Multicast. Directed-threshold versus directed-multicast commands

Summary

This article explains what the "qos directed-threshold" and "qos directed-multicast" commands individually do and when to use them.

Question

What is the difference between directed-threshold and directed-multicast commands? Type of multicast traffic.

Customer Environment

ZD and SZ managed wireless network

Resolution

Ruckus has a feature to convert multicast/broadcast traffic to unicast. The WiFi benefits for this are,
1. AP can send the data at higher rates. This behavior conserves airtime.
2. It also enables 802.11 acknowledgements. Acknowledgement from a receiver ensures reliable data transfer.

Before explaining the commands involved we have to define what is the classification of multicast traffic in Ruckus:
  • IGMP multicast traffic: multicast traffic that uses IGMP protocol. Comand used for this is (to be run from "wlan" context in ZD/SZ CLI)
qos directed-multicast -- > All the IGMP multicast traffic is converted to unicast. Traffic is automatically classified as AC_VI (Video) with Priority=5. If there are no users on the IGMP table, the traffic is thrown away.  This comes active on all WLANs by default (also IGMP Snooping).
no qos directed-multicast -- > IGMP multicast traffic is not converted to unicast.
  • well-known multicast addresses: User-added image 
This traffic is controlled with command (to be run from "wlan" context in ZD/SZ CLI),
qos directed-threshold X -->  All traffic not being IGMP multicast (well-known multicast traffic, broadcast) is converted to unicast until X users on the WLAN. Traffic is classified as AC_BE (Best Effort) with Priority=0. When there are more than X users traffic is then not converted. If X is 0, there's no conversion. By default APs have this value set to 5.
Be careful with any number above 5 since it will have performance impact on the AP.


Direct multicast processes traffic ingress from both wired and wireless interfaces. This command is enabled by default.
Direct threshold processes traffic egress to wireless interfaces.  This command is enabled with value 5 by default.

How to check this configuration on AP

We need to execute a command on each interface, in this example we can see ethernet 0 and wlan 0 interfaces
 
rkscli: get qos eth0
Ruckus Wireless SmartMedia QOS info for eth0 interface
 
QOS Configuration options:
Classification:               Enabled
UDP Heuristic Classification: Enabled
TOS Classification:           Enabled
Dot1p Classification:         Enabled
VID Voice Classification:
VID Video Classification:
VID  BE   Classification:
VID  BK   Classification:
Dot1p Classification VIDs:
Dot1p Marking VIDs:
Directed Multicast:           Enabled
IGMP Snooping Mode:           Enabled
MLD Snooping Mode:            Disabled
Static TOS marking:           Disabled (0x0)
Static Dot1p marking:         Disabled (0x0)
 
General      Mcast->U      Cloned     Filters    TOS-Mark
Stats               0           0       0/0/0    0/0/0/0
 
L2 Mcast      Packets     Unicast    Unk-Drop Known-Mcast
UDP Data         2525           0        2253         720
 
Heuristics      Voice       Video
UDP Packets         0           0
 
IGMP/MLD   Clone1/2/3
Errors          0/0/0
 
No Filters are currently defined on eth0 interface
OK
rkscli: get qos wlan0
Ruckus Wireless SmartMedia QOS info for wlan0 interface
 
QOS Configuration options:
Classification:               Enabled
UDP Heuristic Classification: Enabled
TOS Classification:           Enabled
Dot1p Classification:         Enabled
VID Voice Classification:
VID Video Classification:
VID  BE   Classification:
VID  BK   Classification:
Dot1p Classification VIDs:
Dot1p Marking VIDs:
Directed Multicast:           Enabled
IGMP Snooping Mode:           Enabled
MLD Snooping Mode:            Disabled
Static TOS marking:           Disabled (0x0)
Static Dot1p marking:         Disabled (0x0)
 
General      Mcast->U      Cloned     Filters    TOS-Mark
Stats              15           0       0/0/0    0/0/0/0
 
L2 Mcast      Packets     Unicast    Unk-Drop Known-Mcast
UDP Data            0          15           0         422
 
Heuristics      Voice       Video
UDP Packets         0           0
 
IGMP/MLD   Clone1/2/3
Errors          0/0/0
 
No Filters are currently defined on wlan0 interface
OK
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Article Number:
000002849

Updated:
May 06, 2020 03:59 PM (3 months ago)

Tags:
Performance, Configuration, ZoneDirector, SmartCell Gateway, virtual SmartCell Gateway

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2

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