Exam: 640-802
Exam Objective: Configure, verify and troubleshoot DHCP and DNS operation on a router.(including: CLI/SDM)
Contents
- Introduction
- Technology Background
- Lab Scenario
- Lab Objectives
- Lab Solution
Introduction
This lab will cover
the configuration and verification of DHCP and DNS in a Cisco network.
This is an advanced lab for a CCNA student, as there is now walkthrough
and you are on your own to configure the network according to the
objectives using only the comments and tips for help. At the end of the
lab the completed configurations and verifications "show" commands are
provided. Again, this is a somewhat complex lab for a CCNA student but
try to complete the tasks shown on your own using your own lab.
Lab Topics Covered:
- Frame Relay
- Frame Relay Multipoint
- DHCP server
- DHCP pool
- DHCP Exclude
- DHCP DNS server
- DHCP Lease
- DCHP Database storage
- DCHP Client
- OSPF
- OSPF multipoint
Technology Background
DHCP is build upon BootP, and BootP remains an internal part of DHCP.
Both protocols have been created to provide IP addresses to clients
when needed. The difference between them is that while BootP provides an
IP address to a client according to the client's hardware address on
the BootP server table, DHCP by default provides an IP address
automatically to the client from a pool of IP addresses.
Besides an IP address, the DHCP server can provide the client a lot
of information, such as DNS server IP address, Default gateway IP
address, Domain name and much more.
A Cisco IOS device can be configured to act as:
- a DHCP server - by providing IP addresses when requested to do so
- a DHCP client - when it requests an IP address
- a DHCP relay agent - when it captures IP requests from clients,
adds extra information to the request for user identification purposes,
and forwards the request to the DHCP server
Cisco IOS devices can be configured to act as all of the above and
even in combinations of two or three of roles. The Cisco IOS DHCP Server
feature is a full DHCP Server implementation that assigns and manages
IP addresses from specified address pools within the router to DHCP
clients. If the Cisco IOS DHCP Server cannot satisfy a DHCP request from
its own database, it can forward the request to one or more secondary
DHCP Servers defined by the network administrator.
Lab Scenario
For this lab, the following network topology will be used.
Lab Objectives
Lab Configuration Tasks:
- Set up the network as shown in the diagram using the IP
addresses specified. Configure the frame relay network so that TK3 is
the hub using DLCI 311, 322, and 344 going to routers TK1, TK2, and
TK4. Use subinterfaces on TK1, TK2, TK3, and TK4. Use IP subnet
172.16.123.0/24 with the router number used as the 4th octet. Ensure
that only the DLCI's specified here are used.
- Configure router TK4 as a DHCP server. Create a pool for the
172.16.136.0/25 subnet. Allow the entire subnet but exclude IP
addresses 1-10 and 15. Configure it so that hosts use the DNS servers
at 10.2.6.253 and 10.2.6.254 and with a DHCP lease time of 8 hours.
- Configure TK4 to send the DHCP database information via TFTP to
10.2.6.264, while delaying the writing of records for 10 minutes.
- Configure OSPF in the network in any manner as you wish, as long as
all networks are reachable. For the frame relay cloud, do not use the
broadcast network type on any of the frame relay interfaces.
- Configure the Catalyst switch so that it gets it's IP address from
the DHCP server. Ensure that this switch always gets the IP address
172.16.136.15 and supply the switch with the DNS server and default
gateway information specified in task 2.
Comments and Tips:
Task 1: Not Applicable
Task 2: Routers can be configured to forward DHCP broadcasts (via the
IP helper-address command) or to respond to these requests as a DHCP
server.
Task 3: A DHCP database agent should be configured for this, or the DHCP conflict resolution should be disabled.
Task 4: The network type will need to be changed on each of the frame relay interfaces of the routers.
Task 5: The Catalyst switch will first broadcast for a DHCP server
and then it will RARP. If nothing is received after 10 minutes the
switch will retain the 0.0.0.0 IP address. Remember, by default UDP
broadcasts are not forwarded by routers. Once the switch receives an IP
address it will be written into the configuration.
