Re: Can Windows Firewall affect LAN traffic ?

The Router's NAT firewall affect only Traffic coming in from the Internet.
The Router is a combo unit of Routing Circuit, and a switch in the same box.
LAN traffic is only using the switch.
The difference that you experience could be a result of different setting other Router's DHCP (Computers' IP assignment).
There are differences between Routers in the way they handle the IP assignment. Some Routers keep the same IPs according the computer MAC number.
Others can assigned it in up hazard manner (I.e. giving different IP number to the same computer each time it starts.
The latter can confuse the LAN Traffic. The best is to use a Router that can do Static DHCP. I.e the computer's TCP/IP can be set-to Auto Obtain and they always would get the same IP.
Jack (MS, MVP-Networking).

"Stephen Ford" <stephen_ford_NO_@xxxxxxxxxxxxxxxx> wrote in message news:eQ0I9JDRKHA.488@xxxxxxxxxxxxxxxxxxxxxxx
2-PC LAN + network printer + router

Win XP Pro SP3

Can Windows Firewall affect / stop LAN traffic? The following problem often raises questions about the firewall and I want to understand its relevance. Discussions seems to get very convoluted and end up down blind alleys.

I contend that Windows Firewall (WF) only affects WAN traffic but I suspect that just by replacing router#1 with router#2, this does not result in the WF stopping PC-PC ping traffic. Is that right?

I am trying to replace a router with a new one. With router #1 in place Ping between the PCs works fine. With router#2 in place all network traffic is fine (eg PC-printer, PC-router & PC-Internet) apart from Ping PC-PC.

I have been through the usual issues of network configuration issues ad-nausium includin IP addresses, DNS, sub-net mask etc. In deed if there was a problem, then nothing would work with router#1 in place. But with router#1 in place all network comms is fine. Put router#2 in place and all network traffic is fine apart from ping PC-PC.


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