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UDP broadcast forwarding by Cisco's IP HelperArticle ID: 190930 - View products that this article applies to. This article was previously published under Q190930 NoticeThis article applies to Windows 2000. Support for Windows 2000 ends on July 13, 2010. The Windows 2000 End-of-Support Solution Center
(http://support.microsoft.com/?scid=http%3a%2f%2fsupport.microsoft.com%2fwin2000)
is a starting point for planning your migration strategy from Windows 2000. For more information see the Microsoft Support Lifecycle
Policy
(http://support.microsoft.com/lifecycle/)
.SYMPTOMS
User Datagram Protocol (UDP) broadcasts are transformed into directed datagrams. Upon inspection of the media access control address, network packets have been transformed from the expected broadcast address
(FFFFFFFF) to a specific media access control address.
An event that resembles the following may be logged in the System log of the Master Browser: Event Type: Error Event Source: MRxSmb Event Category: None Event ID: 8003 User: N/A Computer: DC-01 Description: The master browser has received a server announcement from the computer <Browser-Server-in-other-subnet> that believes that it is the master browser for the domain on transport NetBT_Tcpip_{EADD435F-5125-4F5. The master browser is stopping or an election is being forced. For more information, see Help and Support Center at http://go.microsoft.com/fwlink/events.asp. Data: (shown in Words) 0000: 00000000 004e0003 00000000 c0001f43 0010: 00000000 00000000 00000147 00000000 0020: 00000000 00000000 CAUSE
IP Helper has been enabled on a Cisco switch. RESOLUTION
Disable IP Help either completely or on a per UDP port basis. STATUS
This behavior is by design. MORE INFORMATION
Typically, a broadcast should be confined within its IP subnet. However,
notable exceptions occur such as a DHCP (BootP) broadcast. Cisco has
provided functionality in some of its router products called IP Helper to
forward specific broadcast to designated computers. For example, you could
configure all DHCP broadcasts to be directed to the specified DHCP server.
The thinking behind this is a directed datagram will decrease the network
traffic when compared to a broadcast packet propagated to all subnets.
If an IP helper address is specified and UDP forwarding is enabled, broadcast packets destined to the following port numbers are forwarded by default. Time Service Port 37 TACACS Port 49 Domain Name Services Port 53 Trivial File Transfer Port 69 DHCP (BootP) Port 67 and Port 68 NetBIOS Name Server Port 137 NetBIOS Datagram Server Port 138 You can use the Browstat command prompt utility to investigate browsing errors. For more information about browser errors, click the following article number to view the article in the Microsoft Knowledge Base: 188305
For more information, click the following article number to view the article in the Microsoft Knowledge Base:
(http://support.microsoft.com/kb/188305/
)
Troubleshooting the Microsoft Computer Browser service
135464 The third-party products that this article discusses are manufactured by companies that are independent of Microsoft. Microsoft makes no warranty, implied or otherwise, about the performance or reliability of these products.
(http://support.microsoft.com/kb/135464/
)
8003 browsing errors with UDP forwarding
PropertiesArticle ID: 190930 - Last Review: January 17, 2008 - Revision: 5.2 APPLIES TO
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