Multi layer implications in GMPLS controlled networks
draft-bcg-ccamp-gmpls-ml-implications-00
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draft-bcg-ccamp-gmpls-ml-implications-00
CCAMP Working Group D. Ceccarelli
Internet-Draft Ericsson
Intended status: Informational S. Belotti
Expires: January 8, 2013 D. Papadimitriou
Alcatel-Lucent
July 7, 2012
Multi layer implications in GMPLS controlled networks
draft-bcg-ccamp-gmpls-ml-implications-00
Abstract
This document defines requirements and uses cases for the extension
of the OTN MLN work to MRNs. It also provides an evaluation of
already existing solutions againts new requirements.
Status of this Memo
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This Internet-Draft will expire on January 8, 2013.
Copyright Notice
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document authors. All rights reserved.
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described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
2. Applicability Scenarios . . . . . . . . . . . . . . . . . . . 3
3. Requirements . . . . . . . . . . . . . . . . . . . . . . . . . 6
4. Evaluation . . . . . . . . . . . . . . . . . . . . . . . . . . 7
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
6. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 9
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 9
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 9
8.1. Normative References . . . . . . . . . . . . . . . . . . . 9
8.2. Informative References . . . . . . . . . . . . . . . . . . 10
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 10
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1. Introduction
Generalized MPLS (GMPLS) supports the control of multiple switching
technologies: packet switching, Layer-2 switching, TDM (Time-Division
Multiplexing) switching, wavelength switching, and fiber switching
([RFC3945]).
The Interface Switching Capability concept has been defined for the
advertisement of the Switching Capabilities of the different
interfaces of a node [RFC4202], while in the context of Multi Region
Networks (MRN) the Interface Adjustment Capabiltiy concept has been
introduced [RFC5339] for the advertisement of adjustment capacity
within an hybrid node.
With the introduction of G709v3 networks, a new Switching Capability
(OTN-TDM) has been defined [OSPF-OTN] and the ISCD updated in order
to cope with the OTN specific multi stage multiplexing capabilities.
The new Switching Capability Specific Information (SCSI) field
provides information about the bandwidth availability at each layer
of the OTN hierarchy and about the operations that can be performed
on the different layers, in terms of termination and switching
capabilities.
These issues have been addressed in the OTN documents within the OTN
multi layer scope but need to be extended to MRNs, where the
termination of a hierarchical LSP leads to the need of properly
managing different switching capabilities and different adaptation
functions.
Scope of this document is describing new requirements derived from
the extension of OTN MLN hierarchies to MRNs and evaluating impacts
on existing solutions.
1.1. 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].
2. Applicability Scenarios
When moving from OTN MLNs to general MRNs, the multiplexing tree
concept introduced in [OSPF-OTN] needs to be extended so to take into
account both different switching capabilities within the same muxing
tree and mapping adaptations between client hierarchies and server
hierarchies.
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In the following figure an example of muxing tree supporting TDM,
PSC, OTN-TDM and LSC hierarchies mixed together is shown.
VC-4
|
ODU1 STM-16 PSC L2SC
| | | |
| | | |
ODU2 ODU2 ODU1 |
\ \ / /
\ \ / /
\ \ / /
\ \ / /
\ \/ /
\_ _ODU3__/
|
OCh
Figure 1: Muxing tree
As it is possible to understand from the figure above, an MRN
equipment can host a variety of client-server relationships. Four
different scenarios can be identified:
- A signal type X is a client to a Signal type Y (1:1) - e.g.
Ethernet over WDM
- A signal type X is a client to a Intra switching technology
Hierarchy Y (1:N) - e.g. Ethernet over OTN
- An Intra switching technology Hierarchy X is a client to a
Signal Type Y (M:1) - e.g. ODU over WDM
- An Intra switching technology Hierarchy X is a client to an
Intra switching technology Hierarchy Y (M:N) - e.g. SDH over OTN
Being the first three scenarios a particular case of the fourth one,
in the following only the general case of M:N relationship will be
addressed.
This kind of client-server hierarchy can be achieved, depending on
the impelemntation, via single board or a cascade of them. In the
latter case boards are connected via internal links, which can be
either intra or inter switching capaility (e.g. ODU2->ODU3 or
PSC->LSC). Those links should not be modeled as external TE links,
but there is the need to advertise their characteristics and
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availability in terms of bandwidth and optical parameters.
