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How to stop received broadcast

Dear All,

I am using Gige for my WAN connection with 100Meg Internet bandwidth. I can see the increase in received broadcast on Interface. I tried using no ip unreachables, no ip directed-broadcast and no ip unicast-verify but of no help.

Please suggest the cause and remedy to this problem.

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

Queueing strategy: fifo

Output queue: 0/40 (size/max)

30 second input rate 15842000 bits/sec, 13991 packets/sec

30 second output rate 107356000 bits/sec, 15131 packets/sec

2570095849 packets input, 471122662 bytes, 0 no buffer

Received 379910 broadcasts, 0 runts, 0 giants, 0 throttles

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

0 watchdog, 8747367 multicast, 0 pause input

0 input packets with dribble condition detected

1030143908 packets output, 52688175 bytes, 0 underruns

3 output errors, 0 collisions, 2 interface resets

0 babbles, 0 late collision, 0 deferred

3 lost carrier, 0 no carrier, 0 pause output

0 output buffer failures, 0 output buffers swapped out

8 REPLIES

Re: How to stop received broadcast

Receiving broadcasts is something one has little control over. Using broadcasts is normal on ethernet and certainly has it's use. (ARP, dhcp, ..)

You will have to reduce the transmission of broadcasts on the other hosts on the same subnet.

On your local LAN where YOU have control, you can take all measure that you see fit.

On the outside interface this will be harder to achieve because it's your provider that rules there.

However, looking at the numbers above, I would see little reason to complain.

regards,

Leo

Re: How to stop received broadcast

Hi

clear counters on this interface so you can have a better view of how much broadcast you are receiving. it might not be an issue after all.

HTH

Sam

New Member

Re: How to stop received broadcast

Hi Sam,

My LAN broadcast would not impact my WAN interface Broadcast since the IP configured does not belong to the same prefix. I have used my ISP provided WAN ips on gige Interface to establish the connectivity.

This must have been part of ISPs broadcast domain i.e all 1s. Is there any remedy possibly which can help? whats the impact of received broadcast. Few of customer's are complaining of packet drops and we are suspecting received broadcast might be causing issues.

please share any workaround to mitigate this.

Re: How to stop received broadcast

Hi,

I have a router with GE crossed to another router /30 and another GE crossed to a L3 switch using HSRP, both interface broadcast is zero.

Received broadcast is number of received broadcast and multicast. Some of the cause (other than DHCP, etc..) are faulty hardware (your side or your ISP side) - in a LAN environment one host in the same network could have a faulty hardware, mismatch settings (speed/duplex, auto/hardcode), wrong/faulty cable

Regards,

Dandy

Re: How to stop received broadcast

as per previous posts, broadcast is pretty normal. when u clear your interface counters you can monitor objectively.

with regards to packet loss, you need to locate where there are dropped.

ask your customers for traceroute output m and then verify link integrity on each hop. check for interface error, Q drops, CRC errors etc..

looking at show interface from ur 1st post, it seems like you have some issues with 100Mb( assuming you have rate limited your interface to 100Mb only)

30 second output rate 107356000 bits/sec, 15131 packets/sec

HTH

Sam

Hall of Fame Super Silver

Re: How to stop received broadcast

Gaurav

What kind of service is the ISP providing? Is this a Metro Ethernet or is it perhaps DSL or Cable Modem with an Ethernet handoff? I have a customer who has had a similar experience of some packet loss and when we investigated we found that the provider facing interfaces were receiving a large amount of broadcast traffic from the provider. Other than talking to the provider and asking if there was something they could do to reduce the broadcast volume I am not aware of anything to be done about this.

HTH

Rick

New Member

Re: How to stop received broadcast

Hi,

Our ISP has put on rate-limit of 130Mb with exceed-action continue. That means with bursty traffic , it should not drop the packets with full load and with no load.

In both cases (full load/no load), i can see the received broadcast increasing.

MTU 1500 bytes, BW 1000000 Kbit, DLY 10 usec,

reliability 255/255, txload 22/255, rxload 3/255

Encapsulation ARPA, loopback not set

Keepalive set (10 sec)

Full-duplex, 1000Mb/s, media type is RJ45

output flow-control is XON, input flow-control is XON

ARP type: ARPA, ARP Timeout 04:00:00

Last input 00:00:01, output 00:00:00, output hang never

Last clearing of "show interface" counters 1d21h

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

Queueing strategy: fifo

Output queue: 0/40 (size/max)

30 second input rate 13144000 bits/sec, 11826 packets/sec

30 second output rate 87319000 bits/sec, 12894 packets/sec

2002972212 packets input, 3597159099 bytes, 0 no buffer

Received 2177 broadcasts, 0 runts, 0 giants, 0 throttles

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

0 watchdog, 249739 multicast, 0 pause input

0 input packets with dribble condition detected

2158568623 packets output, 4266302986 bytes, 0 underruns

0 output errors, 0 collisions, 0 interface resets

0 babbles, 0 late collision, 0 deferred

0 lost carrier, 0 no carrier, 0 pause output

0 output buffer failures, 0 output buffers swapped out

Re: How to stop received broadcast

This looks like a healthy interface !

are ur customers still dropping packets ?

Sam

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