[Techlunch] Network types - May the Force be with you

[richard.elliott@dfat.gov.au]

>    Darth Vader took two giant strides  toward the immense visiscreen
that occupied the forward wall  of the bridge of his flagship Imperial
star destroyer.  "We've got them now", he rumbled.
Whirling on the technicians cowering at their consoles, Vader snapped,
"Tractor
beam!".>
"Yes, Lord Vader", replied one, bending   attentively tohis task. Then he
looked up  hesitantly.
Vader gestured  dramatically at the  screen, indicating the fleeing
spacecraft. "I want a  tractor beam on that ship", he declared. "Now!".
The technician busied himself with switches and  dials.
"Where's  that tractor beam?" roared Vader, his voice  dark with
menace.
The  other technicians turned frightened  eyes on their peer.
They knew what   happened when Darth  Vader's instructions weren't
executed instantly.
"The tractor beam seems to be down, sir",  quavered the technician.
"What do you mean down?"  Vader inquired with a  disturbing silkiness to
his  voice.
 "It's not accepting  commands, sir", the  technician explained.
 Another  technician  leaned over  and examined the console. "That's odd.
The beam   itself  is showing green", he pointed out.
"Yes, I know", agreed  the  first.
"But I'm not getting any acknowledgment to my   'Engage'
command". He  pressed a button several times  to  demonstrate.
"Maybe the network's down again", suggested  a third  technician.
"Oh, that could be", admitted  the first technician.  "The network  might
be down, Lord  Vader", he informed the large  black figure trembling with
rage.
"What network?" Vader  asked  ominously.
The second technician jumped in. "Since we've  moved  to a distributed
architecture on the Imperial star destroyers, everything is on a network.
It was  felt that the direct  connections were too unreliable."
The third technician added. "The tractor beam is on one of the  peripherals
sub networks, with  the  printers and the scanners. It's not on the main
weapons  network".
"Why isn't the tractor beam on the  weapons network?"  asked Vader, now
more puzzled than  angry.
The  technicians exchanged sheepish looks. It  was embarrassing to have to
point out something so  obvious to a superior. The second technician
cleared his  throat. "Well, sir, the weapons network is a  higher priority.
It makes more sense to put the less commonly  used systems  on a separate
sub network that has lower QOS".
"QOS?" Vader queried.
"Hang on  a second", said  the first technician. "If the network is down,
how come we're getting a green light for the  tractor beam?". The third
technician brightened. "Ah! Maybe  the console is retrieving old MIB data
and  displaying that".
"MIB?" rumbled  Vader.
The first technician answered "We use SNMP to  monitor the network
elements. When the server queries  the element, it stores its current
status. If the network  goes down, it can't query the element anymore, and
all you  have is the latest status in the MIB." He
turned to the other technicians,  musing. "We really should have an
indicator  of when
the last successful query was, instead of  just a green or red light".
"Good idea", said the third  technician. "I'll call tech  support".
"Say", said  the second technician. "How about if we ping  the tractor
beam?  Let me bring up a telnet  window".
"Telnet?" asked Vader, now obviously  confused. "Ping?".
The first  technician glanced briefly at  Vader, a little annoyed at the
interruptions. Why couldn't this guy keep up with the service bulletins?
"The system runs Unix, but the consoles run NT  5", he  replied with
exaggerated patience. "You need a telnet  window to ping the element". He
turned his attention back to  the screen. "That's  strange. It comes back
'active'. Listen,  when you get tech support  tell them we can't engage the
tractor but we can ping  it".
"Right", said the third  technician. "I'm still on hold."  "Here's a
thought",   said the second technician. "What if we just  call the guys
down at tractor control and have them engage the beam manually?".
Vader seemed to brighten up at this, and swivelled  his  head from one to
another.
"Good  idea", said the first  technician. He lifted his communicator  and
tapped the switch several  times. "Nothing", he  said.
The second technician shook his head. "Didn't we tell them we couldn't do
voice and data with that little bandwidth?".
Suddenly Vader noticed the visiscreen and let out a bellow of anger.
"They're gone!" he boomed.
The third  technician looked up smiling. "Hey, I got tech support!".