🚀 go-pugleaf

In article <1993Jan23.002517.22830@nosc.mil>, kent@humu.nosc.mil (Kent K. Kuriyama) writes:
  > I would like to get comments regarding the problems of using multiple
  > class 'C' addresses vice a single class 'B' addresses.  Obviously
  > this is an issue because the NIC is hesitant in granting the rapidly
  > diminishing number of class 'B' addresses.
  > 
  > We intend to have approximately 2000 IP addresses with typically 50
  > address per sub-net.  Using class 'C' address we are looking at 40 sub-
  > nets or approximately 10 'C' addresses.
don't forget that in both the host and the subnet field of an IP address
you should NOT use the values 0 and -1 (all ones).
This implies that the subnetting a class C network can be done in only
the folowing ways:

bit split	# of subnets	max # addr/subnet	total max # usable addrs

0:8		1		254			254
1:7	** illegal **
2:6		2		62			124
3:5		6		30			180
4:4		14		14			196
5:3		30		6			180
2:6		62		2			124
7:1	** illegal **
0:8	** nonsense **

Of course things look different when CIDR is fully available (i.e. you
use a supernet of 2*n class Cs and can ignore the 24:8 split of class C).

  > Questions:
  > 
  > 2)  Someone mentioned that linking up a bunch of 'C' addresses will
  > require the use of some external gateway protocol (make sense - we need
  > to route between class 'C' networks) on our routers.  Is this a big
  > deal?  Is EGP a feature only available on expensive routers?
no, for routing within your "routing domain" you can use the same interior
gateway protocols as you would use within a single B.  Exterior gateway
protocols like EGP (if starting to use one, better try going for BGP)
are only needed between different autonomous systems - i.e. network compounds
with a separate administratgion and routing policy.

  > 3)  Are there any advantages to getting a contiguous set of class 'c'
  > addresses (e.g. 192.101.190,191,192, . . . etc)?
YES;  supernetting - need a power of two with a common prefix

  > 4)  Would there be any problem in implementing a single domain name
  > DNS over multiple class 'C' addresses?
NO - IP addresses and domain names are two COMPLETELY independant name spaces!
The domain name service usually is used to provide a mapping between (some)
IP addresses and domain names;  this mapping can be defined in any way you want.

--
Ruediger Volk
Universitaet Dortmund, Informatik IRB				DE-NIC
Postfach 500 500
D-W-4600 Dortmund 50
Germany

E-Mail: rv@Informatik.Uni-Dortmund.DE
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