HP 200 Series Services And Applications page 178

A Primer on HP Probe
HP Probe Protocol Definition
HP Probe Protocol Definition
HP Probe supports both Ethernet and IEEE 802.3 encapsulation. HP Probe
uses two multicast addresses: a primary multicast address 0x090009000001,
and a secondary proxy multicast address 0x090009000002. Their use will be
explained below. The HP Probe protocol uses 0x8005 as the Ethernet type
and 0xFC for the IEEE 802 SAP. FC is HP's expansion XSAP indicator; the
XSAP for Probe is 0x0503.
The following HP Probe packets are discussed below:
1. Probe Unsolicited Reply *
2. Probe Name Request
3. Probe Name Reply
4. Probe Virtual Address Request (VNA)
5. Probe Virtual Address Reply *
6. Probe Proxy Request
7. Probe Proxy Reply
* Supported by HP routers
Probe Unsolicited Reply
The Unsolicited Reply is transmitted over the primary multicast address
when a node first comes on line and periodically afterwards. The Unsolicited
Reply packet contains complete, updated information about a node.
Included in the packet are the well-known NS services it supports, the
protocols it supports, its name, and machine addresses. A node uses the
Unsolicited Reply packet to announce its presence on the network or to
update information about itself that was transmitted earlier and has
changed. HP routers send an Unsolicited Reply upon booting, but do not
listen for or receive Unsolicited Replies sent by other nodes.
Probe Name Request/Reply
When an NS LAN node (node A) wants to connect with another node (node
B), node A first checks to see if it has a name-to-IP-address map in a data-
base called a Nodal Registry. If it does not, it generates a name request
packet containing the target node's name (node B), and sends it out over the
primary multicast address. All nodes receive the packet, but only the target
node (node B) responds with a name reply packet. The name reply contains
the IP and station addresses and service information (supported NS serv-
ices) in the path report. The other nodes simply discard the request. If there
is no response from the target node, then a Probe proxy request is sent out
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