Forefront TMG 2010 ISP Redundancy : Configuring verification of link status

Modifying dead link detection periods

Howto reduce Dead/Available Link Detection Time out Frequency: Use the following vbs file,

Copy Paste the following code in notepad, and save it as TMG.VBS and edit it as per your requirement. then double click it to run on TMG.

set root=CreateObject("FPC.Root")
set arr=root.GetContainingArray()
set ExtNet=arr.NetworkConfiguration.Networks("External")
set ISPRCfg=ExtNet.ISPRedundancyConfig
ISPRCfg.MinimalResumeTime = 10
ISPRCfg.TestIntervalLinkAvailable = 10
ISPRCfg.TestIntervalLinkUnavailable = 10
ISPRCfg.FailuresToUnavailable = 1
ISPRCfg.SuccessesToAvailable = 1
ISPRCfg.Save

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Configuring verification of link status

In the default setting, TMG checks the status of the ISP link by trying to establish a TCP connection on port 53 (DNS zone transfer) to a list* of root DNS server on a round robin basis. If a connection can be established, TMG will consider the link active.

Although, the IP addresses and the TCP port used for the verification cannot be configured directly from the management console, If you need to modify these settings, e.g. because you setup your TMG server without direct access to the internet, you can do this by using the TMG COM, through simple Visual Basic script like this one: Following script is to change the root dns entries in TMG , which are used while tracking link detection.

set root=CreateObject("FPC.Root")
set arr=root.GetContainingArray()
set ExtNet=arr.NetworkConfiguration.Networks("External")
set ISPRCfg=ExtNet.ISPRedundancyConfig
ISPRCfg.ConnectivityVerificationRemoteIpAddresses.RemoveAll()
ISPRCfg.ConnectivityVerificationRemoteIpAddresses.Add "8.8.8.8"
ISPRCfg.ConnectivityVerificationRemotePort = 53
ISPRCfg.Save</span>

 

Author

Philipp Sand
Microsoft CSS Forefront Security Edge Team
Reference:
http://blogs.technet.com/b/isablog/archive/2009/11/26/tmg-isp-redundancy-unleashed.aspx

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Regard’s

Syed Jahanzaib