Chapter 7: Routing
What are the 2 distance vector routing protocols?
RIPv1 & RIPv2
What are the differences between RIPv1 & RIPv2?
RIPv1: Routing Information Protocol version 1: Has a maximum hop count of 15 and sent out updates every 30 sec. This was problem because every router on the network would send out its routing table at the same time, causing network overloads. Also had no authentication, allowing hackers to run rampant. RIPv2: Added VSLM (Variable-Length Subnet Masking) which allowed networks connected through the router to use different subnet masks. Authentication was added in. Although today it is not used in large networks.
What does the traceroute command do?
Records the route between any two hosts on a network
What do you need for web interface to work?
Router must have a built-in IP address from the factory, or you have to enable the Web interface after you've given the IP address.
Whats the to command to set the IP address for one of the routers ports?
Router# configure terminal Router(config) # interface GigabitEthernet 0/0 Router(config-if) ip address 192.168.4.10 255.255.255.0 Router(config-if) ^Z Router# copy run start
What are the 2 forms of Network Management Software?
Proprietary tools developed by the OEM & Third-Party Tools
If you were to establish port forwarding on a web server to use port 8080 to forward packets to the default port. What would you have to do to access the web site hosted on that server when outside your local network?
(name of the site):8080 Add the :8080 to the end of the web site address information so that it uses that port instead of the default port 80.
What are the processes that take place when you first boot up an OSPF Router?
1.) They send out Hello Packets, to look for other OSPF Routers. 2.)The router builds a "neighborship" thru the Hello Packets 3.)The 2 routers exchange router and network information via Link State Advertisement (LSA) packets. 4.)Once all the routers have formed their own optimal routes, convergence has been obtained, and the process is complete.
What are the 3 steps in creating a TCP/UDP data segment to be sent out to an external machine via PAT Router?
1.)An internal machine on the network attempts to reach out to an external machine (Web Browser > Web Site). 2.)A packet is created containing the Source/Destination IP addresses & Port Numbers at the computer and is the then sent to the router, where these things are then recorded to the NAT translation table. 3.)The Private IP address for the Source IP Address gets swapped for the Public ones on the router (NAT) AND the port number that was recorded gets turned into a unique ephemeral port number (PAT)
What is the 3 step process in setting up a NAT-capable network?
1.)Obtain a block of legitimate IP addresses from an ISP 2.)Assign IP addresses to each computer and onto the LAN connection of the default gateway (Private IP Address of the router) 3.)You assign the IP address of the ISP's router to the WAN connection on that router. (Public IP Address on your router connecting to the ISP)
What are the 5 steps to basic router configuration?
1.)Set Up the WAN Side 2.)Set Up the LAN Side 3.)Establish Routes 4.)[Optional] Configure a Dynamic Protocol 5.)Document and Back Up
What are the 3 steps to getting on a Web Access Interface of a router?
1.)Set a static address for your computer that will place your PC on the same network ID as the router. 2.)Connect to the router (laptop & Xover cable) and check the link lights to verify you're properly connected. 3.)Open up your web browser and type in the IP address.
How big are the AS Numbers and how are the presented?
32-bits | They are displayed as 16-bit numbers separated by a dot. (1.33457)
What are the basic settings that you should enter when using a terminal emulation program on a managed device?
9600 baud | 8 data bits | 1 stop bit | No Parity
What is area 0 called in an OSPF router?
Backbone
What are the 2 other identifiers that are used in a routing table to determine what to do with a packet?
Gateway and Interface
What are Autonomous Systems?
A group of devices with special IP Addresses that are under the control of a single administrative entity that provides connection and a clearly defined routing policy to the internet. Essentially becoming a supportive pillar of the network that is the internet.
What is the default metric value that is commonly used?
A metric value of 1
What is a Distance Vector dynamic protocol defined as?
A protocol that calculates the total cost to get to a specific NetworkID and compare the cost to the total cost of all other routes to get there. The router then selects the route with the lowest cost. LESS COST = LESS OVERHEAD = FAST
What is an AS Number? What is its function?
A special, globally unique identifier that is assigned to an AS in order to communicate with other AS's.
What is a metric defined as in terms of a routing table value?
A value that defines the "cost" of using a route.
What is Route Aggregation?
A way to simplify the routing tables into manageable levels usually be basing the destination route on regional routers. US --> WEST COAST --> NEVADA-->LAS VEGAS --> COX COMM
The name of the Exterior Gateway Protocol that is used as the standard form of AS - AS communication is? And what is its current version?
Border Gateway Protocol (BGP) | BGP-4
What is port forwarding?
Assigning the duties and responsibilities of one port to another. Usually this is done with well known ports being assigned to an ephemeral port.
What is CISCO's proprietary OS?
Cisco IOS
What is the Metric used for OSPF systems? How is this metric determined
Cost, Heavily determined by bandwidth speeds
What is a "hop" defined as when referencing network routes?
Defined as each time a packet goes from one router to the next to get to its destination.
The router uses a combination of what 2 interfaces to match a packet to a route?
Destination LAN IP & Subnet Mask
What is a Gateway Router?
Device that acts as the default gateway to the Internet for all devices connected onto the network.
What are the 3 distinct dynamic routing protocols you need to know for the Network+?
Distance Vector | Link State | Hybrid/Path Vector
What does DNAT stand for and what does it do?
Dynamic NAT: Allows many computers to share a pool of routable IP addresses that number fewer than the amount of PCs actually on the network.
