Copied from the Ciena thread. Apparently Nortel and Lucent are proposing a standard (ASON) for Automatic Switched Optical Network which will use signalling for automatic optical switching. The significance at this time is that Nortel has announced a trial of this standard with Genuity which starts the first of the year. Here is the post from the Ciena thread:
James,
This may be of interest in the subject.
ftp://ftp.t1.org/pub/t1x1/x15.99/9x152800.doc
ABSTRACT:
This contribution reflects a coalesced version of recent proposals from Lucent Technologies and Nortel Networks, suggesting
that ANSI Committee T1 address Automatically Switched Optical Channel Networks (ASON). This contribution was prepared at
the request of, and approved by, participants that met during the 4-7 October 1999 meeting of ANSI T1X1.5.
Considering that ITU-T has included a work item to study the real time set up of OCh connections (in Q.13/15 & Q.14/15), and that
ANSI T1X1.5 is chartered with matters pertaining to Optical Networking, it is proposed that Committee T1 start a work program to
study the requirements and options available to create an Automatic Switched Optical Channel Network (ASON), to actively
contribute to ITU-T to create the necessary and sufficient standards for this to be accomplished.
1 Introduction
Ever since PDH was replaced by SONET, and all manual operations were replaced by TMN operations systems, there has been
the possibility to fully automate the Transport Network. Today we have the ideal opportunity to create the OCh layer network as
an Automatic Circuit Switched Optical Network.
2 Discussion
It is becoming increasingly recognised that automation of the OCh layer network is both practical and useful. Indeed a recent
contribution to ITU-T SG15 [COM15-D558] proposes that consideration be given to the use of signalling protocols to set up OCh
connections in real time. This suggestion generated sufficient interest to be included in the proposed work program for the next
Study Period (ITU-T Q.13/15 & Q.14/15 has included a work item to study the real time set up of OCh connections).
There is clearly a benefit from automatic switching of optical channels, in particular, there is a clear opportunity to create a global
switched optical network. There are a number of value added capabilities proposed for such a capability:
? Reactive traffic engineering. This is a prime attribute and allows the network resources to be dynamically allocated to routes
? Restoration and recovery. These attributes can maintain graduated preservation of service in the presence of network
degradation.
? Linking optical network resources to data traffic patterns automatically will result in a highly responsive and cost effective
transport network.
In order to achieve automatic OCh level switching, which we consider as automation of the OTN, a certain degree of global
standardisation is required. In the USA, T1X1.5 is chartered with matters pertaining to Optical Networking and is carrying out that
charter by actively making USA contributions as required to ITU-T.
3 Requirements
The following requirements are proposed for specifying Automatic Switched Optical Networks:
(a) A signaling method is required for the ASON, and the signal protocol should support circuit switching functions.
(b) The signaling method should re-use as much as possible, existing public circuit switched network protocols (e.g. CCS7, PNNI,
etc) to minimize overall network cost.
(c) The switched connection network should be defined on internationally agreed, geographically sensitive
addressing/numbering schemes (i.e. a hierarchical numbering plan). This will support the opportunity of creating a global
Automatic Switched Optical Network.
(d) A controlling infrastructure should be defined. Figure 1 illustrates the logical architecture for the ASON. The control system
will be aware of the routing needs. It will provide the connection set-up, maintenance, and tear-down functions according to
algorithmic determination of the available network resources.
(e) The following interfaces need to be specified (see Figure 1):
(1) The interface between the network elements and users such as the router, ATM switch, etc. In general these can be
considered client to network interface issues. In this context there are a number of parameters of interest in order to design an
automatic switched network:
? Connection set-up request rate per customer end point, which is needed in order to dimension the control network,
? Connection requests parameters
? Naming scheme for OCh end points
? Scheme for specifying protection needs in connection requests
? Security parameters
? Response time
? time to convey the request between client and network
(2) The interface between network elements within the optical network. Internal OTN connection set up issues may include:
? Signalling and Routing
Any automatic network needs a signalling protocol to carry connection set up requests between subnetworks and perhaps
network elements. The choice of signalling protocol needs to be studied as does the choice of fully distributed signalling
applications running on network elements, or a more centralised approach involving signalling applications running on operations
systems. Signalling protocols may be needed in different flavours to support inter as well as intra domain signalling.
? In addition the Automatic network needs a means to allow the signalling applications to select a route for the particular
connection being set-up. This may involve a routing information exchange protocol and it may be necessary to provide such a
protocol for inter as well as intra domain application.
? Means will be needed to provide an initial view of the topology available for route selection.
? Response times
? time for network to respond to set-up request
? time for network to respond to tear down request
? Communications
? Appropriate communications channels to carry the signalling and routing protocols need to be studied
? Security
? Means are needed to ensure the security of at least any inter domain communications
(3) The interface between the control plane and network elements. The control plane should make the entire control network a
centralized control implemented in a distributed fashion.
(f) A signaling protocol should be defined between control systems and network elements.
(g) An addressing/signaling scheme should to be defined between the “user” (i.e. router, ATM switch, etc.) and the control plane
(through the ASON edge element).
(h) ASON should apply to Optical Channels and be client independent.
Figure 1 Logical view of Automatic Switched Optical Network architecture
4 Proposal
This contribution suggests the proposed requirements to be used as the starting point for defining the Automatically Switched
Optical Networks.
Considering that ITU-T has included a work item to study the real time set up of OCh connections (in Q.13/15 & Q.14/15), and
considering that T1X1.5 is chartered with matters pertaining to Optical Networking, it is proposed that Committee T1 start a work
program to study the requirements and options available to create an Automatic Switched Optical Network, and to actively
contribute to ITU-T to create the necessary and sufficient standards for this to be accomplished.
___________
Best wishes.
VVarges
t1.org
At this website there are quite a few papers on the issue for anyone who may be interested. |
