152 Configuring and Managing IP Interfaces and Services320657-ATracing a RouteYou can trace the router hops necessary to reach an IP host.The traceroute facility uses the TTL (Time to Live) field in the IP header to cause routers and servers to generate specificreturn messages. Traceroute starts by sending a UDP datagram to the destination host with the TTL field set to 1. If arouter finds a TTL value of 1 or 0, it drops the datagram and sends back an ICMP Time Exceeded message to the sender.The traceroute facility determines the address of the first hop by examining the source address field of the ICMPtime-exceeded message.To identify the next hop, traceroute again sends a UDP packet, but this time with a TTL value of 2. The first routerdecrements the TTL field by 1 and sends the datagram to the next router. The second router sees a TTL value of 1,discards the datagram, and returns the Time Exceeded message to the source. This process continues until the TTL isincremented to a value large enough for the datagram to reach the destination host (or until the maximum TTL isreached).To determine when a datagram has reached its destination, traceroute sets the UDP destination port in the datagram to avery large value, one that the destination host is unlikely to be using. In addition, when a host receives a datagram withan unrecognized port number, it sends an ICMP Port Unreachable error to the source. This message indicates to the trac-eroute facility that it has reached the destination.To trace a route to a destination subnet, use the following command:traceroute host [dnf] [no-dns] [port port-num] [queries num] [size size] [ttl hops][wait ms]To trace the route to host server1, type the following command:23x0# traceroute server1traceroute to server1.example.com (192.168.22.7), 30 hops max, 38 byte packets1 engineering-1.example.com (192.168.192.206) 2 ms 1 ms 1 ms2 engineering-2.example.com (192.168.196.204) 2 ms 3 ms 2 ms3 gateway_a.example.com (192.168.1.201) 6 ms 3 ms 3 ms4 server1.example.com (192.168.22.7) 3 ms * 2 msIn this example, server1 is four hops away. The hops are listed in order, beginning with the hop that is closest to theWSS and ending with the route’s destination. (For information about the command options, see the Nortel WLANSecurity Switch 2300 Software Command Reference.)IP Interfaces and Services Configuration ScenarioThis scenario configures IP interfaces, assigns one of the interfaces to be the system IP address, and configures a defaultroute, DNS parameters, and time and date parameters.1 Configure IP interfaces on the WSS_mgmt and roaming VLANs, and verify the configuration changes.Type the following commands:23x0# set interface WSS_mgmt ip 10.10.10.10/24success: change accepted.23x0# set interface roaming ip 10.20.10.10/24success: change accepted.
