You cannot rely on traceroute to show you all the router interfaces that a packet has been through to a destination.
Some ISPs purposely hide routers to make it look like travelling through their domains has less hops than some other domain. But even if there's no trickery involved, many other things can cause you to not see a router in the path: * Routers in the path may be using private addresses * Perhaps there's a tunnel between two routers in the path, with many routers hidden inside the tunnel * Routers and firewalls may be blocking the ICMP Time Exceeded message that traceroute depends on to work Traceroute works by sending UDP datagrams or ICMP echos with an increasing IP Time-to-Live (TTL). It depends on the ICMP Time Exceeded message to come back when a router decrements the TTL to 0. Consider how it works and you will see that there's not much you can do as an end user to see more details on the path if the devices in the path don't want you to see the details. Priscilla Karagozian Sarkis wrote: > > Qn? > Does Trace route path below indicate the exact interfaces/IP > addresses > it phyicsally goes thru.to get to these device interfaces,OR > there are some hidden Device Interfaces that are not seen/shown > on it's way to reach it destination ??? > > I want to know if I can rely on traceroute to come up with a > schematic of how things are connected... assuming you have a > mix of Juniper/Cisco/Foundry devices. and can not rely on sh > cdp neighbor to come up with a schematic of connected interaces. > > > Here is a trace route example : > > Trace 204.1.253.82; Start time 02/17/03 16:50:49 > Tracing route to 204.1.253.82 > 50 bytes from 204.1.253.82: time=15 ms > Hop Avg Diff Address > 1 2 2 192.168.0.1 > 2 14 12 172.31.255.247 > 3 13 -1 192.168.28.33 > 4 14 1 63.209.80.81 > gigabitethernet5-0-155.ipcolo2.LosAngeles1.Level3.net > 5 14 0 209.244.10.249 > gigabitethernet3-1.core1.LosAngeles1.Level3.net > 6 15 1 129.250.9.33 > p16-1-1-3.r21.lsanca01.us.bb.verio.net > 7 15 0 204.1.253.82 > fa-3-47.a04.lsanca01.us.ra.verio.net > End time 02/17/03 16:51:17 > host reached > > > Appreciate an answer.... > Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=63207&t=63133 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
