Regarding UDP Broadcasts and Multicasts

Apr 06, 2006 4 Replies
R
Regarding UDP Broadcasts and Multicasts open original image

Hi folks, I have enabled Ip directed broadcast on one of our Routers, with appropriate helper address. If I enable "ip route-cache flow" on the interface and "show ip cache flow"; I get to see that the incoming interface is the interface on which I have enabled the broadcast ( with helper address) and the Out going Interface as "Null" with the destination IP Address as helper Address I specified. Where as for TCP Traffic Incoming and outgoing interfaces are seen proper. But the UDP Broadcast is getting forwarded to client machines.



Can anyone help me in understanding the basic of this.



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C

If I understand you correctly, you are saying that the functionality is correct but the show command output is showing seemingly incorrect information. My first guess would be that this could be a bug with the show command. Have you looked through the release notes from Cisco for any bugs that match this behavior?

Cisco da Gama

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R

I see the same on all routers, even I was told by my Senior that it is that way it works..... But I am unable to get through this one.

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D

you mention that you have IP helpers enable. I had a problem where my dhcp server was getting pounded by netbios traffic. I needed to add the following commands.

no ip forward-protocol udp netbios-ns no ip forward-protocol udp netbios-dgm

This may have some value to you.

Good Luck, Dan

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