Configuration Multicast for google ChromeCast

[aleopoldie]

Hello experts,

I would like to implement the solution ChromeCast with a WLC2504 for one of our customers.

But i'm a little bit lost with multicast... What do i need to configure on the switches/routers for this ?

Thanks by advance,

AL

[ali aqrabawi · Accepted solution]

if the chromcast use unicast udp packets stream for screen sharing , 

but before this unicast stream start , the client should discover the chromcast first , 

the way it discover it by mDNS (mulicast DNS) client send mDNS query and the chromcast send mdns query response (all messages will be multicast).

as we are talking about multicast , then if the chromecast and the cleint are in same vlan , then no configuration needed on the wLC , you can enable mDNS on the WLC , and the WLC will responding to client in behalf of the chromcast , 

but if the chromcast and the client are in different vlans , then you have to configure multicast routing between the vlans,  to make sure that the multicast packet will be replicated at the router interfaces and send to the other vlan/or network segment , 

the confniguration of these protocols are quite easy , 

summary for the configuartions :

1)on router you have to configure PIM, spares-mode recommended, but Dense-mode is simple :

http://www.cisco.com/c/en/us/support/docs/ip/ip-multicast/9356-48.html

2)on the switches configure igmp snooping , so the traffic will be forwarded only to ports that are interested in this multicast traffic , using command IGMP snooping on the config mode. 

3)on the WLC make sure that the mDNS is enabled on the WLCm, and the mDNS profile has the chromcast service it its available services , see the link below for chromcast deployment guide :

http://www.cisco.com/c/en/us/td/docs/wireless/controller/technotes/7-6/chromecastDG76/ChromecastDG76.html

[aleopoldie]

Hello Ali,

Thank you for your feedback.

The chromecast and client are in the same vlan.

But i have some questions regarding multicast...

For now we are using WLC2504 and Cisco guide recommand to use the multicast-multicast. We will probably replace the WLC by a 5508.

Is it mandatory to use multicast for chromecast ? If yes, why ? There is no way to only use unicast ?

It would be a big thing to configure multicast on this network, that's why i try to know if there is a possibility to bypass the multicast, but I read on the configuration files that the client discovers the chromecast over multicast only...

By advance thanks,

AL

[ali aqrabawi]

since the client and chromcast will be in same vlan then no need for PIM , 

just enable mDNS on the WLC,

regarding the multicast mode , both modes should work fine , but the multicast-multicast is recommended as the WLC will not replicate the same multicast packet to AP APs associated which will utilize the network ,  

if the APs and the WLC are in same vlan , then you can use multicast-multicats mode wthout any additional configuration on the wired , 

you can use the multicast-unicast , as the Multicast is used only when the client trying to discover the chromcast , but the rest of the communication will be unicast , 

if you don't have huge number of APs (in receptive to your network bandwidth) . then you can use multicast-unicast and you don't need to worry about it . 

[aleopoldie]

In my labo it's working but it's not a big network.

For our customer, the WLC and the AP's are not in the same Vlan and there are routing between them... So i need to configure multicast routing ?

Just to be sure. When you say clients and chromecast in the same Vlans, you means they are both connected to the same Vlans right ?

They have 2 sites :

1st site : you have the WLC

2nd site : You have the AP's

And between them there is routing

Right now, they have 2 Vlans mapped to 2 interfaces X and Y. The management in untagged.

If we use the vlan Y for example with a SSID called "ChromeCast". Clients and chromecast are in the same Vlan right ?

[gohussai]

Just to add.

1-On Switch we always use IGMP snooping.

2-On Router PIM pares-mode

3- And on WLC just enable mDNS

[aleopoldie]

this is working now . Thank you :)

AL