IPv4

IPv4

Version
0100  = 4  so IPv4
0110 = 6  so IPv6

IHL  internet header length.
How long is it in Bytes   (IPv4 changes size) (IPv6 is fixed)

TOS  Type of service   which is your QoS  DSCP coloring marking.

Total Length  of the packet including the data. Useful for determining if you need to fragment the packet

Identification  -  identifies the Fragments.

Flags
0  Fragment
1  do not fragment

Fragment offset    this is fragment 1 of 40

TTL   time to live    each hop cuts 1

protocol      8 bits   used by IANA
1  ICMP    (ping)
2  IGMP  (multicast)
6    TCP
17    UDP
50   ESP
51   AH
88   EIGRp
89   OSPF
103  PIM   (multicast)
112   VRRP

Header Checksum   - used to see if the packet is still ok after transport. Changes every header change.

Source address 32 bits
Destination address 32 bits

IP options   not in use.  Used for security , route record and similar.

Padding   so the packet ends on a 32 bit  boundary.



TOS
used for the QoS.

Voip is 101
nothing is 000
PIFFCIN    priority imediate flash flash Critical in network

TOS itself is 4 bits.
It can be used to select a route based on.

Money
reliable
throughput
delay

Assured Forwarding (AF) Behavior Group

	Class 1 (lowest)	Class 2	Class 3	Class 4 (highest)
Low Drop	AF11 (DSCP 10)	AF21 (DSCP 18)	AF31 (DSCP 26)	AF41 (DSCP 34)
Med Drop	AF12 (DSCP 12)	AF22 (DSCP 20)	AF32 (DSCP 28)	AF42 (DSCP 36)
High Drop	AF13 (DSCP 14)	AF23 (DSCP 22)	AF33 (DSCP 30)	AF43 (DSCP 38)

With DSCP they dropped the TOS which nobody used.
The way it works now is Class 4 will have a higher priority.
and if there is congestion the high Drop will be dropped first.


Precedence               AF  1           AF 2       AF 3         AF  4
Low drop precedence 001010 010010 011010 100010
Medium drop precedence 001100 010100 011100 100100
High drop precedence 001110 010110 011110 100110

So a 1 at the beginning is better.  1xx
A 010 will not be dropped.

MTU ethernet 1518
LAN jumbo frames
TCp will retransmit
UDP wont'

Class A 0xxxxxxx   so 0 to 127
Class B  1xxxxxxx   so 128 to 191
Class C  11xxxxx    so 192 223
class D   111xxxxx  so 224 239        multicast
Class E   1111xxxx   so  240 to 255   experimental.

Unicast
Broadcast
Multicast

Private are not routed  10/8  172.16/12     192.168/16
1 class A    16 Class B    256  Class C

You can subnet the addresses above.

Static nat is ONE to ONE   private to Public.

Dynamic  NAT   overloading    is PAT  port Address translation.
Dynamic Overloading    is an internal pool  to an external one.

Inside Local  is the IP of my PC.
Inside Global  is     the Public IP   I get on the web

Outside Global   is the IP of a device on the WWW.
Outside  Local    is    his IP when he is in my STUB/LAN



BOOTP
get IP and gateway  using UDP  replaced

DHCP
Manual is to map a MAC to an IP address.
Automatic    does not expire
Dynamic is from a Pool and expires.

DHCPDiscover.
Router can relay this
DHCP Offer
DHCP request
DHCP acknowledge

DHCPNAK  not acknowledge I am out of addresses.

DHCP should be in the server farm  / datacenter

Internal DNS campus
Edge External
remote datacenter   BOTH



ARP

IPV6

128 Bits instead of 32 bits per address.
Each IP is globally unique
Header is fixed at 40 Bytes
Header will reference options   so it is a fixed size.
Addresses can autoconfigure if required.
IPSEC is built in
MTU discovery
Multiple IPv6 addresses
No broadcast replaced by multicast

Version 0110   IPV6  = 6
Traffic class  8 bits   = TOS
Flow 20 bits    for ordering the flow.
Next Header   to add more
Hop limit  = TTL
source
destination

6
17 udp
50 esp
51 ah
88 eigrp
89 opsf

ipv4 compatible  000000000x.x.x.x

FF multicast
FE  link local
FC  private addressing

Global is routable
64 bits netowrk    64  bits host  (made up from the MAC 48 bits)

To convert a MAC 48 to 64  you add  two  FF FF   in the middle.


FE  is link local can be auto configured

FC  is private addressing    Unique

Globally aggregetable  = aggregate of the IPV6

Anycast is to the nearest.

FF:01 1  all nodes
FF: 01 2  all routers
FF:02  5  OSPF
FF:02 6  OSPF designated
FF:02  9   RIPnG
FF:02 A   EIGRP
FF:02 C   DHCP

ICMPv6 discovers MTu

IPv6  ND  neighbor discovery

IPv6 DNS   AAAAAAAAAAAA
Use the same DNS server.

Stateless link local
Stateless global
Stateful DHCP


Global
Talk to router and gets the prefix
Prefix  +  MAC = address

EIGRP  for  IPv6
RIPnG
OSPFv3
BGP4
ISIS for   IPv6

Dual Stack is both IPv4 and IPv6
Tunneling  IPv6  into an IPv4 tunnel
Translate   IPv6 to IPv4

Dual Stack  - if DNS sends AAAAA it uses IPv6

Automatic Tunnel
IPv4 compatible
6 to 4   the destination has an IPV4 in it    which is used as the tunnel envelope
6 over 4   Multicast over Multicast

ISATAP - Greek, Chinese

Daul stack can use PAT  or NAT-PT

Ciscio 6PE over MPLS

Service Block service the translations.