mls qos trust dscp under router platform interface.

[syjeon]

Hi All.

I want to know what the default behavior about the command 'mls qos trust dscp' under router platform interface. the router is ASR1000 series.

we don't need to put above command line to trust dscp in case of router? otherwise, we have to add it as welll as like switch platform.

please, clarify for me.

Thanks.

[jeevak mukadam]

Hello syjeon,

Please share your run config.

'mls  qos trust dscp' command will match voice traffice 46 from incoming data  and obtain corresponding cos value of 5 from dscp-cos map table.

I have 1 question - How you configure your qos (AUTO OR Manual)

[syjeon]

Hi Jeevak,

I'm doing QoS configuration as manual. If so, the router does not need to have COS since it's not switch.

So, we can think the router can trust DSCP as default behavior, am I right?

[jeevak mukadam · Accepted solution]

Yes, Layer 3 interface and the Layer 3 subinterface always trust  (DSCP) by default.

[syjeon]

Thanks Jeevak.

[kevin_1234]

Hi @jeevak mukadam Do you know if there is any documentation on this? Im unable to find your Statement backed in the ASR1000er Docu.

[Joseph W. Doherty]

Likely there's documentation, somewhere, but generally Cisco routers, by default, ignore IP's ToS.  Actually, such routers don't "trust', again, by default, they ignore.  This also includes they don't, by default, change the ToS either.

Basically, same behavior of Cisco switches, years ago, when QoS wasn't enabled.

BTW, as a suggestion, querying someone on a posting over 10 years old can be very hit or miss.