Network Working Group Fatai Zhang, Ed.
Internet Draft Huawei
Category: Standards Track Guoying Zhang
CATR
Sergio Belotti
Alcatel-Lucent
D. Ceccarelli
Ericsson
Khuzema Pithewan
Infinera
Expires: February 27, 2013 August 27, 2012
Generalized Multi-Protocol Label Switching (GMPLS) Signaling
Extensions for the evolving G.709 Optical Transport Networks Control
draft-ietf-ccamp-gmpls-signaling-g709v3-04.txt
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Abstract
Recent progress in ITU-T Recommendation G.709 standardization has
introduced new ODU containers (ODU0, ODU4, ODU2e and ODUflex) and
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enhanced Optical Transport Networking (OTN) flexibility. Several
recent documents have proposed ways to modify GMPLS signaling
protocols to support these new OTN features.
It is important that a single solution is developed for use in GMPLS
signaling and routing protocols. This solution must support ODUk
multiplexing capabilities, address all of the new features, be
acceptable to all equipment vendors, and be extensible considering
continued OTN evolution.
This document describes the extensions to the Generalized Multi-
Protocol Label Switching (GMPLS) signaling to control the evolving
Optical Transport Networks (OTN) addressing ODUk multiplexing and new
features including ODU0, ODU4, ODU2e and ODUflex.
Conventions used in this document
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].
Table of Contents
1. Introduction .................................................. 3
2. Terminology ................................................... 4
3. GMPLS Extensions for the Evolving G.709 - Overview ............ 4
4. Generalized Label Request ..................................... 5
5. Extensions for Traffic Parameters for the Evolving G.709 ...... 7
5.1. Usage of ODUflex(CBR) Traffic Parameters ................. 8
5.2. Usage of ODUflex(GFP) Traffic Parameters ................ 10
6. Generalized Label ............................................ 11
6.1. New definition of ODU Generalized Label ................. 11
6.2. Examples ................................................ 14
6.3. Label Distribution Procedure ............................ 15
6.3.1. Notification on Label Error ........................ 16
6.4. Supporting Virtual Concatenation and Multiplication ..... 17
7. Supporting Hitless Adjustment of ODUflex (GFP) ............... 17
8. Control Plane Backward Compatibility Considerations........... 18
9. Security Considerations ...................................... 19
10. IANA Considerations.......................................... 19
11. References .................................................. 20
11.1. Normative References ................................... 20
11.2. Informative References ................................. 21
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12. Contributors ................................................ 21
13. Authors' Addresses .......................................... 22
14. Acknowledgment .............................................. 24
1. Introduction
Generalized Multi-Protocol Label Switching (GMPLS) [RFC3945] extends
MPLS to include Layer-2 Switching (L2SC), Time-Division Multiplex
(e.g., SONET/SDH, PDH, and ODU), Wavelength (OCh, Lambdas) Switching,
and Spatial Switching (e.g., incoming port or fiber to outgoing port
or fiber). [RFC3471] presents a functional description of the
extensions to Multi-Protocol Label Switching (MPLS) signaling
required to support Generalized MPLS. RSVP-TE-specific formats and
mechanisms and technology specific details are defined in [RFC3473].
With the evolution and deployment of G.709 technology, it is
necessary that appropriate enhanced control technology support be
provided for G.709. [RFC4328] describes the control technology
details that are specific to foundation G.709 Optical Transport
Networks (OTN), as specified in the ITU-T Recommendation G.709 [G709-
V1], for ODUk deployments without multiplexing.
In addition to increasing need to support ODUk multiplexing, the
evolution of OTN has introduced additional containers and new
flexibility. For example, ODU0, ODU2e, ODU4 containers and ODUflex
are developed in [G709-V3].
In addition, the following issues require consideration:
- Support for Hitless Adjustment of ODUflex (GFP) (HAO), which is
defined in [G.7044].
- Support for Tributary Port Number. The Tributary Port Number
has to be negotiated on each link for flexible assignment of
tributary ports to tributary slots in case of LO-ODU over HO-
ODU (e.g., ODU2 into ODU3).
