Intelligent Network Services through Active Flow Manipulation

Lavian T.; Wang P.; Travostino F.; Subramanian S.; Hoang, D.B.; Sethaput V.; IEEE Intelligent Networks 2001 Workshop (IN2001), Boston, May 2001.



A significant challenge in today’s Internet is the ability to efficiently introduce intelligent network services into commercial high-performance network devices.

This paper tackles the challenge by introducing the active flow manipulation (AFM) mechanism, a key enabling technology of the programmable networking platform Openet. AFM enhances the control functionality of network devices through programmability. With AFM, customer network services can exercise intelligent network control by identifying specific flows and applying particular actions thereby altering their behavior in real time. These services are dynamically deployed in the CPU-based control plane and are closely coupled with the silicon-based forwarding plane of the network node, without negatively impacting forwarding performance. The effectiveness of our approach is demonstrated by several experimental applications on a commercial network node.



Programmable networking, intelligent network control, Active Flow Manipulation, Openet, active networks, traffic flow



The Internet infrastructure has been tremendously evolving to transport increasing network traffic arising from fast introduction of various commercial applications. The Internet is ubiquitous, however, fragmented in structure into large heterogeneous 
network domains controlled by Internet Service
Providers (ISPs). The providers have to rely on a
complex collection of operational management
methodologies and techniques in order to operate
their networks. In this increasingly competitive
environment, it is important for service providers to
easily control their networks. It is also important for
them to allow customization of network services to
differentiate their offerings by rapidly introducing
intelligent network services on demand such as QoS
(Quality of Service) to their clients. In brief, they are
in need of a comprehensive programmable
networking framework through which they manage
their networks intelligently to satisfy the clients’
The fundamental element of the Internet
infrastructure is the network node, e.g., a router or
switch. Typically, the distinction of the data (or
forwarding) and control planes is drawn at each node
with the hardware realizing the forwarding operations
and the software realizing the control operations.
Nowadays, the trend in commercial grade routers and
switches is to accelerate performance critical
forwarding functionality using hardware technologies
such as ASIC (Application-Specific Integrated
Circuit) technology. As a result they provide little
programmability and thus are limited in ability to
deliver intelligent control. However, dynamically
enabling and deploying new intelligent services on
network nodes implies that they must possess not
only high forwarding performance, but also high
degree of programmability.
It is a challenging task to come up with an
enabling technology that allows network service
providers freedom to deploy intelligent services on
current commercial network devices. One of the
requirements for such an enabling technology is that
it must have little or no adverse impact on the
processing performance in the data path. Another
important requirement of such technology is that it
should be distributed rather than centralized in the
To tackle the challenging issues discussed above,
in this paper the emphasis is placed on the Active
Flow Manipulation (AFM) mechanism, which aims to
affect the data traffic in real networks. AFM is a key
enabling technology of the open programmable
networking architecture Openet. The AFM
proposition is that the characteristics of a basic data
flow can be identified and its behaviors can be altered
in real-time by customizing control-plane services.
Openet is a platform-neutral, service-based
internetworking infrastructure developed by Nortel
Networks Corp., aiming to deliver dynamic network
programmability on heterogeneous network devices.
Commercial network devices such as the Nortel
Networks multi-gigabit routing switch Passport [4],
possess the ability to alter traffic flow behaviors in
the silicon-based forwarding plane. The control plane
in such a device, however, lacks userprogrammability required to introduce intelligent
services. Openet provides such programmability to
enable users with control of the forwarding hardware.
This programmability is in this paper manifested as
the ability to alter network behavior of flows in realtime, i.e., AFM, in order to enhance the functionality
of network devices.
This paper introduces the concept of Active Flow
Manipulation for identifying and affecting traffic
flows of interest in silicon-based high-speed network
nodes. It also introduces the Openet open
programmable platform and its mechanisms that can
dynamically enable programmed services in the
control plane. Finally it demonstrates the use of AFM
mechanism with the Openet infrastructure through
several experimental applications.
The remainder of the paper is organized as
follows. Section 2 introduces the mechanism of
Active Flow Manipulation to enable actual network
control in real-time. Section 3 introduces the Openet
architecture, and its mechanisms for dynamic service
deployment. Section 4 presents four AFM
applications that are developed through the Openet
programmability. Section 5 gives a brief review of
related work. Finally, the paper concludes with future