Merry Christmas!

Merry Christmas!

That is all.  Carry on with the plan of the day.

Christmas week

After a week of barely keeping up, I’m now eating lunch, wondering what to do.  There are so many possibilities that could be done.  What should one do with a good 45 minutes of free time (assuming it stays free).

About halfway through writing that sentence, my brain kicked back. 

“Sure, you have lots of possibilities.  But you haven’t done a darn thing that should be doing.” 

So, after listening to my brain I’m back to reading about Active Directory Group Policy configuration.  I think I only have a bit more than 100 pages left on that book before going towards a Security+ book.  From there, it’s on to the stuff that is where I’d want to be in couple of years.  Learning stuff is great, but it’s best to go towards learning stuff to accomplish a task.  And with this, there is a task at hand and a plan.  I’ve just got to slug through all the stuff that is necessary but boring. 

That being said, I’m probably going to try and finish both books during my vacation.  I’m taking a week off after Christmas, so hopefully I’ll be finished with both.  I might actually come back from the vacation with good ideas.  Maybe.  I already have an idea of what needs to be done, I just have to end up doing it. 

As a general thought, it’s hard to get setup to be out of the office for a week (or more).  Really, I’ll be gone for about 7 work days.  That’s just crazy for me.  The last time I took that much time off, I had just had my third child. 

Come to think of it, that was March.  Wow, does time fly.  

Monday morning, a week later

A mental conversation

“It would be cool if I could do that.” says part A

“What makes you think you can’t?” says part B.

“Uhhh…”

“Look,” says part B, explaining the situation to his younger, less intelligent sibling.  “You would know how to do that if you studied to do it.  You’ve already got a plan on how to figure all that out.  Now, you need to quit being a lazy bum and do the work.”

Yes, such conversations do run through my head on occasion.

I think it narrows down to knowing that your thinking controls your actions.  If thinking controls your actions, then you need to think in the proper manner.  Your brain has to understand that action needs to be done.  Your brain needs to get the occasional pep talk about what you have already planned to do.

I wrote that a week ago.  It didn’t ever go anywhere from there.  I’m willing to abandon it where it was. 

Last week was an incredibly off week.  This week is Christmas.  After that is vacation.  We’ll see what the future holds for me.  Right now, I think I’ll leave it with this.    

Friday post

On call can be one of the most hellish weeks.  Though finally moving to hourly, it can also be one of the most lucrative.  If I work my from 8a-5p with a one hour lunch break, I'll be up to 61.5 hours for the week.  I say lucrative, because 21 hours of overtime almost gets me to the point of a double paycheck.

After years of being on salary, I would not go back. Salary is sold on ridiculous lie.  The lie is the person on salary will get paid more even though they don't work 40 hours that week.  I'm not sure that ever happened in the time I was on salary.  It was always 45 hours plus.  So my hourly rate was tanking like a mad man every minute I stuck around.  Now, I feel like I'm being valued with my time.

When I was on salary, for three or four months I worked a week of 70 plus hours one a month.  If I were to do that now, the pay would be astronomical.   Since I've been keeping track this year, the most I've hit is 67.5 hours in a week.   And the pay check was awesome.

Introduction to Networks ch 6

Introduction to Networks Chapter 6

Quiz 

     How does the network layer use the MTU value?

     A) The MTU is passed to the network layer by the data link layer.

     What are 2 functions that are provided by the network layer?

     1) providing end devices with a unique network identifier

     2) directing data packets to destination hosts on other networks

     During the boot process, in what memory location will the router bootstrap program look for the IOS image if a TFTP server is not used?  

     A) flash

          

     When transporting data from real-time applications, such as streaming audio and video, which field in the IPv6 header can be used to inform the routers and switches to maintain the same path for the packets in the same conversation

     A) Flow Label

     Within a production network, what is the purpose of configuring a switch with a default gateway address?

     A) The default gateway address is used to forward packets originating from the switch to remote networks.

