Browse Prior Art Database

Dynamic Detection of Interface Link Status

IP.com Disclosure Number: IPCOM000012067D
Original Publication Date: 2003-Apr-04
Included in the Prior Art Database: 2003-Apr-04
Document File: 1 page(s) / 36K

Publishing Venue

IBM

Abstract

Most operating systems today define a network interface in software that corresponds to a physical Network Interface Card (NIC). It often happens that the link to which the NIC is connected may become inoperable (e.g. someone pulls out a network cable). Most applications do not detect this problem even though the NIC driver is aware that the link status is no longer "available." Applications continue to send packets on the software interface for sometime before realizing that they are not receiving a response. This document proposes a lightweight solution that allows the system to use existing information known by its network adapter to immediately inform upper layers and applications of this information, allowing them to adjust if possible.

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Dynamic Detection of Interface Link Status

The solution will have the NIC driver inform the network interface software that the link status is down (possibly temporarily). Using this information, the network interface marks itself as being unusable and marks all routes using that network interface as being unavailable. Applications will now be able to detect the link problem almost immediately and will use an alternate route through another interface if one is available, or stop sending packets unnecessarily if no alternate route is available. Also, if the interface comes back up at a later time, the network interface software will again be informed of this fact and applications may resume the use of this interface.

Unless the interface layer is informed of inoperable NICs, the application layer will continue to send packets to the interface layer and these packets would be silently dropped. The main advantage of this invention is that by notifying the interface layer that the NIC is no longer available, the application layer is immediately aware of the problem and can take appropriate measures.

Implementation Suggestions: The network interface software must register a callback function with the NIC drivers.

When the link status goes down, the callback function will be invoked by the NIC driver. This function will then proceed to mark the interface as unusable and also invalidate all routes in the network routing tables that use this interface. Any applications t...