Artigo: 314067 - Ver produtos para os quais este artigo se aplica.
This article was previously published under Q314067
For a Microsoft Windows 2000 version of this article, see 102908
There are tools that can provide useful information when you are trying to determine the cause of TCP/IP networking problems under Microsoft Windows XP. This article lists recommendations for using these tools to diagnose network problems. Although this list is not complete, the list does provide examples that show how you can use these tools to track down problems on the network.
You can also start the Network Diagnostics interface directly by using the following command:
netsh diag gui
To use the IPConfig tool to verify the TCP/IP configuration on the computer that is experiencing the problem, click Start, click Run, and then type cmd. You can now use the ipconfig command to determine the host computer configuration information, including the IP address, the subnet mask, and the default gateway.
The /all parameter for IPConfig generates a detailed configuration report for all interfaces, including any remote access adapters. You can redirect IPConfig output to a file to paste the output into other documents. To do this, type:
ipconfig > \folder_name\file_nameThe output receives the specified file name and is stored in the specified folder.
You can review the IPConfig output to identify issues that exist in the computer network configuration. For example, if a computer is manually configured with an IP address that duplicates an existing IP address that is already detected, the subnet mask appears as 0.0.0.0.
If your local IP address is returned as 169.254.y.z with a subnet mask of 255.255.0.0, the IP address was assigned by the Automatic Private IP Addressing (APIPA) feature of Windows XP Professional. This assignment means that TCP/IP is configured for automatic configuration, that no DHCP server was found, and that no alternative configuration is specified. This configuration has no default gateway for the interface.
If your local IP address is returned as 0.0.0.0, the DHCP Media Sensing feature override turned on because the network adapter detected its lack of connection to a network, or TCP/IP detected an IP address that duplicates a manually configured IP address.
If you do not identify any issues in the TCP/IP configuration, go to Method 2.
If you do not identify any issues in the TCP/IP configuration, determine whether the computer can connect to other host computers on the TCP/IP network. To do this, use the Ping tool.
The Ping tool helps you verify IP-level connectivity. The ping command sends an ICMP Echo Request message to a destination host. Use Ping whenever you want to verify that a host computer can send IP packets to a destination host. You can also use Ping to isolate network hardware problems and incompatible configurations.
Note If you ran the ipconfig /all command, and the IP configuration appeared, you do not have to ping the loopback address and your own IP address. IPConfig has already performed these tasks to display the configuration. When you troubleshoot, verify that a route exists between the local computer and a network host. To do this, use the following command:
ping IP addressNoteIP address is the IP address of the network host that you want to connect to.
To use the ping command, follow these steps:
The PathPing tool detects packet loss over multiple-hop paths. Run a PathPing analysis to a remote host to verify that the routers on the way to the destination are operating correctly. To do this, type the following command:
pathping IP address of remote host
If you can ping both the loopback address (127.0.0.1) and your IP address but you cannot ping any other IP addresses, use the Arp tool to clear out the Address Resolution Protocol (ARP) cache. To view the cache entries, type any one of the following commands:
arp -aTo delete the entries, type the following command:
arp -d IP addressTo flush the ARP cache, type the following command:
netsh interface ip delete arpcache
The gateway address must be on the same network as the local host. Otherwise, messages from the host computer cannot be forwarded outside the local network. If the gateway address is on the same network as the local host, make sure that the default gateway address is correct. Make sure that the default gateway is a router, not just a host. And make sure that the router is enabled to forward IP datagrams.
If the default gateway responds correctly, ping a remote host to make sure that network-to-network communications are working correctly. If communications are not working correctly, use the Tracert tool to trace the path of the destination. For IP routers that are Microsoft Windows 2000-based or Microsoft Windows NT 4.0-based computers, use the Route tool or the Routing and Remote Access snap-in to view the IP routing table. For other IP routers, use the vendor-designated appropriate tool or facility to examine the IP routing table.
Most frequently, you receive the following four error messages when you use Ping during troubleshooting:
This error message means that the number of required hops exceeds the Time to Live (TTL). To increase TTL, by use the ping -i command. A routing loop may exist. Use the Tracert command to determine whether misconfigured routers have caused a routing loop.
TTL Expired in Transit
This error message means that no local or remote route exists for a destination host at the sending host or at a router. Troubleshoot the local host or the router's routing table.
Destination Host Unreachable
This error message means that the Echo Reply messages were not received in the designated timeout period. By default, the designated timeout period is four seconds. Use the ping -w command to increase the timeout.
