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Up Controllable Layer 2 Failover (UCL2F) Disclosure Number: IPCOM000235746D
Publication Date: 2014-Mar-25
Document File: 4 page(s) / 120K

Publishing Venue

The Prior Art Database


This article presents a method to reduce the traffic failover time in the L2 failover environment. It delays the downlink traffic to go up to the uplink network until the uplink network is stable, by which, it can reduce the traffic lose for the uplink network is no stable.

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Page 01 of 4

Up Controllable Layer

Up Controllable Layer

222 Failover Failover Failover



In the current L2 failover, when the Monitor Ports are up, the Control Ports will be brought up immediately. Because the Monitor Ports are connected to uplink network, and control ports are connected to downlink network, in practical deployment, the uplink network (especially L3) connecting to the monitor ports which are just linked up are not stable because the protocols running on them need some time to negotiate and converge. If at this time the control ports are brought up, the downlink network traffic will come to the uplink network; but if the uplink network is not stable, then the traffic may be dropped, so the failover time will be long.

Figure 1 L2 Failover & Issue


Page 02 of 4

This disclosure is designed to solve this issue andprovides a loss-free L3 fabric network when provisioning L2 failover. This disclosure designs an Up Controllable L2 failover. (UCL2F)

This disclosure presents the Up Controllable Layer 2 Failover (UCL2F) to help users to solve the problem described in section one. UCL2F will make the L2F Control Ports link up later a time gap than the Monitor Ports. During this time gap, the protocols (OSPF, BGP ……) running on the corresponding uplink network will have enough time to negotiate and converge. When the gap timer expires, L2F Control Ports will be brought up. Then the downlink traffic will be no-drop running on the uplink network.

UCL2F provides L2 Failover the ability to prevent traffic loss when monitor ports failover.

It has two modes:

Timer waited UCL2 Failover

Users manually specify the link up delay up time, and then control ports will delay to linkup fo...