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Network question

Y

Ynog

Golden Member
Say your on a closed network, no routers just hubs and switches.

Is it possible to find out the route a packet takes to go to another machine
on that network. This would be including any switches or hubs it might pass through.
I am not sure if this is possible. I was pretty sure traceroute would only measure hops
through routers, not hubs and switches, but its been a long while since I had to deal
with networking on low level situations.


Also does anyone know where I can find a low level description of how DHCP works.
Besides looking at DHCP server code.
 
You have no routers, no there are no ip addresses being used for communication. Switches operate on layer 1 and 2 of the OSI model.

Layer2 deals only with MAC addresses so you can ping an IP(assuming it is configured correctly) , but you will not be told that you are hitting the switch

whoops....TYPE...FIXED IN BOLD
 
Basically, your switch will have to do an arp request (correct terminology?)to get the MAC of the IP that was requested. The switch will respond by broadcasting it to everyone, and the client PC will answer
 
Everything Goose said. But to add to that your switch maintains a table as well. If the destination machine's mac address has already been resolved then the switch will just forward the packet to that machine without repeating an arp broadcast. You have to clarify the what it is exactly you want to know about DHCP.
 
Much shorter answer: No. From your local machine, all you know about is the MAC address of the remote machine, there's no tracing of the L1 and L2 The only way is to simple trace the path by hand, usually tracing cables.

The ONLY time you can do this administratively is if you have fully managed switches along the line and you can look at the forwarding tables to see what MAC addresses are on what ports. Not common in smaller networks, however.

- G
 
Originally posted by: Garion
Much shorter answer: No. From your local machine, all you know about is the MAC address of the remote machine, there's no tracing of the L1 and L2 The only way is to simple trace the path by hand, usually tracing cables.

The ONLY time you can do this administratively is if you have fully managed switches along the line and you can look at the forwarding tables to see what MAC addresses are on what ports. Not common in smaller networks, however.

- G
Click to expand...

bingo. now if you have the SNMP community strings of the switches then you can used programs that will trace the layer2 route. But if its not under your administrative control, forget about it.
 
Why would you need to find the route/path if it is only local area networking? Only if you have them cross/matrix connected would there not be only one path. You could find the path like mentioned above using the MAC tables on the devices. But, its not like a tracert with IP routing. You have to access the devices via console or snmp or similar.
 
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