Dynamic Network Printer Discovery across Broadcast Domains

Today's networks, are partitioned in multiple distinct broadcast domains, either via VLAN's or simply by routers segregating the network. Even 'simple' home or SOHO networks often consist of multiple broadcast domains, sometimes simply just because the wired and wireless parts of the network are managed by a separate router and a separate wireless access-point.

Dynamic Network Printer Discovery

If the dynamic network printer discovery feature in a PC fails, because the printer is in an other broadcast domain, the OS usually provides a way to manually provide the IP address of the network printer. However you might want to print from devices that do not provide this - for instance the HP ePrint application for Android -, or you simply do not want users to manually configure this settings or even allow them access to it.

IP directed-broadcast

Cisco routers can be configured to forward broadcasts to solve the problem described above.

The example configuration provided below works for an HP Officejet Pro 8500, in VLAN 10 and an Android phone running the HP ePrint app in VLAN 20.

!

! Specifies the the protocol of which a broadcast should be forwarded. 

!

ip forward-protocol udp snmp

! 

!

! Enter the (layer-3) interface configuration mode of the interface attached to the printer.

!

interface FastEthernet 0/1.10

!

! 

! Enable the ip directed broadcast feature

!

ip directed-broadcast

!

!

! Enter the (layer-3) interface configuration mode of the interface from which the broadcasts will ! be sent.

!

interface FastEthernet0/1.20

!

!

! Specify the IP address where the directed broadcast needs to be sent to.

! In our case the printers IP address.

!

ip helper-address 172.30.10.100

!