Chapter 6 Notes

routing - communication between networks

Network Layer

     Provides services to allow end devices to exchange data across the network

     -OSI Layer 3

     -4 basic processes

          -Addressing (end devices)

               end device with configured IP is called a host

          -Encapsulation

               Receives PDU from transport layer.  Adds header.   Now called a Packet

          -Routing - services to direct packets to a destination host on another network

               -each route the packet takes to reach the destination is called a hop

          -Deencapsulation - process of removing headers from lower layers

               

     Operates without knowing/caring of the data being carried

     Media/Path is irrelevant.  Satelite, wireless, cable modem, serial.. doesn't matter

Network Layer protocols

     IPv4

     IPv6

 Characteristics of IP protocols    

     -low overhead

     -connectionless

     -best effort (unreliable) 

     -media independant

     Connectionless - no dedicated end to end connection created before sending.  Kind of like mail.

          -send at any time

          -unaware of the state of the recipient

          -unaware if the receiver can understand the data 

          -no error correction

          -no guarantee packets will arrive in order

Best Effort Delivery

     can't recover from failed/corrupt packets

     bad packets are dropped

     trouble with transmission handled by upper layers if the layer desires

     

Media Independent

     Data link layer responsible for transmitting over media.

     maximum size packet that can be sent is the MTU (maxium transmission unit)

          -data link layer passes the MTU value up to the network layer

          -network layer uses information to determine packet size

          -breaks packets to  fit the MTU.   

          -Fragmentation is necessary to split packet size so it will fit on a device with a smaller MTU

IPv4 Packet

     -In use since 1983

     Packet has 2 parts

          1) IP header

               Significant portions of the header

               -Version - packet version.  Constant at 0100

               -Differentiated services (formerly Type of Service) - used for QoS.   1st 6 bits used by QoS.  last 2 bits used to prevent dropping

               -TTL (Time to Live) 8 bit value to limit the lifetime of the packet.  Reduced at each hop.   If hits 0, router discards packet and returns ICMP Time Exceeded message to the source IP address

               -Protocol - indicates data payload

               -Source IP address

               -Destination IP address

               

          2) Payload

          Remaining fields of the IPv4 header

          -Internet Header Length (IHL) - 4 bit value identifying the number of 32 bit words in the header

          -total length - defines entire packet size, including header and data

          -header checksum - used for error checking IP header.  If values do not match, packet is discarded

          If the packet is fragmented, other fields are used to keep track of the data

          -Identification - unique identifier of a fragment

          -flags - identifies how a packet is fragmented

          -fragment offset - identifies the order in which to place the packet when it arrives at the destination

          

IPv6 packet

     Limitations of IPv4

     -IP address depletion   - only 4 billion available IP addresses.  Quickly running out due to always-on connections

     -Internet Routing Table Expansion - more networks, more routes, more waiting

     -Lack of end-to-end connectivity - Troublesome when NAT and PAT are used.  

     Encapsulating

          -simplification of the IPv6 header

          IPv4 had 20 octets and 12 basic header fields

          IPv6 has 40 octets and 8 basic header fields

          advantages over IPv4

               -better routing efficiency for performance and forwarding rate

               -no requirement for processing checksums

               -simplified and more efficient extension header mechanisms

               -flow label field for per-flow processing with no need to dencapsulate to identify various traffic flows

          IPv6 packet header

               -Version- 4 bit binary.  Constantly set to 0110

               -Traffic Class - equivelant of the differentiaed services field

               -flow label     - used to inform routers and switches to maintain the same path for packet flow so that packets are not reordered

               -payload length

               -next header - equivelent of the IPv4 protocol field.  indicates data being carried

               -hop limit

               -source address

               -destination address

          IPv6 addresses

          -128 bit address

          -colons separate entries into a series of 16-bit hexadecimal blocks

          

Routing

     How a host routes

          Host forwarding decision

               hosts can send a packet to ...

               -itself

               -local host

               -remote host

               local host vs remote host is based on IP address and subnet mask comparison between sender and receiver

               devices beyond the local network segment referred to as remote hosts

     

         

          Default Gateway

               the device that routes traffic from the local network to devices on remote networks

               

               if a host is sending to remote network, it sends to default gateway

               default gateway maintains a routing table 

                    -data file in RAM that stores route information from directly connected networks

                    -also knows remote networks the device has learned

                    

               host must maintain a local routing table to ensure proper delivery

               hosts routing table typically contains of...

