25*N Gbps) 23-255 Unassigned RFC7139
New values are to be assigned via Standards Action as defined in RFC5226.
12. References
12.1. Normative References
RFC2119 Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
RFC2205 Braden, R., Ed., Zhang, L., Berson, S., Herzog, S., and
S. Jamin, "Resource ReSerVation Protocol (RSVP) --
Version 1 Functional Specification", RFC 2205, September
1997.
RFC2210 Wroclawski, J., "The Use of RSVP with IETF Integrated
Services", RFC 2210, September 1997.
RFC3209 Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V.,
and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
Tunnels", RFC 3209, December 2001.
RFC3471 Berger, L., Ed., "Generalized Multi-Protocol Label
Switching (GMPLS) Signaling Functional Description", RFC
3471, January 2003.
RFC3473 Berger, L., Ed., "Generalized Multi-Protocol Label
Switching (GMPLS) Signaling Resource ReserVation
Protocol-Traffic Engineering (RSVP-TE) Extensions", RFC
3473, January 2003.
RFC4328 Papadimitriou, D., Ed., "Generalized Multi-Protocol Label
Switching (GMPLS) Signaling Extensions for G.709 Optical
Transport Networks Control", RFC 4328, January 2006.
RFC4506 Eisler, M., Ed., "XDR: External Data Representation
Standard", STD 67, RFC 4506, May 2006.
RFC4783 Berger, L., Ed., "GMPLS - Communication of Alarm
Information", RFC 4783, December 2006.
RFC6344 Bernstein, G., Ed., Caviglia, D., Rabbat, R., and H. van
Helvoort, "Operating Virtual Concatenation (VCAT) and the
Link Capacity Adjustment Scheme (LCAS) with Generalized
Multi-Protocol Label Switching (GMPLS)", RFC 6344, August
2011.
RFC7138 Ceccarelli, D., Ed., Zhang, F., Belotti, S., Rao, R., and
J. Drake, "Traffic Engineering Extensions to OSPF for
GMPLS Control of Evolving G.709 Optical Transport
Networks", RFC 7138, March 2014.
[G709-2012] ITU-T, "Interfaces for the Optical Transport Network
(OTN)", G.709/Y.1331 Recommendation, February 2012.
[G7044] ITU-T, "Hitless adjustment of ODUflex", G.7044/Y.1347,
October 2011.
[G7041] ITU-T, "Generic framing procedure", G.7041/Y.1303, April
2011.
[IEEE] "IEEE Standard for Binary Floating-Point Arithmetic",
ANSI/IEEE Standard 754-1985, Institute of Electrical and
Electronics Engineers, August 1985.
12.2. Informative References
RFC5226 Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226, May 2008.
RFC5920 Fang, L., Ed., "Security Framework for MPLS and GMPLS
Networks", RFC 5920, July 2010.
RFC7062 Zhang, F., Ed., Li, D., Li, H., Belotti, S., and D.
Ceccarelli, "Framework for GMPLS and PCE Control of G.709
Optical Transport Networks", RFC 7062, November 2013.
RFC7096 Belotti, S., Ed., Grandi, P., Ceccarelli, D., Ed.,
Caviglia, D., Zhang, F., and D. Li, "Evaluation of
Existing GMPLS Encoding against G.709v3 Optical Transport
Networks (OTNs)", RFC 7096, January 2014.
[TDM-OAM] Kern, A., and A. Takacs, "GMPLS RSVP-TE Extensions for
SONET/SDH and OTN OAM Configuration", Work in Progress,
November 2013.
13. Contributors
Yi Lin Huawei Technologies F3-5-B R&D Center, Huawei Base Bantian, Longgang District Shenzhen 518129 P.R. China Phone: +86-755-28972914 EMail: [email protected]
Yunbin Xu China Academy of Telecommunication Research of MII 11 Yue Tan Nan Jie Beijing P.R. China Phone: +86-10-68094134 EMail: [email protected]
Pietro Grandi Alcatel-Lucent Optics CTO Via Trento 30 20059 Vimercate Milano Italy Phone: +39 039 6864930 EMail: [email protected]
Diego Caviglia Ericsson Via A. Negrone 1/A Genova - Sestri Ponente Italy EMail: [email protected]
Rajan Rao Infinera Corporation 169, Java Drive Sunnyvale, CA 94089 USA EMail: [email protected]
John E Drake Juniper EMail: [email protected]
Igor Bryskin Adva Optical EMail: [email protected]
Jonathan Sadler, Tellabs EMail: [email protected]
Kam LAM, Alcatel-Lucent EMail: [email protected]
Francesco Fondelli, Ericsson EMail: [email protected]
Lyndon Ong, Ciena EMail: [email protected]
Biao Lu, infinera EMail: [email protected]
14. Acknowledgments
The authors would like to thank Lou Berger, Deborah Brungard, and Xiaobing Zi for their useful comments regarding this document.
Authors' Addresses
Fatai Zhang (editor) Huawei Technologies F3-5-B R&D Center, Huawei Base Bantian, Longgang District Shenzhen 518129 P.R. China Phone: +86-755-28972912 EMail: [email protected]
Guoying Zhang China Academy of Telecommunication Research of MII 11 Yue Tan Nan Jie Beijing P.R. China Phone: +86-10-68094272 EMail: [email protected]
Sergio Belotti Alcatel-Lucent Optics CTO Via Trento 30 20059 Vimercate Milano Italy Phone: +39 039 6863033 EMail: [email protected]
Daniele Ceccarelli Ericsson Via A. Negrone 1/A Genova - Sestri Ponente Italy EMail: [email protected]
Khuzema Pithewan Infinera Corporation 169, Java Drive Sunnyvale, CA 94089 USA EMail: [email protected]
