How To Assign Ip Address With External Jetdirect 175x

Auto IP Default IP addresses In the past, the default IP address of an HP Jetdirect print server has been 192.0.0.192. This is now known as the legacy default IP address . With new firmware, HP Jetdirect print severs can now assign itself an Auto IP address . Auto IP, as it is referred to as here, can also be referred to as the following:

• IPv4 link local addressing
• APIPA - Automatic Private IP Addressing
• 169.254 /16

Auto IP is an algorithm designed to assign an interface an IP address when a DHCP, BOOTP, or RARP server is not available. The address range of 169.254.0.1 to 169.254.255.254 (referred to as 169.254 /16) is assigned and is treated as a private address.

In addition, the 169.254 /16 address range cannot be routed through any IP routers. Routers should drop packets containing a source IP address that is in the 169.254 /16 range. Therefore, this range is even more restrictive than the typical private IP addresses (10 /8, 172.16 /12, 192.168 /16).

Auto IP is intended for small home or office networks without a DHCP, BOOTP, or RARP server but that still use IP addresses. However, some corporate users manually configure their IP Addresses (for example, they do not use a DHCP, BOOTP, or RARP server) and are used to using the legacy default IP address of 192.0.0.192. Therefore, the HP Jetdirect print server must determine whether which type of network it is on when it is first powered on with factory defaults or cold-reset to factory defaults.

Determining the type of network and assigning a default IP address

When an HP Jetdirect with this newer firmware is powered up for the first time or cold-reset to factory defaults, it goes through its normal algorithms in an attempt to find a DHCP, BOOTP, or RARP server. During this time, it is also sensing broadcast packets from the network. In these packets sensed from the network, if the source IP address of an IP packet or the source IP address in an ARP packet is 169.254.x.x, the HP Jetdirect will increment its "home-network" counter, otherwise the HP Jetdirect will increment its "enterprise-network" counter.

At the end of two minutes, the HP Jetdirect compares the counters. If the "home-network" counter is equal to or greater than the "enterprise-network" counter, an Auto IP address is chosen. The subnet mask will be 255.255.0.0 and the gateway IP address will be the same as the Auto IP address.

If the "enterprise-network" counter is greater, then the legacy default IP address, 192.0.0.192, is chosen.

In order to avoid assigning itself an Auto IP address that is already on the network (a duplicate IP address), the HP Jetdirect will send ARP probes to search for a duplicate IP address. If one is found, then the HP Jetdirect will select another IP address and search for a duplicate again until it finally selects an IP address that is not already on the network.

Wireless HP Jetdirect print servers

The first time a wireless HP Jetdirect is turned on or is cold-reset, it must come up in ad hoc mode. The default IP address will be 169.254.x.x. No "sensing" of the network is done.