               -direct connection

               -local network route

               -local default route

               default route only used to connect outside of the local network

IPv4 routing

               

          If a host wants to send a packet inside the local network

          1) consult the IPv4 route table

          2) match the destination IP address and identify it as being in the same network

          3) send the packet using the local interface

          If a host wants to send a packet outside the local network

          1) consult the IPv4 route table

          2) find there is no exact match for the destination IP address

          3) choose the local default route to pick the forwarding location

          4)  send the packet to the gateway using the local interface

          

IPv6 routing

          

          View routing table in Windows with netstat -r or route print

          If - lists the interface numbers from the interface list

          metric - lists the cost of each route to a destination.  Lower numbers are preferred routes

          network destination - lists the reachable networks

          gateway  - lits the address used by local host to forward outside the network

     ::/0 - IPv6 equivalent of the local default route

     ::1/128  - IPv6 equivalent of the loop back address

     200::/32 - global unicast network prefix

      fe80::/64 local link network route address;  represents all computers in the local network

      ff00::/8     multicast address

     no broadcast addresses in IPv6

Router Routing Tables

     routers store information about 

          directly connected routes

          -known from interfaces physically plugged into the router

          

          remote routes

          -routes that come from other routers.  

          -manually configured  or dynamically configured through the device learning from other routers

          routing table of a router

          -destination network

          -metric associated with the destination

          -gateway to get to the destination

          show ip route

          when a packet arrives at the router, the router examines the routing table.  if the destination network matches a route in the routing table, the router forwards the packet to that route

          if multiple paths to the same location, then lowest metric wins

     directly connected routing table entries

          routers have 2 rotus after IP address is assigned

          

          route source: - how the route was learned

               C: directly connected

               L - local route

          Destination network and how reached

               identifies the address of the network and how a packet can reach the destination

          outgoing interface

               what interface is used to connect to that network

          routers generally have multiple interfaces configured

               common codes for remote networks

               -S: route was manually created by an admin.  Static route

               -D: learned dynamically using EIGRP

               -O: learned dynamically using OSPF

          remote network routing table entries

               route source- how the route was learned

               destination network - the address of the remote network

               administrative distance - trustworthiness of the route source

               metric - value assigned to reach the remote network.  Lower wins

               next hop - ip address of the next router to forward packets to

               route timestamp - when the route was last heard from

               outgoing interface - physical interface to forward a packet

          next hop address

               address of the device that will process the packet next.

          packets can not be forwarded by the router without a route for the destination network.

          if no route, packet is dropped

          router can be configured with a gateway of last resort if the destination is unknown

          

Routers - 

     a router is a computer

     

     branch - small business, medium business, teleworkes

     WAN - large business

     Service provider - large service providers

     router CPU and OS

     

     Router memory 

          RAM  -  store applications and process including

                    -IOS - copied during bootup

                    -running config

                    -ip routing table

                    -ARP cache

                    -packet buffer

                    routers use DRAM

                    volatile memory and requires continual power to maintain information

                    all content lost when powered down

          ROM

               used to store:

               -bootup instruction

               -basic diagnostic software

               -limited IOS

               firmware embedded on an integrated circuit inside the router

               doesn't lose contents when powered down 

          NVRAM

               used as permanent storage for the startup config file

               doesn't lose contents when powered off

          flash 

               used as permanent storage for IOS and system related fields

          router backplane

               has the following connections

               -console ports

               -aux port

               -LAN interfaces

               -Enhanced high-speed WAN interface card (EHWIC) slot

                    modular enhancement slot.  Different interface, different card

          connecting to a router

               routers interconnect many devices

               connections grouped into two categories

               

               management ports - used to configure/manage/troubleshoot.  not used for packet forwarding

               in-band router interfaces - LAN and WAN interfaces configured with IP addressing to carry traffic

               two interfaces can't belong to the same network

          

router bootup

     bootset files - loaded into RAM when booted

          -IOS image file

          -start config file

     

     router bootup process

          1) perform POST and load the bootstrap program

          2) locate and load the Cisco IOS software

          3) locate and load the startup config file or enter setup mode

          locating/loading config file

               can be saved in NVRAM. 

               if not, can be loaded from a TFTP server

               

         show version 

               CPU and amount of RAM

                    some versions write the amount of ram with XXXX/YYYY.   add those two numbers together

               has config register as 0x2102.    changing to other used for password recovery

          

        general config steps

             1)give hostname

             2) set passwords 

                    -enable

                    -console

                    -VTY

                    -use service password-encryption to encrypt password

               3) setup a banner motd

               4) exit config

               5) save configuration

        configuring interfaces

               1) conf t

               2) interface whatever

               3) ip address xxx.xxx.xxx.xxx yyy.yyy.yyy.yyy   where x is IP address, y is subnet mask