Therefore, it is clear that [RFC4328] has to be updated or superceded
in order to support ODUk multiplexing, as well as other ODU
enhancements introduced by evolution of OTN standards.
This document updates [RFC4328] extending the G.709 ODUk traffic
parameters and also presents a new OTN label format which is very
flexible and scalable.
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2. 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].
3. 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-V3]. The corresponding
new signal types are summarized below:
- Optical Channel Transport Unit (OTUk):
. OTU4
- Optical Channel Data Unit (ODUk):
. ODU0
. ODU2e
. ODU4
. ODUflex
A new Tributary Slot Granularity (TSG) (i.e., 1.25 Gbps) is also
described in [G709-V3]. Thus, there are now two TS granularities for
the foundation OTN ODU1, ODU2 and ODU3 containers. The TS granularity
at 2.5 Gbps is used on 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),
the evolving OTN [G.709-V3] 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 [OTN-FWK].
Virtual Concatenation (VCAT) of OPUk (OPUk-Xv, k = 1/2/3, X = 1...256)
is also supported by [OTN-V3]. Note that VCAT of OPU0 / OPU2e / OPU4
/ OPUflex is not supported per [OTN-V3].
[RFC4328] describes GMPLS signaling extensions to support the control
for G.709 Optical Transport Networks (OTN) [G709-V1]. However,
[RFC4328] needs to be updated because it 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 mode which assumes that the Tributary Port Number
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 label format.
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Additionally, procedures about Tributary Port Number assignment
through control plane are also provided in this document.
4. Generalized Label Request
The Generalized Label Request, as described in [RFC3471], carries the
LSP Encoding Type, the Switching Type and the Generalized Protocol
Identifier (G-PID).
[RFC4328] extends the Generalized Label Request, 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 [G709-v1].
This document follows these extensions and a new Switching Type is
introduced to indicate the ODUk switching capability [G709-V3] in
order to support backward compatibility with [RFC4328], as described
in [OTN-FWK]. The new Switching Type (101, TBA by IANA) is defined in
[OTN-OSPF].
This document also updates the G-PID values defined in [RFC4328]:
Value G-PID Type
----- ----------
47 ODU-2.5G: transport of Digital Paths at 2.5, 10 and 40 Gbps
via 2.5Gbps TSG
49 CBRa: asynchronous Constant Bit Rate (i.e., mapping of
CBR2G5, CBR10G and CBR40G)
50 CBRb: bit synchronous Constant Bit Rate (i.e., mapping of
CBR2G5, CBR10G, CBR40G, CBR10G3 and supra-2.488 CBR
Gbit/s signal (carried by OPUflex))
32 ATM: mapping at 1.25, 2.5, 10 and 40 Gbps
51 BSOT: non-specific client Bit Stream with Octet Timing (i.e.,
Mapping of 1.25, 2.5, 10, 40 and 100 Gbps Bit Stream)
52 BSNT: non-specific client Bit Stream without Octet Timing
(i.e., Mapping of 1.25, 2.5, 10, 40 and 100 Gbps Bit
Stream)
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Note: Values 32, 47, 49 and 50 include mapping of SDH.
