How Markets work - Supply and Demand-1

                               Supply and Demand

Microeconomic -
building blocks that create big economy

Opportunity cost

   Implicit versus explicit(accounting) costs
   economic cost versus accounting cost

Sunk cost/benefits - Anything that is common to whatever choices you have can be filtered out of the analysis.

The Determinants of Demand

Law of Demand - When you lower the price of any good or activity, consumers will demand more of that good or activity.

No just price alone. It's important to understand how Price versus non-price factors affect quantity demanded.Price induces just a movement along a given demand curve.Any other factor changes, it'll shift the entire price quantity relationship. For any constant price, quantity demanded will differ if income is changed or substitutes, prices of substitutes or compliments are changed or government taxes and subsidies have been instituted.

Substitutes(lexus, bmw), complement (car,oil) affect the price of the item. some items are substitutes or complement.

The Determinants of Supply

The law of supply - The higher the price the greater the quantity supplied
Technology, input prices, government taxes/susidies

Market Equilibrium 

The point where the demand curve and supply curve intersect.

Lecture slides(PDF)

Definition: The nominal value of a good is its value in terms of money. The real value is its value in terms of some other good, service, or bundle of goods.

Examples:

• Nominal: That CD costs $18. Japan's science and technology spending is about 3 trillion yen per year.
• Real: A year of college costs about the value of a Toyota Camry. Those tickets to see Van Halen cost me three weeks' worth of food!

Relative price is another term for the real price of a good or service. When we say that the relative price of computers has fallen in recent years, we mean that the price of computers relative to or measured in terms of other goods and services—such as TVs or cars—has declined. Relative prices of individual goods and services can decrease even if nominal prices are all increasing, because of inflation.

Wireless installation site survey

Wireless RF signal

The initial placement of an access point is based on an estimate of the signal loss that will occur between the access point and the users of the access point.

The starting point for an estimate depends on how much loss in power a signal would experience in the vacuum of space, without any obstructions or other interference. This is called the free space path loss and is specified in decibels (dB)

The estimate is tuned with an understanding that the actual expected signal loss depends on the medium through which the signal will travel, which is undoubtedly not a vacuum. An RF singal can be affected by

• Reflection(steel, metal door)
• Absorption(water,tree,thick wood)
• Refraction(signal is bent when going through a medium with one density to a medium with another density.eg.water tank)
• Diffraction(signal which is bent while going through a region where reflective obstruction exits can interfere with that part of RF signal that is not bent

Wireless installation site survey

A site survey can be as simple as walking around with a wireless notebook computer and using the utility to measure signal strength.Signal strength can also be determined with a protocol analyzer. The WildPackets AiroPeek analyzer, for example, presents the signal strength for each frame received.

An access point typically sends a beacon frame every 100 milliseconds(ms).When evaluating the various metrics that are provided by wireless utilities, be sure to measure frame corruption and not just signal strength. With a protocol analyzer, capture frames and check for cyclic redundancy check (CRC) errors.

Wireless utility such as the Cisco ACU, WildPackets, OmniPeek, or NetStumbler to check signal strength 

Juniper Junos Interfaces

> show interfaces terse   --similar to sh ip int bri
> show interfaces g0/0/0 --similar to sh int g0/0/0



Backup router

Static route is only available when the system’s routing protocol process (rpd) is running. When Junos devices boot, the routing protocol process is not running; therefore, the system has no static or default routes. To allow the device to boot and to ensure that it is reachable over the network if the routing protocol process fails to start properly, you configure a backup router, which is a router or gateway device that is directly connected to the local system

[edit system]
root# show backup-router    

10.0.1.129 destination 10.0.15.0/24;


Hosts on the 10.0.15.0/24 subnet are reachable through the backup router. If the destination statement is omitted, then all hosts are reachable through the backup router.

Linux Survival Commands

/ is root.
/home/mc7 --> go up to root and go down
home/mc7

# ls -l   --> displays file permission

# chmod --> change mode/permission

#groups --> To get a listing of your group memberships

# cd ~ --> go to home directory. cd ~mc7 --> go to mc7 home directory

Pfsense OpenVPN Roadwarriors

Referred to
http://www.youtube.com/watch?v=odjviG-KDq8
http://blog.stefcho.eu/?p=492
http://www.apollon-domain.co.uk/?p=433

Pfsense site-to-site OpenVPN

PPTP vs OpenVPN vs IPsec VPN
http://www.ivpn.net/knowledgebase/62/PPTP-vs-L2TP-vs-OpenVPN.html

Referred to
http://doc.pfsense.org/index.php/OpenVPN_Site-to-Site_(Shared_Key,_2.0)
http://blog.stefcho.eu/?p=576

Topology

Configure one site as a Server and another as client
Server will listen/wait for client to connect at the specified port. (we can use default port 1194 or different port such as tcp/443)

So, server side firewall must allow traffic from OpenVPN client source IP to access that port.

Routing of additional networks (we can only define one local subnet in openVPN default configuration), add "route 172.16.1.0 255.255.255.0" in advanced configuration box. Of course, the router(pfsense) protecting that network must know how to reach it(add static route)

Access Firewall rules
Fw Access rules via OpenVPN must be configured under OpenVPN tab in firewall section. Firewall in pfsense behaves like cisco ASA - scanning the traffic via incoming interface. So, remember to allow traffic at source firewall (LAN interface) and destination firewall (openVPN) interface.

Dropped Firewall logs

Check OpenVPN logs under Status --> OpenVPN. Check firewall logs under Status --> System Logs.

Pfsense installation using Oracle Virtual Box

Referred to
http://forum.pfsense.org/index.php?topic=47306.0
http://pc-addicts.com/building-the-ultimate-virtualbox-lab-intro/

Download pfsnse .gz file, uncompressed to .img file and convert it to virtual hard disk using "VBoxManage convertfromraw D:\temp\pfSensexx.img D:\temp\pfSensexx..vdi"

Created a VM. Use "Bridge Adapter" to connect pfsense box to local network. Adapter 1 for WAN and adapter 2 for LAN.

(a)pfsense cannot be accessed by WAN interface due to default firewall rule. Use another VM like win XP to access the box via LAN interface. (default userid/password - admin/pfsense)

(b)If (a) is not feasible, we can use VirtualBox option in GNS3 to configure pfsense.

       

Add a cloud and configure it as host machine network adapter

Simulate the lab. First interface of pfsense is em0 and second is em1.