through Albuquerque.
is a single Class A, B, or C network for which all routes to subnets of that network pass through
only other subnets of that same single network. Discontiguous networks refer to the concept
that, in a single Class A, B, or C network, there is at least one case in which the only routes to
one subnet pass through subnets of a different network. An easy analogy for residents in the
United States is the familiar term contiguous 48, referring to the 48 states besides Alaska and
Hawaii. To drive to Alaska from the contiguous 48, for example, you must drive through another
country (Canada, for the geographically impaired!), so Alaska is not contiguous with the 48
states--in other words, it is discontiguous.
that uses a subnet of network 10.0.0.0, but that PVC may be down, causing the discontiguous
network. The temporarily discontiguous network can be overcome with the use of a routing
protocol that transmits masks because the rule of discontiguous subnets can be ignored when
using a routing protocol that transmits masks. Consider the routing updates and routing table
on Albuquerque in Example 6-15, where auto summarization is disabled on all routers.
RIP protocol debugging is on
Albuquerque#
02:48:58: RIP: received v2 update from 172.16.1.253 on Serial0.2
02:48:58: 10.1.7.0/24 -> 0.0.0.0 in 1 hops
02:48:58: 10.1.6.0/24 -> 0.0.0.0 in 1 hops
02:48:58: 10.1.5.0/24 -> 0.0.0.0 in 1 hops
02:48:58: 10.1.4.0/24 -> 0.0.0.0 in 1 hops