5.1.8 tracert and traceroute

5.1.8 tracert and traceroute The traceroute tool allows you to test the whole path between two nodes with a view to isolating the node or link that is causing the problem. traceroute tracerouteis supported on Linux and router operating systems, such as Cisco IOS.tracerouteuses UDP probe messages by default. The command issues a UDP probe for port 33434 with a TTL of 1. The first hop should reduce the TTL to zero and respond with an ICMP Time Exceeded message. The command then increments the port number and TTL by one and sends a second probe, which should reach the second hop router. This process is repeated until the end node is reached, which should reply with an ICMP Port Unreachable response.The output shows the number of hops, the IP address of the ingress interface of the router or host (that is, the interface from which the router receives the probe), and the time taken to respond to each probe in milliseconds (ms). If no acknowledgment is received within the timeout period, an asterisk is shown against the probe. Note that while this could indicate that the router interface is not responding, it could also be that the router is configured to drop packets with expired TTLs silently.traceroute can be configured to send ICMP Echo Request probes rather than UDP by using traceroute -I. The traceroute -6 or traceroute6 commands are used for IPv6 networks. tracert On a Windows system, the same function is performed using the tracert command. tracert uses ICMP Echo Request probes by default. The command issues an Echo Request probe with a TTL of 1. The first hop should reduce this to zero and respond with a Time Exceeded response. tracert then increments the TTL by one each time to discover the full path.tracertcan be used with several switches, which must precede the target IP address or host.You can use the-dswitch to suppress name resolution,-hto specify the maximum number of hops (the default is 30), and-wto specify a timeout in ms (the default is 4,000). If, after increasing the value, destinations are then reachable, you probably have a bandwidth issue to resolve. When used with host names (rather than IP addresses),tracertcan be forced to use IPv6 instead of IPv4 by adding the-6switch.tracert -6 www.microsoft.com