free network analyzer?

Are there any good free ones to help me find nat issues on my network? I keep having a problem accessing a few popular web sites, like aol.com, yahoo.com, etc. I have tried various routers, and my isp has tried various modems too and the problem still happens, but not when I bypass any router I have. The techs determined that there is an issue somewhere within my small 3 computer network causing a nat conflict. How do I find this problem?

 

Try WireShark (free) or Capsa (paid). Capsa's support forum is near . Let's also wait for Stem and the others to step in.

thanatos

 

You begin by putting up more information; system's involved, individual mtu value's, router make/model, etc ....
These two, pccitizen.com and tech-faq.com might help expose an area that's been previously overlooked.

GF

 

Since you only have 3 PCs (and I assume, a small number of any other networked hardware, like printers etc.) have you tried hard coding the IP Addresses for everything, rather than let them be assigned by DHCP? Seems like it might help prevent any address conflicts...

 

Assigning static IPs can solve many a problem. Did for myself and a Friend on our 8+ PC mixed wired\wireless network. As stated, a bit more info. would be helpful.

 

The systems involved are one winxp pro and 2 winxp home computers. Two custom built, and one xp home is a dell. The mtu's are standard for cable, 1500 on all computers. The router is a D-Link DGL-4500, all computers are wired

 

How do I hard code the ip addresses and assign static ip's?

 

You need to disable the DHCP server in your router and manually write the IPs on each machine (My Network Places > Properties > TCP/IP > Properties)

 

Could it be possible that your ISP uses lower mtu setting than the standard 1500 cable?Your symptoms sound very much like what happened to a friend of mine who was on orange broadband(although it was dsl pppoa...not cable).His mtu was 1500 and he could access some sites but not all.It turned out that the ISP uses 1430 ,although he wasn't told that over the phone.Maybe worth just lowering the mtu to make sure?

ellison

 

They use 1500 for sure, had a tech here and he was helpful.

 

Sounds like your on a decent ISP
As well as the packet sniffer suggestions you may want to try visualroute (lite is the free) or trial.I found it pretty useful in the past for locating problems.It does need java enabled to function though.
http://www.visualroute.com/lite.html
ellison

 

Here are the IP settings for this PC. Your default gateway would be your router.

Our DNS server is on our LAN. I assume yours would not be like mine in this photo...

**EDIT**

This link may be helpful too... http://www.homenethelp.com/web/howto/static-ip-address.asp