Avaya 8800 Planning And Engineering, Network Design page 134

Layer 3 network design
The routers in example 2 have the following settings:
• S1 has an OSPF router ID of 1.1.1.1, and the OSPF port is configured with an IP address of
192.168.10.1.
• S2 has an OSPF router ID of 1.1.1.2, and two OSPF ports are configured with IP addresses of
192.168.10.2 and 192.168.20.1.
• S3 has an OSPF router ID of 1.1.1.3, and the OSPF port is configured with an IP address of
192.168.20.2.
The general method used to configure OSPF on each routing switch is:
1. Enable OSPF globally.
2. Insert IP addresses, subnet masks, and VLAN IDs for the OSPF ports on S1 and S3 and for
the two OSPF ports on S2. The two ports on S2 enable routing and establish the IP
addresses related to the two networks.
3. Enable OSPF for each OSPF port allocated with an IP address.
When all three switches are configured for OSPF, they elect a DR and BDR for each subnet and
exchange hello packets to synchronize their link state databases.
Example 3: OSPF on two subnets in two areas
The following figure shows an example where OSPF operates on two subnets in two OSPF areas.
S2 becomes the ABR for both networks.
Figure 56: Example 3: OSPF on two subnets in two areas
The routers in scenario 3 have the following settings:
• S1 has an OSPF router ID of 1.1.1.1. The OSPF port is configured with an IP address of
192.168.10.1 which is in OSPF area 1.
• S2 has an OSPF router ID of 1.1.1.2. One port has an IP address of 192.168.10.2, which is in
OSPF area 1. The second OSPF port on S2 has an IP address of 192.168.20.1 which is in
OSPF area 2.
• S3 has an OSPF router ID of 1.1.1.3. The OSPF port is configured with an IP address of
192.168.20.2 which is in OSPF area 2.
The general method used to configure OSPF for this three-switch network is:
1. On all three switches, enable OSPF globally.
June 2016 Planning and Engineering — Network Design
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