mDNS (Apple Bounjour) between two VLANs through a PA

[myrdin]

Hi,

this is the scenario:

- a PA with two physical L3 interfaces (1 zone per interface, 1 subnet per interface, we call them A and B).

- I have a device in Subnet A which is an Airport thing with a printer attached. Devices in Subnet A they can discover the printer via the Apple Bonjour service

- Devices in Subnet B cannot discover the printer in subnet A

- Traffic from/to these two subnets is completely allowed, no restrictions whatsover, and no NAT.

- Both subnets and devices have the PA interface as default gateway

- i am running 7.1

What i did:

- in network-router, i edited the existing virtual router, went to "Multicast" and enabled Multicast. - 

- RP Static, RP Interface is the Subnet A interface, RP Address the Subnet A interface address

- Group list: 224.0.0.0/4

- Remote Rendevous point: empty

Interfaces: Subnet A interface, Subnet B Interface IGMP/PIM enabled

- added policy from Subnet A zone and Subnet B zone to "Multicast" zone all allowed

- and committed

Still from Subnet B i cannot see the airport via the multicast Bonjour service. Ideas?

thanks heaps

[RFalconer]

By default, Bounjour only works in a single broadcast domain so it won't traverse the firewall.

To get Bonjour to work across subnets, you need to use wide area Bonjour by creating specific DNS entries. 

[myrdin]

thanks RFalconer. 

after a lot more reading, i found out that Bonjour sets ttl=1 by default so crossing a router, although possible, will decrease ttl to 0 and the packet it is discarded. This is by design.

Multicast routing although possible, it will not serve this purpose hence it won't work.

The only way to handle this is to use a bonjour gateway which is a feature some vendors offer, like Aruba or Cisco Meraki. 

[REganEVO]

How can this be accomplished? Can you forward local mDNS queries (224.0.0.251) to something routable (224.0.1.251)? Is that what you're suggesting to cross zones?

[jdanjuma]

If you are reading this in 2020, support for Bonjour has been added to PAN-OS version 10.0.1.