Don and all
<SOAPBOX>
<!---- Disregard if you're busy ----->
CIDR is the wave of the future:
IPv4, finite, scarce and precious.
How do you summarize a route efficiently?
CIDR.
If they ever get around to IPv6, I can't see the masters of the 'net pushing
'one company gets one Class A'
like in the early days of the 'net, circa 1980s.
Or I have a 255.255.255.0 mask and want to use 30 or less addresses and
leave the rest for a freind?
VLSM (Variable length subnet mask) based upon routers speaking CIDR,
(older routing protocols can't) I would change my mask to /27
32=255.255.255.255
-5 (2*5=32)
/27 = 255.255.255.224 .224 b/c 256-32=224 (I know the above is 255, and I
started w/256, but thats life)
then I use 192.168.1.32 = Lan ID
192.168.1.33 First Usable Host IP
192.168.1.62 Last Usable Host IP
192.168.1.63 Broadcast ID for my LAN (note it isn't the
192.168.1.255)
FWIW: Cisco will NOT let you become a CCNP w/o mastery of it.
To help learn it, and Don, this is handy tool for your purposes and needs,
3Com made a tool to do the above,
you can learn to do this in your head but MUCH slower and eats up scratch
paper, so download this tool
ftp://ftp.3com.com/pub/utilbin/win32/3CIPCalc.zip
It's not much for interface, but it lives up to it's promises.
(Its what you grab after you pass your CCNP test, and no one thinks that
CIDR is a cool parlor trick in the crowd you hang with. Like I've never met
a hot babe that was impressed by this, not a one. But tell them you can rid
their 'inbox' of junk email, they'll listen.) Hospital workforces are 75-80%
female, btw.
Classless InterDomain Routing. CIDR
IP addressing technique supported by BGP4 and based on route aggregation.
CIDR allows routers to group routes together to minimize the quantity of
routing information carried by the core routers.
</SOAPBOX>
CIDR lets AT&T sell little networks of say 16, 32, or 64 IPs to some little
spam farm company,
azoogle comes to mind.
I really believe in the layer 3 kill, but dont want collateral damage.
If I can't get them to define their lyr 3 boundaries, AT&T comes to mind,
maybe I can observe my logs, then start with the smallest LAN segment that
represents what has got
through and expand upwards from there.
For the Hosts that have tried to spam me after deploying badguys filtering
review ftp://mailhub.mmcenters.com/imgate/badguys/badguys_caught.map
updated daily (thanks to Len, Chris and all their RegExp Talent)
-A
