Networking Concepts

Address Resolution

Probe and Probe Proxy

NS 3000 LAN, 100VG-AnyLAN, and 100Base-T NIs with the

IEEE 802.3 protocol enabled are able to make use of a proprietary HP protocol called probe. Probe makes it possible for nodes on an NS IEEE 802.3 LAN, 100VG-AnyLAN, and 100Base-T to communicate without a network directory or domain names. A node can determine connection information about a node on the same LAN by sending a multicast probe request out on the network. The target node recognizes its address in the probe request and sends an individually addressed probe reply with the necessary connection information to the requesting node. The probe request/reply mechanism is sufficient to obtain connection requirements within a network.

If the nodes on that LAN are to communicate with other networks, at least one node on the network must have a network directory. The node with the network directory is called a proxy server. By using the probe protocol, a node without a network directory can multicast a request for an internet address from the proxy server. For backup purposes, you should designate at least two nodes to be proxy servers.

Address Resolution Protocol (ARP)

HP e3000 LAN, Token Ring, FDDI, 100VG-AnyLAN, AND 100Base-T NIs are able to make use of a standard protocol called Address Resolution Protocol (ARP). ARP provides IP address to station address resolution. ARP is enabled when the Ethernet protocol or Token Ring is enabled.

Enabling Probe and ARP

With the concurrent configuration of IEEE 802.3 and Ethernet on a network, both the probe and ARP protocols are also enabled. Both protocols broadcast requests to all nodes on the network to resolve the address of a given remote node.

If you disable IEEE 802.3 on a LAN NI, you also disable the probe protocol. Likewise, by disabling Ethernet, you disable the ARP protocol associated with it. You cannot disable both of these protocols simultaneously; at least one must be active to facilitate network communications.

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Chapter 2