[cisco-bba] How to reset DSCP/TOS on LNS?

Andy Saykao andy.saykao at staff.netspace.net.au
Sun Sep 5 20:47:07 EDT 2010

Sorry to re-open this again but is there a way to reset the entire TOS
byte. Our Billing System uses the TOS value (bits 3-6) of the TOS byte
for billing purposes to classify different traffic types (yes I know TOS
value is outdated and we should move to DSCP but that's another story).
If we reset the DSCP value (bits 0-5) or IP Precedence field, this
doesn't really solve our problem of resetting the TOS value to zero.

Take for example where a customer sets TOS Byte to 3.

TOS Byte = 0000 0011

The policy-map applied on the virtual-template will reset the DSCP
fields to 0.

policy-map QOS-POLICY-RESET-0
  set ip dscp 0

The TOS value will now be xxx0 001x because the policy-map only resets
bits 0-5 (a 1 remains in bit 6). We are left with a TOS value of 1. 

We can probably get the Billing System to ignore any TOS value of 1 it
sees but I was just wondering if there was a way to reset the entire TOS
byte or TOS value to zero on the LNS???



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