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Multicast on LWAP AP

sam_manay
Level 1
Level 1

any one experiencing on Multicast problem. In my network, Multicast is perfectly working on wired to wired network, but once using wireless to Wired (multicast server on wired).

Currently I am using WLC (LWAP AP, any advice to solve my problem?

Many thanks in advance,

KindlyRegards,

sam

25 Replies 25

George Stefanick
VIP Alumni
VIP Alumni

Sam ... what is the nature of the problem?

"Satisfaction does not come from knowing the solution, it comes from knowing why." - Rosalind Franklin
___________________________________________________________

m_zabetian
Level 1
Level 1

change your Ethernet Multicast Mode configuration from Disable to unicast (it is located under Controller genera)

ronaldo.melo
Level 1
Level 1

Hi Sam,I'm having the same issue at a customer the quality of image at the clients in wireless is worst.I had configured in both modes (unicast and multicast) but still having problems, in unicast a little better. The code at my WLC is WLC4400-K9-4-2-176. Your problem was resolved?

Regards,

Ronaldo.

I tried also doing video multicast over Wifi. Stream was low (200 kbs) bandwidht, but i discovered that there were much to many dropped or missed packets (around 11%). PCs didn't notice this, but multicast video was unacceptable. I tried changing the QOS settings on the controllers to gold, but didn't help, neither did enabling WMM extensions. Checked also interference via WLC and WISM, but that was ok according to the controller. So know we disabled multicast on wifi because the quality just wasn't good enough

When you change the configuration at controllers to Gold the multicast packets must come market for you have any result. So you need configure a Cos to multicast traffic. I'm having the same problem and I will do QoS for multicast packets soon. I will post the results.

j-mccarthy
Level 1
Level 1

I have a TAC case open about wireless multicast packet loss at the moment. I have done extensive testing with both WiSM and 4404 and I am unable to prevent packet loss when multicasting from wired to wireless network. Unicasting between the same two devices works perfectly so I think there's a multicast issue in the controller software. I've been testing with 5.2.178.0 on both WiSM and 4404. Packet loss occurs on both platforms. Today I tried the new 4.2.205 code on the 4404, still has the problem. I've tried both unicast multicast and multicast multicast delivery methods. I get fairly constant 3-5% loss on a 1mbps stream. I'm verifying the packetloss using RTP Stream analysis on Wireshark on the client machine and also with Iperf.

Has anyone got wireless multicast streams working properly using WLC & lightweight APs with no packet loss?

Hi folks,

Anyone tried with a AP in autonomous mode? At the WLC if you put the traffic “multicast” to unicast mode the WLC will have problems with CPU and performance for normal traffic, I am assuming using more than 6 clients connected at the same time at AP. I have a TAC opened and they explain the quality will never be the same of wired and you need mark the multicast traffic for the WLC and put the SSID to Gold. I didn't have a time yet to do the tests because the wired network of my client is not Cisco.

I've tested unicast multicast mode in my lab with one access point and one wireless client and traffic is being dropped. There is an issue there that is not related to scale.

I've also set the SSID to Gold, had no impact on the problem. If there is no congestion present there should be no need for QoS anyway?

According TAC even you have only one client at AP it is necessary the QoS??? I agree it is not a problem of QoS but you know the TAC… you must following the procedures.

Regards,

Ronaldo.

dancampb
Level 7
Level 7

QoS isn't required for multicast, but definitely recommended especially if the multicast stream is voice or video.

The most common cause of multicast not working is that PIM is not enabled on all of the VLAN's needed. You should have PIM enabled on the VLAN of the controller's management interface, the VLAN of the dynamic interface mapped to the WLAN, any VLAN AP's are on, and any other wired VLAN needed.

Also you should make sure IGMP snooping is enabled on the controller. This of course isn't available until the 4.2 train.

I have multicast working fine. The problem I'm seeing is packet loss of the multicast stream to the client. Consistent 3-4% packet loss makes a 1 mbit video stream pretty unwatchable. There should be no problem receiving a stream of that size.

Unicasting the same stream from the same source (wired PC) to the same destination (wireless laptop) shows 0% packet loss.

The wireless will queue the unicast packet during a roam.

It does NOT do this for multicast.

mpatalberta1
Level 1
Level 1

Set dtim = 2

set beacon = 100

The multicast packet will come out at the beacon.

Unlike unicast the multicast packet is NOT ack knowledged by the client

On my network DTIM=1 Beacon=100

"The DTIM Period is the number of beacon intervals that elapse between transmission of Beacon frames containing a TIM element whose DTIM Count field is 0. Default 1 interval."

That explanation doesnt really help me :)

Regarding the acking of packets - the receipt of UDP traffic unicast is reliable on wireless wheras the receipt of UDP multicast is unreliable?

Why does the client ack a unicast UDP packet but not a multicast UDP packet?

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