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QOS - IP Nbar Protocol-Discovery

Hi Guys,

I am configuring a qos policy and creating access-list to match protocols. Question I have is whether I need to enable ip nbar-protocol discovery to match protocols in access-list ?

class-map match-any Interactive

match protocol citrix

match protocol telnet


Cisco Employee

QOS - IP Nbar Protocol-Discovery


To my best knowledge, it is not necessary to configure the ip nbar protocol-discovery command in order to use match protocol clauses in class-map constructs. The ip nbar protocol-discovery causes the router to start making statistical breakdowns of various protocols passing through a particular interface. However, it has been my experience that this command was not necessary for protocol-based class-maps.

Best regards,


Super Bronze

Re: QOS - IP Nbar Protocol-Discovery


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Peter is correct.

For the original poster, later versions of NBAR can also determine the subtype of later Citrix protocol packets.  This will allow you to distinguish the "screen scraping" packets from printing or disk copying packets.  The latter two sub types you probably don't want to include as interactive traffic.  (NB: for earlier NBAR versions that don't recognize Citrix packet subtypes, I recall there was a Citrix PDLM that did, but I'm not positive.)

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