Neuron: Cisco Switch Firmware Archive Command

First I should introduce this type of post.  For this blog, a neuron will be a short tidbit of information.

Anyone that has upgraded a Cisco switch in the last few years knows that they are usually distributed as a tar archive now.  To install the upgrade you do the following:

#archive download-sw tftp://tftpserver/upgradefile.tar

When you execute the command IOS downloads the file and extracts it onto the flash file system.  All you have to do after that is reboot.

Thanks to Cisco's latest grab for more money, if you don't have SmartNet on a piece of equipment, you can't download IOS code for it.  While this has long been their policy, it is now being enforced.  This isn't too much of a problem unless you have a device that dies and you want to replace it with a replacement that is also not under SmartNet.  The likelihood of the replacement switch coming in with the exact same IOS load is close to nil.  Most admins like to maintain certain revision levels on a certain model which poses the problem of how to get the IOS you want on the replacement.  Well the easiest way that I have found is to use Cisco's archive command again.  Keep in mind that it's best to do this BEFORE you have a switch crash.

#archive upload-sw tftp://tftpserver/firmwarefile.tar

When you execute this command, IOS will combine all of the files on the flash file system related to the IOS code into an tar archive and upload it to your TFTP server.  The resulting tar file can then be used like the stock Cisco firmware tar file.

Telephony Basics Part 1

My last post generated a lot of comments about what I would call traditional telephony or what VoIP (IPT) installers refer to as Analog, Public Telephone Switched Network (PTSN), or Plain Old Telephone System (POTS).  Three years ago I was handed a traditional PBX to manage with very little training or experience beyond Cisco Unified Call Manager.  To me at the time, the phone frame (equivalent to a patch panel in network parlance) looked like a tangled mess of spaghetti that I would never understand.  Thankfully I had a very patient manager and a local telephone consultant that helped me understand how things worked.

Terminology

66 Block

66 block: This is a type of punch down block used to terminate cabling.  The permanent wires are generally placed in the outer columns and the jumpers in the inner columns.  Some 66 blocks however have the permanent in the left most and up to three jumpers.

110 Block

110 block:  This is a type of punch down block used to terminate cabling. The permanent wires are terminated first and then a spacer block with conductors is placed on top where the jumpers are terminated.


Main Distribution Frame (MDF):  This is where the phone system's connections are terminated into either 110 or 66 punch down blocks.  Jumper cables are used to connect these terminations to house cabling, the telephone company demarcation point, or to other intermediary distribution frames.

Intermediate Distribution Frame (IDF):  This is generally a closet or enclosure in a remote part of the building that feeds back to the MDF via large 25 to 100 pair cables.  In the IDF jumpers are run from blocks connected to the feeder cables to blocks connected to house cabling.

Demarc (Demark, Demarcation Point):  This is the demarcation between what is the local telephone company's responsibility and what is the building owner's responsibility.  Usually this is an enclosure with some sort of terminating block inside of it.

Local Exchange Carrier (LEC):  This is the local telephone company that delivers the physical PTSN to the building demarc.  Alternatively in some areas there are Competitive LECs (CLEC) that provide services over the LEC's cabling.

Foreign eXchange Office (FXO):  This is the type of port that usually is connected to PTSN coming from the phone company.  It doesn't provide its own power or ground.

Foreign eXchange Station (FXS):  This type of port is generally found on PBXs and analog adapters for VoIP systems to "power" analog devices like fax machines and analog phones.  It provides ring and supervisory voltage to the line.

66 blade on left, 110 blade on right

Punch-Down Tool

Punch-Down Tool:  This is the device used to terminate a jumper or pair from a cable to a 66 or 110 block.  The tool generally can be used with different blades depending on the style of block you are using.

Spudger

Spudger (aka Spludger, Pick): This tool is used to remove or adjust jumper cables in cabling blocks.  It is very useful to pick out small bits of wire left behind after removing a termination.

66-Block Discovery

Today I got what is now a routine ticket for a MAC-D on a phone.  First a little background, unlike some of my luckier geek friends I don't administer a fancy Cisco Unified Call Manager or Avaya IP system.  My company's phone system is a Siemens/Rolm 9751 MOD 80 installed in 1996 and currently maintained by spare parts and good luck.  That being said, when a MAC-D comes in, it means working on the 66 Blocks in our MDF and IDFs to make the change instead of just having the user plug the phone into their new office's network jack and being done.

What was unique about today's ticket was that it introduced me to a new style of 66 block.  Usually 66 blocks have rows of 4 terminals with the two left ones having their opening facing to the center and the two right ones facing to the center like the picture shows below.

The block that the office I was working on was punched down onto though looked like this.

Notice how the three right most terminals face left and the 1 on the left faces right.  On a normal 66 block, the two terminals on the left are bridged and the two on the right are bridged so you would punch the riser cable to the outside terminal and the jumper to the inside terminal allowing each side to be independent.  On the block I found today it is actually setup to bridge all four terminals together.  You put the riser on the left most block and can put up to three jumpers onto the three right terminals.  From my research, it would seem this style of block was useful for shared lines.

I figured this might be of use to someone else that gets to deal with the inner workings of an old TDM phone system, even if it's just replacing it with something new.