Defining and Configuring Neighbor Discovery презентация

MTU discovery

ICMPv6 Type

ICMPv6 Code

ICMPv6 Data

Checksum

IPv6 Basic Header

ICMPv6 Packet

Next Header = 58 ICMPv6 Packet

ICMPv6 Packet

with MTU = 1500

ICMP error: packet too big Use MTU = 1400

Packet with MTU = 1400

ICMP error: packet too big Use MTU = 1300

Packet with MTU = 1300

Path MTU = 1300

MTU used

Frame Header

Frame Trailer

IPv6 Packet

Minimum MTU = 1280 Octets

Link-Layer Frame

layers:
Ethernet
PPP
FDDI
Token Ring
HDLC
Nonbroadcast multiaccess
ATM
Frame Relay
IEEE 1394

different from the protocol ID in IPv4.

Destination Ethernet Address

IPv6 Header and Payload

0x86DD

Source Ethernet Address

and “complementing” a bit identifying the uniqueness of the MAC address.

where X =

1 = universally unique
0 = locally unique

X = 1

Ethernet MAC Address (48 Bits)

64-Bit Version

U/L Bit

Modified EUI-64 Address

00

90

27

17

FC

0F

17

FC

0F

FF

FE

FF

FE

of a neighbor on the same link
Finds neighbor routers on link
Achieved by using ICMPv6 with IPv6 multicast

prefix and the rightmost 24 bits of every unicast and anycast address

Prefix

0

Lower 24

Interface ID

FF02

FF

24 Bits

IPv6 Address

Solicited-Node Multicast Address

0001

Prefix for Ethernet Multicast

2001

0DB8

1001

000F

02C0

10FF

FC0F

IPv6 Address

FE

17

Src = 0 (::) Dst = solicited-node multicast of A Data = link-layer address of A Query = What is your link address?

DAD uses neighbor solicitation to verify the existence of an address to be configured.

Src = B Dst = A Data = link-layer address of B

ICMP type = 135 Src = A Dst = solicited-node multicast of B Data = link-layer address of A Query = What is your link address?

A and B can now exchange packets on this link.

Neighbor Discovery: Neighbor Solicitation

is a router
S: solicited flag, indicates message sent in response to a neighbor solicitation
O: override flag, indicates advertisement should override existing neighbor cache entry

advertisement packet definitions:
ICMP type = 134
Src = router link-local address
Dst = all-nodes multicast address
Data = options, prefix, lifetime, autoconfiguration flag

Router Advertisement

Neighbor Discovery: Router Advertisements

Router Advertisement

Hosts

promptly receive router advertisements.

Router solicitation packet definitions:
ICMP type = 133
Src = unspecified address
Dst = all-routers multicast address

Router Advertisement

Router Solicitation

advertisement for configuring the interfaces.

1. Router Solicitation:
ICMP type = 133
Src = ::
Dst = all-routers multicast address
Query = Please send router advertisement

2. Router advertisement

1. Router
solicitation

2. Router Advertisement:
ICMP type = 134
Src = router link-local address
Dst = all-nodes multicast address
Data = options, prefix, lifetime, autoconfiguration flag

2. Router advertisement

= All-nodes multicast address
Data = Two prefixes:
Current prefix (to be deprecated) with short lifetime
New prefix (to be used) with normal lifetime

Renumbering

Renumbering is achieved by modifying the router advertisement to announce the old prefix with a short lifetime and the new prefix.

Router Advertisement

a DHCPv6 server:
Mobile devices (phones, PDAs, autos)
Home electronics (TVs, DVRs, appliances)
Field telemetry (oil pipeline gauges)
Autoconfiguration enables massive deployment (millions) of IPv6 nodes.

[ [ ] |
[at ]
[off-link] [no-autoconfig] ]

router(config-if)#

Used to modify prefix advertisement parameters on an interface from their default values.

Cisco IOS Neighbor Discovery Command Syntax

2001:db8:c18:1::/64 2000 1800

interface Ethernet1
ipv6 address 2001:db8:c18:2::1/64
ipv6 nd prefix 2001:db8:c18:2::/64 2000 1800

interface Ethernet0
ipv6 address 2001:db8:c18:1::1/64
ipv6 nd prefix 2001:db8:c18:1::/64 2000 1800

Router2

Router1

Cisco IOS Command for Overriding the Neighbor Discovery Defaults

Router Advertisement

ipv6 nd prefix 2001:db8:c18:2::/64 2000 1800

interface Ethernet0
ipv6 nd prefix 2001:db8:c18:1::/64 2000 1800

Router2

Router1

Cisco IOS Command for Overriding the Neighbor Discovery Defaults (Cont.)

Router Advertisement

Router Advertisement

nd ra lifetime 100

interface Ethernet1
ipv6 nd prefix 2001:db8:c18:2::/64 43200 43200

interface Ethernet0
ipv6 nd prefix 2001:db8:c18:1::/64 43200 43200

Router2

Router1

Cisco IOS Neighbor Discovery Lifetimes

Router Advertisement

Router Advertisement

IPv6 Hosts

preferred address 2001:db8:c18:1:260:8ff:fede:8fbe

Router Configuration before Renumbering:

Router Advertisements

Cisco IOS Network Prefix Renumbering Scenario

prefix 2001:db8:c18:2::/64 43200 43200

New Network Prefix: 2001:db8:c18:2::/64 Deprecated Prefix: 2001:db8:c18:1::/64

Host Configuration:

Autoconfiguring IPv6 Hosts

deprecated address 2001:db8:c18:1:260:8ff:fede:8fbe
preferred address 2001:db8:c18:2:260:8ff:fede:8fbe

Router Configuration after Renumbering:

Router Advertisements

interface Ethernet0
ipv6 nd prefix 2001:db8:c18:1::/64 at Jul 31 2002 23:59 Jul 1 2002 23:59
ipv6 nd prefix 2001:sb8:c18:2::/64 43200 43200

Cisco IOS Network Prefix Renumbering Scenario (Cont.)

or:

discovery, neighbor discovery, and router discovery. ICMPv6 is an integral part of IPv6 but looks similar to a Layer 4 protocol, much like TCP or UDP.
Path MTU is performed by nodes in an effort to determine the largest packet size they can send to a given destination. It is based on a process of sending large packets and listening for ICMPv6 error messages.
Neighbor discovery is a critical process that allows neighbors to determine the link-layer address associated with a given IPv6 address. It also allows hosts to receive prefix information to configure a global-scope address and find the default router.
Before a node can use an address, it must test it for uniqueness on the link. DAD is a process by which a node with a "tentative" address that it would like to use determines if that address is already in use.
Autoconfiguration provides a type of network “plug-and-play,” easily supporting millions of transient nodes and enabling a network environment with support for mobile phones, field sensors, and home appliances.
Cisco routers are IPv6-ready and are configured for IPv6 functions on a global and per-interface basis, depending on the function being enabled.