Lab Solution
Technical Verification For Task 1:
TK1#sho frame map
Serial1/0.1(up): point-to-point dlci, dlci 113(0*71,0*1C10), broadcast
Status defined, active
TK2#sho frame map
Serial 1/0.1 (up): point-to-point dlci, dlci 223(0*DF, 0*34F0), broadcast
Status defined, active
TK3#sho frame map
Serial1/0.1(up): ip 172.16.123.1 dlci 311(0*137, 0*4C70), static,
broadcast,
CISCO, status defined, active
Serial1/0(up): ip 172.16.123.1 dlci 322(0*124, 0*5020), static,
broadcast,
CISCO, status defined, active
Serial1/0(up): ip 172.16.123.4 dlci 344(0*158, 0*5480), static,
broadcast,
CISCO, status defined, active
TK4#sho frame map
Serial0/0.1(up): point-to-point dlci, dlci 443(0*1BB, 0*6CB0), broadcast
Status defined, active
Technical Verification For Task 2:
(Note: This show command was issued after completion of exercise E.)
TK4#sho ip dhcp server st
Memory usage 15644
Address pools 2
Database agents 1
Automatic bindings 0
Manual bindings 1
Expired bindings 0
Malformed messages 0
Message Received
BOOTREQUEST 0
DHCPDISCOVER 1
DHCPREQUEST 1
DHCPDECLINE 0
DHCPRELEASE 0
DHCPINFORM 0
Message Sent
BOOTRELAY 0
DHCPOFFER 1
DHCPACK 1
DHCPNAK 0
Technical Verification for Task 3:
TK4#sho ip dhcp database
URL:tftp://10.2.6.254
Read: Never
Written: Never
Status: Nothing to report.
Delay: 600 seconds
Timeout: 300 seconds
Failures: 0
Successes: 0
Technical Verification For Task 4:
TK1#sho ip ospf interface
Loopback0 is up, line protocol is up
Internet address 192.168.1.1/24, area 1
Process ID 1, Router ID 192.168.1.1, Network type LOOPBACK, Cost: 1
Loopback interface is treated as a stub Host
Serial1/0.1 is up, line protocol is up
Internet address 172.16.123.1/24, Area 0
Process ID 1, Router ID 192.168.1.1, Network Type POINT_TO_MULTIPOINT, Cost: 48
Transmit delay is 1 sec, State POINT_TO_MULTIPOINT,
Timer intervals configured, Hello 30, Dead 120, Wait 120, Retransmit 5
Hello due in 00:00:17
Index 1/5, flood queue length 0
Next 0*0(0)/0*0(0)
Last flood scan length is 1, maximum is 5
Last flood scan time is 0 msec, maximum is 0 msec
Neighbor Count is 1, Adjacent neighbor count is 1
Adjacent with neighbor 192.168.3.3
Suppress hello for 0 neighbor(s)
TK2#sho ip ospf interface
Loopback0 is up, line protocol is up
Internet address 192.168.2.2/24, Area 2
Process ID, Router ID 192.168.2.2, Network Type LOOPBACK, Cost: 1
Loopback interface is treated as a stub Host
Serail1/0.1 up, line protocol is up
Internet address 172.16.123.2/24, area 0
Process ID 1, Router ID 192.168.2.2, Network Type POINT_TO_MULTIPOINT, Cost: 48
Transmit Delay is 1 sec, State POINT_TO_MULTIPOINT,
Timer intervals configured, Hello 30, Dead 120, wait 120, Retransmit 5
Hello due in 00:00:29
Index , flood length 0
Next 0*0(0)/0*0(0)
Last flood scan length is 1, maximum is 1
Last flood scan time is 0 msec, maximum is 0 msec
Neighbor Count is 1, Adjacent neighbor 192.168.3.3
Suppress hello for 0 neighbor(s)
TK3#sho ip ospf interface
Ethernet0/0 is up, line protocol is up
Internet address 172.16.136.3/26, Area 0
Internet ID 1, Router ID 192.168.3.3, Network Type BROADCAST, Cost: 10
