Host 2 queries for printers

The following procedure depicts a service process for mDNS queries for a wireless printer in the form of an example.

Procedure
  1. Host 2 sends an mDNS query for printers.
  2. There is no inbound filter in VLAN 2 of Switch 3 therefore it receives the query.
  3. Switch 3 checks the outbound filter in VLAN 2. As there is no specific outbound filter the default action is permit all.
  4. Switch 3 floods the query in VLAN 2 (except the source port.)
  5. Switch 1 receives the query and check the inbound filters. Permit for the instance name, Host 2, allows the packet on VLAN 2.
  6. Switch 1 checks the outbound filter for VLAN 2. As there is no specific filter and global filter is permit all, it will flood the packet in VLAN 2 (except the source port.)
  7. Switch 1 checks the reflection status. Reflection is enabled on VLAN 2 and VLAN 3. Since VLAN 2 is an incoming VLAN, it will not pass the reflection on VLAN 2.
  8. Switch 1 checks the outbound filters on VLAN 3. There is no rule to deny Host 2 query and the global filter is set to permit all so it will forward the packet to VLAN 3.
  9. Switch 2 receives the service and checks for any inbound and outbound filters in VLAN 3.
  10. There is no specific inbound and outbound filter in VLAN 3 therefore it will flood the query in VLAN 3 (except the source port.)
  11. Reflection is not enabled in Switch 2 therefore it will not pass any further reflection.
  12. Wireless printer 2 responses to the query and switch 2 does not have any inbound and outbound filters therefore it will flood the response to VLAN 3 (except the source port.)
  13. Switch 1 receives the packet as there are no inbound filters in VLAN 3. VLAN 3 has an outbound filter set to deny wireless printer service. The service will not flood VLAN 3.
  14. Switch 1 checks the reflection status which is enabled in VLAN 2 and 3. Since the incoming VLAN is 3, the packet will not forward to VLAN 3.
  15. Switch 1 checks the outbound filter in VLAN 2. As there is no specific filter, it will forward the response to VLAN 2.
  16. Switch 3 receives the response on VLAN 2 as there is no inbound filter to deny this service.
  17. Switch 3 does not have any outbound filters in VLAN 2, so it will flood the response in VLAN 2 (except the source port.)
  18. Host 2 receives the Wireless Printer 2 service response.