CCNP TSHOOT 6.0 - The Cisco Learning Network
CCNP TSHOOT 6.0 - The Cisco Learning Network
CCNP TSHOOT 6.0 - The Cisco Learning Network
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<strong>CCNP</strong>v6 <strong>TSHOOT</strong><br />
R3(config)#int f0/0<br />
R3(config-if)#no ip helper-address 10.1.2.13<br />
R3(config-if)#<br />
*Nov 20 15:53:29.606: UDP: rcvd src=0.0.0.0(68), dst=255.255.255.255(67), length<br />
=308<br />
*Nov 20 15:53:32.606: UDP: rcvd src=0.0.0.0(68), dst=255.255.255.255(67), length<br />
=308<br />
*Nov 20 15:53:41.610: UDP: rcvd src=0.0.0.0(68), dst=255.255.255.255(67), length<br />
=308<br />
*Nov 20 15:53:57.614: UDP: rcvd src=0.0.0.0(68), dst=255.255.255.255(67), length<br />
=308<br />
R3#<br />
<strong>The</strong> above output shows the DHCP relay agent (R3) messages when a helper address is not configured. <strong>The</strong><br />
UDP packets received are from the DHCP client (the source address is 0.0.0.0 port 68) searching for a DHCP<br />
server (the destination broadcast address is 255.255.255.255 port 67). <strong>The</strong>re are no sent messages to the client<br />
because the broadcast is not forwarded to the DHCP server.<br />
R3(config)#int f0/0<br />
R3(config-if)#ip helper-address 10.1.2.13<br />
R3(config-if)#<br />
*Nov 20 15:54:19.547: Reserved port 67 in Transport Port Agent for UDP IP type 1<br />
*Nov 20 15:54:34.035: UDP: rcvd src=0.0.0.0(68), dst=255.255.255.255(67), length<br />
=308<br />
*Nov 20 15:54:34.035: UDP: sent src=10.1.80.1(67), dst=10.1.2.13(67), length=308<br />
*Nov 20 15:54:3<strong>6.0</strong>43: UDP: rcvd src=10.1.2.13(67), dst=10.1.80.1(67), length=308<br />
*Nov 20 15:54:3<strong>6.0</strong>47: UDP: sent src=0.0.0.0(67), dst=255.255.255.255(68), length<br />
=308<br />
*Nov 20 15:54:3<strong>6.0</strong>47: UDP: rcvd src=0.0.0.0(68), dst=255.255.255.255(67), length<br />
=324<br />
*Nov 20 15:54:3<strong>6.0</strong>47: UDP: sent src=10.1.80.1(67), dst=10.1.2.13(67), length=324<br />
*Nov 20 15:54:3<strong>6.0</strong>51: UDP: rcvd src=10.1.2.13(67), dst=10.1.80.1(67), length=308<br />
*Nov 20 15:54:3<strong>6.0</strong>51: UDP: sent src=0.0.0.0(67), dst=255.255.255.255(68), length<br />
=308<br />
<strong>The</strong> above output shows the DHCP relay agent (R3) messages when a helper address is configured. <strong>The</strong> DHCP<br />
exchange between the server and the client are captured.<br />
DLS2#show ip sockets<br />
Proto Remote Port Local Port In Out Stat TTY OutputIF<br />
17 --listen-- 10.1.200.253 1985 0 0 1001 0<br />
17 10.1.50.1 162 10.1.100.253 62682 0 0 0 0<br />
17 --listen-- 10.1.200.253 1975 0 0 11 0<br />
17 10.1.80.1 67 10.1.200.253 67 0 0 2211 0<br />
17 0.0.0.0 0 10.1.200.253 2228 0 0 211 0<br />
17 --listen-- 10.1.200.253 161 0 0 1 0<br />
17 --listen-- 10.1.200.253 162 0 0 11 0<br />
17 --listen-- 10.1.200.253 55485 0 0 1 0<br />
17 --listen-- --any-- 161 0 0 20001 0<br />
17 --listen-- --any-- 162 0 0 20011 0<br />
17 --listen-- --any-- 61812 0 0 20001 0<br />
17 --listen-- 10.1.200.253 123 0 0 1 0<br />
17 10.1.50.1 514 10.1.100.253 58346 0 0 400201 0<br />
<strong>The</strong> above output displays the current connections for this server. <strong>The</strong> remote connection with R3 Fa0/0<br />
(10.1.80.1) shows that the DHCP server is running on DLS2 and listening for requests on port 67 (DHCP server).<br />
All contents are Copyright © 1992–2010 <strong>Cisco</strong> Systems, Inc. All rights reserved. This document is <strong>Cisco</strong> Public Information. Page 18 of 20
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