Guide to Networking Essentials Chapter 8
What is Next Hop in a routing table?
-- The next hop indicates an interface name or the address of the next router in the path to the destination •Total number of routers a packet must travel through is called the hop count
Describe advanced wireless setting: AP modes
-An AP can be set to operate as a traditional access point, a repeater, or a wireless bridge
Describe Rapid Spanning Tree Protocol (RSTP).
-An enhancement to STP that provides faster convergence when the topology changes
What is NIC automatic link aggregation?
-Automatic link aggregation •Enables you to install multiple NICs in one computer and aggregate the bandwidth
What is a negative side effect of STP?
-Devices take longer to create a link with a switch that runs the protocol
Name the two main types of routing protocols
-Distance-vector protocols -Link-state protocols
Most APs offer what 4 security options:
-Encryption -Authentication -MAC filtering -AP isolation
What is an example of an exterior gateway protocol (EGP)?
-Example of EGP is Border Gateway Protocol (BGP)
What does a router do if the incoming frame's destination IP address does not match its IP address?
-If the IP address does not match, the router consults its routing table to determine how to get the packet to the its destination.
What does a router do if the incoming frame's destination IP address matches its IP address?
-If the IP address matches it processes the packet
What happens of the timestamp isn't updated within the aging time?
-If the timestamp isn't updated within the aging time, the entry expires and is removed from the table
If an incoming frame's destination MAC address matches the routers, what does the router do with it?
-If they match, the router strips the frame header and trailer and reads the packet's destination IP address.
Describe advanced wireless setting: Traffic priority
-If your AP is configured for multiple networks you can assign a priority to packets coming from each network
•ACLs are usually configured to block traffic based on what 4 things?
-Inbound or outbound traffic -Source address -Destination address -Protocol
Describe advanced wireless setting: Adjustable transmit power
-Let you control the power and range of the wireless network signal
Name 4 advanced features found in "smart switches".
-Multicast processing -Spanning Tree Protocol -Virtual local area networks -Port security
What is Metric in a routing table?
-Numeric value that tells the router how "far away" the destination network is (also called cost or distance)
Describe the NIC hardware enhancement: Onboard co-processors.
-Onboard co-processors - enable the card to process incoming and outgoing network data without requiring service from the CPU
What is a common Link-state protocol for a router?
-Open Shortest Path First (OSPF) is most common
What do Preboot Execution Environment (PXE) adapters allow a computer to do?
-Preboot Execution Environment (PXE) adapters allow a computer to download an OS instead of booting it from a local hard drive
Describe advanced wireless setting: Wi-Fi Multimedia
-Provides Quality of Service (QoS) settings for multimedia traffic, giving priority to streaming audio or video
What does NIC QOS do?
-QOS allows prioritizing time-sensitive data
Describe the NIC hardware enhancement: RAM buffering.
-RAM buffering - means a NIC includes additional memory to provide temporary storage for incoming and outgoing network data that arrives at the NIC faster than it can be sent out
Name 4 features fond in a router.
-Router interfaces -Routing tables -Routing protocols -Access control lists
What are 2 Distance Vector Protocols used by routers?
-Routing Information Protocol (RIP) and RIPv2 are most common
Describe the NIC hardware enhancement: shared adapter memory.
-Shared adapter memory - the adapter's buffers map directly to RAM on the computer
Describe the NIC hardware enhancement: Shared system memory.
-Shared system memory - a NIC's onboard processor selects a region of RAM on the computer and writes to it as though it were buffer space on the adapter
What is Timestamp in a routing table?
-Tells the router how long it has been since the routing protocol updated the dynamic route
What is packet forwarding?
-The process of moving a packet from the incoming interface to the outgoing interface is called packet forwarding.
What is auto-negotiate mode for a switch?
-The switch sets the mode to the highest performance setting the connected device supports
Describe advanced wireless setting: VLAN support
-To assign wireless networks to wired VLANs
Name most common wireless encryption protocols
-Wired Equivalent Privacy (WEP), Wi-Fi Protected Access (WPA), and Wi-Fi Protected Access 2 (WPA2)
Name three Frame Forwarding Methods.
1) Cut-through switching; 2) Store-and-forward switching; 3) Fragment-free switching
Describe a VLAN trunk port.
A trunk port is a switch port configured to carry traffic from all VLANs to another switch or router.
Name 6 advanced wireless settings.
Adjustable transmit power Multiple SSIDs VLAN support Traffic priority Wi-Fi Multimedia AP modes
Describe the NIC hardware enhancement: bus mastering.
Bus mastering - permits a network adapter to take control of the computer's bus to initiate and manage data transfers to and from the computer's memory
Each switch connection is a ... ?
Collision domain.
Describe cut-through switching.
Cut-through switching - switch reads only enough of the incoming frame to determine the frame's source and destination address (fastest method) Disadvantage: no error checking
Rate Frame Forwarding Methods in terms of their speed.
Cut-through: fastest; Fragment-free: medium; Store-and-forward; Slowest.
What elements do most routing tables have?
Destination network, Next Hop, Metric, How the route is derived, Timestamp.
Describe Fragment-free switching.
Fragment-free switching - switch reads enough of the frame to guarantee that it's at least the minimum size for the network type. Avoiding a common error.
Describe Authentication for a wireless network
If used, users must enter a username and password to access the wireless network
How does a VLAN trunk port work?
