Chapter 8 DHCP

Chapter 8 DHCP

1. DHCPv4

   • Functioning
     • assign addresses
     • Network configuration information in dynamic form
     • It is scalable and relatively easy to administer
     • DHCP detection (DHCPDISCOVER)
       • DHCP offer (DHCPOFFER)
         • DHCP request (DHCPREQUEST)
           • DHCP acknowledgment (DHCPACK)
       • Renovation of the lease
         • DHCP request (DHCPREQUEST)
           • DHCP acknowledgment (DHCPACK)
     • The fields in the messages are the following:
       • Operation code (OP)
       • Type of hardware
       • Hardware address length
       • Jumps
       • Transaction identifier
       • Seconds
       • Indicators
       • Client's IP address
       • Your IP address
       • IP address of the server
       • IP address of the gateway
       • Customer hardware address
       • Server name
       • Boot file name
       • DHCP options
   • Basic configuration
     • A Cisco router that runs Cisco IOS software can configured to work as a DHCPv4 server
     • ¿What is the DHCP relay?
       • In a complex hierarchical network, business servers They are usually located in a server farm.
     • By default, the ip helper-address command Forward the following eight following UDP services:
       • Port 37: Port 49 time: TACACS Port 53: DNS Port 67: client DHCP / BOOTP Port 68: DHCP / BOOTP server Port 69: TFTP Port 137: NetBIOS name service Port 138: NetBIOS datagram service
   • Problem resolution
     • Task 1 of problem solving: resolve conflicts of IPv4 addresses
     • Task 1 of problem solving: resolve conflicts of IPv4 addressesfísica
     • Task 3 of problem resolution: Test connectivity using a static IP address
     • Task 4 of problem solving: verify the configuration of switch ports
     • Task 5 of problem solving: test the operation of DHCPv4 in the same subnet or VLAN
     • is used with the debug ip packet command to show only the DHCPv4 messages

2. DHCPv6

   • SLAAC y DHCPv6
     • is a method in which a device can obtain an address Global unicast IPv6 without the services of a DHCPv6 server
     • ICMPv6 is in the center of SLAAC
     • Router request message (RS)
     • Router announcement message (RA)
     • SLAAC (router advertisement only) DHCPv6 without status (announcement of router and DHCPv6) DHCPv6 with status (DHCPv6 only)
     • it is the default option in Cisco routers
     • The stateless DHCPv6 option informs the client to use the RA message information for the address, but that there are more configuration parameters available from a DHCPv6 server
   • DHCPv6 without status
     • The client router needs a link-local IPv6 address in the interface to send and receive IPv6 messages, such as RS messages and DHCPv6 messages
     • the show ipv6 dhcp pool command verifies the name of the DHCPv6 pool and its parameters
   • Problem resolution
     • the debug ipv6 dhcp detail command is useful to verify the reception and transmission of messages DHCPV6