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Hub Lessons Learned
- Subject: Hub Lessons Learned
- From: mcs101main@xxxxxxx
- Date: Mon, 25 Oct 2004 14:40:03 +0000
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In working with a hub implementation on various PCs there are a few lessons
that I have learned and will share for others that have hub developement
interest.
1. It is possible that a PC with LAN card(s) will only show 127.0.0.1 as
the only available network. In my case it is a laptop when disconnected
from both the wired and wireless networks. This means that a hub should
route traffic on this interface accordingly. I have found that a
255.255.255.255 broadcast IP does not function on 127.0.0.1 and that the
target must explicitly be 127.0.0.1. Note that message viewers also should
be cognizant of a 127.0.0.1-only network as well.
2. It appears that a VPN connection is treated as a virtual interface that
is mapped into the same physical interface as the primary LAN. The fallout
of this is that the interface will report 2 message reception events for
each message received. It does not matter if the VPN connection is alive
or not. Its existance is what creates the problem. There are also
confirmed bugs in some Microsoft Winsock implementations in which two
events are generated on a message reception. I handled the VPN situation
by not forwarding any duplicate reception within a 100 millisecond window.
I suspect that other computers will exhibit unanticipated behaviors and
each needs to be dealt with on a case-by-case basis to understand what a
hub must do to accomdate.
--NextPart_Webmail_9m3u9jl4l_11137_1098715203_0
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<BLOCKQUOTE style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px;
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<P>In working with a hub implementation on various PCs there are a
few lessons that I have learned and will share for others that have hub
developement interest.</P>
<P> </P>
<P>1. It is possible that a PC with LAN card(s) will only
show 127.0.0.1 as the only available network. In my case it is a
laptop when disconnected from both the wired and wireless
networks. This means that a hub should route traffic on this
interface accordingly. I have found that a 255.255.255.255
broadcast IP does not function on 127.0.0.1 and that the
target must explicitly be 127.0.0.1. Note that
message viewers also should be cognizant of a 127.0.0.1-only network as
well.</P>
<P> </P>
<P>2. It appears that a VPN connection is treated as a virtual
interface that is mapped into the same physical interface as the primary
LAN. The fallout of this is that the interface will
report 2 message reception events for each message received. It
does not matter if the VPN connection is alive or not. Its
existance is what creates the problem. There are also confirmed
bugs in some Microsoft Winsock implementations in which two events are
generated on a message reception. I handled the
VPN situation by not forwarding any duplicate
reception within a 100 millisecond window.</P>
<P> </P>
<P>I suspect that other computers will exhibit unanticipated
behaviors and each needs to be dealt with on a case-by-case basis to
understand what a hub must do to accomdate.</P></BLOCKQUOTE>
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