4A Flashcards
_____ hierarchical internetworking model is a three-layer model for network design first proposed by _____.
Cisco
The three-layer Cisco model is a conceptual framework of a network like the concept of the OSI reference model. It divides enterprise networks into three layers: ____, ____, and ____ layer.
core, distribution and access
The core layer is literally the core of the network and is often called a ___-___ ____.
high-speed backbone
At the top of the hierarchy, the core layer’s only purpose is to transport large amounts of traffic ____ and ____.
reliably and quickly
Remember that user data is processed at the distribution layer, and the distribution layer forwards the requests to the core when necessary. These are normally high-speed ___ and ___.
switches and routers
A failure in the core either by a faulty link or device may affect every user especially to the outside world. Therefore, fault tolerance at this layer is essential through ____.
redundancy
Since the core will transport large volumes of traffic, ____ and ____ are major concerns.
speed and latency
Given the function of the core, what are the design functions you need to consider?
- Speed
- Workgroups
- Scalability
- Reliability and Redundancy
- Protocols
The following describes which design function to consider when it comes to the core?
Core layers must be designed with _____ in mind. Don’t do anything to slow down traffic such as applying access control lists, routing, and packet filtering when possible.
Speed
The following describes which design function to consider when it comes to the core?
Don’t support _____ access by connecting devices that belong to the access layer. This defeats the concept of the hierarchical model and the core layer.
Workgroups
The following describes which design function to consider when it comes to the core?
Avoid expanding the core when the internetwork grows (that is, adding routers). If performance becomes an issue in the core, give preference to upgrades over expansion
Scalability
The following describes which design function to consider when it comes to the core?
Design the core for high ____ and ____. Consider
Data Link technologies and media that facilitate both speed and redundancy, such as fiber optics via FDDI, FastEthernet (with redundant links), or even asynchronous transfer mode (ATM) technology.
Reliability and Redundancy
The following describes which design function to consider when it comes to the core?
Select routing ____ with lower convergence times or extremely fast and efficient layer 2 switching devices. Devices at the core layer should not be burdened with any processes that stand in the way of switching packets at top speed. This includes access-list checking, data encryption, address translation.
Protocols
