Chapter 8 Flashcards
(24 cards)
How does a Layer-2 switch differ from a router?
Layer-2 switches use MAC addresses and work at the data link layer; routers use IP addresses and work at the network layer.
How does a Layer-2 switch differ from a VLAN?
Layer-2 switches forward packets using MAC addresses; VLANs use tagging (IEEE 802.1q) to isolate traffic within or between switches.
How does a router differ from a VLAN?
VLANs create subnets inside switches; routers connect different subnets between devices.
When would you use a switched backbone?
To increase efficiency and separate traffic across the network within a building.
When would you use a routed backbone?
To connect different buildings and isolate subnets for better traffic control.
When would you use a VLAN backbone?
When you need to group devices from different locations into the same subnet.
How do routed backbones work?
They use Layer 3 (network layer) addresses to forward packets across subnets, typically with a bus topology.
What happens if you remove routers in each building and use only one core router?
It would work but increase traffic and reduce performance; only one subnet means more broadcast traffic.
How do switched backbones work?
Use a star topology with a central switch (collapsed backbone); all LANs connect into the switch directly.
What are the advantages of routed backbones?
Clear subnet separation and management; controlled broadcast domains.
What are the disadvantages of routed backbones?
Slower performance and more complex configuration/management.
What are the advantages of switched backbones?
Faster performance, easier centralized management, fewer devices, less cost.
What are the disadvantages of switched backbones?
More broadcast traffic, more cable needed, and total failure if the switch fails.
Compare rack-based and chassis-switch based backbones.
Rack-based systems are modular and flexible; chassis switches use pluggable modules and are easily upgradable.
What is a module in a chassis switch?
A plug-in component like a switch, hub, or router that adds functionality or ports.
How does a single-switch VLAN work?
All VLAN traffic stays within one switch; devices are grouped by software into virtual segments.
How does a multi-switch VLAN work?
Multiple switches coordinate VLAN traffic using tagging (802.1q) or encapsulation.
What is IEEE 802.1q?
A standard for VLAN tagging that inserts 16 bytes of VLAN info into Ethernet frames for multi-switch VLAN communication.
What are advantages of VLANs?
Faster performance, better traffic control, supports cross-location subnet grouping, and traffic prioritization.
What are disadvantages of VLANs?
More complex setup and higher cost; usually used in large networks.
How can you improve BN performance?
Identify and eliminate bottlenecks, upgrade devices or circuits, reduce traffic, or prioritize applications.
Why are broadcast messages important?
They provide updates like printer status or server shutdown notices, but should be filtered to limit network load.
What are the preferred backbone architectures by layer?
Access: switched backbones; Distribution: VLANs; Core: routed backbones.
Will Ethernet move into the WAN?
Yes—Ethernet/IP is replacing SONET/ATM in many WANs due to cost and performance benefits.
