
VINES Overview
117372-A Rev. A 1-9
Figure 1-5. VINES Internet Protocol Header
When the router receives a packet, the VINES IP entity on the router handles the
packet according to how it is addressed, as follows:
• Packets destined for the router
When the router receives a packet addressed to itself, it first reassembles the
packet, if it is fragmented. Next, the router ensures that the packet is not
corrupted by checking the checksum, if there is one. Finally, it passes the
packet up to the next level for processing.
• Broadcast packets
When the router receives a broadcast packet, it checks the packet’s hop count
to ensure that it is not zero. In most cases, if the hop count is zero, the router
discards the packet (unless it is a StreetTalk or Time Sync Service packet). If
the node accepts the packet, the router decrements the hop count by one
before retransmitting the packet on all interfaces except for the one that
received it.
Checksum (2 bytes)
Protocol type (1 byte)
Destination network number (4 bytes)
Destination subnetwork number (2 bytes)
Source network number (4 bytes)
Source subnetwork number (2 bytes)
Packet length (2 bytes)
Transport control (1 byte)
18 bytes
VN0005A
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