Transmit Delay is 1 sec, State DR, Priority 1
Designation router (ID) 192.168.1.1, Interface address 172.16.136.1
Backup designation router (ID) 192.168.3.3, Interface address 172.16.136.3
Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
Hello due in 00:00:07
Index1/1, flood queue length 0
Next 0*0(0)/0*0(0)
Last flood scan length is1, maximum is 5
Last flood scan time is 0 msec, maximum is 0 msec
Neighbor count is 3, Adjacent neighbor count is 3
Adjacent with neighbor 192.168.6.6
Adjacent with neighbor 192.168.5.5
Adjacent with neighbor 192.168.1.1 (Designation Router)
Suppress hello for 0 neighbor(s)
Loopback0 is up, line protocol is up
Internet address 192.168.1.1/24, Area 1
Process ID 1, Router ID 192.168.3.3, Network type LOOPBACK, Cost: 1
Loopback interface is treated as a stub Host
Serial1/0.1 is up, line protocol is up
Internet address 172.16.123.3/24, Area 0
Process ID 1, Router ID 192.168.3.3, Network Type POINT_TO_MULTIPOINT, Cost: 781
Transmit delay is 1 sec, State POINT_TO_MULTIPOINT,
Timer intervals configured, Hello 30, Dead 120, Wait 120, Retransmit 5
Hello due in 00:00:04
Next 0*0(0)/0*0(0)
Index 1/5, flood queue length 0
Last flood scan length is 1, maximum is 5
Last flood scan time is 0 msec, maximum is 0 msec
Neighbor Count is 1, Adjacent neighbor count is 3
Adjacent with neighbor 192.168.4.4
Adjacent with neighbor 192.168.1.1
Adjacent with neighbor 192.168.2.2
Suppress hello for 0 neighbor(s)
TK4#sho ip ospf interface
Loopback0 is up, line protocol is up
Internet address 192.168.4.4/24, Area 4
Process ID 1, Router ID 192.168.4.4, Network type LOOPBACK, Cost: 1
Loopback interface is treated as a stub Host
Serail1/0.1 up, line protocol is up
Internet address 172.16.123.4/24, Area 0
Process ID 1, Router ID 192.168.4.4, Network Type POINT_TO_MULTIPOINT, Cost: 64
Transmit Delay is 1 sec, State POINT_TO_MULTIPOINT,
Timer intervals configured, Hello 30, Dead 120, wait 120, Retransmit 5
Hello due in 00:00:17
Index , flood length 0
Next 0*0(0)/0*0(0)
Last flood scan length is 1, maximum is 1
Last flood scan time is 0 msec, maximum is 0 msec
Neighbor Count is 1, Adjacent neighbor 192.168.3.3
Suppress hello for 0 neighbor(s)
TK4#
Technical Verification For Task 5:
Console>(enable)set interface sc0 dhcp renew
Renewing IP address...
Console>(enable) sending RARP request with 00:09:2b:a3:bf:ff
Sending DHCP packet with address: 00:09:2b:a3:bf:ff
Sending DHCP packet with address: 00:09:2b:a3:bf:ff
10.2.6.254 added to DNS server table as primary server.
10.2.6.253 added to DNS server table as backup server.
System name set.
Default DNS domain name set to Test1.net
2002 Mar 06: 20:32:05%MGMT-5-DHCP_S:Assigned IP address 172.16.136.15 from DHCP
Server 172.16.123.4
TKCAT>(enable) sho interf
s10: flags=51<UP, POINTOPOINT, RUNNING>
Slip 0.0.0.0dest 0.0.0.0
sc0: flags=63<UP, POINTOPOINT, RUNNING>
vlan 1 inet 172.16.136.15 network 255.255.255.128 broadcast 172.16.136.127
dhcp server: 172.16.123.4
TKCAT>(enable)
Configuration Verification:
Note: Only the relevant portions of the configuration have been included.
