IP Routing 12 May, 2002 1 Subnetting: Subnet Addressing - - PDF document

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IP Routing 12 May, 2002 1 Subnetting: Subnet Addressing - - PDF document

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IP Routing 12 May, 2002 1 Subnetting: Subnet Addressing

slide-1
SLIDE 1

12 May, 2002 1

IP Routing

2 12 May, 2002 The Computer Communications Course

Subnetting: Subnet Addressing

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  • 10

network id

subnet id host id 31

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SLIDE 2

3 12 May, 2002 The Computer Communications Course

Subnets in Routing Tables

  • 4

12 May, 2002 The Computer Communications Course

Forwarding Procedure

Let Let p p be incoming IP packet be incoming IP packet for each for each entry entry e e in the routing table: in the routing table: if if ( (p.dest_addr p.dest_addr & & e.subnet_mask e.subnet_mask == == e.network_address e.network_address) ) then then if if ( (e.next_hop e.next_hop == ==

direct

direct

)

) then then use direct delivery use direct delivery else else forward the packet to forward the packet to e.next_hop e.next_hop

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SLIDE 3

5 12 May, 2002 The Computer Communications Course

Example IP Network with Subnetworks

FDDI

Backbone 142.18.1.X

142.18.3.9 142.18.3.53 142.18.3.13 142.18.2.4 142.18.2.7 142.18.2.23 142.18.1.3 142.18.1.13 142.18.1.1

The INTERNET

Subnet 142.18.3.X Subnet 142.18.2.X

142.18.3.3 142.18.2.13

6 12 May, 2002 The Computer Communications Course

Supernetting

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✁
  • A

B C

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SLIDE 4

7 12 May, 2002 The Computer Communications Course

CIDR Address Allocation

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  • 8

12 May, 2002 The Computer Communications Course

CIDR Address Allocation: Example

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SLIDE 5

9 12 May, 2002 The Computer Communications Course

CIDR Address Allocation: Example (II)

194.0.0.0 194.255.255.255

194.24.0.0 194.24.7.255 194.24.8.0 194.24.11.255 194.24.16.0 194.24.31.255 2048 1024 1024 4096

Cambridge E d i n b u r g O x f

  • r

d 10 12 May, 2002 The Computer Communications Course

CIDR Address Representation: Example

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SLIDE 6

11 12 May, 2002 The Computer Communications Course

CIDR Routing Tables

  • 12

12 May, 2002 The Computer Communications Course

CIDR Forwarding Procedure

Let Let p p be incoming IP packet be incoming IP packet for each for each entry entry e e in the routing table: in the routing table: if if ( (p. p.dest dest_ _addr addr & & e.mask e.mask == == e.lowest_block_address e.lowest_block_address) ) then then if if ( (

longest match

longest match

)

) then then if if ( (e.next_hop e.next_hop == ==

direct

direct

)

) then then use direct delivery use direct delivery else else forward the packet to forward the packet to e.next_hop e.next_hop

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SLIDE 7

13 12 May, 2002 The Computer Communications Course

CIDR Forwarding Example

Great Britain France

Oxford

R1

R12 R11 R10

R101

194.0.0.0 255.0.0.0 R11 195.0.0.0 255.0.0.0 R12 194.24.16.0 255.255.240.0 R10

Routing table of R1:

14 12 May, 2002 The Computer Communications Course

CIDR Forwarding Example (II)

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slide-8
SLIDE 8

15 12 May, 2002 The Computer Communications Course

IPv6: the Long-term Solution

  • Addresses are 16 bytes (128 bits)

Addresses are 16 bytes (128 bits)

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convention: 8000:0000:0000:0000:0123:4567:89AB:CDEF convention: 8000:0000:0000:0000:0123:4567:89AB:CDEF

  • ::132.65.200.21 for IPv4

::132.65.200.21 for IPv4

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more than 1500 addresses for each m more than 1500 addresses for each m2

2 of surface area on the

  • f surface area on the

planet (an address to every car, or even to every wheel planet (an address to every car, or even to every wheel… …) )

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The IP header is doubled from 20 to 40 bytes The IP header is doubled from 20 to 40 bytes

  • Three type of addresses:

Three type of addresses:

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provider/geographically oriented provider/geographically oriented unicast unicast

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anycast anycast: corresponds to more than one interface : corresponds to more than one interface

  • a packet sent to such address should be received by one of

a packet sent to such address should be received by one of the interfaces sharing the address the interfaces sharing the address

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multicast with support for multicast with support for scoping scoping

  • Interoperability with IPv4

Interoperability with IPv4