Information Technology Reference
In-Depth Information
Internet
Routers
Internet
Firewalls
Enterprise Campus
Backbone
Internet
WAN Routers
Enterprise
Edge
Te l e w o r k e r
MPLS
Branch
Offices
Figure 6-1
Enterprise WAN
WAN C onne ction Mo dule s
The enterprise edge can have multiple WAN interconnections. Common connectivity
modules include but are not limited to the Internet, the demilitarized zone (DMZ), and
the WAN. Internet service providers (ISP) offer many connectivity options for the
Internet and DMZ modules in the enterprise edge. WAN connectivity between an orga-
nization's headquarters and remote sites is generally across a service provider network,
such as with MPLS WAN. Alternative options for connecting branch offices involve
using broadband technologies, such as cable and DSL, coupled with IPsec VPNs over
the Internet.
WA N t e c h n o l o g i e s c a n b e p o i n t - t o - p o i n t ( P 2 P ) o r m u l t i p o i n t s u c h a s F r a m e R e l a y o r
MPLS WAN services. Most WAN service providers offer MPLS WAN solutions where
the enterprise edge router interacts with service providers at Layer 3. Public WAN con-
nections over the Internet are available ranging from cable/DSL technologies all the way
up to multigigabit connectivity options. Typically, these services do not provide any
guarantee of network availability, so they are considered a “best effort” service. Frame
Relay and MPLS network solutions usually have a much higher degree of reliability and
availability.
