Routing and Switching Flashcards
What is a collision domain
Collision domain: A network or segment where a group of nodes competes with each other for access to the media.
Definition of microsegregation
Microsegmentation: The process of dividing up a network by using switches so that only two nodes exist in each collision domain.
Definition of a broadcast domain
Broadcast domain: A network or segment where any node connected to the network can directly transmit to any other node in the area without a central routing device.
Give all characteristics of a collision domain
Collision domains Logical bus Hub and connected nodes Coax bus Switch port and connected node
Give all characteristics of a broadcast domain
Broadcast domains
Not affected by micro-segmentation
Single switch or group of connected switches
Routers define the boundaries
What is STP
A Layer 2 protocol is used to prevent switching loops in switches that support the protocol.
Why do loops occur in layer 2 within switches
Loops happen when there are redundant paths between switches.
Loops can cause broadcast storms when nodes send ARP frames to identify neighbors.
Characteristics of STP
Not all switches support STP! STP is relatively old and slow Replaced by RSTP and SPB protocols Rapid Spanning Tree Protocol Shortest Path Bridging Port states and BPDU
Port states and BPDUs
What happens when blocking occurs
User data is not sent or received.
BPDU data is received and used to determine if the port state should be changed.
Port states and BPDUs
What happens when listing occurs
BPDUs are processed by the switch.
Frames are not forwarded, and the switch does not update the MAC tables
Definition of Packet Switched Networks
A network where data is broken up into separate packets and each packet is separately routed without a dedicated connection between the endpoints.
Give all characteristics of a Packet Switched Network
Each packet finds its own route.
All packets contain routing and sequencing information.
Data is reassembled after all packets are received by the destination host.
Used when networks change often due to network congestion or changing link states.
Definition of Circuit Switching
A switching technique where one endpoint creates a single connection to the other endpoint.
Give all the characteristics of circuit switching
The circuit is the path.
Data flows through the circuit as long as the circuit is active.
When the data transfer is complete, the circuit is closed.
Definition of Distributed Switching
A switching technique where a centralized switch connects and manages switches that have been deployed remotely in a hierarchical configuration.
Characteristics of a Distributed Switching
On telephony networks, it’s called host-remote switching.
The central/host switch:
Connects remote switches to each other and to other networks.
Manages complex calls, whereas remote switches handle local calls.
Provide operation, administration, maintenance, provisioning, and billing.
Can be implemented on data networks and virtual networks, too.
Definition of Routing
The process of selecting the best route for moving a packet from its source to its destination on a network.
Characteristics for Routing
Routers use algorithms to generate and maintain information about network paths.
Metrics are used to determine the best route
When the best route is identified, packet switching gets the data to the destination.
Forwarding a packet from one router to another is called a hop.
What are the metrics for routing when determining the best route?
Bandwidth
Path availability
Path reliability
Communication costs
Definition of Routes
The path is used by data packets to reach a specified destination.
Characteristics of Routes
Added to the routing table.
Contains information about connected and remote networks.
Connected networks directly attached to router interface:
Gateways for hosts on different networks.
Remote networks:
Manually configured on the router.
Set automatically using dynamic routing protocols.
Give the full routing process
The router receives data and reads the destination IP address.
The router reads the routing table to determine which route to use.
The router replaces the existing destination MAC address with the MAC address for the
Give the full process of Local and Remote Delivery Process
The node applies the subnet mask to its own IP address to determine its own network ID.
The node applies the subnet mask to the packet’s destination address to determine the destination network ID.
Once the node has applied the subnet mask, it compares the two network IDs.
If they are the same, then the two nodes are on the same subnet, and the node can deliver the packet.
If the two networks are different, then the two nodes are remote to each other, and the data is routed to the remote network.
Definition of Routing Tables
A database is created manually or by a route-discovery protocol that contains network addresses as perceived by a specific router.
Give all the characteristics of a routing table
Routers use them to decide where to forward packets.
Packets are forwarded from router to router until the destination network is reached.
Features:
You can specify a maximum hop count.
You can specify a route’s cost.
Metrics help quantify which route should be used.
Give the routing table entries
Direct network routes
Remote network routes
Host routes
Default routes
Give a description of the default gateway
Destination: 0.0.0.0.
Appears if the local host has been configured with a default gateway address.
Give a description of a local loopback
Destination: 127.0.0.1
Provides a delivery route for packets addressed to the local loopback address.
Give a description of a local subnet
Destination: network portion of local IP address plus host address of all 0
Identifies the route to the local network. An example is 140.125.0.0.
