Current network devices enable connectivity between end systems given a set of protocol software bundled with vendor hardware. It is impossible for customers to add software functionality running locally on top of network devices to augment vendor software. Our vision is to open network devices so that customized software can be downloaded, allowing for more flexibility and with a focus on industry and customer specific solutions. This brings considerable value to the customer. We have chosen to use Java because we can reuse its security mechanism and dynamically download software. We can isolate the Java VM and downloaded Java programs from the core router functionality. We implemented Java Virtual Machines (JVMs) on a family of network devices, implemented an Open Services framework, and developed an SNMP MIB API and a Network API upon which we can demonstate the value of openness and programmability of network devices.

1. Tal Lavian August , 1999_ Hot Interconnects, Stanford
1 Open Programmable Architecture for Java-enabled Network Devices Page 1
Open Programmable Architecture
for Java-enabled Network Devices
Tal Lavian, Nortel Networks - Advanced Technology Center
Robert F. Jaeger, University of Maryland
Jeffrey K. Hollingsworth, University of Maryland
Keywords: Open Architecture, Programmable Networks, Java-enabled Networking,
JVM, Active Networks, Mobile Agents, Intelligent Agents.
1 Overview
Current network devices enable connectivity between end systems given a set of protocol
software bundled with vendor hardware. It is impossible for customers to add software
functionality running locally on top of network devices to augment vendor software. Our
vision is to open network devices so that customized software can be downloaded,
allowing for more flexibility and with a focus on industry and customer specific
solutions. This brings considerable value to the customer.
We have chosen to use Java because we can reuse its security mechanism and
dynamically download software. We can isolate the Java VM and downloaded Java
programs from the core router functionality.
We implemented Java Virtual Machines (JVMs) on a family of network devices,
implemented an Open Services framework, and developed an SNMP MIB API and a
Network API upon which we can demonstate the value of openness and programmability
of network devices.
2 Open Network Services
2.1 New Programmable Paradigm
We are entering a new era where servers, switches, and routers are participating in
applications. The IEEE P1520 recognized the need for a software infrastructure for
programming networks and has initiatives which propose standard APIs to networking
devices. [28-29].
Programmable network technology allows dynamic downloading of software programs to
network devices and moving intelligence to these devices. Downloading software
enables customized application level computational interconnectivity between servers
and network devices as well as among network devices. Programmable networks is an
enabling technology for a new type of distributed applications that are not technically
possible today.

2. Tal Lavian August , 1999_ Hot Interconnects, Stanford
1 Open Programmable Architecture for Java-enabled Network Devices Page 2
2.2 PC-ifications of Programmable Devices
In network devices like switches and routers, the software and the hardware are bundled
and not openly programmable. We have created an Open Service Architecture that allows
dynamic downloading of programs to theses devices.
Our vision is that network devices will be open like software for PCs. For example, we
buy software and hardware for PCs from different vendors, and then we install and
customize the software on the computer. Network devices like switches and routers are
also computers of a different type. We have implemented programmability
characteristics on these types of computers like the PCs so that additional functionality
can be provided to these devices.
2.3 Enabling Technology
Now, we are able to securely download and run Java applications on network devices.
We can distribute the intelligence to network devices for close-loop interaction on the
nodes. This allows for new types of applications that were not possible until now because
of scalability issues.
We have implemented technology that allows for a class of downloadable applications
which are not bundled with the vendor hardware including enhanced multicast services,
application level filtering, and mobile/intelligent agents [4] [13] [17]. The platform
supports the Active Networking reference architecture upon which multiple non-
interfering Execution Environments can run concurrently [2-7] [9] [12] [14-18] [25].
Operating systems for computers have recently been developed to allow user
customization of services and policies. Exokernel[1]] and Spin[8] provide new kernel
architectures to support safety and extensibility.
2.4 Static Agent vs. Dynamic Agents
Usually, we are managing network devices via “get” and “set”, as static requests to
SNMP agents. Having a dynamic agent on the device opens us to a new set of
applications. Instead of external SNMP requests, we can download software that use
SNMP calls via an internal device loop.
The direction is to open network devices to 3rd
party developers. To facilitate this, we
have created an Open Service Interface[26] using Java with additional security
mechanisms. The interface opens the network devices to 3rd
party vendors and allow
other domain experts to add value to network devices.
Java has taken the computer world by storm. However, it is mainly used by client s and
servers for browser and business applications. Until now, Java did not run on the network
devices.

