Browse Prior Art Database

Universal HA Link Manager

IP.com Disclosure Number: IPCOM000032603D
Original Publication Date: 2004-Nov-08
Included in the Prior Art Database: 2004-Nov-08
Document File: 2 page(s) / 28K

Publishing Venue

IBM

Abstract

Published is a realtime network link status monitor mechanism. Since lots of network problem are due to the disconnection of the directly connected path from the host to switches or another host, we provide a solution to monitor the connection status of the network interface card and signal the high layer applications upon the connection status changes.

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Universal HA Link Manager

Normally, if a network distributed application cares for the connectivity between peer nodes, it will periodically send out heartbeat message to peers. The lack of the receiving heartbeat messages during a certain period of time is considered a disconnection. In order to acquire prompt awareness of the disconnection, the heartbeat messages must be transferred at a very high frequency, which consumes a lot of system resources. Even so, the application still won't know the disconnection until the threshold of missing heartbeat messages are reached, thus it is still not real time.

Working infrastructure

Since lots of disconnection happens in the directly connected network path of the host where the application is running, a solution to real timely monitor the direct connection part of the network will greatly relieve the burden of the high layer applications. Our invention performs this task by taking the advantage of the ndd_flags field in network adapter's structure ndd in the AIX kernel space, which will be updated promptly once the network device driver finds the disconnection happens in the link layer. The same functional field in Linux is iff_flags , and maybe the same or different attribute name in other flavor of UNIX, which our invention is applicable too.

The ndd_flags field value will be changed immediately after the device driver detects a link status change, and the kernel allows developers to register a callback function to handle with each link status change upon each time the value of ndd_flags changes. In our invention, the callback function will wake up a network monitor daemon which is in sleep mode most of the time. When the network link status is good, the deamon only wakes up in each 15 or 30 minutes to do a routine check of the system to make sure the protocol stack and...