Information Technology Reference
In-Depth Information
SP Edge
WAN/Internet
Internet Service
Provider 1
Internet Service
Provider 2
MPLS/MAN
Frame Relay
ATM
PSTN
Figure 2-12
WA N / I n t e r n e t S P E d g e M o d u l e
Enterprises use SPs to acquire network services. ISPs offer enterprises access to the Inter-
net. ISPs can route the enterprise's networks to their network and to upstream and peer In-
ternet providers. Some ISPs can provide Internet services with DSL access. Connectivity
with multiple ISPs was described in the section, “Internet Edge.”
For voice ser v ices, P STN prov iders offer acces s to the global public voice net work. For the
enterprise network, the PSTN lets dialup users access the enterprise via analog or cellular
wireless technologies. It is also used for WAN backup using ISDN services.
WA N S P s o f f e r M P L S , F r a m e R e l a y, AT M , a n d o t h e r WA N s e r v i c e s f o r e n t e r p r i s e s i t e - t o -
site connectivity with permanent connections. These and other WAN technologies are de-
scribed in Chapter 6.
Remote Modules
The remote modules of the Cisco Enterprise Architecture model are the enterprise branch,
enterprise data center, and enterprise teleworker modules.