In the case of ODU multiplexing, the LO ODU (i.e., the client signal)
may be multiplexed into HO ODU via 1.25G TSG, 2.5G TSG or any one of
them (i.e., TSG Auto_Negotiation is enabled). Since the G-PID type
"ODUk" defined in [RFC4328] is only used for 2.5Gbps TSG, 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 1.25Gbps TSG
- ODU-any: transport of Digital Paths at 1.25, 2.5, 10, 40 and 100
Gbps via 1.25 or 2.5Gbps TSG (i.e., the fallback
procedure is enabled and the default value of 1.25Gbps
TSG can be fallen back to 2.5Gbps if needed)
In addition, some other new G-PID types are defined to support other
new client signals described in [G709-V3]:
- CBRc: Mapping of constant bit-rate signals with justification
into OPUk (k = 0, 1, 2, 3, 4) via GMP (i.e., mapping of
sub-1.238, supra-1.238 to sub-2.488, close-to 9.995,
close-to 40.149 and close-to 104.134 Gbit/s CBR client
signal)
- 1000BASE-X: Mapping of a 1000BASE-X signal via timing
transparent transcoding into OPU0
- FC-1200: Mapping of a FC-1200 signal via timing transparent
transcoding into OPU2e
The following table summarizes the new G-PID values with respect to
the LSP Encoding Type:
Value G-PID Type LSP Encoding Type
----- ---------- -----------------
59(TBA) G.709 ODU-1.25G G.709 ODUk
60(TBA) G.709 ODU-any G.709 ODUk
61(TBA) CBRc G.709 ODUk
62(TBA) 1000BASE-X G.709 ODUk (k=0)
63(TBA) FC-1200 G.709 ODUk (k=2e)
Note: Values 59 and 60 include mapping of SDH.
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5. Extensions for Traffic Parameters for the Evolving G.709
The traffic parameters for G.709 are 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 | NMC/ Tolerance |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NVC | Multiplier (MT) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Bit_Rate |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The Signal Type MUST be extended in order to cover the new Signal
Type introduced by the evolving OTN. The new Signal Type values are
extended as follows:
Value Type
----- ----
0 Not significant
1 ODU1 (i.e., 2.5 Gbps)
2 ODU2 (i.e., 10 Gbps)
3 ODU3 (i.e., 40 Gbps)
4 ODU4 (i.e., 100 Gbps)
5 Reserved (for future use)
6 OCh at 2.5 Gbps
7 OCh at 10 Gbps
8 OCh at 40 Gbps
9 OCh at 100 Gbps
10 ODU0 (i.e., 1.25 Gbps)
11 ODU2e (i.e., 10Gbps 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)
NMC/Tolerance:
This field is redefined from the original definition in [RFC4328].
NMC field defined in [RFC4328] cannot be fixed value for an end-to-
end circuit involving dissimilar OTN link types. For example, ODU2e
requires 9 TS on ODU3 and 8 TS on ODU4. Usage of NMC field is
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deprecated and SHOULD be used only with [RFC4328] generalized label
format for backwards compatibility reasons. For the new generalized
label format as defined in this document this field MUST be
interpreted as Tolerance.
In case of ODUflex(CBR), the Bit_Rate and Tolerance fields MUST be
used together to represent the actual bandwidth of ODUflex, where:
- The Bit_Rate field indicates the nominal bit rate of ODUflex(CBR)
expressed in bytes per second, encoded as a 32-bit IEEE single-
precision floating-point number (referring to [RFC4506] and
[IEEE]). The value contained in the Bit Rate field has to keep
into account both 239/238 factor and the Transcoding factor.
- The Tolerance field indicates the bit rate tolerance (part per
million, ppm) of the ODUflex(CBR) encoded as an unsigned integer,
which is bounded in 0~100ppm.
For example, for an ODUflex(CBR) service with Bit_Rate = 2.5Gbps and
Tolerance = 100ppm, the actual bandwidth of the ODUflex is:
2.5Gbps * (1 +/- 100ppm)
In case of ODUflex(GFP), the Bit_Rate field is used to indicate the
nominal bit rate of the ODUflex(GFP), which implies the number of
tributary slots requested for the ODUflex(GFP). Since the tolerance
of ODUflex(GFP) makes no sense on tributary slot resource reservation,
the Tolerance field for ODUflex(GFP) is not necessary and MUST be
filled with 0.
In case of other ODUk signal types, the Bit_Rate and Tolerance fields
are not necessary and MUST be set to 0.
The usage of the NVC and Multiplier (MT) fields are the same as
[RFC4328].
