73 lines
4.8 KiB
HTML
73 lines
4.8 KiB
HTML
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<?xml version="1.0" encoding="UTF-8"?>
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<!DOCTYPE html
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PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<html lang="en-us" xml:lang="en-us">
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
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<meta name="security" content="public" />
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<meta name="Robots" content="index,follow" />
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<meta http-equiv="PICS-Label" content='(PICS-1.1 "http://www.icra.org/ratingsv02.html" l gen true r (cz 1 lz 1 nz 1 oz 1 vz 1) "http://www.rsac.org/ratingsv01.html" l gen true r (n 0 s 0 v 0 l 0) "http://www.classify.org/safesurf/" l gen true r (SS~~000 1))' />
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<meta name="DC.Type" content="concept" />
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<meta name="DC.Title" content="Problem: Duplicate IP address assignments on the same network" />
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<meta name="abstract" content="An IP address should be unique across your network. The DHCP server cannot assign a single IP address to more than one client." />
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<meta name="description" content="An IP address should be unique across your network. The DHCP server cannot assign a single IP address to more than one client." />
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<meta name="DC.Relation" scheme="URI" content="rzakgtroubleshooting.htm" />
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<meta name="DC.Relation" scheme="URI" content="rzakgmanaging.htm" />
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<meta name="copyright" content="(C) Copyright IBM Corporation 2004, 2006" />
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<meta name="DC.Rights.Owner" content="(C) Copyright IBM Corporation 2004, 2006" />
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<meta name="DC.Format" content="XHTML" />
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<meta name="DC.Identifier" content="rzakgproblemdupip" />
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<meta name="DC.Language" content="en-us" />
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<!-- All rights reserved. Licensed Materials Property of IBM -->
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<!-- US Government Users Restricted Rights -->
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<!-- Use, duplication or disclosure restricted by -->
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<!-- GSA ADP Schedule Contract with IBM Corp. -->
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<link rel="stylesheet" type="text/css" href="./ibmdita.css" />
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<link rel="stylesheet" type="text/css" href="./ic.css" />
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<title>Problem: Duplicate IP address assignments on the same network</title>
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</head>
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<body id="rzakgproblemdupip"><a name="rzakgproblemdupip"><!-- --></a>
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<!-- Java sync-link --><script language="Javascript" src="../rzahg/synch.js" type="text/javascript"></script>
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<h1 class="topictitle1">Problem: Duplicate IP address assignments on the same network</h1>
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<div><p>An IP address should be unique across your network. The DHCP server
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cannot assign a single IP address to more than one client.</p>
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<p>Under certain conditions, the DHCP server will attempt to verify that an
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address is not currently in use before it assigns it to a client. When the
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DHCP server detects that an address is being used when it should not be, it
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will temporarily mark that address as used and will not assign that address
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to any client. You can use the DHCP Server Monitor to view which IP addresses
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the server has detected are in use but were not assigned by the DHCP server.
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These addresses will have a USED status and a UNKNOWN_TO_IBMDHCP client identifier.</p>
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<p>Here are some common reasons for this problem.</p>
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<dl><dt class="dlterm">Multiple DHCP servers are configured to assign the same IP address.</dt>
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<dd>If two DHCP servers are configured to assign the same IP address to clients,
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then it is possible for two different clients to receive the same IP address.
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One of the clients will receive the IP address from one of the DHCP servers,
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and another client will receive the same IP address from the other DHCP server.
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Multiple DHCP servers can serve the same subnet or network, but they should
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not be configured with the same address pool or overlapping address pools.</dd>
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</dl>
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<dl><dt class="dlterm">A client has been manually configured with an IP address which is managed
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by DHCP.</dt>
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<dd> The DHCP server typically attempts to verify whether an
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IP address is currently in use before assigning it to a client. However, there
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is no guarantee that the manually configured client is currently connected
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to the network or available to respond when the DHCP server is verifying the
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IP address. So, the DHCP server might assign the IP address to a DHCP client.
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When the manually configured client connects to the network, you will have
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duplicate IP addresses on your network. IP addresses that are managed by DHCP
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should not be used to manually configure the network setup for a client. If
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a client needs to be manually configured with an IP address, that IP address
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should be excluded from the DHCP server's address pool.</dd>
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</dl>
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</div>
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<div>
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<div class="familylinks">
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<div class="parentlink"><strong>Parent topic:</strong> <a href="rzakgtroubleshooting.htm" title="You can view job log and trace data, as well as use troubleshooting lists for common problems.">Troubleshoot DHCP</a></div>
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</div>
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<div class="relconcepts"><strong>Related concepts</strong><br />
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<div><a href="rzakgmanaging.htm" title="The DHCP Server Monitor can help you to monitor and manage leases.">Manage leased IP addresses</a></div>
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</div>
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</div>
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</body>
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</html>
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