#260949 - 20/07/2005 12:48
Really weird networking problem
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pooh-bah
Registered: 27/02/2004
Posts: 1913
Loc: London
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We have two sites connected by a SDSL link, we run a mix of W2K, NT and Linux machines as well as some Thin Clients with no problems. I've just built a new PC with XP Pro (Full, SP2 etc) but it won't get it to see the other side of the network (i.e. the other location) the SDSL connection is via two Zyxel 782R routers, these have been totally tranparent to the network thus far although they do have addresses assigned.
This is our first XP machine this side of the network and I just can't understand where or what the problem could be.
We use static IPs.
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#260950 - 20/07/2005 12:58
Re: Really weird networking problem
[Re: tahir]
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carpal tunnel
Registered: 10/06/1999
Posts: 5916
Loc: Wivenhoe, Essex, UK
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I assume that you have tried moving the new machine onto an IP address that another working machine already uses (and of course disconnecting the other machine at the same time).
_________________________
Remind me to change my signature to something more interesting someday
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#260951 - 20/07/2005 13:18
Re: Really weird networking problem
[Re: tahir]
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carpal tunnel
Registered: 25/12/2000
Posts: 16706
Loc: Raleigh, NC US
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First you claim they're routers, then you claim they're transparent. Those are pretty much mutually exclusive statements, so I'm not quite sure what's going on.
If they're routers, they have to be configured in the host computer as routers, either as the default router or as a static route to another specfic set of networks. Not knowing how your network is set up otherwise I don't know exactly what to tell you other than to compare the routing tables between the new machine and the ones that are working. (Under Windows, this is "route print" from a command prompt.)
If they're transparent, that probably means that they're bridges. I can't think of anything obvious, but they might have some sort of MAC address filtering. Did you or the people your work with set up the currently working computers after the bridge was put in place? If not, can you find the person who did set them up or ther person who installed the bridges and ask if any special configuration was needed on them?
_________________________
Bitt Faulk
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#260952 - 20/07/2005 13:23
Re: Really weird networking problem
[Re: tahir]
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old hand
Registered: 27/02/2003
Posts: 776
Loc: Washington, DC metro
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Have you tried pinging around? The XP sp2 firewall won't reply to pings by default.
Can everything on the XP side see the XP box? Can the XP box see everything on its side? Where do things seem to fail?
Can your xp box ping the router's local interface? The far side router?
-jk
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#260953 - 20/07/2005 13:24
Re: Really weird networking problem
[Re: andy]
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pooh-bah
Registered: 27/02/2004
Posts: 1913
Loc: London
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Quote:
I assume that you have tried moving the new machine onto an IP address that another working machine already uses (and of course disconnecting the other machine at the same time).
I'll give that a go
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#260954 - 20/07/2005 13:43
Re: Really weird networking problem
[Re: wfaulk]
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pooh-bah
Registered: 27/02/2004
Posts: 1913
Loc: London
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Quote:
First you claim they're routers, then you claim they're transparent. Those are pretty much mutually exclusive statements, so I'm not quite sure what's going on.
My limited understanding of them is that they can be used as routers and/or bridges in our application they're used as a bridge.
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#260955 - 20/07/2005 14:06
Re: Really weird networking problem
[Re: tahir]
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carpal tunnel
Registered: 06/10/1999
Posts: 2591
Loc: Seattle, WA, U.S.A.
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Quote:
My limited understanding of them is that they can be used as routers and/or bridges in our application they're used as a bridge.
If they are configured as bridges then a computer at site A would typically use the same IP network and netmask ask computers at site B. Is that so?
_________________________
Jim
'Tis the exceptional fellow who lies awake at night thinking of his successes.
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#260956 - 20/07/2005 14:10
Re: Really weird networking problem
[Re: jmwking]
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pooh-bah
Registered: 27/02/2004
Posts: 1913
Loc: London
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Quote:
Have you tried pinging around? The XP sp2 firewall won't reply to pings by default.
Can everything on the XP side see the XP box? Can the XP box see everything on its side? Where do things seem to fail?
Can your xp box ping the router's local interface? The far side router?
-jk
Pings both ways on the local side, can ping the local router but not the remote one.
