Enterprise Network Architecture Flashcards
What is hierarchical design model
It is where the enterprise is divided up into modular layers with each layering having different functions.
What are the benefits of a hierarchical design model
Simplified network design
highly scalable
improves performance
faster problem isolation
What are the different layers in the hierarchical design model
Access - used for endpoints and users to access the network.
Distribution - Used to aggregate the access layer switches. acts as a service and control boundary between access and core.
Core - Provides connections between the different distribution layers, also known as the backbone.
What is high availability in networking
networks the can operate with high resilience and continuous up-time without failure by considering both network and system level components.
What are some methods for improving HA
Redundant devices and links
Ensuring no or limited SPFs
Using clustering technology
Implementing network monitoring systems.
What are the best ways for improving HA on a router
Using redundant hardware modules, line cards and route processors.
Using routers that support hot-swappable technology
Using SSO with NSF and GR and NSR
Using UDLD & BFD
using FHRPs
What is a route processor / supervisor engine
The component on a router responsible for handling the control plane traffic, the RIB, the FIB and the adjacency table. some routers support redundant RP’s with an active and standby set up.
What is SSO with NSF
Stateful switch over with non stop forwarding allows a active RP to go down and a standby RP to take over usign a synchronised backup to operate to router.
Layer 3 control plane info is not checkpointed therefore neighbours will se router as down. forwarding still occurs.
What is SSO with NSF and GR
GR is graceful restart is used to to protect the layer 3 forwarding plane and interacts with neighbouring routers by using the GR extension on routing protocols this allows routers that are GR aware to keep forwarding traffic to the down router.
requires neighbours to be GR aware.
What is SSO with NSF and NSR
The NSR allows the layer 3 routing control plane info to be checkpointed resulting in no need for other routers to be aware.
requires a large overhead for the RP.
What is SSO with NSF and NSR and GR
It allows routers to utilise both features GR will be sued for GR aware neighbours and NSR for non-GR aware neighbours.
As well as enabling SSO you must enable NSF
true or false
False NSF is enabled as long as SSO is enabled as a default.
What is a two-tier (collapsed core) architecture
When the distribution layer and core are combined into one for smaller environments.
What is a three-tier architecture
Used in large enterprises a separate layer for access, distribution and core.
What is the difference between a Layer 2 access and layer 3 access
The access layer is either operated at a l2 level using STP or at a layer 3 using IP links.