5.1. Usage of ODUflex(CBR) Traffic Parameters
In case of ODUflex(CBR), the information of Bit_Rate and Tolerance in
the ODUflex traffic parameters MUST be used to determine the total
number of tributary slots N in the HO ODUk link to be reserved. Here:
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)
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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-V3]) 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-V3]:
ODUflex(CBR) nominal bit rate = CBR client bit rate * (239/238) / T
The ODTUk.ts nominal bit rate is the nominal bit rate of the
tributary slot of ODUk, as shown in Table 1 (referring to [G709-V3]).
Table 1 - Actual TS bit rate of ODUk (in Gbps)
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
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 = 20ppm
Therefore, a node receiving a PATH message containing ODUflex(CBR)
nominal bit rate and tolerance can allocate 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, and 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.
As shown in Figure 1, assume there is an ODUflex(CBR) service
requesting a bandwidth of (2.5Gbps, +/-100ppm) from node A to node C.
In other words, the ODUflex traffic parameters indicate that Signal
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Type is 20 (ODUflex(CBR)), Bit_Rate is 2.5Gbps and Tolerance is
100ppm.
+-----+ +---------+ +-----+
| +-------------+ +-----+ +-------------+ |
| +=============+\| ODU |/+=============+ |
| +=============+/| flex+-+=============+ |
| +-------------+ | |\+=============+ |
| +-------------+ +-----+ +-------------+ |
| | | | | |
| | ....... | | ....... | |
| A +-------------+ B +-------------+ C |
+-----+ HO ODU4 +---------+ HO ODU2 +-----+
=========: TS occupied by ODUflex
---------: free TS
Figure 1 - Example of ODUflex(CBR) Traffic Parameters
- On the HO ODU4 link between node A and B:
The maximum bit rate of the ODUflex(CBR) equals 2.5Gbps * (1 +
100ppm), and the minimum bit rate of the tributary slot of ODU4
equals 1.301 683 217Gbps, so the total number of tributary slots
N1 to be reserved on this link is:
N1 = ceiling (2.5Gbps * (1 + 100ppm) / 1.301 683 217Gbps) = 2
- On the HO ODU2 link between node B and C:
The maximum bit rate of the ODUflex equals 2.5Gbps * (1 + 100ppm),
and the minimum bit rate of the tributary slot of ODU2 equals
1.249 384 632Gbps, so the total number of tributary slots N2 to
be reserved on this link is:
N2 = ceiling (2.5Gbps * (1 + 100ppm) / 1.249 384 632Gbps) = 3
5.2. Usage of ODUflex(GFP) Traffic Parameters
[G709-V3-A2] recommends that the ODUflex(GFP) will 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.
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Table 2 - Recommended ODUflex(GFP) bit rates and tolerance
ODU type | Nominal bit-rate | Tolerance
--------------------------------+------------------+-----------
ODUflex(GFP) of n TS, 1<=n<=8 | n * ODU2.ts | +/-100 ppm
ODUflex(GFP) of n TS, 9<=n<=32 | n * ODU3.ts | +/-100 ppm
ODUflex(GFP) of n TS, 33<=n<=80 | n * ODU4.ts | +/-100 ppm
According to this table, the Bit_Rate field for ODUflex(GFP) MUST
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.
6. Generalized Label
[RFC3471] has defined the Generalized Label which extends the
traditional label by allowing the representation of not only labels
which are sent in-band with associated data packets, but also labels
which identify time-slots, wavelengths, or space division multiplexed
positions. The format of the corresponding RSVP-TE Generalized Label
object is defined in the Section 2.3 of [RFC3473].
However, for different technologies, it usually needs to use specific
label rather than the Generalized Label. For example, the label
format described in [RFC4606] could be used for SDH/SONET, the label
format in [RFC4328] for G.709.
6.1. New definition of ODU Generalized Label
In order to be compatible with new types of ODU signal and new types
of tributary slot, the following new ODU label format MUST be used:
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ Bit Map ......... ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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The ODU Generalized Label 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 can be figured out locally according to the identifier of the
selected interface carried in the IF_ID RSVP_HOP Object.
