[c-nsp] ToS equivalent to IP Precedence?

[Church, Chuck]

Dave,

	The precedence is the 3 most significant bits of the TOS byte.
It's possible to map one way from TOS to precedence, but not the other
way.  DSCP adds the next 3 bits to the right from the precedence, making
it the 6 most significant bits of the TOS byte.  To my knowledge, the 2
least significant bits are never used for QOS.  Does that help? 


Chuck Church
Lead Design Engineer
CCIE #8776, MCNE, MCSE
Netco Government Services - Design & Implementation Team
1210 N. Parker Rd.
Greenville, SC 29609
Home office: 864-335-9473
Cell: 703-819-3495
cchurch at netcogov.com
PGP key: http://pgp.mit.edu:11371/pks/lookup?op=get&search=0x4371A48D 


-----Original Message-----
From: cisco-nsp-bounces at puck.nether.net
[mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Dave Temkin
Sent: Monday, December 13, 2004 3:46 PM
To: cisco-nsp at puck.nether.net
Subject: [c-nsp] ToS equivalent to IP Precedence?

Noting that the range of ToS bits is 0-255, is there a way to directly
equate a ToS bit of say, 8, to an IP precedence?  My understanding is
that a ToS of 8 is equal to precedence 1?  Is this correct?  I may be
way
off...

I have a situation where I can reflect the ToS bit into a tunneled
packet
but I'm trying to figure out how to set the ToS bit so that I can do
things prec-based.

Thanks,
-Dave
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