Design Models 21
Figure 1-7
Full-Mesh Design
The number of links required for connectivity in a full mesh can be calculated using the
following formula, where n equals the number of routers:
[n(n1)/2]
Under a full-mesh design, if there were 20 sites, 190 links would be required.
NOTE
As the number of sites increases, the issues of management and administration increase as well.
For a large site, a full mesh could easily become an administrative full mess!
The partial-mesh design, shown in Figure 1-8, appears to strike the balance among scalability,
adaptability, and cost. The CCDP can designate certain sites to be hubs and less-critical sites to
be spokes. There are no hard requirements as to which sites must be hubs and which must be
spokes. Likewise, there are no requirements as to the absolute number of sites. Therefore, the
design can easily adapt to any cost constraints.
R1
R2
R3
R4
R5
87200333.book Page 21 Wednesday, August 22, 2001 2:18 PM