TPN (12 bits): indicates the Tributary Port Number (TPN) for the
assigned Tributary Slot(s).
- In case of LO ODUj multiplexed into HO ODU1/ODU2/ODU3, only the
lower 6 bits of TPN field are significant and the other bits of
TPN MUST be set to 0.
- In case of LO ODUj multiplexed into HO ODU4, only the lower 7
bits of TPN field are significant and the other bits of TPN
MUST be set to 0.
- In case of ODUj mapped into OTUk (j=k), the TPN is not needed
and this field MUST be set to 0.
As per [G709-V3], The TPN is used to allow for correct demultiplexing
in the data plane. When an LO ODUj is multiplexed into 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-V3], the TPN field MUST be set as according to the
following tables:
Table 3 - TPN Assignment Rules (2.5Gbps TS granularity)
+-------+-------+----+----------------------------------------------+
|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 |
+-------+-------+----+----------------------------------------------+
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Table 4 - TPN Assignment Rules (1.25Gbps 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|ODU2es and ODUflexes' TPNs |
| |ODUflex| | |
+-------+-------+----+----------------------------------------------+
| ODU4 |Any ODU|1~80|Flexible, != ANY other existing LO ODUs' TPNs |
+-------+-------+----+----------------------------------------------+
Note that in the case of "Flexible", the value of TPN MAY not be
corresponding to the TS number as per [G709-V3].
Length (12 bits): indicates the number of bit of the Bit Map field,
i.e., the total number of TS in the HO ODUk link.
In 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 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 HO ODUk. Each
bit in the bit map represents the corresponding tributary slot in HO
ODUk with a value of 1 or 0 indicating whether the tributary slot
will be used by LO ODUj or not.
Padded bits are added behind the Bit Map to make the whole label a
multiple of four bytes if necessary. Padded bit MUST be set to 0 and
MUST be ignored.
Note that the Length field in the label format MAY also be used to
indicate the TS type of the HO ODUk (i.e., TS granularity at 1.25Gbps
or 2.5Gbps) since the HO ODUk type can be known from IF_ID RSVP_HOP
Object. In some cases when there is no LMP (Link Management Protocol)
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or routing to make the two end points of the link to know the TSG,
the TSG information used by another end can be deduced from the label
format. For example, for HO ODU2 link, the value of the length filed
will be 4 or 8, which indicates the TS granularity is 2.5Gbps or
1.25Gbps, respectively.
6.2. Examples
The following examples are given in order to illustrate the label
format described in the previous sections of this document.
(1) ODUk into OTUk mapping:
In such conditions, 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 into ODUk multiplexing:
In such conditions, this label indicates that an ODUj is multiplexed
into several tributary slots of OPUk and then mapped into OTUk. Some
instances are shown as follow:
- ODU0 into 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| Padded Bits (0) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
This above label indicates an ODU0 multiplexed into the second
tributary slot of ODU2, wherein there are 8 TS in ODU2 (i.e., the
type of the tributary slot is 1.25Gbps), and the TPN value is 2.
- ODU1 into ODU2 Multiplexing with 1.25Gbps TS granularity:
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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| Padded Bits (0) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
This above label indicates an ODU1 multiplexed into the 2nd and the
4th tributary slot of ODU2, wherein there are 8 TS in ODU2 (i.e., the
type of the tributary slot is 1.25Gbps), and the TPN value is 1.
- ODU2 into ODU3 Multiplexing with 2.5Gbps 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| Padded Bits (0) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
This above label indicates an ODU2 multiplexed into the 2nd, 3rd, 5th
and 7th tributary slot of ODU3, wherein there are 16 TS in ODU3 (i.e.,
the type of the tributary slot is 2.5Gbps), and the TPN value is 1.
6.3. Label Distribution Procedure
This document does not change the existing label distribution
procedures [RFC4328] for GMPLS except that the new ODUk label MUST be
processed as follows.
