Using VLANs to Assure Bandwidth to Devices
Backbone
Router (R1)
3524 Switch
CallManager Unity
Site A
Router (R4)
3524 Switch
T-1
512K
Frame
Relay
Cloud
Site B
Router (R5)
3524 Switch
512K
Site C
Router (R6)
3524 Switch
512K
Network
Exchange
The VLANs between Site C and the head office backbone are just an
example, because the real network would have the same VLANs extending to all
sites, through all switches, and across the head office backbone to extend through
www.syngress.com
Figure 11.8 Using VLANs to Assure Bandwidth to Devices
Backbone
Router (R1)
3524 Switch
CallManager Unity
Site A
Router (R4)
3524 Switch
T-1
512K
Frame
Relay
Cloud
Site B
Router (R5)
3524 Switch
512K
Site C
Router (R6)
3524 Switch
512K
Network
Exchange
MGCP (R3)
Gateway
PRI
Telco
FXO
Telco
FXO
Telco
FXO
Telco
H.323 (R2)
Gatekeeper
Head Office
VLAN
Routing
VLAN
Routing
404 Chapter 11 • Designing and Implementing Multisite Solutions
those switches as well. In this type of design, the routers will have QoS controls
in place to assure that the 512 Kbps site circuits are properly managed and not
clogged by any one process.
Instead of running VLANs across the network, one other choice when Frame
Relay is used is to create multiple frame PVCs between the sites and the head
office backbone router.This has the effect of creating logically independent networks
across the same frame connection.While the Ethernet switches are segmented
into discrete networks, the branch office routers do not propagate the site
VLANs to the head office network but communicate to the head office via the
PVCs. Figure 11.9 illustrates this LAN concept.