Shulou(Shulou.com)06/01 Report--

Today, I will talk to you about how to analyze the process of obtaining dhcp IP. Many people may not know much about it. In order to make you understand better, the editor has summarized the following contents for you. I hope you can get something from this article.

The editor will take cirros-vm1 as an example to analyze the detailed process of obtaining DHCP IP.

When you create an instance, Neutron assigns it a port that contains MAC and IP address information. This information is updated synchronously to dnsmasq's host file.

At the same time, nova-compute sets the MAC address of cirros-vm1 VIF.

When everything is ready, the process for instance to obtain IP is as follows:

The cirros-vm1 starts up and sends out DHCPDISCOVER broadcasts, which can be received throughout the flat_net.

The broadcast reaches the veth tap19a0ed3d-fe and is then transmitted to the ns-19a0ed3d-fe on the other side of the veth pair. Dnsmasq listens on it, and dnsmasq checks its host file and finds a counterpart, so dnsmasq sends IP (172.16.1.103), subnet mask (255.255.255.0), address lease period and other information to cirros-vm1 with DHCPOFFER message.

Cirros-vm1 sends a DHCPREQUEST message confirming the acceptance of this DHCPOFFER.

Dnsmasq sends the confirmation message DHCPACK, and the whole process ends.

This process can be viewed in the dnsmasq log. Dnsmasq logs to / var/log/syslog by default.

After reading the above, do you have any further understanding of how to analyze the process of obtaining dhcp IP? If you want to know more knowledge or related content, please follow the industry information channel, thank you for your support.

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