DSCP conversion to TOS.

[Muhannad Abu Shamma]

I am wondering what is the TOS value equivalent to DSCP value AF31?

I have tried to use the charts but I couldn’t understand how to convert it, please can you help me?

Regards,

Muhannad

I am wondering what is the TOS value equivalent to DSCP value AF31?

I have tried to use the charts but I couldn’t understand how to convert it, please can you help me?

Regards,

Muhannad

[Kishore Chennupati]

Hi Muhammad,

A simple formula is this   8 *X+2*Y where X and Y are your AFXY.

so in your case its 8*3+2*1=26. So the decimal value is 26.

HTH

Kishore

[Muhannad Abu Shamma]

Hi Kishore,

I am trying to configure a Local Policy using the PBR:

ip local policy route-map xyz

!

route-map xyz

 match ip address 131
 Set IP TOS ?
 
Here i got only the values from 0-15 but i need to map this (?) value to AF31 and no option to select 26!
 
Please advise?
  
 Regards,
 Muhannad

[lgijssel]

TOS is the original version of the byte which is currently used for dscp.

To my knowledge, there has never been a universally accepted use of TOS, except for the IP Precedence bits.

The current standard (DSCP) allows for more granular setting of qos.

When looking at the issue like this, af31 comes closest to ip prec 3 (011 000), which equals dscp cs3.

The link below provides some background info on TOS vs DSCP:

http://www.cisco.com/en/US/tech/tk543/tk757/technologies_tech_note09186a00800949f2.shtml

regards,

Leo

[Kishore Chennupati · Accepted solution]

Hi Mohammad,

Please see the link which should help you

http://cisconinja.wordpress.com/2008/11/26/marking-dscp-values-with-policy-based-routing/

HTH'

Kishore

[Muhannad Abu Shamma]

Dears,

I think you really helped me out to know it... thank u

To obtain the AF31 DSCP value, i think we need to set the IP precedence to 3 and the ToS should be 4.

Regards,

Muhannad