LOGO IPv6 Application Analysis Xi Chen [email protected]

LOGO

IPv6 Application AnalysisIPv6 Application Analysis

Xi Chen [email protected]

IPv6 Addressing

Overall Application Scenario

IPv6 Addressing

IPv6 Addressing Architecturex:x:x:x:x:x:x:xx is a 16 bits hexadecimal fieldE.g.: 2001:0000:1234:0000:0000:C1C0:ABCD:0876

Case insensitive•2001:0000:1234:0000:0000:c1c0:abcd:0876

Leading zeros in a field are optional:•2001:0:1234:0:0:C1C0:ABCD:876

Successive fields of 0 are represented as ::, but only once in an address• 2001:0:1234::C1C0:ABCD:876• Not valid: 2001::1234::C1C0:ABCD:876Other examples:• FF02:0:0:0:0:0:0:1 => FF02::1• 0:0:0:0:0:0:0:1 => ::1• 0:0:0:0:0:0:0:0 => ::

IPv6 Addressing

IPv6 Addressing Allocation

Allocation Binary Prefix Fraction of address space

Unicast 001 1/8

Link Local address space

1111 1110 10 1/1024

Site Local address space

1111 1110 11 1/1024

Multicast 1111 1111 1/256

The Anycast addressing use the same address allocation as Unicast.

Example:Unicast2080:0:0:0:8:800:200C:317A=1080::8:800:200C:317AMulticastFF01:0:0:0:0:0:0:101=FF01::101

IPv6 Addressing

Interface-IDFP TLA-ID Res NLA-ID SLA-ID

≥3 ≤13 8 24 16 64

Public TopologySite

Topology Interface Identifier

Network Portion Node Portion

FP = Format Prefix (= 001 for globally aggregated unicast addresses)

TLA-ID = Top-level aggreation identifier

RES = Reserved for future use

NLA = Next-level aggregation identifier

SLA-ID = Site-level aggregation identifier

Interface ID = Interface identifier

IPv6 Addressing Format

IPv6 Addressing

MAC Address: 0000:0B0A:2D51 In binary:

00000000 00000000 00001011 00001010 00101101 01010001

Insert FFFE between Company-ID and Node-ID

00000000 00000000 00001011 11111111 11111110 00001010 00101101 01010001

Set U/L bit to 1

00000010 00000000 00001011 11111111 11111110 00001010 00101101 01010001

Resulting EUI-64 Address: 0200:0BFF:FE0A:2D51

Interface ID

IPv6 Addressing

Unicast Addressing

IPv6 Addressing

Anycast Addressing

IPv6 Addressing

Group-ID11111111 flgs

8 4 112

128 bit

scope

4

First 3 bits set to 0Last bit defines address type:0 = Permanent (or well-known)1 = Locally assigned (or transient)

Defines address scope0 Reserved1 Node-local scope2 Link-local scope5 Site-local scope8 Organization local scopeE Global scopeF Reserved

Multicast Addressing Format

IPv6 Addressing

Multicast Addressing

IPv6 Addressing

Link local Addressing

Examples

FE80::0060:08FF:FEB1:7EA2

FE80::200:CFF:FE0A:2C51

Interface-ID1111111010 0

10 54 64

128 bit

IPv6 Addressing

Site Local Addressing

Interface-ID1111111011 0

10 54 64

128 bit

Subnet-ID(SLA-ID)

16

ExamplesFEC0::0060:08FF:FEB1:7EA2

FEC0::200:CFF:FE0A:2C51

ICMPv6

ICMPv6

– Type 1: Destination Unreachable– Type 2: Packet Too Big (MTU)– Type 3: Time Exceeded– Type 4: Parameter Problem– Type 128/129: Echo request/Echo reply

ICMPv6

Code 0 - no route to destination

1 - communication with destination

administratively prohibited

2 - (not assigned)

3 - address unreachable

4 - port unreachable

Type=1 Code Checksum

As much of invoking packetas will fit without the ICMPv6 packetexceeding the minimum IPv6 MTU

32 bits

Unused

Unused This field is unused for all code values. It must be initialized to zero by the sender and ignored by the receiver.

Destination Unreachable

ICMPv6

Code Set to 0 by the sender and ignored by the receiver

MTU The maximum transmission unit of the next-hop link



32 bits

MTU

Packet too big(MTU)

ICMPv6

Code 0 – Hop limit exceeded in transit

1 – Fragment reassembly time exceeded



32 bits

Unused

Unused This field is unused for all code values. It must be initialized to zero by the sender and ignored by the receiver.