3. Tal Lavian August , 1999_ Hot Interconnects, Stanford
1 Open Programmable Architecture for Java-enabled Network Devices Page 3
2.5 New type of Applications
We can add value to network infrastructure by allowing tight code interaction between
business applications and network devices. This new paradigm allows a new type of
distributed applications between servers and swiches/routers. All software in the
applications can be dynamically loaded on to the servers and network devices.
2.6 Domain Experts
Domain experts that work closely with customers know the problems the customer faces
and may bring ideas from other business domains to the development of solutions.
Allowing 3rd
party experts to write custom applications allows for innovative solutions to
customer business requirements.
2.7 Feature-on-demand
Java beans with specific plug-in features can be developed and released quickly
providing feature-on-demand capability to address changing customer needs. This
approach circumvents the need for vendor support to add customer desired capabilities to
network devices and avoids the need for the customer to wait for new features from the
vendor in order to realize capabilities. Also, features can be ported quickly to other
products implementing the Open Service Interface.
3 Open Architecture
3.1 What have we implemented?
We have implemented JVMs on the Nortel Networks Routing and L3 Routing Switch
family of products. We can securely download and safely run Java applications on these
devices and access native code running on these devices [1]. We developed an
architecture that allows for downloading of new code to implement desired features. We
developed several APIs including an SNMP API and a Network API. The SNMP API
allows reading and writing of MIB variables [27]. The Network API allows Java
applications to control the hardware based forwarding and selection of packets to be
delivered to Java applications based on packet signatures. Consequently, our network
devices are programmable allowing for customers to safely run dynamically downloaded
Java code to realize additional functionality.
3.2 Scalability
Network Management via SNMP suffers scalability in applications with massive close-
loop interactions. For example, assume an NMS application that monitors some network
device parameters. Lets assume that we want to gather information on 10 parameters per
port on a device with 100 ports and we want to sample 100 times per second. These
types of applications are not practical in the current SNMP model of centralized
management.
Current technology like RMON provides an interface to allow network devices to collect
statistics locally. It is restricted to a set of predefined types of data that can be collected
and it does not address the scalability problem.

4. Tal Lavian August , 1999_ Hot Interconnects, Stanford
1 Open Programmable Architecture for Java-enabled Network Devices Page 4
We overcome these limitations in our distributed intelligence approach. The data
samples are local calls with no need for SNMP call for each sample. The NMS will be
notified only when needed based on thresholds or trends. This allows an intelligent event
notification mechanism rather than a polling mechanism.
3.3 Security
Computer networks have become vital to businesses. It is critical that the network
functions properly and a loss of operation is not tolerable. To allow the openness that we
are proposing, we needed to implement a strong security architecture. Security is a key
component of the Open Service Interface architecture. It includes security for
downloadable applications and for the device’s code interface. In addition to the Java
language security features, the architecture provides additional security including digital
signatures and code certification.
3.4 The JVM
Implementing a JVM for embedded and real-time environments presents several
challenges. Such environments are especially concerned with reliability, determinism,
and restricted memory. It is also crucially important that new Java programs must work
without disturbing the existing non-Java functionality.
Our JVM design satisfies these requirements by encapsulating the JVM into one
framework. This JVM manages the Java threads and their memory usage within this
framework and presents one unified task to the RTOS. The Open Services Architecture
was designed to insulate core router functionality from Java and JVM failures. Even if
the JVM crashes, the router remains operational.
3.5 But Java is SLOW
Java has often been criticized for its speed and its use in a routing device has been
questioned. With the advent of ASIC technology for fast path data forwarding engines
that achieve Gigabit forwarding rates, no serious routing platform is based on a software
forwarding engine. An active network platform that touches all network packets is
doomed to fail. However, control and management applications are well suited for Java
based network services locally on the network device as well as active applications which
don't require high packet per second rates to operate.
3.6 Java MIB API
The goal is to provide an interface that transparently gives access to the SNMP data,
while hiding the SNMP machinery of PDUs, object identifiers and table iterations. The
MIB gives a fairly object-oriented model to the data, which fits quite naturally onto Java
class decomposition.
The MIB is structured as a collection of groups, with each group containing a number of
variables. Each group is modeled as a Java class, and each variable is modeled with
accessory methods.