What does EIGRP stand for? What is it primarily used for?
Enhanced Interior Gateway Routing Protocol A hybrid of Distance Vectors and Link-State technology that's used by CISCO.
What is the protocol that is used so the AS Numbers are able to communicate with other AS's? What is the protocol that is used within the AS itself?
Exterior Gateway Protocol (EGP) Interior Gateway Protocol (IGP)
How is your home router able to "turn on" NAT? How does it disable NAT?
Go into the NAT settings of your routers configuration page. Under Operating Mode it should be set to Gateway by default. To turn off NAT select the alternative Router mode.
What are the 4 most common criteria for determining a metric value for a route?
Hop Count / Bandwidth / Delay / Cost
What is a BGP in terms of types of routing protocols?
Hybrid Protocol / Path Vector
What is the idea behind the development of Link-State Dynamic Routing Protocols?
Instead of updating the routing tables by sending full routing tables over and over, instead the information of the routing table is updated only when a route changes.
What is the IS-IS and what was its major advantage?
Intermediate System - Intermediate System: A protocol that is similar to OSPF but is able to work with IPv6 before OSPFv3 came onto the scene.
Who uses the IS-IS protocol?
Internet Service Providers (ISP)
What does a Zero address on a routing table stand for? 0.0.0.0 | 128.0.0.0
It mean "Anything". Any value that is between 1-254 is an acceptable address.
How is NAT able to hide IP addresses but still allow the devices connected to communicate?
It replaces the IP address of a device with the source IP address from the outside router.
What does the My traceroute Linux command do?
Its similar to traceroute, but its dynamic, continually updating the route that you've selected.
What is the process of using DNAT?
LAN traffic uses the internal (private) IP addresses. Then when a computer requests for information that is beyond the network, DNAT doles out a routable IP Address
What does MTU stand for and what is its function?
Maximum Transmission Unit: A unit that's determined by the largest frame that a particular technology can handle in order to reduce the fragmentation of packets which leads to better network traffic speeds.
What does NAT stand for what does it to?
Network Address Translation: It hides the IP address of all devices on the LAN, while still enabling the devices to communicate with the internet.
Should you plug a new router into an existing network?
Never! EVER! Plug a router into an existing network
What are the 2 different kinds of protocols that came from Link-State?
OSPF and IS-IS
What are the benefits that OSPF provides to IGP Protocols?
OSPF is able to converge faster (updates routing tables to completion faster) and is much more efficient than RIP protocols.
Which version of OSPF handled IPv4 and which version handled IPv6?
OSPFv2 = IPv4 | OSPFv3=IPv6
What does OSPF stand for and how does it function?
Open Shortest Path First: A protocol that was designed from the ground up to work within a single AS. Effectively making it the most popular IGP Protocol around.
What is DNAT also known as?
Pooled NAT
What does PAT stand for and what does it do?
Port Address Translation: A form of NAT that uses IP addresses & Port Numbers to map traffic to specific machines in the network.
What is Network Management Software in its simplest form?
Software that knows how to talk to your routers, switches, and even your computers to give you an overall view of your network which usually manifest as a web site. Works well for very large networks.
What is one other way to connect to managed devices?
Some routers comes with USB ports to connect to OR thru Telnet/SSH
Where do LSA Packets come from?
Sourced by each router and are flooded from router to router thru each OSPF area.
What is SNAT and what does it do? What is the benefit of doing so?
Static NAT: Maps a single routable (non-private) IP address to a single machine. Enables you to access that machine from outside the network.
What is Route Redistribution?
The ability to intertwine different forms of routing protocol communication.
What is the default route?
The route that every incoming packet takes by default, unless the packet is given a specific route.
How does a router determine which route on the routing table to send the IP Packet to?
The router takes the destination IP address and subnet mask in the packet and compares it to EVERY route in the routing table. If the packet has multiple available routes, the router determines the most efficient route, and sends the packet on said route.
In order for a Distance Vector protocol to work, the routers must do what?
The routers must transfer their entire routing table to other neighboring routers on the WAN. Each Distance Vector protocol has a max number of hops it will send its routing table out to.
What are Edge Routers?
The routers that handle the AS - AS communication
What is the process that takes place when an TCP/UDP Packet is sent back and returned to a clients router?
The sending system reverses the IP addresses and ports of the original TCP/UDP packet by using what was recorded into the NAT Translation Table.
What do routers do with the routes that have the highest cost?
They delete the routes from the router, UNLESS one of the connections break. In which case the routers find one of the high cost routes with the sending of new routing tables and the router uses that route instead.
What were routers able to do with the introduction of Dynamic Routing Protocol?
This enabled routers the "smarts" to talk to each other and be aware of whats happening to not only the routers you are directly connected with, but also with 2+ routers away. Forming network aware routing paths that help with administration between routers in case of any changes.
What is the oldest form of connecting and configuring a managed device?
To use a special serial connector called a Yost/Rollover Cable
How do you enter EXEC.mode in Cisco IOS?
Type: enable Press ENTER which will activate a command prompt #router
What was the one flaw with OSPF until it was just very recently fixed?
Unable to support IPv6
What are the 2 other ways of connecting to managed devices that don't require a physical connection?
Web Access or Network Management Software
After establishing a connection to a managed device with a Yost/Rollover Cable what will you need to do?
You will need to use a terminal emulation program to talk to the router. PuTTY and HyperTerminal
What command line input will bring up the routing table that is used by your computer?
route print
