Packet Loss on Gigabit interfaces for ISR

[Yacine BS]

Hello,

I came through an odd issue. We have an ISR 4331 which is providing Internet Access. Ge0/0 is connected to the LAN and Ge0/1 is connected to the WAN. (check design attached)

After testing the Internet connection reliability with IPERF3, packet loss has been noticed.

After troubleshoot, it is not an issue with IOS or IOS XE. It turns out that when we fix the speed of the 2 ports to 100 we get no packet loss.

Is this an issue with the ISRs or are we missing configuration on the Gig ports?

[Georg Pauwen]

Hello,

can you post the output of show interfaces gigabitethernet0/0 and 0/1 ?

[Yacine BS]

Hi George, I lost the logs but I can assure you that there are no packet drops in input queue or output queue, and there are no unknown protocol drops ...

Thank you,

[Joseph W. Doherty]

A 4331's performance is capped at either 100 Mbps or 300 Mbps (depending on license). Although it has gig interfaces, it's not designed to support sustained gig throughput. That might be the cause of your drops.

[Yacine BS]

Hi Joseph, This router has been licensed for 100 Mbps since it is the bandwidth requested by the client. But what if the clients requests 200 Mbps in the future? Should I add a license and the drops will not happen ? and one more question, what about the LAN interface, is it limited also to 100Mbps?

Thanks

[Joseph W. Doherty]

As I understand it, the bandwidth its capped across the backplane, by license. I.e. if the router only has a 100 Mbps throughput license, that's the maximum that will transit the router.

[Yacine BS]

Hi Joseph,

Thanks again for your reply,

Let me share with you these printscreens of the test with IPERF ( we have specified the bw to 100 Megs).

Yet the packet drops only happen if the speed of the ports is auto or 1000.

[Joseph W. Doherty]

If the ports are running at 100 Mbps, you're rate limiting traffic that would cross the backplane.

What you might try, run ports at 100, but see if you can obtain 100 Mbps in both directions, concurrently.

[Leo Laohoo]

Why the secrecy?
Show us the output to the command "sh interface <WAN PORT>". There are things that we want to see that others may not know the importance of.
Screenshots are of no use because the image is very grainy.