16 bit subnet segmentation

Hi,

I have a 16 bit subnet which is hard to administer especially with Network
speed.

I disable my ghost because it's a network killer.

Can I do segmentation with 16 bit subnet with another router?

I need also to implement IPSEC. Does this going to be a big impact on it?

Can't change my subnet, it's a big task and additional fees because our
integrated VOIP, UNIX and others are already in-placed.

Please advise.

Thanks,
Ricky

 

You can add two 24bit segments alongside of the existing ones and migrate to
the new segments over a period of time. If you can wittle down the 16bit
segment to less than 254 Hosts and have them grouped into IP#s that fall
into a 24bit range,...then all you have to do is change the mask. At that
point even the mask can be changed over time because both a 16 and 24 bit
mask would work for those simultanously.

Once the original 16 segment is split into 24bit segments you could even get
rid of the new ones you created that aren't needed anymore. It is up to you
how to deal with that.

Once you are out of the woods with all this,...always keep your segment at
254 hosts or less (24bit mask). Ethernet looses effieciency after about 300
hosts per segment. It is even true with gigbit however it just isn't as
noticable to "humans".

IPSec is not meant for running between every Host on a LAN. That is
horrible. IPSec has a high overhead. It was intended to be used in a
"point-to-point" situation like maybe a WAN link between two sites.

IPSec's primary purpose is to prevent "eavesdropping" by Sniffers by
encrypting the packets. On the Local LAN your Switches already do that by
isolating the session between a pair of "talking" hosts to its own "virtual
circuit". You have to specifically configure the Switch with a Monitoring
Port to use a Sniffer. So you don't need IPSec for that.

You can do "firewall-like" filtering with IPSec too, but you can do that
without IPSec anyway, so what's the point? Plus the LAN has to be almost
"wide open" just to function normally, so there isn't a lot of filtering
even possible there.

 

I'll try that segmentation, but what is the best way to do that? By bridges
or by router segmentation.

How about the L2TP/IPSEC for VPN on ISA 2004? Right now, I'm only using the
PPTP protocol. Is it advisable to go to ipsec?

Thanks,
Ricky

 

Bridges are just another name for Switches. Switches are Layer2. Segmenting
is Layer3, Routers are Layer3,...so you have to use a Router. There are a
lot of devices being sold now that are both a Router and a Switch in the
same box,...they are called Layer3 Switches. These are a very good option,
just be sure to keep separated in your mind the router functionality from
the switch functionality even though it is happeing in the same box.

VPN is already encapsulated with just using PPTP,...that's what PPTP is. I
have never messed with L2TP/IPSec,...it has never even interested me or made
me curious enough to try. Some people love it,...I couldn't care less
about it. Your choice. I have also never wanted to spend the $$ to buy the
Certs to do it and the MS Cert Services is just too big of a hassel to mess
with for me.

--
Phillip Windell [MCP, MVP, CCNA]
www.wandtv.com

 

Certs are not required for IPSec/L2TP. IPSec provides stronger encryption,
better security, and outperforms PPTP.

 

Are you saying that 16 bit segments can communicate with 24 bits? By what
devices I need to use?

Please advise more.

Thanks,
Ricky

 

As Phillip mentioned, a router.

 

Can you tell me the basic connections? I have ISA 2004 edge firewall. So
how I connect this on the internal?

Thanks,
Ricky

 

You'll need another NIC in the ISA box or you'll need to buy a router.

 

That's true. But it has higher overhead, I doubt it outperforms PPTP. The
security would be better than PPTP, but I still think PPTP is plenty good
enough.
Sorry, I didn't realize Certs weren't required.

 

You must have totally misunderstood what I said. Just re-read it,...I don't
want to type it all over again.

--
Phillip Windell [MCP, MVP, CCNA]
www.wandtv.com

 

Re-read my first post.
Everything is there if you take the time to understand it.

As far as 24bit & 16bit,...I did not say the two networks would interact
without a router,...I said a 24bit and 16bit *masks* could live together
*temporarily* if all the machines IP#s fit within the smaller 24bit range.
This would only be temporary until all the 16bit *masks* were changed to
24bit masks. I probably shouldn't have even mentioned it. Someone who
already understood the stuff would know just what I meant but someone who
doesn't would only be confused.


--
Phillip Windell [MCP, MVP, CCNA]
www.wandtv.com