ip multicast routing between subnets same router

[alexbak79]

Hi all

I’ve been trying a few days now to implement multicast routing on my home network in order to make airplay work between subnets. Specifically between an iphone and a hifi separated by different vlans. Failed, as I have no experience in multicast routing.

So can please anyone enlighten me supposing we have a clean configuration and simple network which consists of two SVIs

Vlan 10: 192.168.1.0 255.255.255.0

Vlan 20: 192.168.2.0 255.255.255.0

any help would be greatly appreciated

ios platform cisco 887

[Reza Sharifi]

Hi,

Since you have 2 different vlans, you need to turn on "ip pim sparse-dense-mode" or just dense-mode under each SVI.

HTH

[alexbak79]

Hi Reza,

Thanks for the reply but no... it's more complicated than you think.

Even media server does not work

[mlund]

Hi

As Reza says, on both interfaces configure "ip pim dense-mode"

in global configure "ip multicast-routing"

Thats it, now it should work.

To verify, use show ip mroute and show ip igmp group

Two commonly reason why multicast routing is not working is

1. ttl is set to one by sender

2. the sender is using 224.0.0.x range

/Mikael

[alexbak79]

Hi Mikael

It seems that bonjour services are always set ttl1 and use 224.0.0.251. Is there a workaround to make this routable between vlans?

Alex

[John Blakley]

The bonjour protocol, as you've found, uses a link-local multicast address. This means that it's not routable outside of its vlan.There is no workaround that I'm aware of unless you put an apple tv (or whatever you're using airplay for) in each subnet.

That being said, you could bridge the 2 vlans but you may as well have a single vlan at that point.

HTH,
John

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[Brett Ferrell]

Yes, I just did this.  Use something like Avahi to rebroadcast the Airplay mdns traffic.  I use a Ubiquiti Edgerouter (Vyatta linux based) which comes with this Reflector capability.  Once I added that, and included it on the VLANs (and added a Firewall rule for port 5353) Airplay between my VLANs works perfectly.

Brett