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Reference Link:
http://support.microsoft.com/default.aspx?scid=kb;en-us;325487
How to troubleshoot network connectivity problems
SUMMARY
========
This article describes ways to troubleshoot network connectivity problems.
MORE INFORMATION
====================
Network connectivity problems have various causes but typically occur
because of incorrect network adapters, incorrect switch settings, faulty
hardware, or driver issues. Some connectivity symptoms are intermittent and
do not clearly point to any one of these causes.
Sometimes an operating system upgrade introduces network connectivity
problems. The same network adapter that worked correctly on an earlier or
different operating system, such as Microsoft Windows 98 or Microsoft
Windows 95, may cause problems after an upgrade. Sometimes a server
relocation introduces a connectivity problem.
The most common causes for connectivity problems are:
o Network adapters and switch ports have mismatching duplex levels or
transfer speed settings.
o Network adapters or switches with transmission rates of 10/100 megabits
per second (Mbps) do not switch over correctly. Some autosense settings may
not correctly detect the speed of some network adapters.
o The network adapter is incompatible with the motherboard or other
hardware or software components and drivers.
Typical error messages include the following:
Error 55: "The specified network resource is no longer available"
(ERROR_DEV_NOT_EXIST).
Error 64: "The specified network name is no longer available"
(ERROR_NETNAME_DELETED).
Error 121: "The semaphore timeout period has expired" (ERROR_SEM_TIMEOUT).
Error 1231: "The remote network is not reachable by the transport"
(ERROR_NETWORK_UNREACHABLE).
The client computer's system event logs may show any one of the following
entries:
Type: Warning
Source: MrxSmb
Event ID: 50
Description: {Lost Delayed-Write-Data} The system was attempting to
transfer file data from buffers to \Device\LanmanRedirector. The write
operation failed, and only some of the data may have been written to the
file.
Type: Warning
Source: MrxSmb
Event ID: 3013
Description: The redirector has timed out to ServerName
Type: Warning
Source: MrxSmb
Event ID: 3036
Description: The redirector detected a security signature mismatch. The
connection has been disconnected.
There may be multiple occurrences of the following TCPIP 4201 entry in the
event logs:
Type: Information
Source: TCPIP
Event ID: 4201
Description: The system detected that network adapter Compaq NC6134
Gigabit NIC was connected to the network, and has initiated normal
operation over the network adapter.
A single TCPIP 4201 event is typical after you restart the computer or
after you disable or enable the network adapter.
Troubleshooting
===============
To troubleshoot network connectivity problems, follow these steps:
1. Use the Ping or PathPing command-line tools to test basic connectivity.
Use Ping to isolate network hardware problems and incompatible
configurations. Use PathPing to detect packet loss over multiple-hop trips.
To watch Ping statistics, use the ping -t command. To see statistics and
continue, press CTRL+BREAK. To stop, press CTRL+C. If you detect lost
packets in the statistics output, this indicates networking problems up to
Open Systems Interconnection (OSI) layer 3 (IP-level connectivity).
If the remote system that you ping is across a high-delay link, such as a
satellite link, responses may take longer. Use the -w (wait) switch to
specify a longer time-out.
For more information about using these tools, see the "Test Network
Connection with Ping and PathPing" section in the Microsoft Windows 2000
Server Resource Kit, or see "Testing the Network Connection with Ping and
PathPing" in Chapter 19 of the Microsoft Windows XP Professional Resource
Kit Documentation.
2. Check the event logs for network-card-related entries or
connectivity-related entries.
For additional information, click the following article number to view the
article in the Microsoft Knowledge Base:
308427 HOW TO: View and manage event logs in Event Viewer in Windows XP
3. Check whether the network adapter is on the Microsoft Hardware
Compatibility List (HCL). To see the HCL, visit the following Microsoft Web
site:
Hardware Driver Quality
4. Check other computers that use the same default gateway that are
plugged into the same hub or switch. If these computers do not experience
network connectivity problems, the problem may be a faulty network adapter
on one computer.
If this is the case, update the network adapter driver to the latest
version.
5. Contact the vendor of each motherboard and update the BIOS of the
boards. Some network adapters and motherboards or BIOS versions are
incompatible. Obtain the latest version from the vendor's Web site or
contact your hardware vendor.
6. Check the network adapter and uplink hardware (hub or switch) for
common settings. Make sure that all complementing network resources
(network adapter, hub, and switch) are set to the same speed and duplex
level. If the media type is set to autosense, autosensing, or autodetect,
or "Auto Select," make sure that all components are autosensing correctly.
On some switches, a duplex setting of Auto may cause it to use half-duplex.
You may have to force it to use full-duplex.
Reset the switch, restart the client, and test the connectivity.
Put the client and the server on a passive hub. If communication resumes,
the problem may be caused by an incorrect network switch configuration.
For more information about how to configure the devices, contact your
hardware vendor.
7. Manually set the network adapter of the computer that has connectivity
problems to half-duplex and a lower speed.
