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HIGH AVAILABILITY FOR A LINK AGGREGATION GROUP (LAG) USING LINK AGGREGATION CONTROL PROTOCOL (LACP)

IP.com Disclosure Number: IPCOM000244863D
Publication Date: 2016-Jan-22
Document File: 8 page(s) / 176K

Publishing Venue

The IP.com Prior Art Database

Abstract

High availability systems and methods are described for LAGs using LACP without hardware assistance. State machines of the LACP standard (IEEE 802.3ad) are enhanced to handle restart Information. An RX state machine is modified to handle restart information sent in an LACP PDU frame to change the current while timer to a configurable value. Due to this, the LACP RX state machine does not expire when the far-end node is performing a warm restart. Reserved bytes in the LACP protocol are used to send NE restart information. The new byte is introduced in the LACP PDU frame which carries the restart information of the node going under warm restart. This information is used by LACP RX state machine at the far end to change the current while timer.

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HIGH AVAILABILITY FOR A LINK AGGREGATION GROUP (LAG) USING LINK AGGREGATION CONTROL PROTOCOL (LACP)

ABSTRACT

[0001]               High availability systems and methods are described for LAGs using LACP without hardware assistance.   State machines of the LACP standard (IEEE 802.3ad) are enhanced to handle restart Information.  An RX state machine is modified to handle restart information sent in an LACP PDU frame to change the current while timer to a configurable value.  Due to this, the LACP RX state machine does not expire when the far-end node is performing a warm restart.   Reserved bytes in the LACP protocol are used to send NE restart information.  The new byte is introduced in the LACP PDU frame which carries the restart information of the node going under warm restart.  This information is used by LACP RX state machine at the far end to change the current while timer.

BACKGROUND

[0002]               Link Aggregation and associated Link Aggregation Group (LAG) combine a number of physical ports together to make a single high-bandwidth data path, so as to implement the traffic load sharing among the member ports in the group and to enhance the connection reliability and provide higher, aggregate bandwidth.  Link Aggregation is defined in vendor-independent standards such as Link Aggregation Control Protocol (LACP) for Ethernet defined in IEEE 802.1AX and IEEE 802.1aq or the previous IEEE 802.3ad.

[0003]               Currently, high availably in Link Aggregation Control Protocol (LACP) uses hardware assistance via a Field Programmable Gate Array (FPGA) or Network Processing Unit (NPU).  For example, the following process can be used:

1.      An LACP controller programs an LACP session in hardware with a desired LACP Protocol Data Unit (PDU) frame. 

2.      Each port consumes one hardware resource.

3.      A hardware assist device keeps on sending LACP PDU frames even at a CONTROL PROCESSOR restart, i.e., a network element (NE) warm restart.

4.      Thus, during the warm restart of the system, the Link Aggregation Group (LAG)remains UP and operational.

[0004]               Devices that do not employ any hardware assist functionality face timeout LACP LAG during a warm restart.  Another alternative is to use a static/manual LAG that does not require the LACP protocol to run.  However, this has limitations that it cannot exchange its capabilities with a partner since no LACP is running.  Accordingly, this approach is not widely deployed.

[0005]               Thus, present hardware assist implementations consume extra hardware resources which can be spared for any other critical applications.  If the number of ports increases, then the number of hardware sessions required for the LAG would increase, increasing the overall cost.  Also, hardware assist may not be used for high availability in Network Functions Virtualization (NFV) as it has a high dependency on hardware.  If there is no hardware assist, then a timeout LACP may occur, and the LAG goes down and is unable to carry traffic.

DETAILED DESCRIPTION

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