Browse Prior Art Database

Network Connect Detection Using Alert-on-LAN

IP.com Disclosure Number: IPCOM000013279D
Original Publication Date: 1999-Nov-01
Included in the Prior Art Database: 2003-Jun-18
Document File: 1 page(s) / 38K

Publishing Venue

IBM

Related People

Eric Kern: AUTHOR [+5]

Abstract

Power on Self Test software installed on all computer systems are increasingly asked to do more tasks in a shorter amount of time. One of these tasks is the retrieval and display of a network interface card's (NIC's) MAC address. This address is obtained from a function call to the NIC. The problem arises when a system is not connected to a network. According to a strict interpretation of the MAC address specification, the NIC needs to be connected to the network in order to respond with a valid MAC address. There are some NICs that do not adhere so strictly to the specification and return the MAC address whether or not they are connected, however, we have run into some specific examples of cards that do respond strictly to the specification. This may not seem like a problem until you consider that a NIC will not know that it is not connected to a LAN until twenty seconds has elapsed without a response. Waiting twenty seconds for the MAC address during POST while the total POST time is suposed to be less then thirty seconds is not an acceptable solution. What is needed is a way of knowing whether or not we are physically connected to a LAN before we ask for the MAC address. This new invention utilizes the Alert-on-LAN in a manner that it was never intentionally meant to run. Additionally, no hardware change is required for this invention to be implemented. When sending an AoL packet, the status registers indicate whether or not the packet has been sent. In order for the status bit to clear, the packet has to be sent and received by a server. If the system is not connected to the network, the status will never clear. We can use this status bit to reduce the amount of time it takes to detect the presence of a network. By sending a broadcast packet across the network, the first system that receives the packet will respond and cause the send bit to clear. We can set the time-out time to a more reasonable value. With this method it is estimated that we can reduce the network not present time from 20 seconds down to about 2 seconds. A 10x Savings in POST time! 1

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Network Connect Detection Using Alert-on-LAN

Power on Self Test software installed on all computer systems are increasingly asked to do more tasks in a shorter amount of time. One of these tasks is the retrieval and display of a network interface card's (NIC's) MAC address. This address is obtained from a function call to the NIC. The problem arises when a system is not connected to a network. According to a strict interpretation of the MAC address specification, the NIC needs to be connected to the network in order to respond with a valid MAC address. There are some NICs that do not adhere so strictly to the specification and return the MAC address whether or not they are connected, however, we have run into some specific examples of cards that do respond strictly to the specification. This may not seem like a problem until you consider that a NIC will not know that it is not connected to a LAN until twenty seconds has elapsed without a response. Waiting twenty seconds for the MAC address during POST while the total POST time is suposed to be less then thirty seconds is not an acceptable solution. What is needed is a way of knowing whether or not we are physically connected to a LAN before we ask for the MAC address.

This new invention utilizes the Alert-on-LAN in a manner that it was never intentionally meant to run. Additionally, no hardware change is required for this invention to be implemented. When sending an AoL packet, the status registers indicate wheth...