IBM SC30-3865-04 DNA IV Terminology and Concepts

vDNA IV does not provide any Phase III compatibility features because it does not

support the DDCMP data link protocols used by all Phase III nodes.

vNCP (the router’s implementation of the DECnet Network Control Program)

implements a subset of the original NCP commands and functions.

DNA IV Terminology and Concepts

This section contains a brief description of DNA IV terminology.

Each node has a 16-bit node address, which is the same for all interfaces on that

node. An address consists of 2 ﬁelds: 6 bits of area number and 10 bits of node

number.Addresses are printed in decimal with a period separating the area and the

node, such as 1.7 is node 7 in area 1. If no area is given, area 1 is assumed. Any

address in the range 1.1 to 63.1023 is legal. Both nodes and areas should be

numbered starting from 1, with few, if any,gaps. This is because the maximum

node number and the maximum area numbers are conﬁguration options and control

the size of many of the routing data structures.

There is no direct correlation between addresses and physical cabling. Routes are

computed to nodes, not wires.

Each Ethernet interface is set to the same 48-bit physical address, which is the

concatenation of a 32-bit preﬁx (AA-00-04-00) and the 16-bit DNA IV node address.

The node address is byte-swapped (to convert from PDP11 to Ethernet byte order).

Thus, DNA IV node 1.1 has EthernetAddress AA-00-04-00-01-04.

Multicast (not broadcast) is also used in routing. The three multicast addresses

used by DNA IV areAB-00-00-02-00-00, AB-00-00-03-00-00, and

AB-00-00-04-00-00.

The implementation of DNA over IEEE 802.5 TokenRing conforms to the

, Version 1.0.0, that includes support forArbitrary MAC

Addresses (AMA).

There are two types of MAC addressing, conventional DNA IV addressing, which is

the concatenation of a 32-bit preﬁx (AA-00-04-00) and the 16-bit DNA IV area/node

address or AMAthat allows the DNA protocol to run on IEEE 802.5 nodes without

their MAC addresses being changed by the DNA protocol. This is necessary if you

follow certain IBM protocol conventions. Youcan select the type of addressing that

you are using through the DNA conﬁguration process (NCP>).

Another type of addressing representation is native bit-order. This type of address is

byte-ﬂopped when sent over the physical layer. For example, the canonical 32-bit

preﬁx shown above (using dashes) is expressed as 55:00:20:00 in native bit-order

with colons separating each byte.

Note: When conﬁguring DNA IV to run overATM LAN Emulation, the AMA must be

used.

Using DNA IV

250 MRS V3.2 Protocol Conﬁg Ref Vol2