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CoS order of operation

‎12-23-2013 04:07 AM

Hello, dear community. I'm frustrated a little regarding CoS functions.

Here is official documentation:

http://www.juniper.net/techpubs/software/junos-security/junos-security10.2/junos-security-swconfig-c...

 

Please compare with Day One book DEPLOYING BASIC QOS page 18:

http://forums.juniper.net/jnet/attachments/jnet/Day1Books/123/1/DO_Deploying_Basic_QoS.pdf

 

cos processing.png

 

Can you please clarify why there is difference?

3 REPLIES 3
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Re: CoS order of operation

‎12-23-2013 09:16 AM

Hello there,

The difference is that 1st diagram is more generic and applicable for products which (1) may not support polcing (i.e. SRX) or (2) may not have fabric (i.e. M7i/M10i/MX80 etc).

The 2nd diagram implies that the product supports policing and has fabric.

HTH

Thanks

Alex

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Re: CoS order of operation

‎12-23-2013 09:24 AM

Thank you for repy. Can you provide me with more detailed inforation? Maybe documentation links/KB? Why there is differense also with rewrite marker operation in output direction?

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Re: CoS order of operation

‎12-24-2013 06:58 AM

Hi there,

 


@enk wrote:

 Why there is differense also with rewrite marker operation in output direction?



Depending on hardware and what is being rewritten, the rewrite can happen both before and after output queueing function.

I.e. in MX ICHIP DPCs, 802.1p bits are rewritten in the EZchip AFTER output queueing.

In MX Trio MPC, L3 COS bits are rewritten by LU block BEFORE output queueing in MQ block (for port-based COS linecards) or QX block (for H-QOS linecards).

if You are interested only in modern Juniper products like MX series routers and don't want to spend time learning legacy stuff, then "Juniper MX series" book has a chapter on MX Trio COS

http://shop.oreilly.com/product/0636920023760.do 

HTH

Thanks
Alex

 

_____________________________________________________________________

Please ask Your Juniper account team about Juniper Professional Services offerings.
Juniper PS can design, test & build the network/part of the network as per Your requirements

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Accept as Solution+Kudo = You are a Star !