Apr 1st, 2008 |
One of the re-occurring cases we see in the Interop Network is the age old
question of “Can you tell me what this MAC/IP address is in the network?”
It seems like a simple question, but it is incredibly hard to solve.
When you trace the path of the traffic what you find is the following:
- The MAC address it attached to a device (a PC)
- The device is connected to a Drop Cable
- The Drop Cable is attached to a ‘Biscuit Box’ (up in the air)
- The Biscuit Box is attached to a RIB of Cat 5 copper
- The Rib is attached to a Patch Panel
- The Patch Panel is connected to a Switch Port
- The Switch Port is on a Blade
- The Blade is in a Switch
- The Switch has one or more Subnets
- The Subnets are all in a PED
- The PED runs back to a Router
- The Router knows the IP Address
One long chain: MAC, Device, Drop, Biscuit, Rib, Patch, Port, Blade,
Switch, Subnets, PED, Router, IP.
But, believe it or not, we know every link in every chain and we are
working with the kind of equipment that makes matching this all together
fairly easy. But it still takes diligence and effort. We have to document
every step of our design and make sure that all our database are up to
date.
But when someone asks (and they always do), “Can you tell me where this
MAC address is ?”, ninety percent of the time we can comfortably say “That MAC is
being used by IP address 45.32.2.31 and it is currently in booth 3002.”
The other 10% of the time we have to we just have to shrug our shoulders
and say “It is on wireless AP 27, and in the lobby, somewhere.” (We can be
more accurate, but wireless users have a bad habit of moving around.)
[...] Finally, we’re helping logistics in the NOC by allowing a physical separation between systems located in the NOC and those in an emergency rack outside of the NOC. If either of these two locations were to fail, [...]