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#260957 - 20/07/2005 14:17
Re: Really weird networking problem
[Re: jimhogan]
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pooh-bah
Registered: 27/02/2004
Posts: 1913
Loc: London
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Quote:
If they are configured as bridges then a computer at site A would typically use the same IP network and netmask ask computers at site B. Is that so?
Yes
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#260958 - 20/07/2005 14:17
Re: Really weird networking problem
[Re: tahir]
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carpal tunnel
Registered: 20/12/1999
Posts: 31596
Loc: Seattle, WA
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Wait, let's rewind a bit... Quote:
but it won't get it to see the other side of the network
Define "see". Precisely, what are you trying to do? What, exactly, are you getting as an error message, if any, when you try to do it?
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#260959 - 20/07/2005 14:23
Re: Really weird networking problem
[Re: tfabris]
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pooh-bah
Registered: 27/02/2004
Posts: 1913
Loc: London
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Quote:
Define "see". Precisely, what are you trying to do?
Attach it to the network, the WINS server and PDC are at the remote site, it can't therefore join the domain.
Quote:
What, exactly, are you getting as an error message, if any, when you try to do it?
The network connection wizard can't see the domain I'm trying to connect to, manually trying to join the domain brings up a very long winded DNS error.
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#260960 - 20/07/2005 14:27
Re: Really weird networking problem
[Re: tahir]
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carpal tunnel
Registered: 20/12/1999
Posts: 31596
Loc: Seattle, WA
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Ah. Windows-specific stuff. Okay, first things first.
Make sure to disable all XP firewall features.
Make sure that "NetBIOS over TCP/IP" is enabled.
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#260961 - 20/07/2005 14:28
Re: Really weird networking problem
[Re: tfabris]
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old hand
Registered: 27/02/2003
Posts: 776
Loc: Washington, DC metro
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Quote:
Ah. Windows-specific stuff. Okay, first things first.
It's not just windows stuff: pings are failing, too.
-jk
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#260962 - 20/07/2005 14:32
Re: Really weird networking problem
[Re: tfabris]
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pooh-bah
Registered: 27/02/2004
Posts: 1913
Loc: London
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Quote:
Make sure to disable all XP firewall features.
Make sure that "NetBIOS over TCP/IP" is enabled.
Done that
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#260963 - 20/07/2005 14:33
Re: Really weird networking problem
[Re: jmwking]
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pooh-bah
Registered: 27/02/2004
Posts: 1913
Loc: London
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Quote:
It's not just windows stuff: pings are failing, too.
-jk
You're right, can't ping it from a linux machine at the remote end either
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#260964 - 20/07/2005 14:40
Re: Really weird networking problem
[Re: tahir]
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old hand
Registered: 27/02/2003
Posts: 776
Loc: Washington, DC metro
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Have you rebooted your routers/bridges?
-jk
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#260965 - 20/07/2005 14:58
Re: Really weird networking problem
[Re: jmwking]
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pooh-bah
Registered: 27/02/2004
Posts: 1913
Loc: London
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Quote:
Have you rebooted your routers/bridges?
I'll be doing that and rebooting the switches too, let you know in the morning if that resolved the issue.
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#260966 - 20/07/2005 15:09
Re: Really weird networking problem
[Re: tahir]
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carpal tunnel
Registered: 06/10/1999
Posts: 2591
Loc: Seattle, WA, U.S.A.
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Quote:
I'll be doing that and rebooting the switches too, let you know in the morning if that resolved the issue.
Might you have an address conflict? If you take new XP machine off net, any chance you can ping that address still?
Was the address previously used elsewhere? If you can look on router/bridge console at ARP entries, does MAC address for that IP match XP machine's NIC?
_________________________
Jim
'Tis the exceptional fellow who lies awake at night thinking of his successes.
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#260967 - 20/07/2005 15:22
Re: Really weird networking problem
[Re: jimhogan]
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pooh-bah
Registered: 27/02/2004
Posts: 1913
Loc: London
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Quote:
Might you have an address conflict? If you take new XP machine off net, any chance you can ping that address still?
Was the address previously used elsewhere? If you can look on router/bridge console at ARP entries, does MAC address for that IP match XP machine's NIC?
No addreses conflict, tried it with various IPs, I don't know that the router stores ARP entries in a viewable format, they're not implicitly set by us anyway. Hopefully rebooting them should get rid of that issue???
