INDUSTRY

Chiaro Networks, developer of true infrastructure-class IP/MPLS routing platforms, has recently been assigned three patents that together contribute to the industry-leading high availability (HA) capabilities of Chiaro's Enstara core router platform. Specifically, the patents provide improvements in the operation of IP routers under network and equipment failure scenarios, minimize the disruption to peer routers during faults, and minimize the cost of providing protection resources to accomplish these improvements. "Patents like this are important because they help establish credibility for a technology company, providing evidence of innovation to support claims of technological and product advantages," said John Marcus, senior analyst at Current Analysis. "In this case, Chiaro's recent patents reinforce the validity of the high-availability claims offered for the Enstara platform." Background on the Patents Current IP router protection depends on re-routing and converging routing tables as quickly and efficiently as possible any time failures occur. Unfortunately, these convergence events can take tens of minutes in certain cases -- which in a communications network is unacceptably long. The Chiaro patents describe technologies that provide redundancy to the router peering session, so that failures within a router are more completely transparent to the IP network. The result is that lengthy convergence times are eliminated for many classes of network faults. In addition, the technologies enabled by the patents work to reduce or eliminate the "bow-wave" effect that happens when a large number of router additions and withdrawals creep across the network in response to an equipment fault. Reducing this bow-wave effect leads to better stability and performance of the entire IP network. "These patents vividly demonstrate the technological underpinnings of the Enstara platform's high-availability capabilities," said Tom McDermott, vice president of technology of Chiaro Networks. "The Chiaro Enstara router fully interoperates with existing IETF (Internet Engineering Task Force) standards designed to enhance IP networks -- such as graceful restart and non-stop forwarding -- but this platform goes further still in providing better fault tolerance and recovery in a manner completely transparent to existing IP routers and networks. These capabilities form a big part of the 'infrastructure-class' nature of the Enstara platform." Also in the Enstara platform, router blade protection switching is fully interoperable with the IETF Fast Reroute standards, providing network operators with additional, cost-effective methods for protecting against facility failures. Details of the Patents: Abstracts from the U.S. Patent Office Patent 6,876,657 -- System and Method for Router Packet Control and Ordering: Hardware interconnected around multiple packet forwarding engines prepends sequence numbers to packets going into multiple forwarding engines through parallel paths. After processing by the multiple forwarding engines, packets are reordered using queues and a packet ordering mechanism, such that the sequence numbers are put back into their original prepended order. Exception packets flowing through the forwarding engines do not follow a conventional fast path, but are processed off-line and emerge from the forwarding engines out of order relative to fast path packets. These exception packets are marked, such that after they exit the forwarding engines, they are ordered among themselves independent of conventional fast path packets. Viewed externally, all exception packets are ordered across all multiple forwarding engines independent of the fast path packets. Patent 6,853,617 -- System and Method for TCP Connection Protection Switching: If an active router Master Control Processor (MCP) fails, a backup MCP switches over without interrupting peer network router connections, because all previously established connection parameters are replicated on both MCPs. Once the MCP programs line cards, the packet forwarding modules and embedded system function without further involvement of the MCP until the next programming update. Messages flow through the backup MCP and then through the active MCP, which outputs messages through the backup MCP. Thus the backup MCP captures state changes before and after the active MCP. Both MCPs maintain replicated queues in which they store replicated messages awaiting processing or retransmission. If acknowledgment of receiving a transmitted message is received from a destination peer router, that message is deleted from both MCPs. If acknowledgment is not received within a predetermined interval, the stored message is retransmitted. Message splicing prevents lost and partially transmitted messages during and after switchovers. Patent 6,879,559 -- Router Line Card Protection Using One-for-N Redundancy: Router line cards are partitioned, separating packet forwarding from external or internal interfaces and enabling multiple line cards to access any set of external or internal data paths. Any failed working line card can be switchably replaced by another line card. In particular, a serial bus structure on the interface side interconnects any interface port within a protection group with a protect line card for that group. Incremental capacity allows the protect line card to perform packet forward functions. Logical mapping of line card addressing and identification provides locally managed protection switching of a line card that is transparent to other router line cards and to all peer routers. One-for-N protection ratios, where N is some integer greater than two, can be achieved economically, yet provide sufficient capacity with acceptable protection switch time under 100 milliseconds. Alternatively, protect line cards can routinely carry low priority traffic that is interruptible, allowing the protect line card to handle higher priority traffic previously carried by a failed working line card. This approach renders unnecessary engineering a network for less than full capacity to allow rerouting in the event of individual line card failure. Consequently, all data paths can be fully utilized. If a particular interface module on one data bus needs removal for maintenance, a duplicate data bus is available intact, allowing hot replacement of any working or protect interface module, even while a line card protection switch is in effect.