Juniper Networks, Inc.

Paul Howard

Paul Raison

John Gibbons

Margaret Zielinski

A network device includes a primary control unit that establishes a network tunnel with another network device. The network device applies a silent failover technique to failover from the primary control unit to a backup control unit while maintaining the network tunnel. The network tunnel may be, for example, a Layer 2 Tunneling Protocol (L2TP) tunnel, and the network device may be an L2TP Access Concentrator (LAC) or an L2TP Network Server (LNS). The techniques may prevent abnormal termination of the network tunnel during the failover. Once the failover from the primary control unit to the backup control unit is complete, the backup control unit synchronizes sequence numbers associated with the network tunnel with sequence numbers of the non-failed network device, and resolves inconsistencies between subscriber session databases of the backup control unit and the non-failed network device.

Silent failover from a primary control unit to a backup control unit of a network device

A network access device is described that uses a modified lower layer two (L2) software interface that is enhanced to operate as a proxy for a dynamic upper L2 software interface when the upper L2 software interface has been torn down, i.e., terminated unbeknownst to a subscriber device. The lower L2 software interface may, for example, be extended to incorporate certain features of the upper L2 software interface to detect such a condition. In the absence of the upper L2 software interface, the lower L2 interface may output a simulated termination request on behalf of the upper L2 interface and in accordance with the upper L2 protocol.

Termination of network connections in absence of a dynamic network interface

Techniques are described for load balancing subscriber sessions across tunnel termination devices. A network device is described, for example, that includes a tunneling module that load balances subscriber sessions across a plurality of tunnel termination devices based on weightings associated with the tunnel termination devices. The weightings may be assigned to the tunnel termination devices by a user, or may be calculated by the network device based on resource constraints associated with the tunnel termination devices. The network device may calculate the weightings, for example, based on a maximum number of subscriber sessions supported by each of the tunnel termination devices. As one example, the techniques may be applied to load balance Point-to-Point (PPP) subscriber sessions across L2TP Network Servers (LNSs).

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Windham, NH, United States of America

Paul Howard