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538 Chapter 8: WAN Protocols and Design
One particularly convenient benefit of global addressing is that new sites can be added with
more convenience. Examine Figure 8-10, with Routers D and E added. The service provider
simply states that global DLCI 43 and 44 will be used for these two routers. If these two routers
also have only one PVC to Router A, all the DLCI planning is complete. You know that Router
D and Router E will use DLCI 40 to reach Router A, and that Router A will use DLCI 43 to
reach Router D and DLCI 44 to reach Router E.
Figure 8-10
Adding Frame Relay Sites: Global Addressing
The remaining samples in this chapter use global addressing in any planning diagrams, unless
otherwise stated. One practical way to determine whether the diagram lists the local DLCIs or
the global DLCI convention is this: If two VCs terminate at a DTE and a single DLCI is shown,
then it probably represents the global DLCI convention. If one DLCI is shown per VC, then it
is depicting local DLCI addressing.
Network Layer Concerns with Frame Relay
As a CCNA, you will need to concern yourself with three key issues relating to Layer 3 flows
over Frame Relay:
·
Choices for Layer 3 addresses on Frame Relay interfaces
·
Broadcast handling
·
Split horizon
The sections that follow cover these issues in depth.
A
B
C
D
E
DLCI 41
DLCI 43
DLCI 40
DLCI 44
DLCI 42
ch08.fm Page 538 Monday, March 20, 2000 5:17 PM