CRT 2.2 Collision and Broadcast Domains
Collision domains
In legacy hub-based Ethernet segments, network devices competed for the shared medium. The network segments that share the same bandwidth between devices are known as collision domains. When two or more devices within the same collision domain try to communicate at the same time, a collision will occur.
_____ interconnect LAN segments, use a MAC address table to determine egress ports, and can lessen or eliminate collisions entirely.
Switches
When a switch receives a _____ frame, it forwards the frame out each of its ports, except the _____ port where the _____ frame was received. Each device connected to the switch receives a copy of the _____ frame and processes it.
broadcast broadcast ingress broadcast
By default, interconnected switch ports attempt to establish a link in _____-duplex, therefore eliminating collision domains. Each _____-duplex port of the switch provides the full bandwidth to the device or devices that are connected to that port. _____-duplex connections have dramatically increased LAN network performance, and are required for _ Ethernet speeds and higher.
full full full 1 Gbps
By default, Ethernet switch ports will autonegotiate _____-duplex when the adjacent device can also operate in _____-duplex. If the switch port is connected to a device operating in _____-duplex, such as a legacy hub, then the switch port will operate in _____-duplex. In the case of _____-duplex, the switch port will be part of a collision domain.
full full half half half
If an Ethernet switch port is operating in _____-duplex, each segment is in its own collision domain. There are no collisions when switch ports are operating in _____-duplex. However, there could be a collision domain if a switch port is operating in _____-duplex.
half full half
Which port speed will be autonegotiated between a host with a 1 Gbps NIC connecting to a Cisco Catalyst 2960 switch with a 100 Mbps port? - 10 Mbps - 100 Mbps - 1 Gbps - 10 Gbps
- 100 Mbps
Which two special characteristics do LAN switches use to alleviate network congestion? (Choose two.) - fast port speeds - fast internal switching - low port densities - small frame buffers
- fast port speeds - fast internal switching
Most access layer switches support _ and _ port speeds. Distribution layer switches support _, _, and _ port speeds and core layer and data center switches may support _, _, and _ port speeds.
100 Mbps 1 Gbps 100 Mbps 1 Gbps 10 Gbps 100 Gbps 40 Gbps 10 Gbps
Pros and cons of broadcasts
Broadcasts are sometimes necessary for initially locating other devices and network services, but they also reduce network efficiency. Network bandwidth is used to propagate the broadcast traffic. Too many broadcasts and a heavy traffic load on a network can result in congestion, which slows down network performance.
When two switches are connected together, the broadcast domain is [DECREASED / INCREASED].
INCREASED
MAC broadcast domain
The Layer 2 broadcast domain is referred to as the MAC broadcast domain. The MAC broadcast domain consists of all devices on the LAN that receive broadcast frames from a host.
Characteristics of switches that alleviate network congestion include the following:
- Fast port speeds - Fast internal switching: Switches use a fast internal bus or shared memory to provide high performance. - Large frame buffers: Switches use large memory buffers to temporarily store more received frames before having to start dropping them. - High port density: A high port density switch lowers overall costs because it reduces the number of switches required.
Which device separates broadcast domains? - access point - hub - router - switch
- router
Broadcast domains
A collection of interconnected switches forms a single broadcast domain. Only a network layer device, such as a router, can divide a Layer 2 broadcast domain. Routers are used to segment broadcast domains, but will also segment a collision domain.
When a device sends a Layer 2 broadcast, the destination MAC address in the frame is set to _____.
all binary ones
