Two Gateways in Network Configuration - Backup gateway is always active
I have a customer who has two links to the Internet. One is a cable connection (Bright House Networks) and the other is a T1 (Megapath). A Windows 2003 server is doing DHCP. In the DHCP configuration the client computers get two gateways
for failover. The primary gateway is the cable connection and the second/backup is the T1. This works great for all Windows XP machines. If the cable goes down, they all switch over to the T1 and then back again when the cable is back up
and the IP address is renewed on the client.
However, on the one Windows 7 Professional computer they are testing, the Internet connection is always the T1. When doing an IPCONFIG, the cable gateway shows first, but it doesn't make a difference. This is driving the customer crazy since
he needs the speed of the cable for downloads. Yes, we could easily configure a static network setting, which would eliminate the T1, but then there goes the redundancy. Also, he wants to roll out Windows 7 to his network (50 computers) without
changing anything and thereby retaining the redundancy.
Anyone know what is going on here?
Thanks,
Tony
April 20th, 2010 12:09am
Hi Tony,
This issue should be related to the multi-homed network configuration. Based on my research, I would like to share the following with you:
Source
IP address selection on a Multi-Homed Windows Computer
Default Gateway Configuration for Multihomed Computers
Hope this helps. Thanks.
Nicholas Li - MSFT
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April 23rd, 2010 10:13am
Nicholas,
Thank you for your reply. I was unaware you had answered my question until just recently. Your links for information on multi-homed computers were interesting but not relevant to the issue. I failed to point out in my original post that
there is only one NIC in the computer. With the dual gateway configuration, we are attempting to use dead gateway detection to fail over to the second ISP connection. A link contained in the second article you cited lead me to knowledge base article
128978, which references dead gateway detection. I checked the registry setting to ensure dead gateway detection is enabled and it appears to be although it seems to use a different key title - DeadGWDetectDefault - instead of EnableDeadGWDetect, which
is mentioned in the article. Are my assumptions correct or does a registry entry with a key title of EnableDeadGWDetect need to be added?
Below is an IPCONFIG of the subject computer showing one NIC with two gateways.
Windows IP Configuration
Host Name . . . . . . . . . . . . : TUNAVAMPIRE
Primary Dns Suffix . . . . . . . : dean.lcl
Node Type . . . . . . . . . . . . : Hybrid
IP Routing Enabled. . . . . . . . : No
WINS Proxy Enabled. . . . . . . . : No
DNS Suffix Search List. . . . . . : dean.lcl
Ethernet adapter Local Area Connection:
Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : Intel(R) 82567LF-2 Gigabit Network Connection
Physical Address. . . . . . . . . : 00-1C-C0-8F-E4-96
DHCP Enabled. . . . . . . . . . . : Yes
Autoconfiguration Enabled . . . . : Yes
Link-local IPv6 Address . . . . . : fe80::4962:459c:8736:4229%2(Preferred)
IPv4 Address. . . . . . . . . . . : 192.168.1.87(Preferred)
Subnet Mask . . . . . . . . . . . : 255.255.255.0
Lease Obtained. . . . . . . . . . : Monday, May 17, 2010 10:58:41 AM
Lease Expires . . . . . . . . . . : Tuesday, May 25, 2010 10:58:34 AM
Default Gateway . . . . . . . . . : 192.168.1.1
192.168.1.254
DHCP Server . . . . . . . . . . . : 192.168.1.205
DHCPv6 IAID . . . . . . . . . . . : 218111168
DHCPv6 Client DUID. . . . . . . . : 00-01-00-01-11-35-D7-E1-00-1C-C0-8F-E4-96
DNS Servers . . . . . . . . . . . : 192.168.1.200
192.168.1.205
65.32.1.65
66.80.130.23
Primary WINS Server . . . . . . . : 192.168.1.205
NetBIOS over Tcpip. . . . . . . . : Enabled
May 24th, 2010 6:00pm
Even if you get this to work, it does not work as you expect. Yes, dead gateway detection should switch over if one connection fails. But there is no mechanism to switch back when the faster gateway becomes available again. It will only try to switch
back if the gateway in use dies.
To effectively manage two Intertnet connections you need a hardware device which can load balance two Internet connections.
Bill
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May 25th, 2010 4:01am
Dead gateway detection actually works quite well at the client's location. All the Windows XP Professional workstations go out the cable connection until it goes down. When that happens, the computers switch to the T1. The network administrator
automatically restarts every computer each night using a script I gave him. When the computers restart, they once again renew their IP addresses and then go out the cable connection as long as the cable ISP has fixed their network outage.
The problem is, on the one Windows 7 Professional workstation, it will not use the cable connection (default gateway 192.168.1.1 om the IPCONFIG listing above) under any circumstances. It always goes out the the T! (192.168.1.254 gateway), and
nobody seems to know why this happens or how to fix it. The issue is stalling a Windows 7 roll-out. It's hard to convince the client he needs new routers to support failover when the current system with Windows XP works exactly like he wants
it to work.
Tony
May 25th, 2010 4:16am
So, I guess no one has any idea on this post? Perhaps, someone might suggest another place to post. I would really like to find out why Windows 7 acts differently than Windows XP as it relates to dead gateway detection. Not only is this
client not going to upgrade until this is resolved, but there is another client configured the same way who may face the same issue soon.
Tony
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June 6th, 2010 8:11pm
Tony, were you able to figure this out? I am in the same situation. I have two internet connections, 10.0.0.1 & 10.0.0.2 and want to setup a server to use the .2 as failover when .1 goes down, then revert back when it is restored. Any info you found
out would be appreciated. Thanks.
March 31st, 2011 1:36pm