Silently dropping QoS marked packets on the greater Internet

Mark Tinka mtinka at
Fri Sep 9 05:04:39 UTC 2011

On Friday, September 02, 2011 10:24:23 PM Jesse McGraw 

>    I've recently run into a hard-to-troubleshoot issue
> where, somewhere out in the greater Internet, someone
> was silently dropping packets from my company that
> happened to be marked with DSCP AF21.  I'd fully expect
> others to either ignore these markings or zero them out
> but just silently dropping them seems unnecessary.

This is broken.

They likely aren't remarking their Internet traffic 
appropriately to avoid having to schedule it internally, and 
thus, perform some kind of action on it per their QoS 

You may consider remarking your traffic one egress to the 
Internet to 0 (safe bet?), but this may be a platform-
specific capability, and can't tell you for sure it will 
work; needless to say, you might not want to do this anyway 

> So, how do you guys treat marked packets that come
> into/through your networks?

We generally remark all ingress IP Transit traffic to 0, 
both for v4 and v6. This includes traffic from IP Transit 
customers. In general terms, trying to provide QoS 
scheduling services to Internet traffic is fairly 

There are special cases where Internet traffic could be 
marked to a non-0 value, but these would be controlled 
situations for interesting business opportunities.


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