Unusual traffic on 7609 - help pls!

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Nov 21st, 2008
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I use a 7609 router to connect to 3 ISPs. Traffic monitored by PRTG v6 on 7609 sometimes go down and then up rapidly (pls see attach file) but traffic on interfaces of 3750 connected to 7609 don't suffer this phenomenon. All modules on 7609 are fabric enable and I use dCEF. I still don't know how to solve this phenomenon. I appreciate your advices!

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Giuseppe Larosa Sat, 11/22/2008 - 02:03
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Hello Huan,

if you are using 32bit counters for octets instead of HC 64bits counters (that can be not available, for example they werent in C6500 with IOS) you can experience a wrapping effect:

when the counter makes its turn around 2^32 -1 it can cause to see sudden falls in graphs that are not real, because the graph is made by substracting from current counter value the older one.

As you can see from the graphs these low peaks are quite regular.

you have 200 Mbps.

it takes:

roughly 160 seconds to

4 10 ^9 bytes / 200 Mbps / 8

to wrap

but your frequency is higher in the order of 10 minutes or more.

However, I would check the MIB used to make the graph.

Hope to help



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