IPv6 Introduction (may 2020)

Alejandro Acosta alejandro@.net @ITandNetworking Today’s content

.- Little bit of history .- IPv6 Header .- IPv6 Neighbor Discovery (ND) Today’s content

.- Little bit of history and the TCP/IP protocols

1969 – Start of ARPANET 1981 – IPv4 definitions and the RFC 791 1983 – ARPANET adopts TCP/IP 1990 – First studies about IPv4 address exhaustion 1993 – Internet begins to be commercially exploited - Increased discussion about a possible address depletion and the increase of the addess routing tables IPv4 Address exhaustion

IPv4 = 4.294.967.296 addresses (*) Initial distribution policy directions

§ Class A o DoD o IBM o US o HP Army o AT&T o USPS o MIT o ......

§ Class B § Class C § Reserved Addresses IPv4 = 4.294.967.296 addresses NOT FULLY TRUE IPv4 Address Exhaustion Proposed solutions

Palliative Solutions §1992 - IETF started ROAD working group (ROuting and ADdressing). §CIDR (RFC 4632) §End use of “classes” = appropriately sized blocks §Network addresses = prefix/length §Routing aggregation = the growth in the size of the routing tables §DHCP §Dynamic address assignment §NAT + RFC 1918 (Address Allocation for Private ) §Enable to connect an entire network with only one public address Solutions

N A T (Network Address Translation Advantages • Reduces the need of public internet addresses • Facilitates the internal network address numbering • Hides the network topology • Only allows the packet entry to our network as a response to a request from the network Disadvantages • Breaks the internet point-to-point model • Hinder the functioning of a number of applications • Not scalable • Increase the process load in the traduction device • False sense of security • Unable to trace the path of the packet • Prevents the use of security mechanisms such as IPSec • Limits of HW & SW Solutions Palliative Solutions: Fall of only 14% Solutions

The measures discussed above generate more time to develop a new version of the IP protocol

•1992 - IETF make the IPng working group (IP Next Generation) •Main questions: •Escalability •Security •Network configuration and management •QoS support •Movility •Routing policies •Transition Solutions Definitive solution

Protocols closely evaluated IPv6

•1998 Defined in RFC 2460 (now RFC 8200) •128 bits for addressing •Base header simplified •Extension headers •Flow identification data (QoS). •IPSEC mechanisms built into the protocol •Performs packet fragmentation/reassembly on the source and destination •NAT is not necessary, allowing point-to-point mechanisms that facilitate network configuration •....

IPv4 Header

It’s integrated by 12 fixed fields. It may contain options or not, therefore it’s size can vary from 20 to 60 Bytes. IPv6 Header

l Simpler l40 Bytes (fixed size) lOnly twice bigger than the older version

l

l More flexible lExtensions through additional headers

l

l More efficient lHeader overhead is minimized lPacket processing cost is reduced IPv6 Header

l Six fields from the IPv4 header were removed IPv6 Header

1 2 1

2 3 4

4 3

l Six fields from the IPv4 header were removed l Four fields had it’s name and it’s location changed IPv6 Header

l Six fields from the IPv4 header were removed l Four fields had it’s name and it’s location changed l The Flow Label field was enlarged IPv6 Header

l Six fields from the IPv4 header were removed l Four fields had it’s name and it’s location changed l The Flow Label field was enlarged l Three fields were unchanged IPv6 Header more Neighbor Discovery lIt uses five types of ICMPv6 messages:

lRouter Solicitation (RS) – ICMPv6 type 133;

lRouter Advertisement (RA) – ICMPv6 type 134;

lNeighbor Solicitation (NS) – ICMPv6 135;

lNeighbor Advertisement (NA) – ICMPv6 type 136;

lRedirect - ICMPv6 Type 137 lA value of 255 is set to the Hop Limit field. lIt can contain options:

lSource link-layer address.

lTarget link-layer address.

lPrefix Information.

lRedirected header.

lMTU Neighbor Discovery (NS)

lLink layer address discovering

lIt determines the link layer addressing of neighbors on the same link.

lReplaces the ARP protocol.

lIt uses multicast address “solicited-node” instead of broadcast.

lThe host sends a NS message informing his MAC address and requests that of the neighbor. Neighbor Discovery (NA)

lLink layer address discovering

lIt determines the link layer addressing of neighbors on the same link.

lReplaces the ARP protocol.

lIt uses multicast address “solicited-node” instead of broadcast.

lThe host sends a NS message informing his MAC address and requests that of the neighbor.

lThe neighbor answers by sending a NA message informing his MAC address. Neighbor Discovery (RA)

l and neighbor discovering

lFinds neighboring routers on the same link.

lDetermines prefixes and parameters related to the address auto configuration.

lIn IPv4, this function is held by the ARP request.

lRouters send RA messages to the multicast address “all- nodes” Router Solicitation (RS) Hosts inquire with Router Solicitation messages to locate routers on an attached link Routers which forward packets not addressed to them generate Router Advertisements immediately upon receipt of this message rather than at their next scheduled time

l.- Hosts will send to the ‘All Router IPv6 Multicast Address’ (FF02::2)

l.- All layer 3 multicast addresses have a corresponding layer 2 mac address (33:33:xx:xx:xx:xx) where xx:xx:xx:xx are the last 32 bits of the layer 3 multicast address)

https://www.slideshare.net/kriz5/cisco-i-pv6labandtechtorialworkshop-v0 Neighbor Discovery (redirect)

lRedirect

lIt sends Redirect messages.

lIt redirects a host to a more appropriate first hop router.

lIt informs the originator host that the destination is on the same link.

lThis mechanism is the same as the existing one in IPv4.

Somewhere else

Paquete IPv6 Questions? Comments?

Alejandro Acosta [email protected] @ITandNetworking