When a node receives a generalized label request for setting up an
ODUj LSP from its upstream neighbor node, the node MUST generate an
ODU label according to the signal type of the requested LSP and the
free resources (i.e., free tributary slots of ODUk) that will be
reserved for the LSP, and send the label to its upstream neighbor
node.
In case of ODUj to ODUk multiplexing, the node MUST firstly 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
value used by existing LO ODU connections in the selected HO ODU link,
and configure the expected multiplex structure identifier (ExMSI)
using this TPN. Then, the assigned TPN MUST be filled into the label.
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In case of ODUk to OTUk mapping, TPN field MUST be set to 0. Bit Map
information is not REQUIRED and MUST not be included, so Length field
MUST be set to 0 as well.
In order to process a received ODU label, the node MUST firstly learn
which ODU signal type is multiplexed or mapped into which ODU signal
type accordingly to the traffic parameters and the IF_ID RSVP_HOP
Object in the received message.
In 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 type (according to the total TS
number of the ODUk, or pre-configured TS type), so that the node,
based on the TS type, can multiplex the ODUj into the ODUk. 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 ExMSI and determine whether there is any mismatch
defect.
In case of ODUk to OTUk mapping, the size of Bit Map field MUST be 0
and no additional procedure is needed.
Note that the procedures of other label related objects (e.g.,
Upstream Label, Label Set) are similar to the one described above.
Note also that the TPN in the label_ERO MAY not be assigned (i.e.,
TPN field = 0) if the TPN is requested to be assigned locally.
6.3.1. Notification on Label Error
When receiving an ODUk label from the neighbor node, the node SHOULD
check the integrity of the label. An error message containing an
"Unacceptable label value" indication ([RFC3209]) SHOULD be sent if
one of the following cases occurs:
- Invalid value in the length field.
- The selected link only supports 2.5Gbps TS granularity while the
Length field in the label along with ODUk signal type indicates
the 1.25Gbps TS granularity;
- The label includes an invalid TPN value that breaks the TPN
assignment rules;
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- The reserved resources (i.e., the number of "1" in the Bit Map
field) do not match with the Traffic Parameters.
6.4. Supporting Virtual Concatenation and Multiplication
As per [RFC6344], the VCGs can be created using Co-Signaled style or
Multiple LSPs style.
In case of Co-Signaled style, the explicit ordered list of all labels
reflects the order of VCG members, which is similar to [RFC4328]. In
case of multiplexed virtually concatenated signals (NVC > 1), the
first label indicates the components of the first virtually
concatenated signal; the second label indicates the components of the
second virtually concatenated signal; and so on. In case of
multiplication of multiplexed virtually concatenated signals (MT > 1),
the first label indicates the components of the first multiplexed
virtually concatenated signal; the second label indicates components
of the second multiplexed virtually concatenated signal; and so on.
In case of Multiple LSPs style, multiple control plane LSPs are
created with a single VCG and the VCAT Call can be used to associate
the control plane LSPs. The procedures are similar to section 6 of
[RFC6344].
7. Supporting Hitless Adjustment of ODUflex (GFP)
[G.7044] describes the procedure of ODUflex (GFP) hitless resizing
using LCR (Link Connection Resize) and BWR (Bandwidth Resize)
protocols in OTN data plane.
For the control plane, signaling messages are REQUIRED to initiate
the adjustment procedure. Section 2.5 and Section 4.6.4 of [RFC3209]
describe how the Share Explicit (SE) style is used in TE network for
bandwidth increasing and decreasing, which SHOULD be still applicable
for triggering the ODUflex (GFP) adjustment procedure in data plane.
Note that the SE style SHOULD be used at the beginning when creating
a resizable ODUflex connection (Signal Type = 21). Otherwise an error
with Error Code "Conflicting reservation style" SHOULD be generated
when performing bandwidth adjustment.
- Bandwidth increasing
In order to increase the bandwidth of an ODUflex (GFP) connection,
a Path message with SE style (keeping Tunnel ID unchanged and
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assigning a new LSP ID) is sent along the path.