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#260968 - 20/07/2005 15:57
Re: Really weird networking problem
[Re: tahir]
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carpal tunnel
Registered: 20/12/1999
Posts: 31596
Loc: Seattle, WA
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How about more basic stuff... Can the machine communicate with other PCs on its own side of the WAN? In other words, are we sure its NIC and driver and cable are all working?
And do you have another windows-based PC on this same side of the WAN that does work?
Let's also see an output of ipconfig /all for reference. Perhaps also an ipconfig /all for a computer that does work.
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#260969 - 20/07/2005 16:04
Re: Really weird networking problem
[Re: tfabris]
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pooh-bah
Registered: 27/02/2004
Posts: 1913
Loc: London
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Quote:
How about more basic stuff... Can the machine communicate with other PCs on its own side of the WAN? In other words, are we sure its NIC and driver and cable are all working?
And do you have another windows-based PC on this same side of the WAN that does work?
Let's also see an output of ipconfig /all for reference. Perhaps also an ipconfig /all for a computer that does work.
Yes
and
Yes
This is IPCONFIG /ALL from a working PC on the same side of the LAN:
Windows 2000 IP Configuration
Host Name . . . . . . . . . . . . : flickpc
Primary DNS Suffix . . . . . . . :
Node Type . . . . . . . . . . . . : Hybrid
IP Routing Enabled. . . . . . . . : No
WINS Proxy Enabled. . . . . . . . : No
Ethernet adapter Local Area Connection:
Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : NETGEAR FA310TX Fast Ethernet Adapter
r (NGRPCI)
Physical Address. . . . . . . . . : 00-A0-CC-D0-0A-C0
DHCP Enabled. . . . . . . . . . . : No
IP Address. . . . . . . . . . . . : 121.1.0.90
Subnet Mask . . . . . . . . . . . : 255.255.255.0
Default Gateway . . . . . . . . . : 121.1.0.30
DNS Servers . . . . . . . . . . . : 213.130.130.99
213.130.128.205
Primary WINS Server . . . . . . . : 121.1.0.254
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#260970 - 20/07/2005 16:09
Re: Really weird networking problem
[Re: tahir]
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carpal tunnel
Registered: 20/12/1999
Posts: 31596
Loc: Seattle, WA
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Okay, so let's see an ipconfig /all from the non-working PC for comparison.
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#260971 - 20/07/2005 16:09
Re: Really weird networking problem
[Re: tahir]
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pooh-bah
Registered: 27/02/2004
Posts: 1913
Loc: London
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This si the one that doesn't work:
Windows IP Configuration
Host Name . . . . . . . . . . . . : FLKPC2
Primary Dns Suffix . . . . . . . :
Node Type . . . . . . . . . . . . : Hybrid
IP Routing Enabled. . . . . . . . : No
WINS Proxy Enabled. . . . . . . . : No
Ethernet adapter Local Area Connection:
Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : Intel(R) PRO/100 VE Network Connecti
on
Physical Address. . . . . . . . . : 00-0D-60-C3-D9-9F
Dhcp Enabled. . . . . . . . . . . : No
IP Address. . . . . . . . . . . . : 121.1.0.40
Subnet Mask . . . . . . . . . . . : 255.255.255.0
Default Gateway . . . . . . . . . : 121.1.0.30
Primary WINS Server . . . . . . . : 121.1.0.254
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#260972 - 20/07/2005 16:11
Re: Really weird networking problem
[Re: tahir]
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carpal tunnel
Registered: 20/12/1999
Posts: 31596
Loc: Seattle, WA
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heh. Notice the difference? No DNS on the non-working PC.
This totally reminds me of some of the questions on the Microsoft certification tests. 
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#260973 - 20/07/2005 16:15
Re: Really weird networking problem
[Re: tfabris]
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pooh-bah
Registered: 27/02/2004
Posts: 1913
Loc: London
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Quote:
heh. Notice the difference? No DNS on the non-working PC.
This totally reminds me of some of the questions on the Microsoft certification tests.
Sorry removed the DNS settings whilst testing (just in case) they've been in there most of the day and I've just retested with them in, still no action.