5. Tal Lavian August , 1999_ Hot Interconnects, Stanford
1 Open Programmable Architecture for Java-enabled Network Devices Page 5
3.7 Inter-operating with SNMP MIB Compiler
There are a large number of variables in the MIB and it is tedious and error prone to
generate the Java bindings for them all by hand. To automate the binding, we provide a
MIB compiler that takes the standard ASN.1 textual representation of the MIB and
generates the necessary Java code. This approach is similar to other mibgen tools and
results in a Java API which represents the MIB tree. Javadoc pages document the Java
MIB API that results from the input MIB definition.
An incremental strategy for MIB variable access is the result of this research. MIB
variables are queried and set by constructing SNMP PDUs that are sent to the loopback
interface of the device and delivered to the underlying SNMP stack. This approach
allows us to evolve from the loopback strategy by incrementally adding direct low-level
implementations of selected time-critical methods.
4 Applications Examples
4.1 Close-loop Applications
Creating a closed-loop mechanism on the device itself allows for the development of
tight local management applications. We can develop applications utilizing tight
interactions with the traffic pattern and the device capabilities. We can move some of the
intelligence of NMS and policy servers to the network devices. This allows for new types
of applications that are not feasible with centralized management schemes.
4.2 Example 1: Interactions with Business Applications
Currently, business applications are running on servers and networking applications are
running separately on network devices. There is very limited interconnection at the
application level. Downloading and running Java applications on network devices
enables collaborations between network devices and applications running on other
servers. Business applications can take advantage of distributed computing in an
environment consisting of applications running on network devices which leverage the
local-loop directly on the device. For instance, an electronic auctioning service can use
routers to filter bids which are no longer acceptable given that the bid price has already
been surpassed [10]. Another application can dynamically configure the output priority
queues on the network device as part of the application needs.
4.3 Example 2: Interactions with other network devices
Currently, network devices interact using a pre-defined set of protocols bundled with the
hardware. There are no interactions or sharing variables that is not within the confines of
bundled vendor software. In the Open Service Interface architecture, network devices
can run non-bundled distributed applications that interact at the application layer with
applications running on other devices. For example, a community of routers can make a
dynamic configuration decision based on bottlenecks or load. The decision making
process can be done as part of a distributed application within this community.

6. Tal Lavian August , 1999_ Hot Interconnects, Stanford
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4.4 Example 3: Mobile Agents
The architecture provides a platform for mobile agent technology. Mobile agents to
perform information gathering such as L2 connectivity or traceroute are made possible
through the Network API. The mobile agent performs some work on the local device
and moves to the next device to continue the work. For example, roaming diagnostic
agents can gather performance information along the path from a client to the server. This
mobile agent can identify and even solve problems along the network path.
4.5 Example 4: Active Networks
By developing an Open Services Interface, we provide a platform upon which Active
Networking Execution Environments (EEs) can be hosted. We allow for running Java-
based EEs as services on the router that can host active applications downloaded in the
Active Network Encapsulation Protocol for distribution to EEs.
4.6 Example 4: Local QoS implementation
Instead of configuring the QoS mechanisms from remote station, we can do it locally on
the network device. For example, we can monitor locally the traffic patterns and
configure the QoS parameters based on policy that is pushed to the device as an
application.
5 Conclusion
We are entering a new era where servers, switches, and routers participate in networking
applications. This is a powerful new technology that enables dynamic downloading of
end-user applications. We provide an open set of network services upon which new
applications can be built to customize the behavior of network devices as well as
management networks. We provide tools to developers enabling them to use their
domain expertise to create solutions to specific business challenges. Introducing domain
expertise into the development process creates a virtual community of developers that can
bring innovation to networking customers.
The Nortel Open Service Interface functional prototype implements this enabling-
technology which is the foundation of this paradigm shift. The ability to download
dynamic agents to network devices is much more powerful than the current use of static
agents. Dynamic program loading into the switching and routing elements of a network
bring new opportunities for configuring and managing large, complex, and high
performance networks. Pushing intelligence into the network elements themselves solves
the scalability problems inherent in a centrally managed network.
6 References
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7. Tal Lavian August , 1999_ Hot Interconnects, Stanford
1 Open Programmable Architecture for Java-enabled Network Devices Page 7
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