What is a good QOS book?

[dennylester]

With the help of Paresh here in these forums I got QOS working, I think, but would like a good book to explain things in easy to understand format.

The articles and white papers on the Cisco site are great, except they often leave me wondering why one way may be better than another. They give very basic examples with little explanation as to what is actually occurring.

Thanks,

Denny

[pkhatri]

Thanks for your acknowledgment, Denny.. glad to see you've got it working.

Well, I might try and help you out with this one as well :-). The following book is really good, and I've used it to prepare for the CCIP QoS exam:

Cisco QOS Exam Certification Guide (IP Telephony Self-Study), 2nd Edition (ISBN: 1587201240).

There are two other books that I have read from cover to cover and found excellent material:

End-to-End Qos Network Design: Quality of Service in LANs, WANs, and VPNs (ISBN: 1587051761)

Cisco Catalyst® QoS: Quality of Service in Campus Networks (ISBN: 1587051206)

If I were to get just one, it would be the first one, though.

Hope that helps.

Paresh

[Patrick Laidlaw]

Denny,

I would have to recommend I would have to recommend End-to-End QOS Network Design: Quality of service in LANs, WANs, and VPNSs from Cisco Press

http://www.ciscopress.com/title/1587051761

This has to be one of the best books for explaining and giveing explicit configs on QOS from and end to end standpoint.

Patrick

[etiennebuxin]

I would also recommend this book for QoS, as well as any Cisco Live session with Tim Szigeti. I attended one in 2017 in Berlin; the kind of session when it's over, the only thing you want is to do QoS for the rest of your life

You can find the recording of the sessions for free at ciscolive.com, just need a CCO account.

[Joseph W. Doherty]

Excellent suggestion!

I was just looking at the demand library, and it appears most presentations before 2021 are not kept.

That said, found 83 (?) presentations with QoS mention.  Some are all about QoS, so one of them might cover material like the one you attended in 2017; perhaps "better" (Cisco QoS recommendations have changed much since their Olympic model of decades ago - IMO, their model was less than ideal then, and through all their revisions, even until now).

(Although I don't agree with the Cisco QoS model, their documentation and presentations are generally excellent and most necessary to use their QoS features effectively, although they don't always make clear some of the gotchas.  My favorite case example, when I first started to use Cisco QoS, it just wasn't working as well I expected it should.  I finally stumbled across a TechNote that described how QoS effectiveness might be degraded, by default device behavior.  In my case, soon as I read what the default behavior was, I immediately thought "might be" was likely wishful thinking; and so it was.  I.e. I overrode the default, and QoS then worked as well as I expected.  The underlying problem, IMO, the TechNote behavior, at the time [don't know about now], was only mentioned once if you searched Cisco's web site!  Yet, without changing the default, QoS was very much degraded.  [One can wonder if those might have tried using QoS considered it not worth the effort since it didn't seem very effective because of this.])

[Joseph W. Doherty]

BTW, link to Cisco Live on-demand library: https://www.ciscolive.com/on-demand.html

Documents I found, whose primary subject appears to be QoS, although generally working with specific Cisco technology and can get pretty technical on the Cisco technology.  However, some do provide a somewhat general background on some QoS concepts.

[Joseph W. Doherty]

Oh, and worth consideration:

https://www.ciscopress.com/articles/article.asp?p=2756478

https://www.ciscopress.com/store/end-to-end-qos-network-design-quality-of-service-for-9780133116106

[M_Neman]

Hi Patrick,

i know this Post is quite old, was looking for some recommendations for QOS, landed here, searched for the book and unfortunately not available anymore. do you have any other recommendation please ? i am looking for a book which covers LAN/WAN from an Enterprise point of view.

Thanks.

[Joseph W. Doherty]

Regarding a recommendation for an Enterprise LAN/WAN QoS book, I haven't yet found one that's really good, IMO.  Many have useful nuggets, but in the whole, IMO, don't provide fully effective QoS models.

Regarding "some recommendations", for what purposes?  Doing QoS well, requires, IMO, possibly as much understanding as the rest of networking.  The latter concerning itself with getting frames/packets from A to B, while QoS concerns itself with how well that's accomplished.  So, are there specific QoS subject recommendations you have in mind?

BTW, the above may seem somewhat negative, but I'm actually a huge proponent of QoS, having spent years working out effective QoS.  But, one of the reasons it took me years is lack of effective presentation material about QoS.

[M_Neman]

Thanks for your reply.

yes i am looking for a book which covers l2/l3 QoS. my main concern is to learn the classification using dscp values and how does it work.

Thanks,

[Joseph W. Doherty]

Any half decent QoS book should explain classification and DSCP marking, fairly well.

Basically DSCP is just for efficiency.  In theory, possibly complex analysis of how traffic should be classified only needs to be done once.  All subsequent transit devices might "trust" the DSCP tag avoiding the need for doing complex analysis again.

Where DSCP can become complicated is deciding how specific traffic should use different DSCP values (for which both a RFC and Cisco have recommendations - almost identical) and then deciding how different QoS techniques should be applied.  It's the latter that one size, generally, does NOT fit all, although Cisco has (one size) recommendations for that too (with the caveat it may need modifications for local need).

Cisco's AutoQoS incorporates both their QoS classification and processing recommendations (at the time that version was introduced) tailored for the capabilities of the device.

BTW, for the most part, you can ignore L2 QoS, al least on many Cisco "L2 only" devices as they often can work with L3 information.

[M_Neman]

i have seen couple of videos and documents where the Mark the traffic using some ACLs and then do the priority or queuing, but where i work i dont see those acls... what i see is as following (just a simple config).

class-map match-any XYZ
match dscp cs7
match dscp cs6
!
class-map match-any XYZ1
match dscp ef
!
class-map match-any XYZ2
match dscp af41
!

and so on. and then some policy-maps where the above classes are matched and policing are done.

as said above, i have gone through some cisco documentation and videos on youtube but still i am feeling the gap, and trying to understand following,

 in above class-maps, dscp values are matched, how the switch knows the dscp values if we didnt set those on traffic ? does it know automatically ? to clear these doubts, i just want your/community help to give me a link or a good decent book name to read.

i will really appreciate it.

[Joseph W. Doherty]

DSCP is a recommendation for how to use the ToS byte.  The ToS byte is maintained end-to-end unless a transit device changes it.

So, the DSCP value, in your case, is assigned somewhere upstream, possibly even at the source.  It's often reset at first transit device.

As to a book recommendation, again, haven't found any I would recommend, but any from a major technical publisher would be about the "best".

[M_Neman]

above config sample was taken from one of the access switches, on the destribution Swithces we have the same config but with less class-maps, so i dont know where the DSCP Values are assigned. any way thanks for your help. i  will look for some Docemntation or books to deepen my knowledge.

[Joseph W. Doherty]

". . . so i dont know where the DSCP Values are assigned."

First, are there any matches on them?

It's not uncommon to have generic policies that, in any specific application, will never hit some of its match statements.

Second, again, source host can assign values.  Very common for VoIP hosts to assign DSCP EF (for bearer packets, signally packets should be using a different marking) and video conferencing (DSCP AF4x) hosts, less common otherwise.  CS6 might be seen for a routing protocol's packets, so generally not seen on an edge port.  CS7, is the ultimate priority, cannot recall anything that uses it.