As part of troubleshooting, you can verify the reachability of local and remote destinations. You can ping your default router by its IPv4 or IPv6 address. You can obtain the local IPv4 address of your default router by entering netsh interface IPv4 show routes. You can obtain the link-local IPv6 address of your default router by entering netsh interface IPv6 show routes. Pinging the default router tests whether you can reach local nodes and whether you can reach the default router, which forwards IP packets to remote nodes.

When you ping the default IPv6 router, you must specify the zone identifier (id) for the interface on which you want the icmpv6 echo request messages to be sent. The zone id for the default router is listed when you enter the ipconfig /all command.

If you are able to ping your default router, ping a remote destination by its IPv4 or IPv6 address. If you are unable to ping a remote destination by its IP address, there might be a routing problem between your node and the destination node. Enter tracert -d ipaddress to trace the routing path to the remote destination you use the -d command-line option to speed up the response by preventing tracert from performing a reverse DNS query on every near-side router interface in the routing path.

The inability to reach a local or remote destination might be due to incorrect or missing routes in the local IP routing table. To view the local IP routing table, enter the netsh interface IPv4 show routes or netsh interface IPv6 show routes command. Use the command output to verify that you have a route corresponding to your local subnet. The route with the lowest metric is used first. If you have multiple default routes with the same lowest metric, you might need to modify your IP router configuration so that the default route with the lowest metric uses the interface that connects to the correct network.

You can add a route to the IP routing table by using the netsh interface IPv4 add route or netsh interface IPv6 add route command. To modify an existing route, use the netsh interface IPv4 set route or the netsh interface IPv6 set route command. To remove an existing route, use the netsh interface IPv4 delete route or netsh interface IPv6 delete route command.

If you suspect a problem with router performance, use the pathping -d ipaddress command to trace the path to a destination and display information on packet losses for each router in the path. You use the -d command-line option to speed up the response by preventing pathping from performing a reverse DNS query on every near-side router interface in the routing path.

Checking ipsec policies and windows firewall

The problem with reaching a destination node might be due to the configuration of internet protocol security (ipsec) or packet filtering. Check for ipsec policies that have been configured on the computer having the problem, on intermediate IPv6 routers, and on the destination computer. On computers running windows xp or later, ipsec is configured using windows firewall with advanced security.

In many cases, packet filtering is configured to allow specific types of traffic and discard all others, or to discard specific types of traffic and accept all others. Because of this, you might be able to view web pages on a web server, but not ping the web server by its host name or IP address.

Each network connection configured on a computer can be enabled or disabled in the windows firewall. When enabled, IPv4 and IPv6 drop incoming requests. During troublehshooting, you can disable the windows firewall for a specific IPv4 or IPv6 interface with the netsh interface IPv4 set interface interface=NameOrIndex firewall=disabled and netsh interface IPv6 set interface interface=NameOrIndex firewall=disabled commands. You can also completely turn off the windows firewall with the netsh firewall set opmode disable command. Don't forget to reenable the firewall when you are done troubleshooting.