Give a description of a network interface
Destination: local IP address
Identifies the route to the host’s local network card. An example is 140.125.10.25.
Give a description of subnet broadcast access
Destination: network portion of local IP address plus host address of all .255
Identifies the route for broadcasts on the local subnet. An example is 140.125.255.255.
Give a description of a multicast broadcast address
Destination: 224.0.0.0
Identifies the address for sending multicast transmissions.
Give a description of an Internetwork broadcast address
Destination: 255.255.255.255
Identifies the route for broadcasts to the entire network. However, most routers will not pass these broadcasts.
Give a full description of the network destination address
Contains the network ID of a destination address.
Is the search point when processing the routing table.
Can be listed as a complete address, but the router will be more efficient if listed as a network ID.
Give a full description of a network mask
Specific to each routing entry.
Determines how much of a packet’s destination address needs to match the network destination field of a routing entry before that route is used to deliver the packet.
Give a full description of a gateway
Indicates the address where the packet is delivered on its first hop.
Can be the local loopback address, a local IP address, the host’s own default gateway address, or the address of an adjacent router.
Give a full description of an interface
The IP address of the local port that a host uses to send data.
Once a destination entry is found, data is sent to the interface entry listed in the same line as the destination.
Give a full description of a metric
The cost of the route.
Determined by the number of hops.
Used to decide which route to use when there are multiple routes to a destination.
Explain the Windows command route print
Display routing table entries.
Explain the Windows command route add
Add static entries to a routing table.
Explain the Windows command route delete
Remove static entries from a routing table.
Explain the Windows command route change
Modify an existing route.
Explain the Windows command route -p
Make the specified route persistent across reboots when used with the add command.
Explain the Windows command route -f
Clear a routing table of all entries.
Explain the Linux command route
Display host names.
Explain the Linux command route -n
Display IP addresses instead of hostnames.
Explain the Linux command netstat -rn
Display the routing table with the –r option.
Display the IP addresses instead of hostnames with the –n option.
Explain the Linux command IP route list
Display routing table entries.
Give the definition of route aggregation
A method of combining routes in a routing table to save space and simplify routing decisions.
Give a full description of the route aggregation
The number of routing tables increases as the network grows.
Route aggregation can:
Save space in the routing table.
Simplify routing decisions by combining routes to multiple smaller networks.
Reduce routing advertisements to neighboring gateways.
Defintion of routing protocols
Dynamic routing uses software that automatically creates routing table entries.
Give all route protocols
Distance-vector routing
Link-state routing
Hybrid routing
Path-vector routing.
Definition of AS
AS: (Autonomous System) A self-contained network on the Internet that deploys a single protocol and has a single administration. Also called a routing domain.
Features of AS
Can connect to other networks or other ASes.
Do not share routing information outside the AS.
Give a full description of the interior route
Arranged inside an AS.
Controlled by AS administrator.
All interfaces connect to subnets within the AS.
No connection to external networks.
Give a full description of the exterior route
Reside outside an AS but handle data from the AS.
Generally found on the Internet backbone.
Give a full description of the border or edge router
Located at the boundary of an AS.
At least one interface in the AS and at least one outside of it.
Provide connection to remote networks.
Placed between two private networks or a private network and the Internet.
Give a full description of inside an AS
Data transfer begins and ends within the AS.
Only possible recipients are on the same local network.
Derive destination MAC address via ARP.
Give a full description of between adjacent networks
Shared border routers.
Data is sent to the border router, which transfers it to the destination node.
Single point of contact.
Give a full description of between remote networks
Data is sent to a border router of the source network (default gateway).
If that router does not recognize the destination address, it sends the data to its own default gateway.
Data transfers from default gateway to default gateway until the destination network are reached, or the message times out.
Give a full description of static routing
A type of routing is used by a network administrator to manually specify the entries in the routing table.
Where does static routes remain
Static routes remain in the routing table whether or not the destination address is active.
True of False
Static routes can change without administrator
False
Static routes do not change unless the administrator changes them.
Characteristics of static routing
Characteristics:
Useful in small networks with no redundant routes and no topology changes.
Keeps bandwidth use (due to dynamic routing updates) low.
Administrator-configured routes trusted over dynamically created routing table entries.
When a static default gateway is assigned, no alternate gateway
Is used.
Give a full description of static routing tables
Manually configured.
Easy to create and use for small networks.
Also acceptable to use for an extranet with a border router that points to the border router of an external network.
What are the advantages of static routing
Advantages:
No additional network traffic to maintain routes.
Increased security to protect rogue routers from sending bad routing information.
