How to stop received broascast

Unanswered Question
Sep 7th, 2007

Dear All,

I am getting received braodcast on my WAN interface. Is there any mechanism available to stop it?

I have already tried no ip directed-broadcast and no ip unicast-verify & no ip unreachable. No help.

Input queue: 0/75/1/24 (size/max/drops/flushes); Total output drops: 18446516

Queueing strategy: fifo

Output queue: 0/40 (size/max)

5 minute input rate 59507000 bits/sec, 8222 packets/sec

5 minute output rate 8374000 bits/sec, 7705 packets/sec

2510671362 packets input, 1760307854 bytes, 0 no buffer

Received 10 broadcasts, 0 runts, 0 giants, 1 throttles

0 input errors, 0 CRC, 0 frame, 1 overrun, 0 ignored

0 watchdog, 95029 multicast, 0 pause input

0 input packets with dribble condition detected

3293051759 packets output, 2201778598 bytes, 0 underruns

3 output errors, 2522767556 collisions, 2 interface resets

0 babbles, 947718043 late collision, 0 deferred

3 lost carrier, 0 no carrier, 0 pause output

0 output buffer failures, 0 output buffers swapped out

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Edison Ortiz Fri, 09/07/2007 - 16:20

Looking at your interface, I wouldn't be concerned about the broadcast you've received. 10 broadcast packets with the kind of traffic you are receiving (59.5Mbits, when you took the sample) is nothing.

I'm sure the broadcast traffic stat isn't increasing, right ?

However, you should be concerned about the collisions on the outgoing packets and the output drops.

Is this an ethernet interface or a serial ? Based on the speed reported, it seems to be a LAN interface, if so - make sure you address any duplex/speed mismatch.

gaurav_thapar79 Fri, 09/07/2007 - 20:32


It was a 100M EoSDH WAN link wherein the received broadcast counter is not increasing randomly. I have seen in most of the cases that the received broadcast counter is increasing erratically i.e means increasing at fast pace. More specifically in case of internet bandwidth links either on serial or Fastethernet/Gige.

Please share the cause and remedy of received broadcast.

Edison Ortiz Sat, 09/08/2007 - 12:28

You can place an ACL on the interface to block broadcast traffic but the router will still process the packet and drop it just like is doing now. With new IOS, all IP directed broadcasts are dropped.

As I stated before, don't be too concerned about the broadcast traffic you are receiving. Based in your output, you have bigger problems such as: output drops and collisions.


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