large number of output drops what's the cause?

Unanswered Question
Sep 13th, 2008

Hi all have to point to point metro Ethernet 10Mb connection between two sites. Users on both sides are complaining of slow internet. These are two medium size medical offices with about 50 users at each location. The remote end connects to the local end then we have another connection out to the local side to a Cisco ASA out to our ISP. So internet traffic for the remote end is routed over the metro-E then to the ASA out to the internet. We also have IP phones that our used over the Metro-E. I see a lot of output drops. Now I've always thought that output drops were from over utilization but, this is a 10Mb link I wouldn't think that it would be saturated. I've attached "sh int" on both the remote side that has all of the drops and the local end. Would it be the case that the link from our ASA to ISP is not large enough.

Any suggestions?



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bbxie Sat, 09/13/2008 - 19:21

although there're 343 output drop and 343 not buffer in ther remote router's g0/1, but since you have not cleared the interface counter, so it is hard to say if there's a problem in this interface. So pls. use "clear counter g0/1" to clear both local and remote router's g0/1, then wait for a while and check the interface again, if there still have the same error, then it is the link's issue. Otherwise you have to check your ASA/WAN router's out interface to ISP, to check if there are some errors under the interface, then according to the error mesg to check if it is a bandwidth bottleneck or cable/interface hardware issue.

Another method to assist you to troubleshooting is you can do some ping test from remote office to local office when you feel the speed to access internet is slow

, for example: 1. try to ping local router's G0/1, if slow, then means your metro-E link has problem; 2. try to ping ASA's outside interface, if ping 1 is ok, ping 2 has timeout or long delay, then check all the L3 hops between local router and ASA; if bothe ping 1 and 2 are ok, then your ISP link or ISP internal network have problem, you need to ask ISP engineer to solve the problem

Joseph W. Doherty Sun, 09/14/2008 - 03:24

As Bo mentions there's only 343 drops on the remote interface (in your attachement). However, even discounting how long a period this is over, it's also over 385,280,604 output packets. We're usually more interested in the drop rate percentage than the absolute count, and yours is very low and would, but itself, would not usually represent an issue.

Since you note "both sides" complain of "slow internet", you might want to focus more on what's happening on your Internet link connection with your ISP. So yes, it's possible "Would it be the case that the link from our ASA to ISP is not large enough.", your Internet connection isn't large enough for about 100 users. Much also depends on how they are using the Internet.


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