Multihoming Scenario: Addresses Taken from Different Providers

One possibility for large domains is to take IP addresses from different providers based on geographic location. Consider Figure 3-16. Largenet has taken its IP addresses from two different providers, ISP1 and ISP2. With this design, each provider will be able to aggregate its own address space without having to list specific ranges from the other provider. ISP1 would advertise the aggregate 198.24.0.0/13, and ISP2 would advertise the aggregate 198.32.0.0/13. Both aggregates ..

LAN Topology

Like an OSPF designated router (DR), an IS-IS DIS exists to simulate a point-to-point topology across a multipoint environment. Because of this, a DIS is sometimes called a pseudonode. Despite their similarities, the IS-IS DIS is subtly different from OSPF.  The DIS exists separately at Level 1 and Level 2, and there is not a backup DIS. An OSPF DR is elected for life; IS-IS allows preemption if another router comes on line with a higher priority. Fewer adjacencies are..

OSPF Areas

OSPF provides two levels of hierarchy throughout an area. An area is a 32-bit number that can be defined either in an IP address format of "Area 0.0.0.0" or as a decimal number format, such as "Area 0." Area 0 is a backbone area, which is required if more than one area is configured. All areas must be connected to Area 0; otherwise, virtual links are needed, as shown in Figure 8-18. Figure 8-18. Using a Virtual Link Where an Area Is Not Attached to the Backbone Example 8-..

VPN Components

Now that you have a basic understanding of what a VPN is, let's discuss the components that make up a traditional VPN. Not every VPN implementation will include any or all of these components. Plus, based on the requirements listed in your security policy, you might not need all of these components. Therefore, you need to examine your security policy to determine which VPN implementation (or implementations) has the necessary components to meet your security policy's requirem..

Using DLSw to Bridge Between Ethernet and Token Ring

DLSw includes the capability to bridge different kinds of media. One common example of this is bridging an Ethernet segment to a Token Ring. dlsw-ether-branch#configure terminal Enter configuration commands, one per line.  End with CNTL/Z. dlsw-ether-branch(config)#interface Loopback0 dlsw-ether-branch(config-if)#ip address 10.1.3.5 255.255.255.252 dlsw-ether-branch(config-if)#exit dlsw-ether-branch(config)#access-list 200 permit 0x0000 0x0D0D dlsw-ether-branch(config)#..