CCNA Discovery 2 - Chapter 4

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CCNA Discovery 2 - Chapter 4

  1. 1. Planning the Addressing Structure Working at a Small-to-Medium Business or ISP – Chapter 4Version 4.1 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public 1
  2. 2. Objectives Describe how IP Addressing is implemented in the LAN. Subnet a given network to allow for efficient use of IP address space. Explain how Network Address Translation (NAT) and Port Address Translation (PAT) are used in a network. © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public 2
  3. 3. IP Addressing in the LAN IP addressing identifies hosts and network devices IP address format: dotted-decimal notation Hierarchical structure: network and host octets © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public 3
  4. 4. IP Addressing in the LAN Address classes A, B and C: used to identify hosts or networks Address classes D and E: multicast and experimental uses © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public 4
  5. 5. IP Addressing in the LANFirst octet bit patterns and classes: Class A: first bit is always 0 Class B: first two bits are always 1 and 0 Class C: first three bits are always 1, 1 and 0 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public 5
  6. 6. IP Addressing in the LAN Reserved address space for private networks Private IPs are not routable on the Internet Consumer networking devices give out private IPs through DHCP © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public 6
  7. 7. IP Addressing in the LAN RFC 917, Internet Subnets Subnet mask separates network bits from host bits Routers read subnet masks left to right, bit for bit – Bits set to 1 are part of the network ID – Bits set to 0 are part of the host ID © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public 7
  8. 8. IP Addressing in the LANClassful subnetting: Use bits from the host space to designate a subnet ID All resulting subnets use the same subnet ID © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public 8
  9. 9. IP Addressing in the LANClassless subnetting features: CIDR: identify networks based on the number of bits in the network prefix VLSM: divide address space into networks of various sizes © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public 9
  10. 10. IP Addressing in the LANCommunicating between subnets: Each subnet is a separate network Router is needed to communicate between them Each router interface is the default gateway for its subnet © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public 10
  11. 11. NAT and PAT Network address translation (NAT) allows private users to access the Internet by sharing one or more public IP addresses © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public 11
  12. 12. NAT and PAT NAT operation is transparent to users Benefits include improved security and scalability © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public 12
  13. 13. NAT and PAT Inside local network Outside global network © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public 13
  14. 14. NAT and PAT Dynamic NAT assigns outside global addresses from a pre-defined pool Static NAT assigns a permanent registered global IP to an individual private host IP © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public 14
  15. 15. NAT and PAT PAT translates multiple local addresses to a single global IP address © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public 15
  16. 16. NAT and PAT PAT conversations use a unique temporary IP address and port number combination Port numbers above 1024 Maximizes use of addresses and security © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public 16
  17. 17. NAT and PATIP Nat issues: Additional workload to support IP addresses and port translations Careful network design and equipment selection Accurate configuration © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public 17
  18. 18. NAT and PAT Temporary solutions to address depletion: subnetting, private IP addressing, and NAT Improvements proposed by using IPv6: – More address space and better space management – Easier administration – Support for advanced network capabilities © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public 18
  19. 19. NAT and PATIPv6 address notation: 128 bits 32 hexadecimal digits Three-part hierarchy: global prefix, subnet and interface ID © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public 19
  20. 20. Summary IP addressing can be tailored to the needs of the network design through the use of custom subnet masks. Classless subnetting gives classful IP addressing schemes more flexibility through the use of variable length subnet masks. Network Address Translation (NAT) is a way to shield private addresses from outside users. Port Address Translation (PAT) translates multiple local addresses to a single global IP address, maximizing the use of both private and public IP addresses. © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public 20
  21. 21. © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public 21

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