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- DHCP (Dynamic Host Configuration Protocol) Examples
- ===================================================
- 1. WiredDHCP
- ------------
- This scenario introduces how DHCP works when multiple hosts and a single DHCP
- server are present. At random startup times, the clients request IP addresses
- from the server, which serves them from its address pool.
- client[0], client[1], ..., client[9] receive the addresses 192.168.1.100 through
- 192.168.1.109, respectively. The lease time is configured to be relatively low
- (1000s), causing the clients to periodically renew their addresses.
- 2. WirelessDHCP
- ---------------
- This is a real-life example where wireless hosts are configured by the
- DHCP server while the rest of the network (all wired interfaces) are
- configured manually using the IPv4NetworkConfigurator.
- Once the wireless clients associate with the AccessPoint, they send
- out a DHCPREQ and receive their own IP addresses along with the
- gateway address. At t=3s the clients start pinging the 'remote' server
- verifying whether the received IP and gateway address is correct.
- 3. RebootingDHCP
- ----------------
- This scenario demonstrates how DHCP works when a client or a server reboots.
- The client starts DHCP initialization at 0.5s, and receives IP address
- 192.168.1.100 shortly after.
- The client shuts down at 60s and reboots at 70s. The behavior implemented
- in DHCPClient is that the client remembers its last assigned IP address
- after the reboot, and if the address has not expired yet, then DHCP will
- start up in the INIT-REBOOT state and tries to reallocate this old IP address.
- In this example, the client's old lease has not expired yet (the lease time
- in this scenario is 150s), thus the client will successfully renew it.
- The server shuts down at 80s and reboots at 90s, and loses its lease database.
- When client reaches T1 timeout at 145s (T1 = 0.5*leaseTime), it tries to
- extend its current lease. This request will be rejected by the server, because
- it no longer knows about the client. After the refusal, the client restarts
- the whole DHCP process, and asks for a new address. The server will offer the
- first available address from its pool, which is again 192.168.1.100 since there
- are no other clients in the network.
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