A downstream node compares the old Traffic Parameters (stored
locally) with the new one carried in the Path message, to
determine the number of TS to be added. After choosing and
reserving new free TS, the downstream node sends back a Resv
message carrying both the old and new LABEL Objects in the SE
flow descriptor, so that its upstream neighbor can determine
which TS are added. And the LCR protocol between each pair of
neighbor nodes is triggered.
On the source node, the BWR protocol will be triggered by the
successful completion of LCR protocols on every hop after Resv
message is processed. On success of BWR, the source 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.
- Bandwidth decreasing
The SE style SHOULD also be used for ODUflex bandwidth decreasing.
For each pair of neighbor nodes, the sending and receiving Resv
message with old and new LABEL Objects will trigger the first
step of LCR between them to perform LCR handshake. On the source
node, the BWR protocol will be triggered by the 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.
Similarly, after completion of bandwidth decreasing, a ResvErr
message SHOULD be sent to tear down the old control state.
8. Control Plane Backward Compatibility Considerations
As described in [OTN-FWK], since the [RFC4328] has been deployed in
the network for the nodes that support [G709-V1], control plane
backward compatibility SHOULD be taken into consideration. More
specifically:
o Nodes supporting this document SHOULD support [OTN-OSPF].
o Nodes supporting this document MAY support [RFC4328] signaling.
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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.
9. Security Considerations
This document introduces no new security considerations to the
existing GMPLS signaling protocols. Referring to [RFC3473], further
details of the specific security measures are provided. Additionally,
[GMPLS-SEC] provides an overview of security vulnerabilities and
protection mechanisms for the GMPLS control plane.
10. IANA Considerations
- G.709 SENDER_TSPEC and FLOWSPEC objects:
The traffic parameters, which are carried in the G.709
SENDER_TSPEC and FLOWSPEC objects, do not require any new object
class and type based on [RFC4328]:
o G.709 SENDER_TSPEC Object: Class = 12, C-Type = 5 [RFC4328]
o G.709 FLOWSPEC Object: Class = 9, C-Type = 5 [RFC4328]
- Generalized Label Object:
The new defined ODU label (Section 6) is a kind of generalized
label. Therefore, the Class-Num and C-Type of the ODU label is
the same as that of generalized label described in [RFC3473],
i.e., Class-Num = 16, C-Type = 2.
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11. References
11.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC4328] D. Papadimitriou, Ed. "Generalized Multi-Protocol Label
Switching (GMPLS) Signaling Extensions for G.709 Optical
Transport Networks Control", RFC 4328, Jan 2006.
[RFC3209] D. Awduche et al, "RSVP-TE: Extensions to RSVP for LSP
Tunnels", RFC3209, December 2001.
[RFC3471] Berger, L., Editor, "Generalized Multi-Protocol Label
Switching (GMPLS) Signaling Functional Description", RFC
3471, January 2003.
[RFC3473] L. Berger, Ed., "Generalized Multi-Protocol Label Switching
(GMPLS) Signaling Resource ReserVation Protocol-Traffic
Engineering (RSVP-TE) Extensions", RFC 3473, January 2003.
[RFC3945] Mannie, E., "Generalized Multi-Protocol Label Switching
(GMPLS) Architecture", RFC 3945, October 2004.
[RFC6344] G. Bernstein et al, "Operating Virtual Concatenation (VCAT)
and the Link Capacity Adjustment Scheme (LCAS) with
Generalized Multi-Protocol Label Switching (GMPLS)",
RFC6344, August 2011.
[OTN-FWK] Fatai Zhang et al, "Framework for GMPLS and PCE Control of
G.709 Optical Transport Networks", draft-ietf-ccamp-gmpls-
g709-framework, Work in Progress, August 2012.
[OTN-INFO] S. Belotti et al, "Information model for G.709 Optical
Transport Networks (OTN)", draft-ietf-ccamp-otn-g709-info-
model, Work in Progress, July 2012.
