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OSI Layer 3: Routed and Routing Protocols

NLSP

NetWare Link Services Protocol (NLSP) is based on ISO's IS-IS routing pro-
tocol. It is a link-state routing protocol, not a distance-vector protocol such
as RIP. Most of the problems with RIP that were listed previously are com-
mon to all distance-vector routing protocols. NLSP is not subject to these
problems.

The current version of NLSP, version 1.1, supports a multitude of

advanced routing features:

Multiple areas

Route aggregation

Hierarchical addressing

Network summarization

NLSP is similar to IS-IS because it defines areas. It offers solutions to

many of the problems that we discussed with RIP and SAP, and can actually
work as a replacement for all RIP and SAP communication between servers
(or routers).

Every NLSP router (remember that NLSP-enabled NetWare servers are

NLSP routers) builds and maintains three databases:

Adjacency

Link state

Forwarding

These three databases are listed in the order in which they are built. The

adjacency database can be unique on every router. On each of its NLSP-
enabled interfaces, each router meets every other NLSP router on that net-
work segment. On an Ethernet interface, for example, there can be several
other NLSP-enabled devices (other routers, servers, and so on). On a point-
to-point WAN interface, there is only one other device. All of this informa-
tion goes into the adjacency database; once it is built, each router knows all
of its NLSP neighbors on all connected networks.

AppleTalk Protocols

Just as IP and IPX had their own rules, AppleTalk has its own way of doing
things. Addressing, location of services, and communication are a bit differ-
ent than with other protocols. There are also several concepts that just don't
have parallels elsewhere.

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