A virtual link can be used to connect an area to Area 0 when a direct link is not possible. A virtual link traverses an area between the remote area and Area 0 (see Figure 4-5).

A stub area is an area that does not receive routes that were learned from a protocol other than OSPF or were statically configured. These routes typically send traffic outside the AS. Therefore, routes from a stub area to locations outside the AS use the default gateway. A virtual link cannot be configured across a stub area. A Not So Stubby Area can import limited external routes only from a connected ASBR.

OSPF Routers and LSAs

OSPF routers keep track of the state of the various links they send data to. Routers share OSPF link state advertisements (LSAs) with other routers. Various LSA types provide detailed information on a link for sharing within an area or summary information for sharing outside an area. External LSAs provide information on static routes or routes learned from other routing protocols.

OSPF defines various router types:

•Backbone routers have an interface in Area 0. They condense and summarize information about all the areas in the AS and advertise this information on the backbone.

•Area border routers (ABRs) connect areas to the OSPF backbone (in the case of virtual links, the an ABR may connect to another ABR that provides a direct connection to Area 0). An ABR is a member of each area it connects to.

•Internal routers (IRs) route traffic within an area. When two routers in an area discover each other through OSPF Hello messages, they are called OSPF neighbors. Neighbors share detailed information on the topology of the area using local LSAs.

•Autonomous system boundary routers (ASBRs) connect to other ASes. ASBRs use other protocols such as BGP or RIP to communicate outside the AS. The ASBR performs route redistribution; i.e., when it learns routes from other protocols, it originates external LSAs that advertise those prefixes within the AS.

Metrics and Route Selection

You can configure the metric type of external routes originated through route redistribution. The metric type influences the routes computed by other OSPF routers in the domain.

OSPF determines the best route using the assigned cost and the type of the OSPF route. The following order is used for choosing a route if more than one type of route exists:

1Intra-area (the source and destination address are in the same area)

2Inter-area (the source and destination are not in the same area, i.e., the route crosses the OSPF backbone)

3External Type 1

4External Type 2

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6200 SERIES specifications

The Dell 6200 Series is a notable line of workstations designed for professionals seeking powerful computing solutions in fields such as engineering, architecture, and design. With its robust architecture and advanced technology, this series stands out for its ability to handle demanding applications while offering reliability and performance.

One of the key features of the Dell 6200 Series is its powerful processing capabilities. It typically includes Intel Xeon processors, which provide multiple cores to manage multitasking efficiently. This allows users to run complex simulations or render high-resolution graphics without experiencing lag or slowdown. The processors are designed for optimal thermal management, allowing for sustained performance during extended work sessions.

Another significant aspect of the Dell 6200 Series is its graphics capabilities. These workstations often come equipped with NVIDIA or AMD professional-grade graphics cards, ensuring that they are equipped to handle graphically intensive tasks, such as 3D modeling and video editing. The support for advanced rendering technologies allows professionals to work with high-fidelity visuals and complex datasets with ease.

In terms of expandability, the Dell 6200 Series is designed with flexibility in mind. Users can customize their workstations with a range of configurations, including varied RAM capacities and storage options. This flexibility ensures that the workstation can be tailored to meet the specific requirements of different workloads. The incorporation of Solid State Drives (SSDs) enhances data access speeds, significantly improving boot times and overall system responsiveness.

Additionally, the Dell 6200 Series includes comprehensive connectivity options to facilitate integration with various peripherals and networks. With multiple USB ports, Ethernet ports, and support for multiple display outputs, users can connect to external devices easily, promoting an efficient workflow.

Security features are also a priority in this series. The workstations typically include advanced security measures, such as TPM (Trusted Platform Module) technology, which helps protect sensitive data through hardware encryption and secure storage.

Overall, the Dell 6200 Series delivers a blend of power, flexibility, and security that makes it an excellent choice for professionals in need of a dependable workstation. With its advanced technologies and ample expansion options, users can feel confident that their equipment can handle both current and future demands, making it a smart investment for any professional environment.
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