[OTN-OSPF] D. Ceccarelli et al, "Traffic Engineering Extensions to
OSPF for Generalized MPLS (GMPLS) Control of Evolving G.709
OTN Networks", draft-ietf-ccamp-gmpls-ospf-g709v3, Work in
Progress, April 2012.
[G709-V3] ITU-T, "Interfaces for the Optical Transport Network (OTN)
", G.709/Y.1331, December 2009.
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[G709-V3-A2] ITU-T, "Interfaces for the Optical Transport Network
(OTN) Amendment 2", G.709/y.1331 Amendment 2, April 2011.
11.2. Informative References
[G709-V1] ITU-T, "Interface for the Optical Transport Network (OTN),"
G.709 Recommendation (and Amendment 1), February 2001
(November 2001).
[G709-V2] ITU-T, "Interface for the Optical Transport Network (OTN),"
G.709 Recommendation, March 2003.
[G798-V2] ITU-T, "Characteristics of optical transport network
hierarchy equipment functional blocks", G.798, December
2006.
[G798-V3] ITU-T, "Characteristics of optical transport network
hierarchy equipment functional blocks", G.798v3, consented
June 2010.
[G.7044] ITU-T, "Hitless adjustment of ODUflex", G.7044 (and
Amendment 1), February 2012.
[RFC4506] M. Eisler, Ed., "XDR: External Data Representation
Standard", RFC 4506, May 2006.
[IEEE] "IEEE Standard for Binary Floating-Point Arithmetic",
ANSI/IEEE Standard 754-1985, Institute of Electrical and
Electronics Engineers, August 1985.
[GMPLS-SEC] Fang, L., Ed., "Security Framework for MPLS and GMPLS
Networks", Work in Progress, October 2009.
12. Contributors
Jonathan Sadler, Tellabs
Email: jonathan.sadler@tellabs.com
Kam LAM, Alcatel-Lucent
Email: kam.lam@alcatel-lucent.com
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Xiaobing Zi, Huawei Technologies
Email: zixiaobing@huawei.com
Francesco Fondelli, Ericsson
Email: francesco.fondelli@ericsson.com
Lyndon Ong, Ciena
Email: lyong@ciena.com
Biao Lu, infinera
Email: blu@infinera.com
13. 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: zhangfatai@huawei.com
Guoying Zhang
China Academy of Telecommunication Research of MII
11 Yue Tan Nan Jie Beijing, P.R.China
Phone: +86-10-68094272
Email: zhangguoying@mail.ritt.com.cn
Sergio Belotti
Alcatel-Lucent
Optics CTO
Via Trento 30 20059 Vimercate (Milano) Italy
+39 039 6863033
Email: sergio.belotti@alcatel-lucent.it
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Daniele Ceccarelli
Ericsson
Via A. Negrone 1/A
Genova - Sestri Ponente
Italy
Email: daniele.ceccarelli@ericsson.com
Khuzema Pithewan
Infinera Corporation
169, Java Drive
Sunnyvale, CA-94089, USA
Email: kpithewan@infinera.com
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: yi.lin@huawei.com
Yunbin Xu
China Academy of Telecommunication Research of MII
11 Yue Tan Nan Jie Beijing, P.R.China
Phone: +86-10-68094134
Email: xuyunbin@mail.ritt.com.cn
Pietro Grandi
Alcatel-Lucent
Optics CTO
Via Trento 30 20059 Vimercate (Milano) Italy
+39 039 6864930
Email: pietro_vittorio.grandi@alcatel-lucent.it
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Diego Caviglia
Ericsson
Via A. Negrone 1/A
Genova - Sestri Ponente
Italy
Email: diego.caviglia@ericsson.com
Rajan Rao
Infinera Corporation
169, Java Drive
Sunnyvale, CA-94089
USA
Email: rrao@infinera.com
John E Drake
Juniper
Email: jdrake@juniper.net
Igor Bryskin
Adva Optical
EMail: IBryskin@advaoptical.com
14. Acknowledgment
The authors would like to thank Lou Berger and Deborah Brungard for
their useful comments to the document.
Intellectual Property
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