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264 Chapter 8: AppleTalk
RTMP
As mentioned earlier in this chapter, RTMP is responsible for establishing and maintaining
routing tables for AppleTalk routers. RTMP is a distance-vector protocol and is quite similar to
RIP in functionality. Like RIP, the maximum hop-count is 15. Like RIP, RTMP is chatty and
consumes a great deal of bandwidth. It is recommended that RTMP not be used on WAN links,
especially low-speed WAN links, because of its excessive bandwidth consumption. RTMP must
be used on the LAN because AppleTalk workstations and servers rely on RTMP to pass
AppleTalk information on the network. Like RIP, RTMP relies on split horizon. CCDPs who
insist on using RTMP will not be able to use partial mesh as a design solution.
EIGRP
EIGRP supports AppleTalk routing and reduces routing traffic on the WAN. It saves bandwidth
because it sends routing updates only when changes occur. IGRP has fast convergence time,
converging within 1 second after a link failure.
AppleTalk devices use RTMP exclusively. Do not use EIGRP on the AppleTalk LAN. Do use
EIGRP for routing in the WAN core. Figure 8-6 illustrates the quick convergence of EIGRP.
Figure 8-6
EIGRP Convergence
EIGRP:
·
Overcomes 15 hop-count limitation
·
Allows for a partial-mesh design when split horizon is disabled
·
Does not send frequent routing updates
NOTE
AppleTalk EIGRP is different from IP and IPX EIGRP. IP and IPX EIGRP routers share a
common autonomous system ID. When enabling AppleTalk EIGRP, each router must have a
unique process ID.
RTMP
only
Enhanced IGRP
RTMP
only
100­199
3 hops to cable
range 100­199
87200333.book Page 264 Wednesday, August 22, 2001 2:37 PM