DHCP, DHCPv6, IP Routing

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

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s