Involves the switch adding a tag to each frame that must traverse the trunk port, the VLAN tag identifies which VLAN the traffic originated from.
What advantage do multilayer switches offer?
Packet routing between VLANs is done within the switch instead of having to exit the switch to a router.
Name 5 PC bus options.
Peripheral Component Interconnect Express (PCIe) Peripheral Component Interconnect (PCI) Peripheral Component Interconnect-Extended(PCI-X) PCMCIA USB - Universal Serial Bus
What are high-end switches referred to as?
Smart switches or managed switches.
Describe Multilayer Switches.
Some advanced switches have all the functions of a managed switch (Layer 2) but add Layer 3 capabilities.
Describe Switch Port Security.
Stops unauthorized access to the switch's ports. Enables an administrator to limit how many and which MAC addresses can connect to a port.
Describe Store-and-forward switching.
Store-and-forward switching - switch reads the entire frame into its buffers before forwarding it Switch examines the FCS field to make sure it contains no errors before forwarding the frame.
Describe multicast processing found in smart switches.
Switches process multicast frames in one of two ways: As broadcasts and sends them out all ports (low-end); or by forwarding the frames only to ports that have registered the multicast address (Used by switches that support Internet Group Management Protocol (IGMP))
What layer do switches work on?
Switches work at the Data Link layer (Layer 2)
What are VLANS used for?
They improve management and security of the network and give more control of broadcast frames. Also they allow administrators to group users and resources logically instead of by physical location.
Describe how a switch forwards frames.
They receive frames on one port and forward them out the port where the destination device can be found
Describe Spanning Tree Protocol (STP)
This enables switches to detect when there is a potential for a switching loop. If detected, one of the switch ports goes into blocking mode, preventing it from forwarding frames that would create a loop.
What is Auto-MDIX mode?
This is when the switch port detects the type of device and cable it's connected to, it switches receiving and transmitting pins so a straight-through or crossover cable can be used.
What is a switching loop?
This occurs when a frame is forwarded from one switch to another in an infinite loop.
Describe advanced wireless setting: Multiple SSIDs
Two or more wireless networks can be created with different security settings
Describe a Virtual Local Area Network (VLAN).
VLANS) - enable you to configure one or more switch ports into separate broadcast domains. It's like separating a switch into two or more switches that aren't connected to one another.
Name 4 Basic wireless settings on most APs
Wireless network mode, Wireless network name (SSID), Wireless channel, SSID broadcast status.
What is Wireless network mode?
allows you to choose which 802.11 standard the AP should operate under
•Most inexpensive switches run in what mode?
auto-negotiate mode
Static routes ...
can be entered in a routing table manually
Describe a NIC's work.
•A NIC makes the connection between a computer and the network medium
What does a PC bus does?
•A bus makes the connections between a computer's vital components
How do VLANS communicate with each other?
•A router is needed to communicate between VLANs
What is a routing protocol?
•A set of rules that routers use to exchange information so that all routers have accurate information about an internetwork to populate their routing tables
What does a switching table hold?
•A switching table holds MAC address/port pairs that tell the switch where to forward a frame, based on the destination MAC address.
Describe AP isolation for a wireless network.
•AP isolation - creates a separate virtual network for each client connection. -Clients can access the Internet but can't communicate with each other
What is an Access Control List?
•Access Control List (ACL) - A set of rules configured on a router's interface for specifying which addresses and which protocols can pass through an interface and to which destinations
What does Advanced Configuration Power Management Interface (ACPI) offers wake-on LAN do?
•Allows an administrator to power on a PC remotely by accessing the NIC through the network
How does a switch fill its switching table?
•As network devices send frames, the switch reads each frame's source address and adds it to the table along with the port it was received from.
Describe a Distance-vector protocol.
•Distance-vector protocols share information about an internetwork's status by copying a router's routing table to other routers (routers sharing a network are called neighbors)
Each switch port is considered a (......)?
•Each switch port is considered a collision domain, because -Switches do not forward collision information to any other ports.
How are exterior gateway protocols used?
•Exterior gateway protocols (EGP) are used between autonomous systems
What does a switch do if a frame's destination address isn't found in the switching table.
•If a frame's destination address isn't found in the switching table the switch forwards the frame out all ports.
How are interior gateway protocols (IGP) used?
•Interior gateway protocols (IGP) are used in an autonomous system (AS), which is an internetwork managed by a single organization
Describe Link-State Protocols.
•Link-state protocols share information with other routers by sending the status of all their interface links to other routers.
Describe MAC filtering for a wireless network.
•MAC filtering - enables you to restrict which devices can connect to your AP
What are three ways a route gets into the routing table?
•Network is connected directly •Administrator enters the route information manually (called a static route) •Route information is entered dynamically, via a routing protocol
What is a routing table?
•Routing tables are composed of network address and interface pairs that tell the router which interface a packet should be forwarded to.
What is speed of convergence, when talking about routing tables?
•Speed of convergence refers to how fast the routing tables of all routers in an internetwork are updated when a change in the network occurs
How does a switching table prevent stale entries?
•Switching tables prevent stale entries by including a timestamp when an entry is created and when a switch receives a frame from a device already in it's table, it updates the entry with a new timestamp.
What is the aging time for a switch?
•The period of time a table keeps a MAC address is called the aging time
When a router interface receives a frame what does it do?
•When a router interface receives a frame it compares the destination MAC address with the interface's MAC address
What is packet filtering?
•When an ACL blocks a packet it is called packet filtering
