ipv6

www.professordkinney.com

04/10/23Instructional Design-Computer Networking - Bridges Educational Group

Introducing IPv6


Introducing IPv6Lessons Summary:

Introducing basic IPv6Understanding IPv6Configuring IPv6 Routing


IP version 6 (IPv6) was developed to overcome the limitations of the current standard, IP version 4 (IPv4). IPv4 allows end systems to communicate and forms the foundation of the Internet as we know it today. However, one of the major shortcomings of IPv4 is its limited amount of address space. The explosion of new IP-enabled devices and the growth of undeveloped regions have fueled the need for more addresses.

In the United States, the Department of Defense (DoD) is a primary driver for the adoption of IPv6.

• IP version 6 (IPv6) combines expanded addressing with a more efficient and feature-rich header to meet the demands for scalable networks in the future.

• One key benefit is that IPv6 can recreate end-to-end communications without the need for Network Address Translation (NAT)

• Cisco Systems currently supports IPv6 in Cisco IOS Software Release 12.2(2)T and later.IPv6 routers do not perform fragmentation. Instead, a discovery process determines the optimum maximum transmission unit (MTU) to use during a given session.

• Link-layer technologies already perform checksum and error control. Because link-layer technologies are relatively reliable, an IP header checksum is considered to be redundant.


Introducing IPv6


Introducing IPv6IPv6 FEATURES

Large Address Spaces

IPv6 Address Unicast address– Link local: FE80::/10, Scope is configured to single link. The address is unique

only on this link, and it is not routable off the link. (similar to 169.254.x.x private address)

– Site local: FEC0::/10 (similar to private address)– Global: Globally unique, so it can be routed globally with no modification. A

global address has an unlimited scope on the worldwide Internet. Packets with global source and destination addresses are routed to their target destination by the routers on the Internet.

Multicast address: IPv6 does not have broadcast addresses. The range of multicast addresses in IPv6 is larger than in IPv4. For the foreseeable future, allocation of multicast groups is not being limited.

Anycast address: An anycast address identifies a list of devices or nodes; therefore, an anycast address identifies multiple interfaces. A packet sent to an anycast address is delivered to the closest interface, as defined by the routing protocols in use types.

64 bits reserved for the interface ID16 bits reserved for the end site16 bits reserved for the service provider32 bits reserved for service providers

04/10/23

Instructional Design-Computer Networking - Bridges Educational Group

Introducing IPv6


Introducing IPv6Special address

Defining Address Representation

Defining Address Representation Leading zeros in a field are optional, so 09C0 = 9C0 and 0000 = 0. Successive fields of zeros can be represented as “::” only once in an

address. An unspecified address is written as “::” because it contains only zeros.

IPv6 Global Unicast and Anycast addressGlobal unicast addresses are defined by a global routing prefix, a subnet ID,

and an interface ID. The current global unicast address assignment by the Internet Assigned Numbers Authority (IANA) uses the range of addresses that start with binary value 001 (2000::/3), which is one-eighth of the total IPv6address space and is the largest block of assigned block addresses.

Addresses with a prefix of 2000::/3 (001) through E000::/3 (111), with the exception of the FF00::/8 (1111 1111) multicast addresses, are required to have 64-bit interface identifiers in the extended universal identifier (EUI)-64 format.

When a unicast address is assigned to more than one interface, thus turning it into an anycast address, the nodes to which the address is assigned must be explicitly configured to use and recognize the anycast address.


Introducing IPv6

Defining Host Interface AddressesAn IPv6 address has two parts:– A subnet prefix representing the network to which the interface is

connected. The subnet prefix is a fixed 64-bit length for all current definitions.

– A local identifier, sometimes called a token, which uniquely identifies the host on the local network. The local identifier is always 64 bits and is dynamically created based on Layer 2 media and encapsulation. In the simple case of an Ethernet medium, the local identifier is usually derived from the EUI-48 MAC address.

Link Local Address


Introducing IPv6

The address is unique only on this link, and it is not routable off the link. Packets with a link-local destination must stay on the link where they were generated

Link-local addresses are dynamically created using a link local prefix of FE80::/10 and a 64-bit interface identifier in a process called stateless auto configuration.

