we have switch acting as L2 switch connected with PC , when the pc boot using PXE echnology the boot failed, when we connect IP-phone between the switch and the PC the Boot works fine.. how ever on the network on another IDF when PC connected directly to the switch boot is ok we checked both ports configuration and it was identical.
First of all we need to know what PXE is and what is needed from our Switch
Pre-boot Execution Environment (PXE) is a protocol designed by Intel. It enables a computer to boot over a network. The PXE client is located in the ROM of the network adapter. When the computer boots, the BIOS invokes the PXE client to the memory and displays the command menu. After the user selects the PXE client, the PXE client is downloaded to the local computer through the network.
The following two problems need to be solved for the successful running of the PXE protocol:
1. Who configures the IP address of the computer when the computer is started?
2. Which protocol is used to download the Linux kernel and root file system?
A The DHCP server is used to dynamically allocate IP addresses to the PXE client. However, the DHCP server assigns IP addresses to the PXE client. Therefore, when configuring the DHCP server, PXE-specific configurations need to be added.
B For the second problem, the TFTP client already exists in the ROM where the PXE client resides. The PXE client uses the TFTP client to download required files from the TFTP server.
According to the preceding principles, the PXE can work properly only when the following conditions are met:
1. Obtain the correct IP address. -------- We can obtain a normal IP address regardless of whether we are directly connected or connected through an IP phone. Therefore, we can ignore this problem.
Compare the configurations of the two switches. The two switches are used as Layer 2 devices and have no special configuration with working switch.
2. Download the correct IP address from the server through TFTP.------- we can capture packets to check whether the files obtained by the PXE client are correct.
2.1、working PC without ip phone------request undionly.kpxe
2.2、not working PC without ip phone------request x86PC\UNDI\BStrap\BStrap.0
PXE server configuration
The comparison shows that the files requested by the normal PC are different from those requested by the abnormal PC. Therefore, the normal PC can work only when the undionly.kpxe file is requested.
this confirm that issue not from the switch but from the PXE server itself after which not related to network device[switch]
checking the packet captuer to confirm if switch working as expected or not