Basic Concepts

NEID and NEIP

• NEID

  On a data communication network (DCN), a network element (NE) is uniquely identified by an ID but not an IP address. This ID is called an NEID. A 24-bit NEID consists of a subnet number and a basic ID. The leftmost 8 bits of an NEID indicate a subnet. The rightmost 16 bits of an NEID indicate a basic ID. Each NE is assigned a default NEID before the NE is delivered.

  As the unique identities of NEs on a DCN, NEIDs must be different from each other. If the NEIDs of two NEs on a DCN are identical, route flapping occurs.

• NEIP

  NEIP addresses help managed terminals access NEs and allow addressing between NEs in IP networking. An NEIP address consists of a network number and a host number. A network number uniquely identifies a physical or logical link. All the NEs along the link have the same network number. A network number is obtained using an AND operation on the 32-bit IP address and subnet mask. A host number uniquely identifies a device on a link.

  An NEIP address is derived from an NEID when an NE is being initialized. An NEIP address is in the format of 128.subnet-number.basic-ID.

  The following example uses the default NEID 0x09BFE0, which is 1001.10111111.11100000 in binary format. The basic ID is the 16 least significant bits 10111111.11100000, which is 191.224 in decimal format. The subnet number is the 8 most significant bits 00001001, which is 9 in decimal format. Therefore, the NEIP address derived from 0x09BFE0 is 128.9.191.224.

  Before the NEIP address is manually changed, the NEIP address and NEID are associated; therefore, the NEIP address changes if the NEID is changed. Once the NEIP address is manually changed, it no longer changes when the associated NEID is changed.

  

  To improve the system security, it is recommended that the NEIP address be changed to the planned one.

DCN Core Routing Table

A DCN core routing table consists of mappings between NEIP addresses and NEIDs of NEs on a DCN.

To use a GNE to access a non-GNE, an NMS searches the DCN core routing table for the destination NEIP address that maps the target NEID. Then, the NMS sends a UDP packet to the destination NEIP address. Therefore, to implement the DCN feature, a DCN core routing tables must be available on each device.