Cisco Support Community
Showing results for 
Search instead for 
Did you mean: 

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. And see here for current known issues.


Wan stability and SRST


im having an indirect voice issue. my phones at a remote location goes down for half a second (probably once a day trying to go into SRST mode). ive identified the issue but that about as far as i can get. here it is. if i clear the counters on the router and then wait till the phones drop, i see "throttle" being incremented. clear again and same thing happens. no interface resets or crc etc. It's defintely the throttle but im not too sure what this means. i did some searching and they said its explorer packets. that cleared things up a lot - Kidding :)

See below and any help would be greatly appreicated as usual

Received 47201389 broadcasts, 0 runts, 0 giants, 1 throttles


Re: Wan stability and SRST

Throttles are generated when the router's CPU is running high, and locks the

interface for one second in order to keep handling the packets correctly.

From the "show process cpu history " we can find if this box CPU utilization is high and why?


Re: Wan stability and SRST

I found this:

Throttles - When the Input Q (process switching) fills up on an interface,

the CPU assumes that something is misbehaving on that interface (broadcast

storm, SNMP storm) since the processor is not able to keep up with the

incoming packet rate (hence the Q filling up). The processor throttles the

interface to protected itself and the other well-behaved interfaces. This

means that it ignores interrupts from that particular interface for one

second. When the interface gets a packet and sends an interrupt to have it

stored and switched, the processor doesn't answer. Thus the packet is

dropped at the hardware level. Throttled means interrupts were disabled for

the interface. We do this for any interface when the input queue is filled.

Packets in the input queue are processed before interrupts are enabled

again, so no traffic will enter the port.

You can increase the input

queue, but if they still happen, look at the switching path, and see if you

can fast switch traffic without causing some other problem. If the Input Q

never returns to 0, then you might have packets stuck in the Q. In that case

you can do a 'show buffer old' or 'show buffer input-int xx' to find out

what packets are stuck. There is no counter that keeps track of how many

packets were dropped during the throttle interval.

First of all please try to increase the Input Queue on the fastethernet

interface as follows.

config t

int fa1/1

hold-queue 120 in

Also u may post this in the Routing forum so some experts in that area can help us as well.


Re: Wan stability and SRST

thanks a lot for the response. i found some documents last night explaining this and as well i enabled some accounting to see if a mac add might be overloading the interface. its a little strange that we enabled nbar and around that same time it started occuring. nabar was disabled but issue still continued.

im monitoring. im hoping its a PC thats causing this and the accounting should show me

thanks again....chalk this one up as another learning experience for me :)


Re: Wan stability and SRST

just and FYI

the issue seems to be fixed. spent the night by the customer and it seems as though it was an issue with the ISP switch and nothing on our internal network. took a lot of time but at least we got it.

P.S that was defintely not a fun experience :)

CreatePlease to create content