Simon The Geek

Passed and Chuffed

2010-10-18T14:34:00.000-07:00

The Home CCNA Lab

2010-10-02T11:23:00.000-07:00

More than half way through the T216 course and still working using packet tracer, netlabs and the home lab.

Thanks to ebay, i am now have a home lab of:
1801 Router,
851 Router,
two 837 Routers,
1750 Router with serial card,
1721 Router with serial card,
and various 2900 switches.

So far, the 1841 has proven invaluable as my 'core' router. It has the most flash, RAM and interfaces to connect to the others.

One of the 837 routers that was bought 'sold as seen' in a bundle is incapable of storing an IOS in flash. It starts ok, goes through post then into ROMMON>, when i go through the restore process it always gives a bad checksum and wont recognise the image. Good practive though, and my top tip is the tftp recovery process is CASE SENSITIVE in rommon! (took a while to figure that out!)

Cheers
STG

Why bother subnetting?

2010-10-02T10:36:00.000-07:00

I had a conversation with a friend the other night and he asked "What is the subnet mask used for?". Pretty simple question and I embarked on a long drawn out waffling explanation where at the end he wasn't understanding because I wasn't clear. This was my fault. I'm going to try to answer the question better here.

An ip address consists of 32 binary bit, some of it identifies the which network, and the rest identifies the host (the actual device in most cases). This could give 2^32 individual numbers which makes 4 294 967 296 unique numbers. This isn't enough numbers for all the equipment in the world so the address was divided into two parts.

The 32 binary bits of the ip address are usually shown as dotted decimal format (e.g. 192.168.1.12) but it needs a subnet mask to tell what part of the address relates to the network portion and what part related to the host portion. To us an analogy, image the network potion are road names/town and the host portion are house numbers. If you were given an address of High St, Oswestry. Then you could find roughly where your going, but to reach an uniquely identify your destination you need the house number too! The classful subnet mask for the above address is 255.255.255.0.

The first 3 octects are the network portion i.e. 192.168.1.0

The last octet relates to the actual host 12.

There are quite a lot of binary calculators and tables online to help. This one is quite useful.

The subnet mask becomes much more useful when sub-netting (VLSM) or super-netting (CIDR).

Sub-netting is where you have been given an ip address and subnet mask but you need to divide it into more manageable portions. Again, to continue the analogy you have the address 123 High Street, Oswestry given to you. When you take ownership of the building you are given four walls and a roof, nothing else! Its up to your to divide this space into kitchen, living room, bedrooms etc.

Hope this helps.

STG

Slow Windows Startup

2010-08-25T08:14:00.001-07:00

My company windows xp laptop is plodding along but starting to show its age. No DVD-ROM for me, still working with CD-ROM. All the programs over the years have started to really slow down the start up process to the point where I need to go away for a brew (and possibly lunch) before its in a usable state. Time to stop all the applications demanding updates on every reboot!

Start > Run > msconfig

The above open the following:

I've gotten rid of all the applications that aren't actually needed, and saves about 5 minutes on booting.

Need to convince the company to use Linux!
STG

T155 Linux: An Introduction

2010-07-24T08:34:00.000-07:00

Looking at this since it the OU sent me the details. T155 looks like a nice introduction, and having followed some on the reviews have bitten the bullet and registered. Heres an Interview with the Creator of the Course.

STG

CCNA - OSPF

2010-05-29T10:06:00.000-07:00

OSPF Key Features:

Open Shortest Path First

Link State using Dijkstra algorithm. Fast Convergence, Event driven updates and builds a topology map.

OSPFv2 = IPv4, OSPFv3=IPv6.

Convergence is fast, classless routing (vlsm and cidr). Metric is Bandwidth and A.D. is 110.

e.g. O 10.10.10.0/24 [110/10] via etc etc

O 10.10.11.0/24 [110/1785] via etc etc

Sends partial updates, only when there is a change (Link State Advertisements LSAs and contain one or more Link state Update)

How to setup:

Router(config)# router ospf

to enable an instance of ospf.

Router(config-router)# network area

means the network above is advertised because the interface it is on matches the ip address. The router will now send hello packets and form neighbours.

The process is locally significant, the area id is globally significant.

If you have a quad zero static route then you can advertise it to others using the default-information originate command.

Verifying the setup:

show ip protocols- displays information about the routing protocols running.

show ip route - displays the routing table, (but only the best paths)

show ip ospf neighbor - shows displays the directly connected neighbours and their state.

show running-config: show you how the router is set up.

The Router ID:

This determines whether the router is the designated router (DR) or Backup designated router( BDR). The DR is responsible for updating other routers and the backup is ready to take over. (Other routers are called DRothers)

A router id can be set by either:

1. the command Router(config-router)#router id

2. The highest ip address of any of the loopback addresses

3. highest ip address on ANY physical interface.

you cannot have tow routers with the same id in an ospf domain.

"My implementation of OSPF wont form neighbourhood adjacencies!"

If I had a pound for every time heard this....

1. check the subnet masks to make sure the routers are on the same network.

2. Check the hello and dead timers match.

3. OSPF areas don't match?

4. check the network commands used on each router, especially the wildcard masks.

The DR election process can be rigged: use the command:

Router(config-if)#ip ospf priority <0 to 255>

where:

0 isn't eligible for DR or BDR,

1 is the default

>1 means it will become the DR unless there is a high number.

This is good! If you have a high memory core router servicing 20 remote routers then you'll want it to be the DR for that instance of OSPF.

The Metric:

Cisco cost for OSPF = 10^8/Bandwidth in bps.

56k dial up line would be 1785.

