IT 341 Final GMU

Converged Network?

A network where multiple types of traffic are all under one network

Saves a lot of money

What is a Cisco Borderless Network?

Allows organizations to connect anytime anywhere with any type of secure device easily

Borderless switched networks are what 4 things?

Hierarchical

Modular

Resilient

Flexible

Converged networks that are part of organization have 3 parts...what are they?

Core - The center

Distribution - connection to the core

Access - Switches are used to connect to the distribution and give access to the users

Switched LANS allow for what?

Flexibility

traffic management

Features like: QoS, security, wireless

Fixed vs modular vs stackable switch form factor?

Fixed - number of ports and abilities is set, no changes

modular - extra ports and other things can be added later

stack-able - switches are stacked a connected by cables to operate as one big switch

How does a switch learn what devices are on a network?

It builds a table called a MAC address or CAM table

This table saves the device port.

What does a switch do when it gets a frame that is not in the CAM table?

The switch floods all known ports except the one that they got the frame from. The correct port will accept the frame.

Store and forward vs cut-through?

- gets the entire frame and finds the CRC, if valid the frame is forwarded

- forwards the frame before it has been fully received. It at least reads the destination address

Collision domain?

all ports belong to the same collision domain

all ports have a collision domain of their own

How doe switches help alleviate network congestion? 3

segment the collision domains by port

provide full duplex communication

buffer large frames

Switch Boot Sequence? (5)

1. POST

2. Run boot loader software

3. Boot loader does CPU initialization on a low-level

4. initializes the flash file system

5. Loads the IOS operating system

What are the steps required to find a IOS image?

- Tries to boot with info already available in BOOT environment

- if not found, perform a top-to-bottom search through the file system

- IOS initializes the interface using the Cisco IOS commands from NVRAM

Whats NTP protocol

Network time protocol - uses to synchronize the clocks of computer systems data networks

Split into a client and server

What is a VLAN?

Logical partition of layer 2

multiple VLANs can exist

each has its own broadcast

How do you pass packets from VLAN to VLAN?

isolated, unaware of each other

so you must use a router to pass packets.

Benefits on a VLAN?

- groups of secure information can be separated from the rest of the network

- cost reduction

- small broadcast domains

- Better IT staff efficiency since users can be grouped by requirements

Types of VLANs and what they do?

- Data VLAN = user generated traffic

- Default VLAN = all switch ports are part of this VLAN after boot

- Native VLAN = used to untag traffic

- Management VLAN = used for managing the switch with SSH, Telnet, HTTP

Voice VLANs?

Sometimes called VoIP - very demanding

VLAN Trunks?

Carries multiple VLANs

established between two switches so devices on the same VLAN cam communicate

IEEE 802.1q - popular VLAN trunk protocol

How can you control broadcast domains?

VLANS have a broadcast domain of their own

Help control the reach of broadcast frames

Tagging Ethernet Frames?

This occurs when a frame tag is added to a frame with the proper VLAN identification.

Switches add the frame and remove the frame when its its time to forward

Frames belonging to the native VLAN are?

Not tagged since this is the default VLAN

What is the default native VLAN on a cisco router?

VLAN 1

What happens if a frame is sent to a switch that has no ports on a native VLAN and no trunk links to any other VLANs?

The frame is dropped since it has no where to go

VLANs are split into two categories? what are they?

Normal Range VLANs

Extended Range VLANs

Normal Range VLANS?

numbered 1 to 1005

conf stored in flash memory

VTP used to managed VLAN between switches

Extended Range VLANs?

numbered 1006 to 4096

conf stored in the NVRAM

VTP not used or learned

VLANs are often associated with what?

an IP address, so IP address outside of a certain range often don't connect correctly

What does "switchport trunk allowed vlan" do?

command that specifies which VLANs are allowed in a trunk link

What is routing? (Basic level)

moving traffic between networks

What are some things routers can do?

- use static and dynamic routing to build routing tables

- determine the best path for a packet

- encapsulate the packet and forward it

Static assigned IP addresses?

manually assigned IP address, subnet mask and default gateway

used for servers or printers where you need to always no the destination

Dynamically assigned IP addresses?

IP info is assigned by the DHCP

this is how most hosts work

Steps to configure a basic router? (4)

- name the device

- secure management access

- configure the banner

- save the config

What is AD (Administrative distance) and is it better to have a lower or higher number?

- this is the distance from the router to the device or function

- the lower the AD the closer. For example, an AD of 0 would mean that something is directly connected.

What is the routing table and what does it store?

- file stored in the RAM that contains info like...

directly connected routes

remote routes

next hops or networks

What does "show IP route" do?

display the routing table contents like

local route interfaces

directly connected interfaces

static routes

dynamic routing protocol

What is inter-VLAN routing?

The process of forwarding network traffic from one VLAN to another through a router

VLANs cannot forward traffic even if they are not the same switch without some sort of assistance

What is router on a stick?

one of the routers interfaces is configured as a 802.1Q so it can read VLAN tags. Subinterfaces are created for each VLAN with an IP address.

Members on that VLAN use that subinterface IP address as the default gateway

What does VLAN trunking do? (Use of multiple VLANs out)

This allows many VLANS to use just one physical port on the switch to connect it to the router rather than multiple.

ICMP echo request is?

a may of pinging a device to see if it is connected and working properly.

Tracert?

utility used to confirm that a pouting path took place between two devices

Two ways routers can learn about remote networks?

Manually - entered manually into the routing table

Dynamically - automatically learned using the dynamic routing protocol

Static routing advantages over dynamic?

