vEdge order of operations

[js1452264@gmail.com]

Hello;

in cisco website (https://www.cisco.com/c/en/us/td/docs/solutions/CVD/SDWAN/cisco-sdwan-design-guide.html#OrderofOperations) i read that Scheduling and queueing comes before local egress policy but in other websites (https://www.networkacademy.io/ccie-enterprise/sdwan/policies ) i found the opposite.

Iwant t know witch one is correct and why?

Thank you.

[Kanan Huseynli]

Hi,

of course, the most reliable info is from Cisco documents.

Local Egress Policy happens after QoS as in Cisco CVD:

https://www.ciscolive.com/c/dam/r/ciscolive/emea/docs/2019/pdf/TECCRS-2014.pdf

page 84

HTH,

[bahkobg85]

Well, in the official ciscopress book on Cisco SD-WAN it is stated that Queueing and Scheduling happen after the Local Egress Policy. (see attached image).

It doesn't make sense to place packets in Low-latency Queue and then make ACL lookup and drop them (basically denied packets filling the output queues). Additionally, regular Cisco IOS and IOS-XE routers do Queueing and Scheduling at the very last step, so the point is not 100% clear to me. I can't comprehend how the queueing and scheduling could happen before ACL. The router places all packets into respective queues, then makes ACL lookup (if the ACL has thousands upon thousands of lines, all packets wait), and then it decides to drop some of the packets before transmitting?

[bahkobg85]

In the official Cisco SD-WAN configuration guide, it is stated that Scheduling happens after the Local Egress Policy (screenshot attached). Refer to the link below.

https://www.cisco.com/c/en/us/td/docs/routers/sdwan/configuration/qos/vEdge-20-x/qos-book/forwarding-qos.html