+--------------------------------------------------------+
| +------------+ Eth +------------+ |
| | | | | | |
| OTU-1 +----+ | | +----+ | |
| +----+ | | +--> + | | |
| | 8 | | | 4 | | |
| OTU-1 |ODU1+------+| |ODU2+------+| OTU-3 |
| +----+ |ODU-2 |..........>+ |ODU-3 |+----------|-->
| | +------+|Internal | +------+| |
| OTU-1| | |Physical | | | |
| +----+ | | Link + | | |
| +----+ | (OTU-2) +----+ | |
| | | | | |
| +------------+ +------------+ |
+--------------------------------------------------------+
Figure 2: Cascaded muxponder
Moreover, as described in [RFC5212], in a hybrid node there is the
need to take into account also the node's internal adjustment
capabilities between the switching technologies supported. An
example of hybrid node with different switching matrices is shown in
the following figure, where both an SDH and OTN matrix are available
and the two switching elements are internally interconnected so that
it is possible to terminate some resources (e.g. OTN interface Y1)
or provide adjustment for the SDH traffic (e.g. OTN interface Y2
toward the SDH matrix). In addition to the internal links between
matrices it is possible to have internal links between matrices and
cascaded cards for the creation of the muxing hierarchy. In the
example below both the SDH and OTN matrices are client to an
ODU2->ODU3 muxponder (through interfaces Y4 and Y5), which in turn is
client to an OCh WSS.
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| 10GbE
+-------------------------+-------------+
| | |
| | |
+-+ | +---------+ | |
|X| | X1 | | | |
__+-+__|__________| \ / | | |
| ` \/ | X3 | |
| X2 | /\ '''| | ODU2 |
| |''''' / \ | | | Y6+---+ | +---------+
| | | +---+ | | +---+ | | | |
| | | |SDH| + | Y5 | | ODU3| | |
| | |__+---+__| +-----+ +----+| | |
| | | | || OTU3/OCH| +---+ |
| | | | ++----------+ |WSS| +---
| | Y4 | | || Y7 | +---+ |Y8
| | +----------+ ...... +----+| | |
+-+ | | | \ / | | ___| |+--+ | | |
|Y| | |Y2 | \/ | | | +---+|OT| | | |
+-+ | .....| /\ |Y3| | +--+ | +---------+
-------+----------+ / \ | | | |
| Y1 | .... | |
| | +---+ | | + |
| | |OTN| | | ODU2 |
| |__+---+___| |
+---------------------------------------+
Figure 3: Hybrid node with optical muxponder and different switching
matrices
3. Requirements
In order to deal with all the scenarios depiscted in the previous
sections, protocol extensions need to take into account the following
set of requirements.
1. It must be possible to identify from which branch of X to
which branch of Y the mapping is performed. Due to a restricted
connectivity to a given switching layer, not all the indicated
branches are really available. An example of such limitations can
be seen in figure Figure 3, where for example the SDH client can
be mapped only on itnerface Y5 of the muxponder board or the
10GbEth on interface Y6. In figure Figure 1 it is also possible
to see that the OTN has a hierarchy with 3 branches (i.e.
ODU1->ODU2->ODU3, ODU2->ODU3 and ODU1->ODU3) and an SDH signal can
be mapped only over the ODU2->ODU3 branch while an Ethernet one
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can be mapped only on the ODU1->ODU3). So it is not eough to say
that SDH can be mapped over ODU or Eth over ODU as further info is
needed. Moreover it is also not enough to say that Eth is mapped
over ODU1 because in the same example 2 different branches have
the ODU1 as the top most layer (i.e. ODU1->ODU2->ODU3 and
ODU1->ODU3) and not both of them can support Eth mapping.
2. Adaptation information from X to Y to be used both in case of
Y being switched and X mapped over it or in case of both X and Y
being switched. Please note that more than one type of adaptation
might be availble.
3. Amount of available bandwidth in the mapping between X and Y
(as per actual IACD definition)
4. It must be possible to advertise intra-switching capability
associated to internal links. A typical case is a hierarchy
gained through the cascade of multiple cards (e.g. trasnponders,
muxponders) and the link from one board to the other one has a
given bandwidth.
5. It must be possible to advertise inter-switching capability
associated to internal links. A typical case is a M:N client-
layer hierarchy gained through the cascade of multiple cards (e.g.
SDH client to a muxponder card) and the link from one board to the
other one has a given bandwidth.
4. Evaluation
[RFC6001] defined the Interface Adjustment Capability Descriptor
(IACD) for the advertisement of internal adjustment capability of
hybrid nodes [RFC5212]. This is the only object defined in routing
for the management of hybrid nodes. It provides the information for
the forwarding/switching capability and is used in addition to the
ISCD.
