Information Technology Reference
In-Depth Information
network service based on the computing and storage resources. The instruction
is constituted by a number of basic actions, such as output and drop action,
which implement stateless packet forwarding operations.
3.3 Cast Table
Services are the sequence of service atoms and are scheduled by the Cast ta-
ble. Labelcast could extend the service based on the resource of computing and
storage. With the repaid increase of processors performance and memory capac-
ity, network nodes has a strong ability of computing and storing in addition to
the general forwarding hardware, which could provide the running platform for
service to implement network protocol semantics and status-related services of
packets processing in depth in the key data path.
Service atoms are implemented through application programs running on the
platform, and provide advance functions related to network protocols, such as
modification or replacement of any packet fields, forwarding based on rules and
storing and loading of data. On the other hand, service atoms could modify the
content of rules in forwarding layer, which could impact the process of subsequent
packets, and could assimilate packets and produce new packets. Service atoms
are developed by network vendors and could be extended by upgrading programs.
a)
Buffer primitives
: The allocation operation of the shared buffer or dedicated
buffer memory for applications, which are denoted by
bufferAlloc
,
atom-
Service
=
bufferAlloc
(restrictions) to abstract the allocation operation of
storage resources required by the service applications.
b)
Threading primitives
: The operations for the creation of threads, which are
denoted by
createThd
,
atomService
=
createThd
(restrictions) to abstract
the allocation operation of computing resources applied by services.
c)
Registeration primitives
: The operation of adding user-defined function to
a thread, which are denoted by
registerFun
,
atomService
=
registerFun
to
dynamically load service functions.
Packets process involving a variety of services, for example, IP over MPLS pro-
cess includes the options-specific modification of packets, in stack and out stack
operations of labels, and the output control operations. Multiple service primitive
perform in order, which constitutes a processing service, and pass the interme-
diate processing results through Metadata, which recorded in the state field of
the Cast table entries, to implement more complex processing in networks.
Service atoms are application programs based on the computing and stor-
age resources within network elements and implement protocol-related packet
processing in depth on the key data path. Service atoms could be upgraded
to implement new services and to support new network protocol-related packet
processing, which could avoid the complex upgrade of hardware of forwarding
layer and increase the flexibility of Labelcast. At the same time, network re-
searchers could design new services of packet processing through reconfiguring
the sequence of service and developing new service atoms, which could support
new network architectures, based on opening resources within network devices.
