Unanswered Question
Sep 15th, 2008


On my FR ckt i am ssening the following broadcasts..its reapidly increasing..

pls let me know it there any issue with the link.

Broadcast queue 0/64, broadcasts sent/dropped 1136/0, interface broadcasts 1055



I have this problem too.
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Richard Burts Mon, 09/15/2008 - 19:01


Without some additional information I do not think that we can give you a good answer. What you have posted seems to indicate that there have been 1136 broadcasts. But without knowing how many packets have been transmitted we do not know whether 1136 is a small percentage or a large percentage or what.

And we do not have any information about how the router is configured and what might be running on that interface. For example if you have configured RIP as a routing protocol to run on that interface then a larger number of broadcasts is normal (since RIP updates are sent as broadcasts and are sent on a frequent interval).

So if you can provide information about how the router is configured and the output of show interface then perhaps we can give better answers.



sateeshk10 Tue, 09/16/2008 - 06:54


I am useing EIGRP for routing. pls find the below show int

Serial1/0 is up, line protocol is up

Hardware is GT96K with integrated T1 CSU/DSU

MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec,

reliability 255/255, txload 91/255, rxload 21/255

Encapsulation FRAME-RELAY, loopback not set

Keepalive set (10 sec)

LMI enq sent 7113, LMI stat recvd 7113, LMI upd recvd 0, DTE LMI up

LMI enq recvd 0, LMI stat sent 0, LMI upd sent 0

LMI DLCI 1023 LMI type is CISCO frame relay DTE

Broadcast queue 0/64, broadcasts sent/dropped 16557/0, interface broadcasts 15371

Last input 00:00:04, output 00:00:02, output hang never

Last clearing of "show interface" counters 19:45:39

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

Queueing strategy: weighted fair

Output queue: 0/1000/64/0 (size/max total/threshold/drops)

Conversations 0/4/256 (active/max active/max total)

Reserved Conversations 0/0 (allocated/max allocated)

Available Bandwidth 1158 kilobits/sec

30 second input rate 130000 bits/sec, 40 packets/sec

30 second output rate 556000 bits/sec, 57 packets/sec

2497572 packets input, 856554113 bytes, 0 no buffer

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

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

3544879 packets output, 5852475 bytes, 0 underruns

0 output errors, 0 collisions, 0 interface resets

0 output buffer failures, 0 output buffers swapped out

0 carrier transitions

DCD=up DSR=up DTR=up RTS=up CTS=up

Richard Burts Tue, 09/16/2008 - 09:32


Thank you for the additional information. I believe that to answer this issue it would be helpful to review the broadcast queue, why Frame Relay needs it, and how Frame Relay uses it.

Frame Relay acts as a multi-access media. Most multi-access media (such as Ethernet) is able to send a single frame out an interface and for multiple devices connected on that segment to receive and process the broadcast. But Frame Relay is not able to send a single frame out the interface and have multiple devices receive and process it. So Frame Relay uses the broadcast queue to achieve this functionality. When Frame Relay has a broadcast frame (or a multicast frame) it makes copies of the frame (a copy for each PVC on which the frame will be sent) and Frame Relay uses the broadcast queue to manage the transmission of these copied frames.

My guess is that your EIGRP hello messages and updates are multicast and are being sent through the broadcast queue. You could prove this by temporarily making your Frame Relay interface passive in EIGRP. If you do this I predict that the count in the broadcast queue will stop increasing. And if you make the interface active in EIGRP then I predict that the count will start to increase again.



sateeshk10 Tue, 09/16/2008 - 09:39


Thanks for info..

Will it going to impact on my network..



Richard Burts Tue, 09/16/2008 - 11:42


I believe that this is normal behavior and will not impact your network.




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