Request Timed Out
This error message means that the destination host name cannot be resolved. Verify the name and the availability of DNS or WINS servers.
Ping request could not find host
IPSec can improve security on a network, but changing network configurations or troubleshooting problems more difficult. Sometimes, IPSec policies require secured communication on a Windows XP Professional-based computer. These requirements can make it difficult to connect to a remote host. If IPSec is implemented locally, you can turn off the IPSEC Services service in the Services snap-in.
If the difficulties end when you stop the IPSec services, IPSec policies are either blocking the traffic or requiring security for the traffic. Ask the security administrator to modify the IPSec policy.
Because of mistakes in packet filtering, address resolution or connectivity may not work. To determine whether packet filtering is the source of a network problem, turn off TCP/IP packet filtering. To do this, follow these steps:
To determine the cause of connectivity problems when you are trying to connect to a specific server through NetBIOS-based connections, use the nbtstat -n command on the server to determine what name the server registered on the network.
The nbtstat -n output command lists several names that the computer has registered. The list will include a name that looks similar to the computer's name that is configured on the Computer Name tab under System in Control Panel. If not, try one of the other unique names that the nbtstat command displays.
The Nbtstat tool can also display the cached entries for remote computers from #PRE entries in the Lmhosts file or from recently resolved names. If the name that the remote computers are using for the server is the same, and the other computers are on a remote subnet, make sure that the other computers have the computer's name-to-address mapping in their Lmhosts files or WINS servers.
To determine why a TCP/IP connection to a remote computer stops responding, use the netstat -a command to show the status of all activity for TCP and UDP ports on the local computer.
Typically, a good TCP connection shows 0 bytes in the Sent and Received queues. If data is blocked in either queue or the state of the queues is irregular, the connection may be faulty. If data is not blocked, and the state of the queues is typical, you may be experiencing network or program delay.
For two hosts to exchange IP datagrams, both hosts must have a route to each other, or they must use default gateways that have a route. To view the routing table on a Windows XP-based host, type the following command:
Tracert sends ICMP Echo Request messages that have incrementally higher values in the IP header TTL field to determine the path from one host to another through a network. Then Tracert analyzes the ICMP messages that are returned. With Tracert, you can track the path from router to router for up to 30 hops. If a router has failed, or the packet is routed into a loop, Tracert reveals the problem. After you locate the problem router, you can contact the router administrator if the router is offsite, or you can restore the router to fully functional status if the router is under your control.
If you receive the following error message during configuration, determine whether the default gateway is located on the same logical network as the computer's network adapter:
Compare the network ID part of the default gateway IP address with the network IDs of the computer's network adapters. Specifically, verify that the bitwise logical AND of the IP address and the subnet mask equals the bitwise logical AND of the default gateway and the subnet mask.
Your default gateway does not belong to one of the configured interfaces
For example, a computer that has a single network adapter that is configured with an IP address of 172.16.27.139 and a subnet mask of 255.255.0.0 must use a default gateway of the form 172.16.y.z. The network ID for this IP interface is 172.16.0.0.
See the "Configuring TCP/IP" topic in the documentation for the Microsoft Windows XP Professional Resource Kit.
See "Introduction to TCP/IP" in the TCP/IP Core Networking Guide of the Microsoft Windows 2000 Server Resource Kit for general information about the TCP/IP protocol suite.
See "Unicast Routing Overview" in the Internetworking Guide of the Microsoft Windows 2000 Server Resource Kit for more information about routing principles.
See "TCP/IP Troubleshooting" in the TCP/IP Core Networking Guide of the Microsoft Windows 2000 Server Resource Kit for more information about IP packet filtering.
For additional information, click the following article numbers to view the articles in the Microsoft Knowledge Base:
(http://support.microsoft.com/kb/308007/ )How to troubleshoot home networking in Windows XP
(http://support.microsoft.com/kb/325487/ )How to troubleshoot network connectivity problems
(http://support.microsoft.com/kb/299357/ )How to reset Internet Protocol (TCP/IP) in Windows XP
(http://support.microsoft.com/kb/307874/ )How to disable simplified sharing and set permissions on a shared folder in Windows XP
(http://support.microsoft.com/kb/810881/ )"Access is denied" error message when you try to open a folder
(http://support.microsoft.com/kb/214759/ )Access denied error when attempting to connect to a network share
(http://go.microsoft.com/fwlink/?LinkId=151500)for other considerations.
Artigo: 314067 - Última revisão: quarta-feira, 22 de maio de 2013 - Revisão: 1.0
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