AT THE PROMPT, TYPE TRACERT TARGET-IPADDRESSAND PRESS THE ENTERKEY....

2. At the prompt, type tracert target-ipaddressand press the Enterkey.Replace target-ipaddresswith the IP address of the remote networkhost you are attempting to connect with. This can also be a host name. The display will now include a list of the routers the packets have successfullycrossed, along with the length of time the packet took to reach that network

Head of the Class…

segment.

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-i Specifies the IP address of the local interface from which the query was sent.

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-r Specifies how many times an SNMP query is to be resent.The default value is0.

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-t Specifies how long to wait for an IGMP neighbor query reply.The default isthree seconds.The mrinfo command displays the interfaces for both the multicast router and itsneighbors on each interface. It also provides the names of the neighboring domains, themulticast routing metric, and the TTL.Also, the netsh utility, discussed in the “Using netsh Commands” section earlier in thischapter, can display the configurations of protocols, filters, and routes. It also allows you toreconfigure interfaces. Don’t overlook this valuable tool as an option for troubleshooting IProuting.

Common Routing Problems

If you suspect that your RRAS server isn’t functioning properly, start by making sure theRRAS server is running.You might be surprised how many times the cause of the problemturns out in fact the that RRAS is not turned on.Most TCP/IP administrators spend much of their time troubleshooting the hardware.Connectors go bad, NICs die, and cables break or are cut.You need to troubleshoot andrepair these elements before you start looking at the software. Consider these potentialtrouble spots first:

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Check for basic communication between systems first. Broken cables, loose con-nections, and so on can cause what might look like much more complex prob-lems.

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Make sure that your systems are in compliance with the standards you’ve chosen.This means you need to verify all devices on your Ethernet are broadcastingEthernet and not something else. Make sure you have the correct types of cables.An example of this is the common mistake beginners sometimes make usingRG59A/U cable instead of RG58A/U.The former cable type is used in broad-casting specifically with video; the latter is used with IEEE 802.3 10Base2 net-works.

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Carefully isolate your problem to a single LAN, MAN, or WAN segment by goingthrough each individually. Keep in mind it is extremely rare for two segments togo down at the same time.

Interface Configuration Problems

Make sure that the RRAS server is configured to perform as an IP router. Open theRRAS Microsoft Management Console (MMC) and verify all your settings. Make sure thatyou have enabled RRAS on the Windows Server 2003 machine you are expecting to per-form as a router. It could be that you have the wrong server configured. Also, keep in mindthat the system must first make the physical connection to the network. After that, it mustmake the logical connections.The router also might not be receiving routed data from other routers.Take a look atthe routing table to see that the router is receiving routes from the other routers. If there isanything there other than Localin the Protocol column, the router is receiving routes viathe routing protocols. If not, double-click the rest of the settings in this section and payparticular attention to the appropriate protocol.

RRAS Configuration Problems

Routing for the correct LAN protocol may not be enabled. If you’re using IP routing,make sure that IP routing is enabled on the IP tab of the server’s property sheet. Also, makesure that you have IP routing protocols attached to each of the interfaces where they areneeded.The wrong protocol could be installed, or the right protocol could have been installedon the wrong interface.The correct protocol must be installed on the appropriate interfacefor this to work correctly.

Routing Protocol Problems

One of the most common problems you’ll face with RIP for IP is incorrect routing tableentries. If you’re seeing wrong or inconsistent routes in the routing tables, or if routes aretotally missing, you should look at the following possibilities:

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The wrong version of RIP could be in use.

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Silent RIP hosts might not be receiving updates.

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The subnetting scheme on your network could be incompatible with yourrouting infrastructure.

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A router might be using the wrong password.

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Routing filters might be too restrictive.

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Packet filters might be too restrictive.

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Neighbors might be incorrectly configured.

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Default routes might not be being propagated.If your router is using OSPF, make sure that the Enable OSPF on this interfacecheck box is selected.This option is in the interface’s OSPF Propertiesdialog box.Also make sure that your router is receiving routing information from the other routerson the network. Do this by opening the routing table and looking at the Protocolcolumn. One of the following might be the problem with OSPF:

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OSPF might not be enabled on the desired interface.

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The neighboring router might be unreachable.

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The OSPF settings may not match on each of the neighboring routers.

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The stub area configuration or area ID on neighboring routers may not match.

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Interfaces may not be configured with OSPF neighbor IP addresses.

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There may not be a designated router (DR) for the network.

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Packet filtering may be too restrictive.

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Summarized routes may be configured improperly.

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ASBR source or route filtering may be too restrictive.If a routing table entry is marked as being either OSPF or RIP, then information fromsome of the other routers on your network is getting through. If you do not see any OSPFor RIP entries in the table, you have a problem.

TCP/IP Configuration Problems

EXAM