               4) description blah

               5) no shutdown

               6) exit config

               7) save

        verify interface configuration

               show ip interface brief

               show ip route

               show interfaces

               show ip interface

default gateway on a switch

     1) interface blah

     2) ip address xxx yyy  (x is IP, y is subnet)

     3) no shutdown

     4) ip default-gateway xxx.xxx.xxx.xxx   (x is IP address)

     

     IP address on a switch is only used to mange the switch

     if you want it accessible from anywhere, it needs a default gateway

Learning and marginalizing

It’s often great theory that gets me to go do certain things.  The end result seems something attainable and desirable.  Often times, I’m not wrong.  But what I’m going against now is both desirable and exceptionally time consuming.  I know what I want.  I’ve wanted it since I first started learning to program back in 1997 or 1998.  Even though the end seems in sight, it’s still a long way to go.  Maybe that’s why I keep playing “it’s a long way to the top if you want to rock and roll”.   As far as songs go, that one is incredibly accurate. 

I don’t think before I ever contemplated a path towards achievement.  I know I didn’t in my twenties.  Now, in my thirties I have an idea of where I want to go.  I guess the interesting thing is that despite all the technological changes that have taken place in the last 15 years or so, the process towards achievement hasn’t changed.  I suppose some things never do, despite all the achievements.

Really, what I learned out of going through the CCNA material is this: despite technological achievement in learning, it’s still a lot of work.  Despite being able to memorize more or learn more, learning is still a lot of work.  And if you want to learn a decent amount of material, you will be putting in a lot of work.  There is no other option.  There is no easy way.  I can’t remember if it was Star Wars or some version of Star Trek that had students standing in learning bubbles, practicing material and waving their hands like manic crazies.  That might be the future, but such a situation is years away.

I’ve heard frequently about the greatness of technological input and the “race to the top”.  It’s the idea that students are growing smarter and smarter every generation.  The last generation won’t be able to keep up with the learning achievement of the next generation.  But there’s something inherently missing from all of those discussions.  I don’t know what it is, but it’s probably the same thing inherently wrong with the “race to the bottom”.  I find the duality strange that people can discuss both possibilities (students getting dumber and dumber, and students getting smarter and smarter) in the same breath.  So which is it? 

Or are we simply dealing with outliers?  I think that is more likely scenario.  The seconds option is one that I like to think is true.  American society has marginalized male achievement, so after being told for years that our achievements don’t mean anything the average male has given up.  It’s not that female achievement is less or less desirable.  It’s that we’ve spent a lot of time marginalizing specific groups and telling them their work is useless.  So that group is leaving the race, and dropping into things that are easy for them. 

Once again, me talking about thing things I have no empirical research on.  But it makes sense to me.  

Insurance

So, it’s an on-call week.  Generally that means everyone and their dog decides I need to work on some special project for them.  It can make me feel good that I have the interest of so many, but really.  Can’t it all wait until next week when I’m back to peace and patience and not neck deep in a thousand different people yelling at me to fix things yesterday?

Enough of that train of thought.

It’s that time of year for insurance, and it’s strange that I think I’m finally properly insured, or at least close to where I should be.  I’ve got car, renters, health, life, short term disability, and long term disability.  Which makes for expensive bills but decently mitigated risk.  It seems stupid, but I think I’m finally covered to the point where I should be.  Is it expensive?  You bet.  But it’s worth it. 

Do I really want to contemplate to contemplate what would happen if I fell off a ladder and was injured and couldn’t work?  Not really, but I don’t want to be homeless, either.  Sure, it’s expensive but you should deal with getting all of the above if you can.  I reduce a bit of the cost by raising deductibles and elimination periods.  I generally keep two weeks in vacation and cash in the bank, so an elimination period of two weeks is easy on short-term disability. 

Maybe Nial Ferguson was right. Either that, or I need to quit reading so many books.  

But it's hard to not read so many books when it becomes easy to pick and choose the parts that mean a lot and fit together.  I think most of the books I've read in the last two or three years have changed my perspective in some way.   Mostly for the better.  Or at least I'd like to think so.