DHCP Steps – DORA
Discover – broadcast messages
Offer – server responds with this
Request – client responds with request to use what’s offered
Ack – serrver acknowledges that it is leased
ip helper – address to configure router to replay dhcp messages to server
service dhcp
interface _______
ip helper-address x.x.x.x
ip dhcp excluded – address x.x.x.x x.x.x.x
prevents DHCP from assigning those ip address
ip dhcp pool POOL-A
creates pool which hands out ip addresses in POOL-A
169 ip address means problem
APIPA – IPv4 address when server unavailable possibly a layer 2 issue
169.254.0.0 /16
IPv6
neighbor discovery – IPv6 protocol for address auto config, duplicate addresses, detection, router, neighbor, prefix discovery, neighbor address resolution, parameter discovery
EUI-64 – 1st half of mac address, 7th bit flipped, FFFE, last half of mac address
SLAAC – enables device to configure its own IPv6 address and default gateway without DHCPv6 server
Cisco Routers enable manually on interface
IPv6 address autoconfig
Router Solicitation – messages to determine whether there are any routes connected to local link then wait for
Router Advertisement – to identify prefix used by router (default gateway)
Stateless DHCPv6
Routers RA – used by clients to automatically determine IPv6 address
DHCPv6 Operation
Solicit – sends FF02 which is all DHCPv6 multicast addresss
Advertise – server responds with unicast messages to offer ip address info
Request – client sends this confirming address provided and parameters
Reply – server finalized w/this message
DHCPv6 Relay Agents – relays solicit messages to DHCPv6 server in different IPv6 network
Packet Forwarding – forwarding packets through router, ip routing
Layer 3 to Layer 2 mapping found in arp cache
ARP – used on ethernet lan by devices to determine layer 2 mac of known layer 3 ip address
FIB contians layer 3 info similar to ip routing table
Adjacency table contains frame header info required by router used by CEF stores layer 3 addressing for all FIB entrires
CEF – cleans info from routing table and layer 3 to layer 2 mappsings
control plain – protocols between routers
data plane – process forwards packets through multilayer switch
AD – used to maniupulate path selection
Static route – manualy configured by admin using ip route or IPV6 route command
proxy arp – allows router to respond to ARP requests with its own mac address if it has route in routing table to ip address in arp request
