Packet Optical Integration (POI)
Use Cases for Abstraction and Control of Transport Networks (ACTN)
Huawei Technologies
Leela Palace
Bangalore
Karnataka
560008
INDIA
dhruv.ietf@gmail.com
Huawei Technologies
Bantian, Longgang District
Shenzhen
Guangdong
518129
P.R.China
zhang.xian@huawei.com
Telefonica
SPAIN
ogondio@tid.es
Routing
ACTN BOF
This document describes the Abstraction and Control of
Transport Networks (ACTN) use cases related to Packet and
Optical Integration (POI), that may be potentially
deployed in various transport networks and apply to different
applications.
The transport networks are in an unique position to embrace the
concepts of software defined networking (SDN) because of the existing
separation in control and forwarding plane via GMPLS/ASON. The path
computation element (PCE) and its
stateful extension can further provide
a central control over the resources. Abstraction and Control
of Transport Network (ACTN) is focused on building over
the existing blocks by adding programmability, access and control over
abstract virtual topologies. provides detailed
information regarding this work.
It is preferable to coordinate network resource control and
utilization rather than controlling and optimizing resources at each
network layer (packet and optical transport network) independently.
This facilitates network efficiency and network
automation.
This document explores the Packet and Optical Integration (POI) use cases
of ACTN to help provide
programmable network services like access to abstract topology and
control over the resources. Increasingly there is a need for
packet and optical transport networks to work together to provide
accelerated services. Transport networks can provide useful
information to the packet network allowing it to make intelligent
decisions and control its allocated resources. In this POI use-case,
we regard packet networks as a consumer to transport networks. It is
interesting to note that the Packet networks themselves may have
their ultimate clients to support.
The use case described in this document are primarily concerned
with 'packet network as a consumer' in a single trusted domain.
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 .
The following terminology is used in this document.
Abstraction and Control of Transport Networks.
Path Computation Element. An entity (component,
application, or network node) that is capable of computing a network
path or route based on a network graph and applying computational
constraints.
Packet and Optical Integration
Virtual Network Topology Manager
Connections (or tunnels) formed across the optical transport network,
can be used as virtual TE links in the packet network. The
relationship is reduced to determining which tunnels to set
up, how to trigger them, how to route them, and what capacity to
assign them. As the demands in the packet network vary, these
tunnels may need to be modified.
An entity in packet network (maybe a Path Computation Element (PCE),
Virtual Network Topology Manager (VNTM) , Controller
etc..) should be aware of the abstract topology of the transport
network. The topology may consist of established tunnels in transport
network or ones that can be created on demand.
The level of abstraction is dependent on various management,
security and policy considerations. This
abstract topology information in the packet network can be utilized
in various cases, as detailed in the following sections.
Currently there is a schism between network planning for packet
and optical transport networks. Sometimes these networks are administered, operated
and planned independently even when they are a part of a single trusted domain.
Any change in traffic requirements
requires long business process to make changes in the network. In dynamic
networks this is no longer acceptable.
A unified Packet+Optical traffic planning tool can be developed which
uses the traffic demand matrix to plan the optical transport network. Further based
on traffic demand changes, historical data, traffic prediction and
monitoring, changes should be made to the optical transport network. An
access to abstract topology of the optical transport network based on
established and potential
(on-demand) tunnels in transport network can provide mechanism to handle this.
Further optical bypass may be established automatically to offload the
continuous changing traffic to transport network allowing streamlined
business process between packet and optical transport networks.
Congestion management and synergized network optimization for packet
and transport networks can eliminate the need for overbooking of
transport networks as dumb pipes. Application could be written that
provide automated congestion management and network optimization.
Automated congestion management recognizes prolonged congestion
in the network and works with the controllers to add bandwidth
at a transport layer, to alleviate the congestion, or make changes
in the packet layer to reroute traffic around the congestion.
For such applications there is a clear need for an abstract network topology of
optical transport layer, further there is also a need for a synergy of cost and SLA across
optical and packet networks.
The protection and restoration are usually handled individually in Packet and
optical layer. There is a need for synergy and optimized handling of
protection of resources across layers. A lot more resources in the optical
transport network are booked for backup then actually required since there is a lack
of coordination between packet and optical layers. The access to abstract graph
of transport network with information pertaining to backup path information
can help the packet network to handle protection, shared risk, fault
restoration in an optimized way. Informing the packet network about both working and
protection path which are either already established, or potential path can
be useful.
A significant improvements in overall network availability that can be
achieved by using optical transport shared-risk link group (SRLG) information
to guide packet network decisions; for example, to avoid or minimize common
SRLGs for the main (working) path and the loop free alternative or traffic
engineered fast reroute (LFA/TE FRR) back-up path.
Shared risk information need to be synergized between the packet and optical.
A mechanism to provide abstracted SRLG information can help the packet network
consider this information while handling protection and restoration.
In certain networks like financial information network (stock/
commodity trading) and enterprises using cloud based applications,
Latency (delay), Latency-Variation (jitter), Packet Loss and
Bandwidth Utilization are associated with the SLA. These SLAs must
be synergized across packet and optical transport networks. Network optimization
evaluates network resource usage at all layers and recommends or executes
service path changes while ensuring SLA compliance. It thus makes more
effective use of the network, and relieves current or potential congestion.
The main economic benefits of ACTN arise from its ability to maintain
the SLA of the services at reduced overall network cost considering both packet
and optical transport network. Operational benefits of the
ACTN also stem from greater flexibility in handling dynamic traffic such as
demand uncertainty or variations over time, or optimization based on cost or
latency, or improved handling of catastrophic failures.
In some deployments, optical transport network may further be divided into multiple
domains, an abstracted topology comprising of multiple optical domains
MAY be provided to the packet network. A Seamless aggregation
and orchestration across multiple optical transport domains will be a great help in
such deployments.
Another interesting deployment involves multiple packet network domains.
There exist scenarios where the topology provided to the packet network
domains may be different based on
the initial demand matrix as well as, management, security and
policy considerations.
The ACTN framework as described in
should support the aggregation and orchestration across network domains
and layers.
None, this is an informational document.
PCEP Extensions for Stateful PCE
[draft-ietf-pce-stateful-pce]
Framework for Abstraction and Control of Transport Networks (draft-ceccarelli-actn-framework)