Introduction To Bootp Client - Huawei Quidway S3100 Series Operation Manual

Operation Manual – Management VLAN
Quidway S3100 Series Ethernet Switches
Acknowledgement. Upon receiving the DHCP_Request packet, the DHCP server
that owns the IP address the DHCP_Request packet carries sends a DHCP_ACK
packet to the DHCP client. In this way, the DHCP client binds TCP/IP protocol
components to its network adapter.
IP addresses offered by other DHCP servers (if any) through DHCP_Offer packets
but not selected by the DHCP client are still available for other clients.
2) The DHCP client accesses the network for the second time
In this case, the DHCP client establishes connections with the DHCP server through
the following steps.
After accessing the network successfully for the first time, the DHCP client can
access the network again by broadcasting a DHCP_Request packet that contains
the IP address assigned to it last time instead of a DHCP_Discover packet.
Upon receiving the DHCP_Request packet and, when the IP address applied by
the client is available, the DHCP server that owns the IP address responds with a
DHCP_ACK packet to enable the DHCP client to use the IP address again.
If the IP address is not available (for example, it is assigned to another DHCP
client), the DHCP server responds with a DHCP_NAK packet, which enables the
DHCP client to request for a new IP address by sending a DHCP_Discover packet
once again.
3) The DHCP client extends the lease of an IP address
IP addresses assigned dynamically are only valid for a specified period of time and the
DHCP servers reclaim their assigned IP addresses at the expiration of these periods.
Therefore, the DHCP client must be able to extend the period if it is to use a
dynamically assigned IP address for a period longer than allowed.
By default, a DHCP client updates its IP address lease automatically by sending
DHCP_Request packets to the DHCP server when half of the specified period expires.
The DHCP server, in turn, responds with a DHCP_ACK packet to notify the DHCP
client of the new lease if the IP address is still available. The DHCP clients implemented
by the switches support this lease auto-update process.

2.2 Introduction to BOOTP Client

A BOOTP client can request the server for an IP address through BOOTP. It goes
through the following two phases to apply for an IP address.
Sending a BOOTP request packet to the server
Processing the BOOTP response packet received from the server
To obtain an IP address through BOOTP, a BOOTP client first sends a BOOTP request
packet to the server. Upon receiving the request packet, the server returns a BOOTP
response packet. The BOOTP client then retrieves the assigned IP address from the
response packet.
Huawei Technologies Proprietary
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Chapter 2 DHCP/BOOTP Client Configuration