Connect the system to a switch that is configured to half-duplex and
10-Mbps, or use a 10-Mbps hub, to see if connection can be established at a
lower transmission speed.
To increase performance, increase the speed settings manually to 100 Mbps,
and then restart the computers. Test for network connectivity loss,
increase the setting to full-duplex, and then restart the computers. If
network loss occurs, reduce the duplex setting and the speed to the
previous settings.
8. Swap the network cable between the failing system and the hub or
switch.
9. Replace the network adapter with a network adapter that has been tested
and proven reliable. To do this, follow these steps:
a. Remove the network adapter diagnostics program.
b. Remove the network adapter in Network properties.
c. Install the new network adapter.
10. Run Network Monitor at the same time on both ends of the network
connection. After you filter the traces on the addresses of the two
systems, compare both traces to see if you can see the same traffic.
Use TCP Retransmit, the Network Monitor Experts tool, to detect TCP
retransmissions. To do this, follow these steps:
a. Start Network Monitor.
b. On the Tools menu, click Experts, and then click TCP Retransmit in the
left pane.
c. Click Add to Runlist.
d. Click Run Experts.
If frames are missing in one of the traces, check all intermediate cabling,
hubs, switches, and routers for hardware or configuration errors.
In Network Monitor, view the Capture Statistics summary frame. This frame
is the last frame of the trace. If it contains a value other than 0 in the
following statistic counters, the connectivity problem may be caused by a
hardware or configuration problem:
STATS: MAC CRC Errors = 0
STATS: MAC Frames Dropped due to HardWare Errors = 0
Network switches and server network adapters have to have the duplex
settings matched for communication to function correctly. Both must be set
to full-duplex or half-duplex. They cannot be mismatched.
The computers on a local area network (LAN) typically share a common
full-duplex network medium. This configuration permits two computers to
transmit data at the same time.
Connectivity problems may occur if either of the following conditions is
true:
o The computer was moved to a new Ethernet switch port that automatically
senses network speed. However, the computer's network adapter is configured
to force full-duplex communication with a static network transfer speed
setting (10 Mbps, 100 Mbps, or 1 gigabit per second [Gbps]).
o Both the Ethernet switch port and the computer's network adapter are
configured to force 100-Mbps or 1-Gbps full-duplex communication. However,
the Ethernet switch or the network adapter may not be able to communicate
at that rate or may not be able to use full-duplex transmissions.
You can improve network performance in an Ethernet LAN environment by using
full-duplex hardware. This configuration permits two-way communication
between networked devices. Without full-duplex hardware, information is
sent one way and then sent the other way. Packets frequently collide on the
network in a half-duplex hardware configuration, and every time a collision
occurs, the packets that collided must be resent. This creates even more
traffic that can decrease network performance.
With full-duplex, transmit and receive paths are separate. Therefore, you
can transmit and receive at the same time, and collisions are prevented.
Because of the increased throughput and lack of collisions, full-duplex is
more susceptible to bad cable terminations or to cable attenuation that
exceeds recommended limits. This can generate data retransmissions that
become sufficient to degrade performance.
REFERENCES
===========
For additional information about troubleshooting connectivity problems on
the network, click the following article numbers to view the articles in
the Microsoft Knowledge Base:
102908 How to troubleshoot TCP/IP connectivity with Windows 2000 or
Windows NT
141299 Disabling bus mastering on 3Com 3C590 PCI network cards
148426 Troubleshooting Event ID 3013
154989 3Com Fast EtherLink and EtherLink III adapter configuration
156326 No network access with DEC network adapter
170950 Intermittent loss of connectivity while using Compaq NetFlex-3
174812 The effects of using Autodetect setting on cluster network
interface card
191606 Dell 3c905b Oemsetup.inf file has errors
192250 3Com 3c905b prevents write of Memory.dmp
217305 Full duplex support with Windows NT
224131 Network switch with full-duplex incompatible with half-duplex
network interface cards (NICs)
247609 Poor performance with Catalyst 2948G LAN switch
243294 TCP Header Checksums Shown as Invalid in Network Monitor
259080 Window 2000 Professional Client starts slower than Windows NT 4.0
Workstation Client in SBS 4.5 network
259336 Internet connection sharing problem with multiple 3C905B network
adapters
298733 Logon problems with 10/100 Ethernet hubs and switches
306983 An Inf error occurs during installation of a network adapter on a
Windows 2000-based computer
315978 Network problems with a router in Windows XP
320729 Network+ Certification Training Kit comments and corrections
325122 Internet Control Message Protocol Destination Unreachable (Code =
0x0D) packets
324717 Connection stays pending for AS/400 systems with gigabit adapter
The information in this article applies to:
o Microsoft Windows XP Home Edition
o Microsoft Windows XP Professional
o Microsoft Windows 2000 Professional
o Microsoft Windows 2000 Server
o Microsoft Windows 2000 Advanced Server
o Microsoft Windows NT Workstation 4.0
o Microsoft Windows NT Server 4.0
Shilpa Sinha
This posting is provided "AS IS" with no warranties, and confers no rights.
