User guide

12-26 E
XTREME
W
ARE
S
OFTWARE
U
SER
G
UIDE
I
NTERIOR
G
ATEWAY
R
OUTING
P
ROTOCOLS
Area 0 is the backbone area. It is located at the headquarters and has the following
characteristics:
• 2 internal routers (IR1 and IR2)
• 2 area border routers (ABR1 and ABR2)
• Network number 10.0.x.x
• 2 identified VLANs (HQ_10_0_2 and HQ_10_0_3)
Area 5 is connected to the backbone area by way of ABR1 and ABR2. It is located in
Chicago and has the following characteristics:
• Network number 160.26.x.x
• 1 identified VLAN (Chi_160_26_26)
• 2 internal routers
• A virtual link from ABR1 to ABR2 that traverses both internal routers.
In the event that the link between either ABR and the backbone fails, the virtual link
provides a connection for all routers that become discontiguous from the backbone.
Area 6 is a stub area connected to the backbone by way of ABR1. It is located in Los
Angeles and has the following characteristics:
• Network number 161.48.x.x
• 1 identified VLAN (LA_161_48_2)
• 3 internal routers
• Uses default routes for inter-area routing
Two router configurations for the example in Figure 12-5 are provided in the following
section.