Block 7 Flashcards
_______ ________ consists of the data link later specifications that often define how devices are to be physically and logically connected.
Network topology
Ex. Bus & Ring topologies
________ __________ defines how devices are addressed at the data link layer.
Physical Addressing.
Also known as: physical, hardware, machine, or MAC addresses
_____ _________ uses Cyclic Redundancy Check (CRC) or Frame Check Sequences (FCS) to detect errors in transmissions.
Error detection and notifications
What reorders frames that are received out of sequence?
Sequencing of data frames
____ ______ moderates the transmission of data so that the receiving device is not overwhelmed with more traffic that it can handle at one time.
Flow control
What is the PRIMARY METHOD of flow control for switches?
Buffering
________ is a forwarding technique used in packet-switched networks.
Bridging
________ devices depend on flooding and examination of source addresses in received packed headers to locate unknown devices.
Bridging Devices
True/False?
Bridges are considered software based.
True
True/False?
Switches are hardware based devices that use Application Specific Integrated circuits(ASIC) for faster operation.
True
True/False?
Bridges have advance Spanning-Tree control.
False
Bridges have limited Spanning-Tree control.
True/False?
Switches have limited Spanning-Tree control.
False.
Switches have ADVANCE Spanning-Tree control
Bridges can have up to __ ports.
Up to 16 ports
Switches can have _________ of ports
Hundreds.
Only limited by the amount of ports available.
Q.1 _________ domain is a physical or logical network segment in which data lackeys can collide with each other.
Q.2 What reduces this from happening?
- Collision domain
2. CSMA/CD
_________ domain is a logical network segment defined by it’s router port connection.
All network devices can communicate with each other by using broadcasts.
Broadcast Domain
255.255.255.255
Switches use ____ to build and maintain MAC address tables.
Application-Specific Integrated Circuits (ASIC)
Layer 2 switches are built to provide what 4 things?
Hardware-based bridging
Wire speed
Low latency (low delay)
Low cost
What are considered the MOST COMMON type of switches?
They provide network segmentation by breaking up collision domains
Ethernet Switches
What are the MAJOR switch functions?
(A)ddress Learning
(L)oop Avoidance
(F)orward/Filter Decision
Which major switch function does this fall under?
The switch has no choice but to flood the network with this frame because it just try and learn the location of the destination device.
(A)ddress Learning
Under the major switch functions what happens if a workstation does not talk for a period of time on a network?
Chances are that it’s MAC address heads aged out (removed) from the table.
If the destination hardware address is known and listed in the database, then the frame is _________ out only on the correct exit interface.
Forwarded
This helps preserve bandwidth on the other network segments
Frame filtering
What are the 3 switching methods?
Store & Forward
Cut-Through (Real Time)
Fragment Free (Modified Cut-Through)
(SaCF)
With this frame switching method, the switch copies the entire frame into it’s buffers and computes the CRC (Cyclic Redundancy Check). If no errors are present the MAC address is used to determine the appropriate interface to use.
Store & Forward
This method is BEST for sending error free frames but consumes the greatest amount of processing time
This frame switching method provides reduced latency. Provides no error checking but results in the fastest processing time.
Cut-Through (Real Time).
LAN switch copies only the destination (first 6 bytes)
In this frame switching method the switch waits for the COLLISION WINDOW (64 bytes) to pass before forwarding.
Fragment Free ( Modified Cut-Through)
Better error checking than the cut-through mode, with practically no increase in latency
Switches or Bridges in a network environment can create what is referred to as a “____ ____ __ _____”
Single point of failure
A ____ is simply having more than one path to a destination that causes instability in the MAC address table.
Loop
The instability of of loops causes why 3 things?
Broadcast Storms
Multiple Frame Copies
Multiple Lopps
When referring to loop avoidance if the switches flood broadcasts endlessly throughout the internetwork it’s called….?
Broadcast Storms
When referring to loop avoidance problems; _______ _______ ______ Is when a device can receive multiple copies of the same frame because the frame can arrive from different segments at the same time.
Multiple Frame Copies
MAC address filter table will be confused. Constantly updating the MAC filter table
In reference to loop avoidance this is one if the BIGGEST PROBLEMS.
Multiple Loops
Loops can occur within other loops
This protocol is used by layer 2 devices to STOP NETWORK LOOPS in networks that have more than one physical link to the same network.
Spanning Tree Protocol
Designed to detect loops and close or open the necessary ports to avoid such loops.
What 2 categories can Ethernet switch components divided into?
External & Internal components
Which category of Ethernet switch components are the physical connections to the switch?
External components.
Most Ethernet switches include a _______ ____ and _______ _________
Console port and network interfaces
Which external component allows locally direct access to the switch during configuration?
Console Port
This is where you must connect when you initially configure a “blank” switch
This external component is where you will connect your end devices such as your computers or printers.
Network interfaces
A switch may also have uplink ports used for high speed connectivity to another switch or router.
True/False?
A switch MUST have an IP address.
False.
A switch only requires an IP address if telnetting is required.
What are the internal components of an Ethernet switch?
Hint - they are similar to those you find in any standard computer system.
ROM
Flash memory
NVRAM
RAM
Explain the internal components of an Ethernet switch.
ROM, RAM, Flash memory and NVRAM
ROM- where diagnostic and bootup routines are stored. Can’t be changed (burned-in)
Flash memory- holds the IOS
RAM- called volatile memory. Config file and the IOS are executed during operation
NVRAM- non-volatile memory. Stores the startup config file (Start)
What is a LOGICAL grouping of network computers and resources connected to an administratively defined ports on a layer 2 switch?
