topic Re: Multicast on LWAP AP in Wireless

Multicast on LWAP AP

sam_manay — Sun, 04 Jul 2021 00:17:11 GMT

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

Re: Multicast on LWAP AP

George Stefanick — Tue, 17 Mar 2009 00:43:49 GMT

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

Re: Multicast on LWAP AP

m_zabetian — Fri, 20 Mar 2009 16:46:41 GMT

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

Re: Multicast on LWAP AP

ronaldo.melo — Thu, 26 Mar 2009 16:56:06 GMT

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.

Re: Multicast on LWAP AP

gnijs — Wed, 29 Apr 2009 19:38:02 GMT

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

Re: Multicast on LWAP AP

ronaldo.melo — Wed, 29 Apr 2009 19:55:21 GMT

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.

Re: Multicast on LWAP AP

j-mccarthy — Wed, 20 May 2009 09:23:01 GMT

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?

Re: Multicast on LWAP AP

ronaldo.melo — Wed, 20 May 2009 13:16:03 GMT

Hi folks,

Anyone tried with a AP in autonomous mode? At the WLC if you put the traffic â€œmulticastâ€ 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.

Re: Multicast on LWAP AP

j-mccarthy — Wed, 20 May 2009 13:40:30 GMT

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?

Re: Multicast on LWAP AP

ronaldo.melo — Wed, 20 May 2009 13:51:05 GMT

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 TACâ€¦ you must following the procedures.

Regards,

Ronaldo.

Re: Multicast on LWAP AP

dancampb — Wed, 20 May 2009 16:06:16 GMT

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.

Re: Multicast on LWAP AP

j-mccarthy — Wed, 20 May 2009 23:32:06 GMT

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.

Re: Multicast on LWAP AP

mpatalberta1 — Fri, 22 May 2009 01:35:34 GMT

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

Re: Multicast on LWAP AP

j-mccarthy — Fri, 22 May 2009 02:08:18 GMT

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?

Re: Multicast on LWAP AP

mpatalberta1 — Fri, 22 May 2009 02:39:34 GMT

The multicast packet is sent by the infrastructure on all ap. it does not know who is going to receive them. For example dhcp does this. Thus you cannot rely on who will ack the multicast.

I am using the multicast for voice with wpa2 personal. In general except during a roam we get no loss. However we do have 1 redundant data packet in the multicast packet.

The roam with an open infrastructure we do not loose any noticable packets.

The roam on wpa2/psk as result of a soft handoff we have no loss. We only have data loss during a distressed roam.

Turn off the aironet ie.

Re: Multicast on LWAP AP

mpatalberta1 — Fri, 22 May 2009 02:40:52 GMT

The wireless will queue the unicast packet during a roam.

It does NOT do this for multicast.

Re: Multicast on LWAP AP

mpatalberta1 — Fri, 22 May 2009 02:42:38 GMT

I should mention you could use the cisco igmp method. This option is suppose to improve the multicast performance.

Re: Multicast on LWAP AP

j-mccarthy — Fri, 22 May 2009 02:47:05 GMT

I am using Cisco IGMP. There is no roaming involved. One client, one access point, one WLC & one multicast server.

Voice (MOH I assume)is probably ok because the bandwidth of the stream is so low (64kbps).

With a 1mbps video stream the packet loss is really noticeable. Looks like delivering video over wireless multicast is a non runner.

Re: Multicast on LWAP AP

Matthew Fowler — Fri, 22 May 2009 04:58:30 GMT

Probably the biggest issue is, as mentioned, the fact that 802.11 multicast is not ACKed while 802.11 unicast is. The test would be to get a wireless sniff of the unicast video and see if the retransmit percentage is about the same as the multicast drop percentage.

What power saving is the client doing? Have you tried setting it to being constantly awake?

Re: Multicast on LWAP AP

j-mccarthy — Fri, 22 May 2009 05:02:09 GMT

hi mat, i haven't mucked around with power settings on the client to be honest. thats interesting idea because i am seeing different levels of packet loss with different clients. ibm t60 with an intel 3945 seems a lot worse than a dell d600 for example.