- Not advertised over the network, so better security

- use less bandwidth and dont use CPU cycles to calculate communication routes

- the path a static route uses to send data is known

Static routing disadvantages?

- initial config and maintenance is time-consuming

- config can have errors

- admin is needed to maintain route info

- doesnt scale well with a growing network

- requires knowledge of the whole network for implementation

When should you use static routes?

- small networks with not alot of growth

- routing in a stub network

- using a single default route

- connect to a specific network

- provide a backup route incase the primary route fails

Whats a stub network?

- is a network accessed by a single route and it has no other neighbors

What is a default static route?

a route that matches all packets

a route that all IP packets are sent to that a routing table doesn't not already know

is a route with 0.0.0.0/0 as its destination

A Next-Hop creates one of three routes types, what are they and what does each one do/know?

Next-hop route - only the next -hop IP address is specified

Directly connected static route - only the router exit interface is specified

Fully specified static route - the next hop and exit interface are specified

What are the purposes of dynamic routing protocols?

- discover remote networks

- maintaining updated routing info

- best path to destination

- ability to find next best path

Advantages to dynamic routing?

- share info about remote networks

- determine best path/ update routing table

- dynamic routing requires less overhead

- less work for admin to config and maintain

- independent of network size

Disadvantages of dynamic routing?

- part of a routers resources (CPU) are dedicated for protocol operation

- more complex to implement

- less secure

- route depends on topology

When is a network completely converged?

- When all routers on the network have complete and accurate info

What is convergence time?

time it takes for routers to share info, find best paths and update routing table

Speed of propagation?

amount of time it takes for router in a network to forward routing info

IGP? (Interior Gateway protocol)

Used for routing inside of a network group

EGP? (Exterior gateway protocols)

Used for routing between LAN, protocol used for the internet

What does distance vector mean?

distance refers to how far

vector refers to the direction

so its how far the connection is going and in what direction

RIPv2?

Simple distance vector routing protocol

IGRP?

First gen cisco protocol (not used anymore)

EIGRP?

New and advanced version of vector routing

How does a distance vector work?

use routers as sign posts along the way to the final destination

How does a link-state router work?

No sign posts, makes a complete map of the network topology using link-state information

Types of Link-State protocols?

OSPF and IS-IS

What does a classful routing protocol do? What problems does this create?

- doesnt send subnet mask info in updates

- cannot provide CIDR info, when this was creates network were only class A

Which routing protocols are bad? Which are good?

BAD: RIPv1 RIPv2 IGRP

Good: EIGRP OSPF IS-IS

RIPv1 vs RIPv2?

Both: uses hop count as a metric, max of 15 hops, then dies, updates every 30 seconds

RIPv1: updates at 255.255.255.255

everything else is not supported

RIPv2: updates at 224.0.0.9

Everything else is supported

IGRP vs EIGRP?

Both: use bandwidth and delay has a metric

IGRP: updates on 255.255.255.255

Everything else is not supported

EIGRP: updates on 224.0.0.10

Everything else is supported

OSPF Router exchange packet?

packets used to discover neighboring router and exchange routing information

OSPF "Hello packets"?

after the router sends out exchange packets, if the neighbor is present it tries to find the next neighbor after that one

OSPF LSA?

These are packets that constantly flood the network to tell the cost and state of each router on the network

Single area vs multiarea OSPF?

single are - who router configuration is OSPF

Multiarea - many different areas can be connected by a OSPF in the middle

good for large organizations because if a link fails in one of the areas, the other networks dont have to close down.

Whats the OSPF type 1 packets other name?

Hello packet

OSPF - what does the passive interface do?

Helps to limit the number of ports OSPF messages ares sent out of since only other OSPF devices would gain any information from it.

What do ACLs do?

Allow the user to configure certain rules of how different networks and hosts can connect

What is an ACL?

list of permit or deny statements know as ACEs

What is static packet filtering?

analyzes the incoming and outgoing packets and passes or drops them based on criteria

How does the ACL work?

The ACL puts a deny on the end of every single packet, the deny blocks all traffic, but will permit any items that have at least one permit block also attached to them

Standard ACLs vs Extended ACLs?

Standard - only look at the source address

Extended - look at the source, destination, TCP and UDP ports, and protocol type

What are the three P's of ACL?

one ACL per protocol, One ACL per direction, One ACL per interface

Where should you place extended ACLs on a network?

The closest to the outside traffic to block incoming problems at the startQ

Where should you use standard ACLs on a network?

as close to the destination as possible since they are not as effective as extended

What are the three DHCPv4 methods?

Manual allocation, automatic allocation, dynamic allocation

DHCPv4 - Manual Allocation?

pre-allocated and assigned IPv4 address to a client is set up.

DHCPv4 - Automatic Allocation?

assigns a static IPv4 address permanently to a device, selecting it from a pool of addresses

DHCPv4 - Dynamic Allocation?

dynamically assigned addresses from the pool but only for a limited amount of time. This is the most used method

Procedure for DHCPv4? (4)

Discover, Offer, request, pack slide 6 Ch 10

What is NAT?

a way to translate network addresses from private to public. This helps save public IPv4 addresses from being used.

Static NAT?

one to one mapping of local and global addresses.

Useful when you want servers to be accessed outside of the network

Dynamic NAT?

pool of public addresses and assigns them first come first server.

When inside private IP requests to send info outside the network the pool is used to assign an address

What is PAT? (Port address Translation)

maps multiple private addresses to a single public IPv4 addresses/or a few.

uses the source port to keep track of where traffic should go

also called nat overload