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#260974 - 20/07/2005 16:18
Re: Really weird networking problem
[Re: tahir]
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pooh-bah
Registered: 27/02/2004
Posts: 1913
Loc: London
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I found the mac address of the remote router/bridge amd manually added an arp entry for it and one of the Linux servers at the remote end, it can ping the router but not the server, it couldn't ping either before.
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#260975 - 20/07/2005 16:27
Re: Really weird networking problem
[Re: tahir]
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carpal tunnel
Registered: 20/12/1999
Posts: 31596
Loc: Seattle, WA
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Try forcibly changing the non-working PC's IP address to match the one that works. Either turn off or temporarily change the IP address on the working PC so that it doesn't conflict. See if that makes it work temporarily.
If so, then it's something in the routers that are configured to only accept the traffic from the working PC's IP address.
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#260976 - 20/07/2005 17:12
Re: Really weird networking problem
[Re: tahir]
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carpal tunnel
Registered: 06/10/1999
Posts: 2591
Loc: Seattle, WA, U.S.A.
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Quote:
No addreses conflict, tried it with various IPs, I don't know that the router stores ARP entries in a viewable format, they're not implicitly set by us anyway. Hopefully rebooting them should get rid of that issue???
From what you say here and what you've posted in follow-ups, it does small like an ARP issue (masks look conventional/OK, no DNS dependency -- problem producible at IP level). If bridge is storing misassociated MAC for that IPin ARP table, then that would explain. If you can afford to power cycle bridge/s real soon, I would do that before pulling any more hair (yes, it should clear ARP entries/cache....I always count to 10 while powered off!)
_________________________
Jim
'Tis the exceptional fellow who lies awake at night thinking of his successes.
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#260977 - 21/07/2005 07:33
Re: Really weird networking problem
[Re: jimhogan]
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pooh-bah
Registered: 27/02/2004
Posts: 1913
Loc: London
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Thanks very much guys, it was definitely something in an arp table somewhere, rebooted all switches, routers etc and now everythings OK.
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#260978 - 21/07/2005 12:14
Re: Really weird networking problem
[Re: jimhogan]
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pooh-bah
Registered: 13/09/1999
Posts: 2401
Loc: Croatia
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Incidently, one of my users had a somewhat similar problem this morning (local switched network, one client can't ping the server, everything else OK). The same solution - rebooting the switch, in this case - worked. Sigh! It is not only Windows any more that get tired and require reboot here and there... 
_________________________
Dragi "Bonzi" Raos
Q#5196
MkII #080000376, 18GB green
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#260979 - 21/07/2005 13:20
Re: Really weird networking problem
[Re: bonzi]
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old hand
Registered: 27/02/2003
Posts: 776
Loc: Washington, DC metro
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I run a wireless connection from my Tivo and Empeg MLord dock via a 10 bT Hub (not switched) and a wireless bridge. It had been working fine for about a year. A few weeks ago, the empeg traffic simply refused to go through the bridged link. The Tivo was connecting properly, getting daily updates from the web. I could reach the empeg through the hub just fine. If I rebooted the bridge, it'd sometimes work but just for a while. I updated the firmware on both wireless endpoints, to no avail.
I instituted a "ping empeg -t" on a machine on the other side of the wireless link, and it's been fine since. Annoying solution, but it's working for now.
-jk
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#260980 - 21/07/2005 13:25
Re: Really weird networking problem
[Re: jmwking]
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carpal tunnel
Registered: 24/12/2001
Posts: 5528
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Is it a proper bridge or an ethernet converter type device? Ethernet converters are design to only have 1 device plugged into them because they take on the MAC address of the device connected.
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#260981 - 21/07/2005 14:18
Re: Really weird networking problem
[Re: tman]
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old hand
Registered: 27/02/2003
Posts: 776
Loc: Washington, DC metro
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It's theoretically a proper bridge (a consumer grade bridge, so you never really know). It worked fine for two devices for a year, I've had guests' laptops plugged into it many times as a third device, with no problems. It's only the empeg traffic that's giving trouble. I've been thinking of replacing it with a newer setup anyway, so I've not worked on the problem a lot.
What I'd really like is a pair of wireless devices: One as a firewall and AP (with external VPN capability so I can listen to my home, docked empeg from work), and the other as a wireless bridge and AP (to give me better coverage on my deck out back). WPA2 and a/b/g (or just a and g). I'm just starting my hunt, though.
-jk
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