A Cisco Rodek consists of multiple components the major internal components of esis karate include a
central processing unit or C-p you know various physical interfaces such as serial interfaces or fast
ethernet interfaces or gigabit interfaces a random access memory or RAM ROM or read only memory flash
memory as well as nv ram or non volatile RAM.
A router is similar to a computer and has several hardware and software components.
So as an example in a PC today you may have a flash drive or hard drive and in a similar way a router
has flash as well as memory and C.P the rotas you or central processing unit executes operating instructions
such as system initialization or routing functions and switching functions.
A router may run a rotting protocols such as OSPF and when OSPF recalculates the rats to add to the
running table the central processing unit needs to do those computations.
The Rotto also has RAM or random access memory and spooled.
This is very similar to a PC.
RAM is a volatile memory and any data is stored in RAM is lost when the router is powered down or restarted.
So in the same way as on a PC.
If you are working in Microsoft Word and you lose power to your PC you'll lose any changes to the Microsoft
Word document.
If you haven't saved the document to your hard drive.
So if you turn the PC off and you've made some changes without saving them those changes are lost because
the word changes are only stored in RAM and haven't been written to the hard drive.
So a router has RAM which is read write memory and contains software and data structures that allow
the rodded to function.
Now in some cases with PCs when you boot up a PC the operating system which is stored on the hard drive
is loaded into memory.
That's not always possible because of the size of operating systems and the amount of RAM available
in a PC.
However a Cisco router today copies the entire Cisco Iowas software into RAM Gerring the boot process.
That didn't take place in the past but that's what happens today in a similar way when you make changes
on a Rodda those changes are written to the running configuration.
The running configuration is stored in RAM and unless you save that configuration to the startup config
which is stored in nonvolatile RAM or nv ram your changes will be lost.
So the running configuration of arrays stored in RAM and when you save your configuration it's copy
to the startup config which is stored in nonvolatile RAM which means that when the router is turned
off those configuration changes are saved and not lost.
So nv ram or nonvolatile RAM is used to store information such as the start up config which is not lost
when the router is turned off or loses power so the running configuration file is the file that stores
the configuration commands that the Cisco Iowas software is currently using on the router.
Typically all commands that are configured on the Rodda are stored in the running config.
There are always some exceptions to the rule but generally the show run command shows you the configuration
that's currently being used by the router.
Once again nv ram doesn't lose its information when the radio is powered off.
This is Iowa software uses nv ram to permanently store the router's configuration in the startup config.
When you make changes to the Cisco router using the C'mon lining to face those changes are made to the
running can fake if you want to save for those changes you need to use commands such as copy running
config startup config to copy the configuration from RAM to nv ram or from the running config to the
startup config.
Flash memory is nonvolatile computer memory and is used as the permanent storage for the operating system
and other files.
This is very similar to the hard drive or flash drive.
On PCs today depending on the size of the flash.
Multiple copies of the Cisco Ioway can be stored in Flash.
Other files such as music on hold which is used in coal manage express environments can also be stored
in Flash.
When a Cisco router boots up it will copy the Iowas software from flash into RAM Gerring the boot process
and then the CPA will execute the IRS.
Some very old models of Cisco routers such as the twenty five hundred ran the Ioway from memory and
flash at the same time but these days the entire operating system is copied into RAM and is run from
RAM in a similar way to a hard drive or flash drive on a computer.
When the rotors turned off flash memory doesn't lose its contents.
Rom is another form of permanent storage.
This memory contains microcode for basic functions to start and maintain the router and includes the
bootstrap code and power on self test or post run.
Also contains run monitor or Rumson which is used for password recovery and for Rodda disaster recovery
functions.
Run is nonvolatile So the contents are maintained even when the rod is turned off or rebooted.
The Rotto also stores the IP writing table the stores information about directly connected and remote
networks and is used to determine the best path to a local remote network up cache is also used by the
Rodda and thus contains the IP version for address to mac address mappings which is very similar to
the OP Kashan APC.
The OP cache on broad as is used on ethernet interfaces and is used for example when the Rodda pings
I another device from the local subnet.
The router will send out an upper crust and when it receives an up response that information is stored
in the OP cache.
Typically however it's populated when PCs are forwarding traffic through a router to a remote destination.
PCs will send an op request for their default gateway and the Rotto will reply and hence the OP cache
will be populated.
Routers also have packet buffers when packets are received on interfaces they are stored in buffers
that also stored in buffers before they exit an interface.
As an example if an interface is congested the buffer of the outgoing interface will fill up with packets
in the queue to be processed out of that interface.
I wrote it also has the configuration register which is stored in nv ram.
This is used to control how a router boots you could configure this valley to get a router to boot into
run one or two mode or to bypass the startup config to do it password recovery and can be used for other
functions such as changing the speed of the console port.
Erato has multiple interfaces and may include an exit report which is used in the past for modem connections.
It'll have a console port.
It may have a USP interface it may have serial interfaces for Ethan it interfaces gigabit interfaces
and may contain other components such as PV DMD's which are used in voice environments for transcoding.
These have what are called DSP or digital signal processors to convert analog voice into a digital stream.
Various other types of interfaces and components may be found in routers and even servers can be installed
in routers today.