ISR 4321 Performance Oversubscription

[hotpackets]

I have an ISR 4321 with a 100M license that terminates a 100M WAN circuit. The 100M on the 4321 is an aggregate throughput (all flows through the box). My 100M WAN circuit is 200M in aggregate (100 in/100 out). I've oversubscribed the box 2:1.

When my aggregate flows pass 100M and starts getting dropped by the 100M Global Shaper applied by Cisco to enforce the 100M license, where would those drops be seen? Is there a command I can use to view what's being dropped by the shaper?

I assume that QOS wouldn't help, but I don't have the means to test it. If I have 50M coming in from the WAN, then I only have a 50M budget left for outbound traffic. But my QOS policy is based on the 100M WAN circuit. Am I correct to assume that QOS wouldn't matter in this case and the box would indiscriminately drop traffic that exceeds 50M outbound?

[Philip D'Ath]

I don't know for sure, but I understand that whenever the global policer "kicks in" in logs a message saying it is doing so.

If you only need Ethernet connectivity you could look at routers like the 1100-4P and 1100-8P - which are cheaper and will kick the 4321's arse.

https://www.cisco.com/c/en/us/products/collateral/routers/1000-series-integrated-services-routers-isr/datasheet-c78-739512.html

[hotpackets]

Do you know what the log message says? Any keywords I can use to filter for?
We've standardized on the 4000 as some sites require much higher throughput.

EDIT: Never mind, I found the log message: %BW_LICENSE-5-THROUGHPUT_THRESHOLD_LEVEL

[Joseph W. Doherty · Accepted solution]

"Am I correct to assume that QOS wouldn't matter in this case and the box would indiscriminately drop traffic that exceeds 50M outbound?"

Yes and no. In theory, for example, you might have 100 Mbps LAN ingress, and no WAN inbound, so then QoS on 100 Mbps WAN egress would "trigger" QoS. Of course, wouldn't expect this to normally happen.

BTW, to exceed the 100 Mbps performance limit you could upgrade the license to the (latest) "boost" license. Likely your 4321 could then support 100 Mbps LAN and WAN, concurrently.

[hotpackets]

Thanks. I also just finally got a response from our Cisco rep confirming my assumption.
I got a quote for the boost license the other day, and it sucks that we can't get it as an upgrade to our existing license.

[hotpackets]

The following command shows what the global shaper is dropping:

show platform hardware qfp active feature lic-bw oversubscription all 

[Mark Malone]

handy command thanks +5