Virtual Local Area Network (VLAN)
True/False?
VLAN’s can be used to break up broadcast domains in layer 2 switched networks
True
____ _______ is also called a broadcast domain and all connected devices see all broadcast packets that are transmitted.
Flat Network
True False?
As the number of VLAN’s increase so do the number of Broadcast Domains.
False
As the number of VLAN’s increase the number of Broadcast Domains decrease (inversely proportional)
True/ False?
VLAN, Broadcast Domain and Subnet are interchangeable terms?
True
Increased security, no geographical barriers, flexibility and scalability, and broadcast control are all benefits of ____
VLAN’s (Virtual Local Area Networks)
Which VLAN benefit does this fall under?
Any unauthorized device connected to a switch port will not function or provide access to network resources?
Increased security
B/c the admin controls each switch port as whatever resources it is allowed to use.
Which VLAN benefit does this fall under?
You are no longer confined to creating workgroups based on physical locations.
No geographical barriers
Which VLAN benefit does this fall under?
Adds flexibility to your network by limiting or adding only the device you want in the broadcast domain regardless of it’s physical location
Flexibility and Scalability
Which VLAN benefit does this fall under?
Able to create smaller broadcast domains within a switch by assigning different ports in the switch to different sub-networks.
Broadcast domains
VLAN port membership assignments are split into two types. What are they?
Dynamic and Static
What must be used to assign a dynamic VLAN membership?
VMPS (VLAN Membership Policy Server)
In regards to VLAN Memberships: This service will tell the switch port which VLAN it belongs to based on the MAC address of the device that connects to the port.
VMPS (VLAN Membership Policy Server)
In regards to VLAN Memberships which type has the administrator create VLANs and assigns the respected ports to it.
Typical method and MOST secure
Static VLANs
What are the two types of LINKS modes?
Access Link and Trunk Link
In regards to LINK modes which is a link that is assigned to one VLAN?
Access Link
Example is a connection between any host device and a switch
In regards to LINK modes which is thought of as neutral? They will carry traffic for all VLANs unless you specifics otherwise
Trunk Link
Which protocol automatically negotiates with other Cisco devices when they connect?
Dynamic Trunking Protocol
In regards to LINKS modes which one is used as a point-to-point connection for switch to other switches, routers, or servers?
Large traffic flow
Trunk Link
In regards to VLAN Identification Methods: what uniquely assigns a user-defined ID to each frame?
Frame Tagging
What are the two identification methods that Cisco switches support?
ISL (Inter-Switch Link) and IEEE 802.1q
In regards to VLAN Identification Methods: which is a Cisco proprietary protocol. It is a way of encapsulating a VLAN frame with an added header and trailer
Inter-Switch Link Protocol (ISL)
In regards to VLAN Identification Methods: which is an open source standard method that uses an internal tagging process by modifying the existing internal Ethernet frame
IEEE 802.1q Standard
Which Cisco proprietary protocol allows for the creation, addition, deletion, modification and synchronizing of VLANs from a central point of control within an administrative domain
VTP (VLAN Trunking Protocol)
What are the 3 VTP modes of operation?
Server
Client
Transparent
In regards to VTP modes which one os the central point (management) for VLAN creation within a domain?
Server
In regards to VTP modes which one will receive info from the VTP server via the trunk link using multicast messaging?
Syncs to the highest revision number
Client
In regards to VTP modes which one doesn’t participate on the VTP domain, but they still receive and forward VTP advertisements through trunk links?
Transparent
Will maintain it’s own database
What 4 things will a VTP advertisement include?
Management Domain Name
Configuration revision number
VLANs
Parameters for each VLAN
What are the 3 types of messages used with VTP advertisements?
Client request
Summary advertisements
Subset advertisements
In regards to VTP advertisement message types which one can send requests for VLAN information to the server?
Client requests
The servers in turn will respond with both summary and subset advertisements.
In regards to VTP advertisement message types which one is sent out every 300 seconds on VLAN-1 of whenever a change occurs.
Summary advertisements
What 3 things do the summary advertisements contain?
Management domain name
Configuration revision number
Updater identity
True/False?
If a switch was part of another internetwork it is best to clear everything from it’s memory and then power-cycle it.
True
Part of Threat of High Revision Numbers
___ is a standardized protocol that provides a stable, fault tolerant, loop free network environment while selecting the fastest network path when redundant links exist within an internetwork
STP (Spanning Tree Protocol)
In regards to STP the ______-____ _________ chooses one path on which to forward frames and places the other redundant links in blocking state to stop any network loops from occurring.
Spanning-tree algorithm
______-____ ________ is the selected BEST PATH through the network that does not from a loop.
Spanning-Tree Instance
What is a layer 2 device that is in control of the Spanning-Tree?
Root Bridge
Device with the lowest bridge ID
True/False?
All ports on the root bridge are called designated ports and are set to “Forwarding”
True
Forwarding means they will pass data
After the root bridge has been selected, all other remaining switches will become ___-____ ______
Non-Root Bridge
They will synchronize with the root bridge
What is used to exchange information between layer 2 devices with STP capability?
BPDUs (bridge protocol data units)
What is the default priority on all devices running the IEEE version of STP?
32768
It can be changed by the network administrator to a lower number
A __________ port is one that is active and forwarding traffic
Connects one switch to the root port on another switch, but it doesn’t have to.
Designated Port (Forwarding)
____ ports are in forwarding mode and provide a constant connection to the root bridge from the non-root bridge so advertisements and updates are received
Root Port (Listening)
___-__________ ports are used to prevent loops.
Non-Designated (Blocked)
