1. Module 3: Designing IP Addressing

2. Module Overview Designing an IPv4 Addressing Scheme Designing DHCP Implementation Designing DHCP Configuration Options Designing an IPv6 Addressing Scheme Designing an IPv6 Transition

3. Lesson 1: Designing an IPv4 Addressing Scheme Considerations for Determining Hosts per Subnet Considerations for Determining Number of Subnets Guidelines for Designing IPv4 Addressing

4. Considerations for Determining Hosts per Subnet When determining the number of hosts per subnet, consider: All devices on each subnet, including routers Network design specifications Router and switch performance Future growth  The 2 n -2 method to determine host bits required for hosts

5. Considerations for Determining Number of Subnets When determining the number of subnets, consider: WAN locations  Security zones within each location Capacity on each segment Future growth  The 2 n method to determine the number of bits required for subnets

6. Guidelines for Designing IPv4 Addressing Use classless routing protocols Use variable-length subnetting to divide IP ranges Use supernetting to combine IP ranges Use public addresses only when a host needs to be connected directly to the Internet Use classless IP addressing Use private addresses if you use an indirect connection to the Internet, such as a proxy server or NAT

7. Lesson 2: Designing DHCP Infrastructure Options for Automatic IP Address Assignment DHCP Communication Process Design Options for DHCP Server Methods for Improving DHCP Server Availability Securing DHCP Servers Guidelines for Designing DHCP Infrastructure

8. Options for Automatic IPv4 Address Assignment OptionDescription DHCP IP address and configuration options are delivered by a DHCP server APIPA Generates a 169.254.x.x address when a DHCP server cannot be contacted Not suitable for domains or Internet access Alternate IP Uses an alternate configuration with options when a DHCP server cannot be contacted Useful for roaming users in some cases

9. DHCP Communication Process DHCP clients and servers communicate with broadcast messages  Broadcast messages by default do not cross routers By default, a DHCP server is required on each subnet Use DHCP relays to allow a centralized DHCP server to service DHCP clients

10. Methods for Improving DHCP Server Availability Redundancy option Details Split scope Divides DHCP scopes between multiple DHCP servers 80:20 rule: one DCHP server provides 80% of the address range; the second server provides 20% Failover clustering Allows two or more physical servers to be managed as a single, logical server Clustering enables a local method of failover, which achieves greater fault tolerance Standby server Gets activated only when need arises Requires manual administration to ensure failover

11. Securing DHCP Servers DHCP authorization :  Prevents unauthorized Windows servers from running the DHCP service  Does not stop rogue DHCP servers running other operating systems  Enterprise Administrators can authorize a DHCP server Windows-based groups :  DHCP Administrators local group has permission to configure DHCP servers  Server Operators and Administrators can also configure DHCP servers  DHCP Users local group has permission to read DHCP server configuration

12. Guidelines for Designing DHCP Infrastructure In virtualization scenarios, consider using the internal DHCP server For a combined DHCP infrastructure, base DHCP server locations on the physical characteristics of the LAN or WAN infrastructure Provide high availability for DHCP Limit each DHCP server to 1,000 scopes DHCP servers have low resource utilization and are good candidates for virtualization

13. Lesson 3: Designing DHCP Configuration Options Using Superscopes in DHCP Infrastructure Using Reservations in DHCP Infrastructure

14. Superscopes in DHCP Infrastructure Superscopes:  Are used when two subnets are present on the same physical segment  Configure the DHCP to recognize the two subnets as a single physical segment  Ensure that only one DHCP response is sent instead of one DHCP response for each subnet  Reduce DHCP-related network traffic

15. Using Reservations in DHCP Infrastructure Reservations:  Link a specific IP address with a specific MAC address  Are an alternative to static IP addresses  Are easier to manage and modify than static IP addresses  Can be used for printers to hosts with associated firewall rules

16. Lesson 4: Designing an IPv6 Addressing Scheme Benefits of IPv6 IPv6 Address Types Guidelines for Designing an IPv6 Addressing Scheme

17. Benefits of IPv6 Some benefits of IPv6 are:  Larger address space  Hierarchical design for routing efficiency  Includes support for IPsec  Includes support for Quality of Service  Stateful and stateless address configuration  New extensible header format that minimizes overhead  Neighbor Discovery replaces ARP broadcasts

18. IPv6 Address Types Address TypeDescription Global unicast Equivalent to public IPv4 addresses Link-Local unicast Automatically assigned to each host for communication on the local subnet Unique local unicast Equivalent to IPv4 private addresses Site local unicast Similar to unique local but depreciated Multicast Equivalent to IPv4 multicast with an additional scope option Anycast A unicast address that has been assigned to multiple computers

19. Guidelines for Designing an IPv6 Addressing Scheme  Be aware that most older applications do not support IPv6  Use a hierarchical design for routing efficiency  Obtain a global unicast IPv6 address to communicate on the IPv6 Internet  Do not use the global ID of a unique local address for subnetting  Randomly generate the global ID of a unique local address  Use stateless autoconfiguration to simplify address assignment  Use DHCPv6 to assign additional configuration options such as DNS servers