PLP in SD-WAN explained

[PetFro]

Hello Dear Cisco (and SD-WAN) community.

Can someone please explain to me, what is the PLP (Packet Loss Priority) in SD-WAN? It can be configured in Rewrite data policies, ACLs and on few other places. Is it referring to Drop Probability in AF classes in DHCP markings of IP packet? Or is it somethng else? Is this setting (PLP High or Low) propagated to another router, outside of SD-WAN, or is it just for internal usage, during packet processing? Documentation is vague regarding this topic.

I am looking for your thoughts and answers.

[MuhammadAbdulMalik30077]

From my understanding PLP is determined based on the RED mechanism.  Since RED literally means (Random Early Detection), a packet may be marked RANDOMLY with a LOW PLP.  This means that in the case of congestion this packet can be dropped.  If the PLP is set to High, then the packet won't be dropped.

If you were to set a rate Policer on an interface and the rate or burst is exceeded , the interface will begin to mark packets with a PLP of low if in the Exceed Field of the QoS policy is set to "drop".  If the Exceed field is set to "remark" then the packet PLP will be set to High.  Once the packet is marked with a High or Low PLP (packet loss priority) the router interface may drop the low PLP packets if needed before dropping the PLP packets set to High.

[inderdeeps · Accepted solution]

Check "Configure Rewrite rule" on the below link, It will tell you about PLP as an example

https://sdwan-docs.cisco.com/Product_Documentation/Software_Features/SD-WAN_Release_17.1/08Forwarding_and_QoS/03Forwarding_and_QoS_Configuration_Examples 

Regards
Inderdeep Singh

www.thenetworkdna.com

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