Information Technology Reference
In-Depth Information
WAN
Internet
ADSL
T1
Acess
Router
Figure 7-8
Small Branch Design
The infrastructure components are dual-access routers, external Layer 2 / Layer 3
switches, laptops, desktops, printers, and IP phones. Dual Frame Relay links provide the
private WAN services, which are used to connect back to the corporate offices via both of
the access routers.
Layer 3 protocols such as EIGRP are typically deployed. Because there are two routers,
Hot Standby Router Protocol (HSRP) or Gateway Load Balancing Protocol (GLBP) can be
used to provide redundancy gateway services. QoS can also be used to provide guaran-
teed bandwidth for VoIP, and policing can be used to restrict certain traffic classes from
overwhelming the available bandwidth. Cisco IOS features such as QoS, access control
lists (ACL), and RIP routing capabilities are available in the IP Base feature set, but IP uni-
cast routing and multicast routing require the IP Services feature set.
The medium branch design supports using a higher-density external switch or using the
EtherSwitch module with the ISR to create trunks to the external access switches. The
Cisco Catalyst 3750 series switches have StackWise technology, allowing multiple
switches to be connected and managed as one. This also increases the port density avail-
able for end-user connections. With Cisco StackWise technology, customers can create a
single, 32-Gbps switching unit that can connect up to nine 3750 series switches using a
variety of fiber and copper ports, allowing greater flexibility with the connection options.
Figure 7-9 illustrates the medium branch design using dual routers back to the corporate
office where the corporate resources are located.