Configure only what you need.
What are the disadvantages of static routing
Disadvantages: Manual maintenance is required. One network change might require many routing table updates (on all routers affected by the change). Prone to configuration errors. Less efficient than dynamic routing.
Definition of Dynamic Routing
A type of routing that automatically builds and updates routing tables by using route discovery operations.
Characteristics of Dynamic Routing
Routers send data to adjacent routers to share information about networks.
Connected to
Can reach
Routing table entries are created automatically.
Provide a more accurate network description
Updated more often than static routing tables
When network congestion or device failures occur, routers with
dynamic routing protocols can detect the problem and calculate
alternate routes.
Route redistribution enables routes to be shared across different
routing protocols.
Give a full description of Distance-vector routing protocols
Used on packet-switched networks.
Calculates route costs and routing table entries.
The fewest number of hops is generally the best route.
“How far” and “in what direction.”
Give a full description of Link-state routing protocols
Floods routing information to all routers.
Results in a more complex route database.
Route quality, bandwidth, and availability information shared.
Route characteristics are factored in with hop count to determine the best route.
Give a full description of Hybrid routing protocols
Combination of distance-vector and link-state routing methods.
Link cost and network bandwidth are factors for determining the best route.
Give a full description of Path-vector routing protocols
Used in inter-domain routing.
Routers keep track of routes to a destination but can treat entire ASes as single nodes.
Definition of Route Convergence
The period of time between a network change and when the routers update to reach a steady-state once again.
Give the process of Distance-Vector Routing
1)Each router passes a copy of its routing table to its neighbors and maintains a table of minimum distances to every node.
2)Neighboring routers add the routes to their own tables, incrementing the metrics to reflect the extra distance to the end network.
Distance = hop count
Vector = address of the next-hop
3)When a router has two routes to the same network, it selects the route with the lowest metric.
Assumption: Fewer hops mean faster delivery.
Give a full description of Link State Routing
Routers communicate: When a link changes Periodic hello messages Faster convergence than distance-vector routing. More expensive to implement: Requires more power and memory
Give a full description of path-vector routing protocols
order and exterior routers communicate with each other.
Add presence to the path and forward to the next AS.
If destination within its AS forwards to interior routers.
BGP
Routing policies enable routers to react to:
Network congestion
Offline nodes
Possible duplicate routes
Based on distance-vector, but designed to be more scalable.
Give all the characteristics of Hybrid Routing Protocols
EIGRP
Combines characteristics of distance-vector and link-state routing.
Depends on neighboring routers to advertise route costs.
Maintains topology table.
Other features:
Supports classful and classless subnet masks
Usable on multilayer switches
Lower convergence times, higher network stability
No dependence on network protocol
Definition of VLANs
A logical grouping of ports on a switch.
Give a full description of VLANs
Nodes connected to a switch port that has been assigned to a VLAN can communicate only with those nodes that are also connected to the VLAN.
Division of a physical switch into several logical switches.
Use cases: Traffic management Security Traffic segregation QoS
Give the assignment of switch port 1
Switch 10
Give the assignment of switch port 2
VLAN 15
Give the assignment of switch port 3
VLAN 25
Give the assignment of switch port 4
VLAN 35
Give the assignment of switch port 5
Switch 12
Give the assignment of switch port 6
VLAN 35
Give the assignment of switch port 7
VLAN15
Give the assignment of switch port 8
VLAN 25
Give a full description of the VLAN Assignment
Group nodes into the same VLAN:
Router routes packets between VLANs.
Assign ports to VLANs:
Manually configure each port on a switch.
Associate a VLAN with a node’s MAC address.
Usually single port on the switch belongs to only one VLAN at a time:
Trunk ports or port mirroring is the exception.
Definition of Port tagging
Port tagging: In VLANs, a way to connect a variety of network hardware, including switch-to-switch, server-to-switch, server-to-server, or switch-to-router.
Give all the characteristics of Port tagging and untagging
Data that needs to be forwarded outside of the VLAN is tagged using 802.1q encapsulation.
Switches connected by trunk links extend VLANs beyond one switch or even building.
Uplink ports are used for inter-switch communication, so they must be tagged as part of the VLAN.
Default VLAN requires port tagging if multiple switches contain VLAN members.
An untagged port is any port that connects a switch to a host, as
opposed to another switch, server, or router.
Definition of VTP
A VLAN management protocol developed by Cisco enables switches to update each other’s VLAN databases.
Give a full of description of VTP and modes
Fast, automated advertisement of VLAN creation or deletion. Modes: Server mode Client mode Transparent mode
