Cisco Confidential 1 © 2010 Cisco and/or its affiliates. All rights reserved. CCNA DHCP Deepdive November, 2011 Jaskaran Kalsi & Anton Merckushov Assoc. Technical Managers Europe/CEE/RCIS Cisco Networking Academy

© 2011 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 2 CCNA & DHCP DHCP Overview DHCP Self-paced Learning Interactive Troubleshooting Summary

© 2010 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 3  Provide a brief review of DHCP.  Demonstrate a brief example of how DHCP can be administered.  Provide a brief description of the troubleshooting scenarios that are available.  Provide an overview of the DHCP IPD offering and its components.  Focus on the use of Packet Tracer as a simulation tool and create an interactive session where the audience troubleshoots and pre- configured network.

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Cisco Confidential 5  DHCP is an area that not only students struggle with but also instructors.  DHCP is covered in both CCNA Discovery & Exploration.  CCNA Discovery:  CCNA Discovery 1 - Chapters 5 & 9  CCNA Discovery 2 - Chapters 5 & 9  CCNA Exploration:  CCNA Exploration 1 - Chapter 2  CCNA Exploration 3 - Chapters 2 & 5  CCNA Exploration 4 - Chapter 7  RFC 2131

© 2010 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 6  Purpose of DHCP in a network…  Static vs. Dynamic  DHCP servers and options  DHCP operation  Example of router IOS DHCP configuration with multiple pools  Useful DHCP related IOS show commands  DHCP issues and troubleshooting tips

© 2010 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 7  Manual Addressing (static):  Static IP Addresses are typically assigned to routers, servers, and network printers.  Enables remote administration.  Dynamic Address (using DHCP):  Automates assignment of IP address configuration.  Dynamic IP addresses are typically assigned to PC’s, laptops, and other mobile devices.  Facilitates movement of portable devices on the network.  Reduces administrative burden on network staff and virtually eliminates entry errors.  DHCP can be used to allocate IPv4 as well as IPv6 addresses.

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© 2010 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 9  A DHCP server typically provides DHCP clients with:  IP Address; Subnet Mask; Default Gateway; DNS server(s); & Lease Time.  Benefits of a Network Server providing DHCP:  More scalable than other solutions.  Offloads DHCP function from network devices.  Relatively easy to manage.  Benefits of a Router providing DHCP:  Simple solution for small branch office or wireless home network.  Less costly because a dedicated DHCP server is not required.  Cisco IOS provides a DHCP server in routers and multilayer switches.

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© 2010 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 11  Client broadcasts a Discovery message.  Server responds with a potential IP address offer.  Client sends request to use the suggested address.  Server responds with an acknowledgment.

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© 2010 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 13 R1(config)# ip dhcp excluded-address R1(config)# ip dhcp excluded-address R1(dhcp-config)# ip dhcp pool LAN-POOL-1 R1(dhcp-config)# network R1(dhcp-config)# default-router R1(dhcp-config)# domain-name span.com R1(config)# ip dhcp excluded-address R1(config)# ip dhcp excluded-address R1(dhcp-config)# ip dhcp pool LAN-POOL-2 R1(dhcp-config)# network R1(dhcp-config)# default-router R1(dhcp-config)# domain-name span.com

© 2010 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 14

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© 2010 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 16  Task 1: Resolve IP address conflicts. R2# show ip dhcp conflict IP address Detection Method Detection time Ping Feb :28 PM Gratuitous ARP Feb :12 AM  Task 2: Verify physical connectivity. R2# show interface type/number  Task 3: Configure client with static address and test connectivity.  Task 4: Verify Switch Port Configuration (STP Portfast & Other Commands)

© 2010 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 17  Task 5: Verify DHCP server information with client/server on the same subnet. Issues can include:  Incorrect information being provided by the DHCP server.  Service not enabled on DHCP server.  Client not set up as DHCP client.  Rogue DHCP server in the subnet.  Task 6: Verify DHCP communication between client/server on different subnets. Issues can include:  DHCP relay issues.  IP helper address missing or incorrectly configured.

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Cisco Confidential 19 © 2010 Cisco and/or its affiliates. All rights reserved.

Cisco Confidential 20  Developed by Cisco IPD Team for use by CCNA-level instructors.  Uses a scenario-based trouble ticket problem and resolution approach with Packet Tracer simulations.  Configure/correct problems in order for the network to function.  Helps reinforce an instructor’s understanding of various protocols and technologies, in this case DHCP.  Provides multiple preconfigured PT troubleshooting scenario topologies with good/bad PT files for each trouble tickets.  First two pages of the guides available for each scenario can be used as a student assignment.

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Thank you.