In this paper, we present five case studies of advanced networking functions that detail how a network processor (NP) can provide high performance and also the necessary flexibility compared with Application-Specific Integrated Circuits (ASICs). We first review the basic NP system architectures, and describe the IBM PowerNP architecture from a data-plane as well as from a control-plane point of view. We introduce models for the programmer's views of NPs that facilitate a global understanding of NP software programming. Then, for each case study, we present results from prototypes as well as general considerations that apply to a wider range of system architectures. Specifically, we investigate the suitability of NPs for Quality of Service (active queue management and traffic engineering), header processing (GPRS tunneling protocol), intelligent forwarding (load balancing without flow disruption), payload processing (code interpretation and just-in-time compilation in active networks), and protocol stack termination (SCTP). Finally, we summarize the key features as revealed by each case study, and conclude with remarks on the future of NPs.
Abstract. Network processors have been developed to ease the implementation of new network protocols in high-speed routers. Being embedded in network interface cards, they enable extended packet processing at link speed as is required, for instance, for active network nodes. Active network nodes start using network processors for extended packet processing close to the link. The control and configuration of high-performance active network nodes with network processors such that new services can benefit from the additional processing capacity offered is nontrivial since the complexity to configure a node while providing sufficient level of abstraction is hard to master. In this paper, we present PromethOS NP which is a modular and flexible router architecture that provides a framework for dynamic service extension by plugins with integrated support of network processors, namely the IBM PowerNP 4GS3 network processor. We briefly introduce the PowerNP architecture in order to show how our active networking framework maps onto this network processor and provide results from performance measurements. Owing to architectural similarities of network processors, we believe that our considerations are also valid for other network processors.
This paper presents the elements of a framework enabling QoS-aware service deployment over programmable heterogeneous networks. For ease of service deployment, it is expected that network management tools will require the network itself to participate in this task so as to be able to scale to very large numbers of network elements, with widely varying programmability levels. Three categories of service deployment are considered, namely services spanning along paths in the network, services involving only selected nodes, and combinations of both. The underlying hierarchical structure and the representation of capabilities used by the mechanism to deploy new services into a network automatically are presented. A formal description of the mechanism based on a Gather-Compute-Scatter paradigm is introduced and then illustrated by examples of all three service-deployment categories.
No abstract
Proxy-PAR is a minimal version of PAR (PNNI Augmented Routing) that gives ATM-attached devices the ability to interact with PNNI devices without the necessity to fully support PAR. Proxy-PAR is designed as a client/server interaction, of which the client side is much simpler than the server side to allow fast implementation and deployment.The purpose of Proxy-PAR is to allow non-ATM devices to use the flooding mechanisms provided by PNNI for registration and automatic discovery of services offered by ATM attached devices. The first version of PAR primarily addresses protocols available in IPv4. But it also contains a generic interface to access the flooding of PNNI. In addition, Proxy-PAR-capable servers provide filtering based on VPN IDs [1], IP protocols and address prefixes. This enables, for instance, routers in a certain VPN running OSPF to find OSPF neighbors on the same subnet. The protocol is built using a registration/query approach where devices can register their services and query for services and protocols registered by other clients.
For the implementation of multipoint-to-point connections in ATM, various approaches exist, each with its own advantages and disadvantages. VP-based methods require unique sender identification but they do not require reassembly in merging points. In contrast, VC-based methods do not require unique sender identification but they do require reassembly in. merging points. It is likely that VC merging will be the method of choice as it is scalable and yet relatively simple to implement. One of its drawbacks is the increased output buffer space required at the switches because of packet reassembly at the merging points. This paper investigates the impact of the switch architecture and characteristics on the output buffer space by means of simulation. The results obtained demonstrate that for typical switch architectures, VC merging does not require significant additional buffering compared to VP merging.
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