Virtual routers open up new services

New developments in equipment used to build backbone IP networks, especially the emergence of virtual backbone routing, are setting the stage for a complete shift in the distribution of Internet services.

Virtual routers will enable new Internet services that are isolated from other network users and provide control over network performance, Internet address and routing administration, management and security.

Virtual backbone routers logically subdivide a physical router into multiple virtual routers. Each virtual router runs a separate instance of the routing protocols and has dedicated I/O ports, buffer memory, address space, route table and network management software.

A service based on virtual backbone routers gives the client the control and security of running a private backbone network, without the capital expense.

The software that controls and manages the virtual routing capability is modular; multiple instances of the software (for multiple virtual routers) are executed on a true multiprocess operating system, such as Unix.

Each virtual router's processes are isolated and protected from others using the process and memory protection capabilities inherent in the operating system. This ensures a high level of data security and eliminates the possibility of a faulty software module corrupting the data on another virtual router.

The packet-forwarding functions of many carrier-class routers are implemented in hardware to achieve wire-speed performance when connected to high-speed SONET/Synchronous Digital Hierarchy interfaces. In a system with virtual routing capability, these hardware functions can be logically subdivided and flexibly assigned to a particular virtual router.

The physical I/O ports or label switched paths on which packets are received or transmitted are put under the control of the software modules that comprise a virtual router. Packet buffer memory and forwarding tables are subject to per-virtual-router resource limits to ensure that no virtual router can impact the operation of another.

Virtual routing technology lets each virtual router execute separate instances of the routing protocol software (for example, Open Shortest Path First, Border Gateway Protocol, Intermediate System to Intermediate System) and network management software (for example, SNMP or command line interface). Thus, each virtual router can be independently monitored and managed by the user.

The separate protocol instances give each virtual router a completely separate IP address domain that can be independently configured without the risk of conflict. The management functions let each virtual router be configured and managed as a separate and independent entity. A user-based security model also ensures that all network management functions and information that pertains to a particular virtual router are accessible only to those given access privileges.

Each virtual router's packet forwarding path is isolated from the other, enabling administrators to engineer the performance of each virtual router separately and independently. Large traffic bursts flowing across one virtual router in the system will not affect others. This ensures that end users of this service receive consistent network performance.

Virtual routers also offer independent policing and Internet Engineering Task Force Differentiated Services capabilities, letting the virtual router deliver completely customized services to end users. The I/O ports assigned to each virtual router can be programmed to count arriving packets and ensure they do not exceed a prespecified contract. Packets are then sorted into multiple queues according to their service class.

As virtual routing capability becomes more pervasive in the backbone network, its ability to dynamically provision exact end-user bandwidth needs, while offering maximum end-user control and management of that bandwidth, will spawn a host of competitively priced, highly customized IP services. These services will dramatically reshape the way providers and customers perceive the world of purchased bandwidth.

Blume is director of product marketing at IronBridge Networks. He can be reached at cblume@ironbridge networks.com.