Nope. Bits is bits. It's all in how the router chooses to read them.... DSCP combines the old TOS and IPP fields into one larger field. You cannot do both at once, with the exception that the IPP values map directly to DSCP Class Selectors (CS6 through CS1).
Absolutely. For the most part, TOS has been deprecated. At Layer 2, it has been replaced with 802.1Q/p Class of Service (CoS) marking. At Layer 3 in a DiffServ environment, the equivalent is the IP Precedence (IPP) field. DiffServ uses the entire TOS byte (including the IPP bits) to create both the DSCP code point marking (6 bits, 0-63), and the last two bits for Explicit Congestion Notification (ECN), kinda like you'd see in a Frame Relay cloud. If you're running Differentiated Services for your QoS, you should running DSCP at Layer 3 and (if you need it) CoS at Layer 2.
For the record, there are 14 standard DSCP code points for Per Hop Behavior (PHB), plus IPP level 1 through 6 map directly to Class Selectors, special DSCP code points with the last three bits set to all zeros.
Of course, your upstream ISP will most likely remark your traffic once it hits his administrative domain, but that's to be expected.
Tim Szigeti and Christina Hattingh co-wrote an excellent QoS book that ties it all in together. It has been well worth the money for me as both a teaching and reference source.
We are pleased to announce availability of Beta software for 16.6.3.
16.6.3 will be the second rebuild on the 16.6 release train targeted
towards Catalyst 9500/9400/9300/3850/3650 switching platforms. We are
looking for early feedback from customers befor...
Introduction Featured Speakers Luis Espejel is the Telecommunications
Manager of IENova, an Oil & Gas company. Currently he works with Cisco
IOS® and Cisco IOS XE platforms, and NX to some extent. He has also
worked as a Senior Engineer with the Routing P...
In this session you can learn more about Layer 3 multicast and the best
practices to identify possible threats and take security measures. It
provides an overview of basic multicast, the best security practices for
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