Installing and Administering OSI Transport Services

74 Chapter 2

Planning Your Network

General LAN Questions

• Is ES/IS (end system/intermediate system) protocol supported?

Most systems today support the ES/IS protocol. This protocol allows

systems to dynamically maintain information about the NSAP to

MAC address mapping for systems on a LAN. By using this protocol,

a great deal of conﬁguration can be avoided.

• Can this system behave as an IS?

An intermediate system is capable of forwarding trafﬁc from one

subnetwork to an IS on another subnetwork. This system should

support both the ES/IS and IS/IS protocols. HP systems do not behave

as an IS.

• Will this subnetwork use the NULL subset of CLNS?

The NULL subset of CLNS is used for systems that are on an isolated

LAN network. When NULL subnetting is used, no trafﬁc can be

forwarded via routers.

The beneﬁt of the NULL subnet is reduced protocol packet size (on

the order of 40 bytes per packet).

The drawback is the inability to communicate outside the

subnetwork.

• Is your LAN link conﬁgured for IEEE 802.3?

If you want to conﬁgure OTS CLNS over 802.3, you must use SAM to

conﬁgure your LAN link to use IEEE 802.3.