Unique-Local Address:Unique-Local Addresses Used For: Local communications Inter-site VPNs Not routable on the InternetReinvention of the deprecated site-local? It’s future is unclear.


Introducing IPv6

IPv6 Multicast AdsressFF02::1:FFXX:XXXX — Solicited-node multicast on link, where XX:XXXX is

the rightmost 24 bits of the corresponding unicast or anycast address of the node. (Neighbor solicitation messages are sent on a local link when a node wants to determine the link-layer address of another node on the same local link, similar to Address Resolution Protocol [ARP] in IPv4.)address


Introducing IPv6

Multicast Use Broadcasts in IPv4 Interrupts all devices on the LAN even if the intent of therequest was for a

subset Can completely swamp the network (“broadcast storm”) Broadcasts in IPv6Are not used and replaced by multicast MulticastEnables the efficient use of the network Multicast address range is much

larger.IPv6 Multicast Address ExamplesRIPngThe multicast address AllRIPRouters is FF02::9Note that 02 means that this is a permanent address and has link scopeOSPFv3The multicast address AllSPFRouters is FF02::5The multicast address AllDRouters is FF02::6 EIGRPThe multicast address AllEIGRPRouters is FF02::A


Introducing IPv6

IPv6 AStateless (RFC2462)Host autonomously configures its own Link-Local address Router solicitation

are sent bybooting nodes to request RAs for configuring the interfaces.StatefulDHCPv6 – required by most enterprises.RenumberingHosts renumbering is done by modifying the RA to announce theold prefix with a short lifetime and the new prefix Router renumbering

protocol (RFC2894), to allow domain-interior routers to learn of prefix introduction / withdrawal


Introducing IPv6

Auto-configuration client sends router solicitation (RS) messages. Router responds with router advertisement (RA)This includes prefix and

default route . Client configures its IPv6 address by concatenating prefix received with its

EUI-64 address


Introducing IPv6

RenumberingRouter sends router advertisement (RA) This includes the new prefix and default route (and remaining lifetime of the old address) Client configures a new IPv6 address by concatenating prefixreceived with its EUI-64 address Attaches lifetime to old address


Introducing IPv6


Introducing IPv6IPv6 Technology scope

IPv6 Routing• Similar to IP version 4 (IPv4) classless inter-domain routing (CIDR), IPv6

uses longest-prefix match routing. • Routing protocol: RIPng, OSPFv3, EIGRP, ISIS, MP-BGP• Static routing: A router must be able to determine the link local address

of each of its neighboring routers to ensure that the target address of a redirect message identifies the

neighbor router by its link-local address.

RIPngBased on IPv4 RIP version 2 (RIPv2) and similar to RIPv2 • Uses IPv6 for transport • IPv6 prefix, next-hop IPv6 address • Uses the multicast group FF02::9, the all-RIP-routers multicast group, as the destination address for RIP updates • Updates sent on UDP port 521


Introducing IPv6

Command: – Router(config)#ipv6 router rip bkacad – Router(config-router)#maximum-paths 2 – Router(config)#interface fa0/0 – Router(config-if)ipv6 rip bkacad enable

OSPFv3 overview OSPFv3 is OSPF for IPv6 (RFC 2740) Based on OSPFv2, with enhancements Distributes IPv6 prefixes Runs directly over IPv6 Completely independent of OSPFv2


Introducing IPv6

Difference from OSPFv2 Runs over a link, not a subnet Multiple instances per link Topology not IPv6 specific Router ID Link ID Standard authentication mechanisms Uses link local addresses Generalized flooding scope Two new LSA types s from OSPFv2

Multi-Protocol BGP forIPv6 – RFC2545IPv6 specific extensions Scoped addresses: Next-hop contains a global IPv6 address and/or potentially a link-local address


