IT 341 Final GMU

Converged Network?

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

Benefits: Saves a lot of money and only one physical network to install and manage.

What is a Cisco Borderless Network?

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

unifies wired and wireless access(policy, access control and performance management)

networks services and endpoint services managed by an integrated management solution

Borderless switched networks are what 4 things?

Hierarchical-(Facilities understanding the role of each device at every tier)

Modular-(allows seamless network expansion and integrated services)

Resilient-(provides an always available network)

Flexible-(allows intelligent traffic load sharing

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/Role of Switched Networks?

Flexibility

traffic management

Features like: QoS, security, wireless and new tech support

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

Switching General Concepts

Makes decisions based on?

Ingress port - where a frame enters the device.

Destination address

maintains a table that it uses to determine how it will forward traffic.

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.

Switch Forwarding Methods

Store and forward

Cut-through

Store and forward vs cut-through?

- gets the entire frame and finds the CRC, if valid the frame is forwarded to destination address(error-checking,automatic buffering) Cisco's primary LAN switching method

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

fragment-free switching

a form of cut-through where the first 64 bytes are read and then it is forwarded.

Collision domain?

all ports belong to the same collision domain

all ports have a collision domain of their own

switch ports operate at full duplex( eliminates collisions, bidirectional) if connected to such device, and will operate at half duplex(collision domain,unidirectional) if connect to such devices

Broadcast Domain

a single domain formed by one switch, or multiple switches.

Too many will cause a lot of congestion.

How doe switches help alleviate network congestion? 3

segment the collision domains by port

provide full duplex links

buffer large frames

low per-port cost

port speed

fast internal switching

Switch Boot Sequence? (5)

1. POST (power-on-slef-test)

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

Recovering from a system crash

1. connect the PC to the switch console port

2. configure the terminal on the PC

3. disconnect the switch's power cord.

4. reconnect power cord right after, hold mode button

5. type switch at the command prompt to run the boot loader.

configure a switch

You will need the IP address(assigned to an SVI), subnet mask and the default gateway

1. conf t

2. interface vlan ...

3. ip addresss ...... subnet mask...

4. ip default gateway....

5. wr

show interface (interface_id) command

to check duplex and speed settings

fiber ports operate at one speed and are always full-duplex

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

SSH(secure shell)

Provides an encrypted management connect, prefer to telnet.

Port Security

Controls the amount of Valid Mac address allowed to transmit information through switch port, by using static secure MAC ad(manual) or Dynamic secure MAC address(dynamically learned).

Port Security Violation Modes

Protect

Restrict

Shutdown(default)

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

separate LAN devices, user and devices don't matter.

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(better security)

- cost reduction

- small broadcast domains

- Better IT efficiency since users can be grouped by requirements

Types of VLANs and what they do?

- Data VLAN = user generated traffic

- Default VLAN(VLAN 1)= all switch ports are part of this VLAN after boot

- Native VLAN = used to carry untag traffic that does not originate at a VLAN port

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

Voice VLANs?

Sometimes called VoIP - very demanding

supports time-sensitive voice traffic

transmission priority

VLAN Trunks?

Carries multiple VLANs

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

IEEE 802.1q - popular VLAN trunk protocol

How can you control broadcast domains?

VLANS can be used to control the spread of broadcast domains because they have a broadcast domain of their own

Help control the reach of broadcast frames

Frame tagging

when a VLAN identification header is added to a frame

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

Creating VLANs

SW1#conf t

SW1(config)#vlan 10 SWI(config)#name firstvlan

end

VLANs are often associated with what?

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

all devices in a VLAN must be in the same IP network

What does "switchport trunk allowed vlan" do?

command that specifies which VLANs are allowed in a trunk link

Inter-VLAN routing

layer 2 switches cannot forward traffic between VLANs without the assistance of a router

Inter-VLAN Routing Options

Legacy inter-VLAn routing

Router-on-a-Stick

Layer 3 switching using SVIs

Legacy Inter-VLAN Routing

Different physical router interfaces are connected to different physical switch ports, where each switch port is configured with a different VLAN.

router on a stick inter-VLAN routing

A single physical interface on the router connects to a trunk port on a switch and routes traffic between multiple VLANs on a network.

verify sub interface configurations

show vlan

show ip route

What is routing? (Basic level)

connetcs one network to another and determines how to efficiently move traffic between networks

LANs

Ethernet networks that contain PCs, printers and servers.

WANs

used to connect networks over large geographical areas

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

"show ip interface brief" command

You can see a summary of which interfaces you have on your router

show ip route

Displays the contents of the IPv4 routing table stored in RAM.

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

directly connected entries

Route source

Destination network

outgoing interface

remote network entries

route source

destination network

administrative distance

metric

next hop

route timestamp

outgoing interface

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

-summarizes routing table entries

Whats a stub network?

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

Summary Static Route

multiple static routes all using the same exit interface or next-hop IP address

destination networks must be contiguous

What is a default static route?

a route that matches all packets(used when a packet doesn't have a specific route)

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

default static route used...

when connecting a edge router to a service provider network.

when connecting a stub router

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

troubleshoot a missing route

ping

traceroute

show ip route

show ip int brief

show cdp neighbors detail

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

dynamic protocol uses

good for large networks

help network administrator manage the network

main components of dynamic routing

data structures

routing protocol messages

algorithms

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

RIPv1

First generation legacy protocol

RIPv2?

Simple distance vector routing protocol

automatically summarizes networks at major network boundaries.

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( routing protocol) and IS-IS(provider network)

link-state protocols advantages

each router builds its own topological map

immediate flooding of LSPs

hierarchical design

link-state disadvantages

maintaining a link-state and SPF tree requires more memory

more cpu processing

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

- doesnt send subnet mask info in updates(RIPv1, IGRP)

- 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

routing protocol metrics

a metric is a measurable value given by the routing protocol to routes based on their usefulness

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