Router 1:
TK1#sho run
!
hostname TK1
!
!
interface Loopback0
ip address 192.168.1.1 255.255.255.0
!
interface Ethernet0/0
ip address 172.16.15.1 255.255.255.192
half-duplex
!
interface Serial1/0
no ip address
encapsulation fram-relay
no frame-relay inverse-arp
!
interface Serial1/0.1 point-to-point
ip address 172.16.123.1 255.255.255.0
ip ospf network point-to- multipoint
frame-relay interface-dlci 113
!
router ospf 1
log-adjacency-changes
network 172.16.0.0.0.0.255.255 area 0
network 192.168.1.0.0.0.0.255 area 1
!
!
end
Router 2:
TK2#sho run
!
hostname TK2
!
!
interface Loopback0
ip address 192.168.2.2 255.255.255.0
!
interface Serial1/0
encapsulation frame-relay
no frame-relay inverse-arp
!
interface Serial1/0.1 point-to-point
ip address 172.16.123.2 255.255.255.0
ip ospf network point-to- multipoint
frame-relay interface-dlci 223
!
router ospf 1
log-adjacency-changes
network 172.16.123.0.0.0.0.255 area 0
network 192.168.2.0.0.0.0.255 area 2
!
!
end
Router 3:
TK3#sho run
hostname TK3
!
!
interface Loopback0
ip address 192.168.3.3 255.255.255.0
!
interface Ethernet0/0
ip address 172.16.136.3 255.255.255.192
ip helper-address 172.16.123.4
!
interface Serial1/0
no ip address
encapsulation frame-relay
no frame-relay inverse-arp
!
interface serial1/0.1 multipoint
ip address 172.16.123.3 255.255.255.0
frame-relay interface-dlci 311
frame-relay interface-dlci 322
frame-relay interface-dlci 344
!
router ospf 1
log-adjacency-changes
network 172.16.136.0.0.0.0.255 area 0
network 192.168.3.0.0.0.0.255 area 3
!
!
end
Router 4:
TK4#sho run
!
hostname TK4
!
ip dhcp database tftp://10.2.6.254 write-delay 600
ip dhcp excluded-address 172.16.136.10
ip dhcp excluded-address 172.16.136.15
ip shcp ping packet 4
!
ip shcp pool Test1
network 172.16.136.0 255.255.255.128
domain-name Test1.net
default-router 172.16.136.3
option 66 ip 10.2.6.136.3
netbios-node-type-h-hode
dns-server 10.2.6.254 10.2.6.254
lease 0 8
!
ip dhcp pool cat
!
!
!
!
interface Loopback0
ip address 192.168.4.4 255.255.255.0
!
interface Ethernet0/0
ip address 10.1.4.4 255.255.252.0
!
interface Serial0/0
no ip address
encapsulation frame-relay
no frame-relay inverse-arp
!
interface Serial0/0.1 point-to-point
ip address 172.16.123.4 255.255.255.0
ip ospf network point-to- multipoint
frame-relay interface-dlci 443
!
!
router ospf 1
log-adjacency-changes
network 172.16.123.0.0.0.0.255 area 0
network 192.168.4.0.0.0.0.255 area 4
network 10.1.4.0 0.0.0.255 area 44
!
!
end
Catalyst:
TKCAT>(enable) sho run
!
#ip
#learn from dhcp server 172.16.123.4
interface sc0 1 172.16.136.15 255.255.255.192
set ip route 0.0.0.0/0.0.0.0 172.16.136.3
!
#dns
set ip dns server 10.2.6.254 primary
set dns server 10.2.6.253
set ip dns domain Testking.com
!
References:
Understanding DHCP And DNS
http://www.cisco.com/en/US/prod/collateral/iosswrel/ps6537/ps6554/ps6600/ps6641/prod_presentation0900aecd803116a7.pdf
Configuring DHCP
http://www.cisco.com/en/US/docs/ios/12_2/ip/configuration/guide/1cfdhcp.html
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