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In a legacy NetWare network, servers and
routers may be configured to use IPX RIP and the Service Advertising
Protocol (SAP) to exchange information with peers. As time-driven
protocols, IPX RIP and SAP generate updates every 60 seconds by default.
These updates can crowd low-speed WAN links, especially in large
internetworks.
EIGRP can redistribute IPX RIP and SAP
information to improve overall performance. In effect, EIGRP can take over
for these two protocols. An EIGRP router will receive routing and service
updates and then update other routers only when changes in the SAP or
routing tables occur. Routing updates occur as they would in any EIGRP
network - using partial updates. EIGRP sends SAP updates incrementally on
all serial interfaces by default. However, you must manually configure
incremental SAP updates on LAN interfaces (e.g., Ethernet, Token
Ring, and FDDI).
Like IP RIP, IPX RIP restricts a network's
diameter to 15 hops. By using EIGRP to redistribute IPX RIP, a network's
diameter can expand to EIGRP's comfortable limit of 224 hops. Moreover,
EIGRP's more advanced metric, which uses bandwidth and delay, replaces
Novell RIP's less optimal metric derived from hop count and ticks.
The obvious shortcomings of IPX RIP and SAP
spurred Novell's development of a proprietary link-state routing protocol
for NetWare: NetWare Link Services Protocol (NLSP). A link-state protocol,
NLSP replaces both RIP and SAP. On servers running NetWare 3.11 or later,
administrators can choose between using RIP/SAP or NLSP. Note that since
Cisco IOS version 11.1, EIGRP can redistribute NLSP as well as IPX RIP.
EIGRP Support for AppleTalk
EIGRP can also take over for AppleTalk's Routing Table Maintenance
Protocol (RTMP). As a distance-vector routing protocol, RTMP relies on
periodic and complete exchanges of routing information. To reduce
overhead, EIGRP redistributes AppleTalk routing information using
event-driven updates. EIGRP also uses a configurable composite metric to
determine the best route to an AppleTalk network. RTMP uses hop count,
which can result in suboptimal routing.
AppleTalk clients expect RTMP information
from local routers, so EIGRP for AppleTalk should be run only on a
clientless network, such as a WAN link.
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