View Source: NetworkingNotes - Waikato Linux Users Group

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See also NetworkingBestPractices
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!! Use of RFC:1918 addresses for routers
This has issues such as:
<verbatim>
 [Host A] <-> [Router B] <-> [Router C] <-> [Router D] <-> [Router E] <-> [Host F ]
</verbatim>

Now, Router B has a route to some RFC:1918 space (perhaps Host A is even on RFC:1918 behind [NAT]), Router D is numbered using RFC:1918 space (differently routable than Router B).  Now, if the link from Router D and router E has a smaller [MTU] than the rest of the network, and Router B has reverse path filtering on, then A can no longer talk to F.  If A traceroutes to F then it misses seeing D as well for the same reason.

RFC:1918 is evil and should be avoided at all costs, if you must use it, use it only on the edges on networks you control.

!! IP Aliases
Network interfaces can be assigned more than one [IP] address.

Eg, to create aliases for the range 192.168.0.1 - 192.168.0.20:

![FreeBSD]:
<verbatim>
for i in `jot 20 1` ;
do
  ifconfig fxp0 inet 192.168.0.$i alias ;
done
</verbatim>

!Linux distros:
(old way)%%%
<verbatim>
for i in `seq 1 20` ;
do
   ifconfig eth0:$i 192.168.0.$i ;
done
</verbatim>

(new way)%%%
<verbatim>
for i in `seq 1 20` ;
do
  ip addr add 192.168.0.$i dev eth0 ;
done
</verbatim>
This also lets you assign a range, eg:
<verbatim>
  ip addr add 192.168.0.0/24 dev eth0
</verbatim>
However, old tools like route(8) and ifconfig(8) won't show you anything added using this method.

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!!!Other
This page discusses the difference in tuning networking on various OS's: http://foureleven.org:81/rosetta-stone-performance-tuning.html

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CategoryNetworking

One page links to NetworkingNotes:

NetworkingBestPractices

Last edited on Tuesday, September 20, 2005 3:39:34 pm by JohnMcPherson

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