Introducing IPv6

NEXT_HOP and NLRI are expressed as IPv6 addresses and prefixAddress Family Information (AFI) = 2 (IPv6)Sub-AFI = 1 (NLRI is used for unicast)Sub-AFI = 2 (NLRI is used for multicast RPF check)Sub-AFI = 3 (NLRI is used for both unicast and multicastRPF check)Sub-AFI = 4 (label)IPv4-IPv6 Co-existence/TransitionA wide range of techniques have been identified and implemented,

basically falling into three categories:Dual-stack techniques, to allow IPv4 and IPv6 to co-exist in thesame devices and networksTunneling techniques, to avoid dependencies when upgradinghosts, routers, or regionsTranslation techniques, to allow IPv6-only devices to

communicate with IPv4-only devices Expect all of these to be used, in combination

04/10/23


Introducing IPv6

IPv6 to IPv4 Transition MechanismThe two most common techniques to transition from IPv4 to IPv6 are as follows:– Dual stack – IPv6-over-IPv4 (6to4) tunnels• For communication between IPv4 and IPv6 networks, IPv4 addresses can be encapsulated in IPv6 addresses.


Introducing IPv6

Cisco IOS Dual Stack Using IPv6 on a Cisco IOS router requires that you use the global

configuration command ipv6 unicast-routing. This command enables the

forwarding of IPv6 datagrams. A dual-stack node chooses which stack to use based on the

destination address. A dual-stack node prefers IPv6when available.

A new application programming interface (API) is defined to support both IPv4 and IPv6 addresses and Domain Name System (DNS) requests.

Past experience in porting IPv4 applications to IPv6suggests that for most applications it is a minimal change in some localized places inside the source code.

04/10/23


Introducing IPv6

Overlay Tunnels Tunneling IPv6 traffic over an IPv4 network requires one edge

router to encapsulate the IPv6 packet inside an IPv4 packet and another router to de-encapsulate it.

Tunneling is an integration method where an IPv6 packet is encapsulated within another protocol, such as IPv4.


Introducing IPv6

This method of encapsulation is IPv4 protocol 41 and has the following characteristics:

Includes a 20-byte IPv4 header with no options and an IPv6 header and payload.

Considered dual stacking, which enables the connection of IPv6 islands without converting an intermediary network to IPv6.

Tunneling presents these issues:– The MTU is decreased by 20 octets (if the IPv4 header does not

contain any optional field). – Difficult to troubleshoot.


Introducing IPv6

Encapsulation can be done by edge routers between hosts or between a host and a router.

Tunneling does not work if an intermediary node between the two end points of the tunnel, such as a firewall, filters out IPv4 protocol 41, which is the IPv6-over-IPv4 encapsulation.


Introducing IPv6

Example of Configure The command that enables the IPv6 overlay tunnel is tunnel mode ipv6ip.


Introducing IPv6

6to4 tunneling• The 6to4 tunneling method automatically establishes the

connection of IPv6 islands through an IPv4 network. • Each 6to4 site receives a /48 prefix, which is the concatenation of

0x2002 and the hexadecimal IPv4 address of the edge router.• In Figure , the IPv4 address of the edge router is 192.168.99.1. As

a result, the prefix of its IPv6 network is 2002:c0a8:6301::/48 because c0a86301 is the hexadecimal representation of 192.168.99.1. The IPv6 network can substitute any IP address in the space after the first 16-bit section (0x2002).


Introducing IPv6

NAT-PT forIPv6NAT-PT(Network Address Translation – Protocol Translation)RFC 2766 & RFC 3596 Allows native IPv6 hosts and applications to communicate with

native IPv4 hosts and applications, and vice versa Easy-to-use transition and co-existence solution


prefix is a 96-bit field that allows routing back to theNAT-PT device

Introducing IPv6


Introducing IPv6

NAT-PT packet flow

Points of note:ALG per application carrying IP addressNo End to End securityNo DNSsecNo IPsec because different address realmsEasy IPv6 / IPv4 co-existence mechanismEnable applications to cross the protocol

barrier


Introducing IPv6

Lessons Learned:IPv6 featuresIPv6 addressingIPv6 routing


Introducing IPv6

ipv6

Technology

global address

anycast address

ipv6 special address

link local address

mac address

unspecified address

ipv6 routing

private address global