Time Exceeded

ICMPv6

Code 0 - erroneous header field encountered

1 - unrecognized Next Header type encountered

2 - unrecognized IPv6 option encountered



32 bits

Pointer

Pointer Identifies the octet offset within the invoking packet where the error was detected.

The pointer will point beyond the end of the ICMPv6 packet if the field in error is beyond what can fit in the maximum size of an ICMPv6 error message.


Pointer

Parameter Problem

ICMPv6

Code 0

Identifier An identifier to aid in matching Echo Replies to this Echo Request. May be zero.

SN A sequence number to aid in matching Echo Replies to this Echo Request. May be zero.

Data Zero or more octets of arbitrary data.

Type=128 Code=0 Checksum

Data

32 bits

Identifier Sequence Number

Echo Request

ICMPv6

Code 0

Identifier The identifier from the invoking Echo Request message.

SN The sequence number from the invoking Echo Request message

Data The data from the invoking Echo Request message.

Type=129 Code=0 Checksum

Data

32 bits

Identifier Sequence Number

Echo Reply

Neighbor Discovery

Neighbor Discovery

Defines five ICMPv6 packets1. Router solicitation (RS)2. Router advertisement (RA)3. Neighbor solicitation (NS)4. Neighbor advertisement

(NA)5. Redirect

Neighbor Discovery

Router solicitation (RS)


Reserved

32 bits

Options....

Neighbor Discovery

Router advertisement (RA)


Reachable Time

32 bits

Hop Limit M O Reserved Router lifetime

Retransmit Timer

Options....

Neighbor Discovery

RS and RA procedure

Neighbor Discovery

Router advertisement in routers

Neighbor Discovery


Reserved

32 bits

Target address

Options....

Neighbor solicitation (NS)

Neighbor Discovery


Reserved

32 bits

Target address

Options....

R S O

Neighbor advertisement (NA)

Neighbor Discovery

Redirect


Reserved

32 bits

Target address

Options....

Destination address

Neighbor Discovery

A

B

C

D

E

F G

Default GW-List

ABC

ICMP Redirect to Router B

Path used with Default Gateway "A"

Host 3

Sent data to Host 3 using Default GW "A"

Redirect traffic via Router B

Redirect Procedure

Neighbor Discovery

Check neighbor cache for existing next-hop entry for particular destination

Check whether destination is on- or off-link On-link: Sent directly to destination Off-link: Sent to default router Identify link-layer address of next-hop

Next Hop Discovery

Neighbor Discovery

Uses Neighbor solicitation & advertisements Node checks neighbor cache first If no entry exists, node creates IP entry with state

INCOMPLETE Node then sends NS to solicited-node multicast

address Source address of NS is a unicast address Receiving node responds with NA indicating it‘s

own link-level address Soliciting node updates neighbor cache entry

from INCOMPLETE to REACHABLE upon receiption of NA

Address Resolution

Neighbor Discovery

2 ways to verify neighbor reachability: Using hints from upper-layer protocols From responses to neighbor solicitations

Forward direction communication (FDC) must be possible for a neighbor to be REACHABLE

FDC is verified if forward progress is being made by an upper-layer protocol (i.e. TCP, receiption of TCP acks)

If no verification can be received from upper-layer protocols (like UDP): Node actively probes neighbors to determine reachability state

Probes are sent in conjunction with traffic. No traffic, no probes! Probe is neighbor solicitation (NS) Neighbor advertisement (NA) reply is expected to establish FDC

Neighbor Unreachability Detection

Neighbor Discovery

Must be performed by all nodes Performed before assigning a unicast address to an interface Performed on interface initialization Not performed for anycast addresses Link must be multicast capable New address is called "tentative" as long as duplicate address

detection takes place1. Interface joins all-nodes multicast group2. Interface joins solicited-node multicast group3. Node sends (one) NS with

Target address = tentative IP addressSource address = unspecified (::)Destination address = tentative solicited-node address

If address already exists, the particular node sends a NA reply withTarget address = tentative IP addressDestination address = tentative solicited-node address

If soliciting node receives NA reply with target address set to the tentative IP address, the address must be duplicate

Duplicate Address Detection

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Documents

LOGO IPv6 Application Analysis Xi Chen [email protected]