"MikeS@MLS" <(E-Mail Removed)> wrote in message
news:9384B5CF-7E9A-4A19-AB67-(E-Mail Removed)...
> 2: Subnet Mystery: assume an interface (NIC) is assigned an address of
> 192.168.109.12, with a subnet mask of 255.255.255.224. The interface is
> plugged into a VLAN that is assigned the subnet of 192.168.109.0/27. How,
> then, does Windows end up assigning a route of 192.168.109.255 to that
> NIC?
It is still the Master Broadcast Address for the Master Subnet which is
still 192.168.109.0---192.168.109.255 inspite of the subneting you are
doing. The same issue occurs on the opposite end as well because the first
"split" shares the same Network ID with the Master Subnet and its Master
Network ID (192.168.109.0). This is why with older networking equipment you
would "loose" the first and last address block (known affectionately as the
"Subnet Zero" and the "all ones subnet") when you did a subnet split. In
later equipment you would loose the last block (all ones subnet) but got to
use the first one (Subnet Zero). Actually to be more specific, you could
always "use" them,...it was just a matter of how many "issues" that causes
back then compared to the number of "issues" it causes today,...but TCP/IP
itself has not changed. Now in the most modern equipment you get to keep and
use both of them. So I believe in the Windows routing table this is a
"legacy" thing.
For documentation of that:
Subnet Zero and the All-Ones Subnet [IP Addressing Services] - Cisco
Systems
http://www.cisco.com/en/US/tech/tk64...tml#subnetzero
As far as "how" Windows builds the routing table,...it just does it based on
the Nic configurations,...so if you configure the nics correctly, the the
route table is correct. But misconfigure the nics and the route table
likewise become incorrect.
> This is causing a problem because the x.x.x.255 address falls outside of
> the
> subnet address range, and my ISA server is barfing over an address that's
> visible on that interface's routing table that's not assigned to it's
> network. I guess I could add it to the ISA netowork definition, but I
> would
> prefer to know why Windows is doing this (especially since that isn't the
> correct broadcast address for that interface).
Options:
1. Just ignore ISA's "barfing", I don't think it is hurting anything...
Also note, I believe ISA will block and complain about any broadcst
address even if it is the correct one because it just simply stops all
broadcasts just like a router does.
2. ...or add this to the Internal Network Definition's Addresses Tab
underneath your current entry:
192.168.109.255 ---- 192.168.109.255
It's not like that address will ever get used for anything anywhere that
would cause a problem anyway.
Since most people have ISA sitting on their first primary subnet that is
usually a full 254 host segment,..this is never an issue.
--
Phillip Windell
www.wandtv.com
The views expressed, are my own and not those of my employer, or Microsoft,
or anyone else associated with me, including my cats.
-----------------------------------------------------
Technet Library
ISA2004
http://technet.microsoft.com/en-us/l...chNet.10).aspx
ISA2006
http://technet.microsoft.com/en-us/l...chNet.10).aspx
Understanding the ISA 2004 Access Rule Processing
http://www.isaserver.org/articles/IS...cessRules.html
Troubleshooting Client Authentication on Access Rules in ISA Server 2004
http://download.microsoft.com/downlo...7/ts_rules.doc
Microsoft Internet Security & Acceleration Server: Partners
http://www.microsoft.com/isaserver/p...s/default.mspx
Microsoft ISA Server Partners: Partner Hardware Solutions
http://www.microsoft.com/forefront/e...epartners.mspx
-----------------------------------------------------
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