ASA QOS Question

[Gabriel Hill]

New Location. 1.5mbps DSL. A few phones, thin clients, and one desktop.
Simple setup : 2960 ------ ASA ----- ISP (DSL) 1.5mbps up/down

Couple questions:

1. I have theoretically 1500000bits to allot out in this policy map. The desktop,thin clients, and default class added together are limited to 775kbps. Does this mean the remaining 725kbps is given to the voice class? If so, if the voice class didn't have the priority command under it would it still receive the 725kbps left over?

2. Would there be any need to do policing on incoming traffic as well? For example adding: police input 500000 : to the desktop class / modifying the ACL to include the reverse traffic. I am not sure if that would be superfluous or not, I know the ISP isn't going to allow more than 1.5mbps download, but I don't want the desktop machine to be able to cause congestion for traffic coming into the outside interface of the ASA (possibly degrading voice quality <-- my worry).

Current Config:

priority-queue OUTSIDE

class-map wyse-terminals
match access-list 100
class-map desktop
match access-list 101
class-map voice
match dscp ef
!
policy-map QOS
class voice
  priority
class desktop
  police output 500000
class wyse-terminals
  police output 75000
class class-default
  police output 200000

service-policy QOS interface OUTSIDE

Thanks,

[Edison Ortiz · Accepted solution]

As you are policing all classes, the remaining bandwidth during max usage under all classes will be 725kbps.

However, if all classes are running below their police value, voice will use all available bandwidth (i.e. greater than 725kbs).

The priority command simply instructs to dequeue the packet from the ASA before any other packet.

Think of a VIP person boarding the plane.

As far as inbound policer, it's useless. The packet has arrived to the device hence already consumed ISP bandwidth.

Regards,

Edison

[Gabriel Hill]

Thank you for your reply. Makes sense.