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Lower SC | Lower Encoding| Upper SC | Upper Encoding|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Max LSP Bandwidth at priority 0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Max LSP Bandwidth at priority 1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Max LSP Bandwidth at priority 2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Max LSP Bandwidth at priority 3 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Max LSP Bandwidth at priority 4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Max LSP Bandwidth at priority 5 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Max LSP Bandwidth at priority 6 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Max LSP Bandwidth at priority 7 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Adjustment Capability-specific information |
| (variable) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4: IACD format
The information needed for addressing the requirements listed in
Section 3 are:
- Mapping from a client to a server layer
- Connectivity constraints: need to describe optical transponder
muxing scheme with positioning and restricted connectivity in
order to provide end to end connectivity. In the example shown in
picture Figure 1, the capability of muxing an SDH hierarchy is
shown, but the SDH cannot be injected in any branch of the OTN
hierarchy. There is the need to specify that the SDH hierarchy
can be only muxed into the ODU->ODU3 branch of the OTN hierarchy
and not in all of them.
Multistage interswitching capability: The IACD only allows the
multiplexing of a hierarchy of a given switching capability into a
hierarchy of a different swithcing capability (aka single stage
muxing in OTN documents), but it must be possible to advertise
also multi-stage muxing scenarios like the one in the reference
muxing tree, where an SDH hierarchy is muxed over an OTN
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hierarchy, which is againg muxed over an OCh (two levels of
muxing).
[EDITOR NOTE: following notes to be considered]
We also defined two more cases depending on the node capabilities with respect to the client hierarchy X.
A. Both Signal type/Hierarchy X and Y can be switched by the NE, i.e. it has a matrix able to switch X and a matrix able to switch Y but the interface is only Y capable. The advertisement will include the following pieces of information
- ISCD referring to Y
- IACD
- Adaptation information for X--Y
B. Only Signal type/Hierarchy Y can be switched by the NE while X is only mapped into Y: The advertisement will include the following pieces of information
- ISCD referring to Y
- Adaptation information for X--Y
5. IANA Considerations
6. Contributors
7. Acknowledgements
8. References
8.1. Normative References
[OTN-FWK] F.Zhang, D.Li, H.Li, S.Belotti, D.Ceccarelli, "Framework
for GMPLS and PCE Control of G.709 Optical Transport
networks, work in progress
draft-ietf-ccamp-gmpls-g709-framework-05", September 2011.
[OTN-INFO]
S.Belotti, P.Grandi, D.Ceccarelli, D.Caviglia, F.Zhang,
D.Li, "Information model for G.709 Optical Transport
Networks (OTN), work in progress
draft-ietf-ccamp-otn-g709-info-model-02", October 2011.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2154] Murphy, S., Badger, M., and B. Wellington, "OSPF with
Digital Signatures", RFC 2154, June 1997.
[RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328, April 1998.
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[RFC2370] Coltun, R., "The OSPF Opaque LSA Option", RFC 2370,
July 1998.
[RFC3630] Katz, D., Kompella, K., and D. Yeung, "Traffic Engineering
(TE) Extensions to OSPF Version 2", RFC 3630,
September 2003.
[RFC4201] Kompella, K., Rekhter, Y., and L. Berger, "Link Bundling
in MPLS Traffic Engineering (TE)", RFC 4201, October 2005.
[RFC4202] Kompella, K. and Y. Rekhter, "Routing Extensions in
Support of Generalized Multi-Protocol Label Switching
(GMPLS)", RFC 4202, October 2005.
[RFC4203] Kompella, K. and Y. Rekhter, "OSPF Extensions in Support
of Generalized Multi-Protocol Label Switching (GMPLS)",
RFC 4203, October 2005.
[RFC5250] Berger, L., Bryskin, I., Zinin, A., and R. Coltun, "The
OSPF Opaque LSA Option", RFC 5250, July 2008.
[RFC5340] Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF
for IPv6", RFC 5340, July 2008.
[RFC6001] Papadimitriou, D., Vigoureux, M., Shiomoto, K., Brungard,
D., and JL. Le Roux, "Generalized MPLS (GMPLS) Protocol
Extensions for Multi-Layer and Multi-Region Networks (MLN/
MRN)", RFC 6001, October 2010.
8.2. Informative References
[G.709] ITU-T, "Interface for the Optical Transport Network
(OTN)", G.709 Recommendation (and Amendment 1),
February 2001.
[G.709-v3]
ITU-T, "Draft revised G.709, version 3", consented
by ITU-T on Oct 2009.
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Authors' Addresses
Daniele Ceccarelli
Ericsson
Via A. Negrone 1/A
Genova - Sestri Ponente
Italy
Email: daniele.ceccarelli@ericsson.com
Sergio Belotti
Alcatel-Lucent
Via Trento, 30
Vimercate
Italy
Email: sergio.belotti@alcatel-lucent.com
Dimitri Papadimitriou
Alcatel-Lucent
Copernicuslaan 50
Antwerpen B-2018
Belgium
Email: dimitri.papadimitriou@alcatel-lucent.be
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