10Mbps fast ethernet interface = 10

Lower is preferred. Remember: If you lower the cost, it becomes a more attractive route, but doesn't make it faster. Don't point everything to that dial up modem!

CCNA EIGRP

2010-05-22T12:17:00.000-07:00

EIGRP Key Features:

Enhanced Distance Vector Routing Protocol : Cisco Propriety

Distance Vector protocol where distance is a metric measured using Bandwidth, delay, (and possibly load and reliability) using the DUAL algorithm.

Administrative Distance of 5 for a summary route, 90 for an internal route and 170 for an external EIGRP route.

Has a topology table as well as the routing table, which contains backup loop-free (but only if it meets the feasibility condition). This saves convergence time as DUAL doesn't have to start the network discovery process again.

EIGRP is a reliable transport protocol, using Diffusing Update ALgorithm. Mulitcast address of 224.0.0.10 (port 88).

Packets used:

Hello - discovery of neighbours (UDP)

Update (and its ACK) - Multicast (TCP) or Unicast when required by a single router.

Query and Reply - Multicast (TCP)

EIGRP uses Autonomous system numbers (1 to 65535) for WANs ( and usually ISPs), and all routers in the same large must have the same number. The process ID is the local group of routers sharing updates, it is an instance of EIGRP within a group and all in this smaller group need the same number.

How to setup:

create an instance of EIGRP

Advertise the network using network address only if classful, network address and wildcard mask if classless.

Confirm Adjacencies have formed using 'show ip eigrp neighbors'.

Example commands to use:

Router(config)# router eigrp 20

Router(config-router)#network 192.168.100.0 0.0.0.255

Shows:

show ip eogrp neighbor

show ip protocols

debug eigrp fsm/packet

Notes:

the Null0 routes lead to nowhere, and is used to lose packets that dont have real destinations from summarising.

Bandwidth (k1) and delay (k3) can be changed to tweak the instance for performance.

Reliability 255/255 = 100%

Hello timers must match for adjacencies to form.

CCNA RIP

2010-05-15T10:08:00.000-07:00

RIP Key Features:

Distance Vector protocol where distance is a metric measured as hops usingf the Bellman-Ford algorithm.

Administrative Distance of 120 (There is a league table of ADs, where the closer a route is to 1 is chosen).

Version 1 is classful and therefore no VLSM support. Version 2 is classless and VLSM supported.

>15 hops is unreachable.

Port 520

Uses split horizon with poison reverse.

Example commands to use:

Router(config)# router rip

Router(config-router)#network 192.168.100.0

My routers, Birmingham and Manchester are directly connected using a serial cable and ive used loopbacks to represent other networks.:

Notes:

No hops means directly connected,

1 Hop is the next router.

2 hops is two routers away!

Use the passive-interface command to stop rip updates being sent out on that interface.

Disable auto-summary if the networks are discontinuous.

A default route is used to represent routes that are not locally administered and propergated by the command default-information originate command in the config-router setup.

Caution with Commands:

Version 1 means send and receive only rip version 1

Version 2 means send and receive only rip version 2(and don't forget to use the no auto-summary command to make sure its classless summaries)

No version means send and receive both Versions of RIP.

Use debug ip rip to see the router processing the rip protocol live.

CCNA Routes

2010-05-04T11:21:00.000-07:00

CCNA Revision : T216 : Routes, Static, Default and Dynamic.

Static routes are ones you enter on a router to let it know which interface or to which network to send traffic for a particular network.

An example of a static routes:

Router(config)# 192.168.1.0 255.255.255.0 192.168.2.0

send all packets for network 192.168.1.0 out of an interface belonging to the network 192.168.2.0

Router(config)# 192.168.1.0 255.255.255.0 Serial 0

send all packets for network 192.168.1.0 out of interface serial 0

Why do this?

1. Because you are have only one router on a site.

2. You have a route you really want to use, if you configure a static one, it is given an Administrative distance of 1 and will always be used prior to one found by a routing protocol.

Why not to do this?

1. In a large network the maintaining of static routes would be time consuming.

2. it isn't fault tolerant, if an interface goes down, all the static routes using that interface are removed from the routing table.

Summary Static Routes can be used if both:

A) The destination networks can be summarised into a single address.

B) The multiply static routes are using the same exit or next hop interface.

Create a summary route by aggregating the addresses and subnet mask, (the address is the most common LHS bits).

Default Static Route is used to mop up any traffic that doesn't have a match in the routing table.

Routers use the most specific match and recursive lookup and can be configured using a quad zero address as:

Router(config)# 0.0.0.0 0.0.0.0 Serial 0

When a router looks up an up address it looks for the most matching bits to the least matching. 0.0.0.0 means 'don't have to match any bits on this address' so if you have nothing better in the routing table send it this way.

It is also referred to the gateway of last resort.

Dynamic Routes are ones populated in the routing table by a routing protocol.

CCNA Routing Protocols Intro

2010-05-03T05:09:00.000-07:00

At the heart of what Cisco does is routing. Moving packets of data from one network to another.

Routers use information about their surrounding gained from connected, static routes and dynamic routing protocols to determine what to do at a Network Layer 3 of the OSI model packet (the Internet layer in the tcp/ip model) when it arrives at an interface.

Connected Routes:

Physically attached to the router are the connected routers. These are the networks attached to the physical interfaces of the router. This interfaces of a router are given an ip address and are effectively hosts within the sub-network they are given.

Configuration Example:

London(config)#interface fa0

London(config-if)#ip address 192.168.10.1 255.255.255.0

Static Routes:

These are routes where you tell the router which direction to go. Why would you use these? When its a very small network, When there is only one router connected to an ISP, When there is a hub and spoke topology and only one real way to go and when you NEED packets to flow in a particular direction (i.e. through a high capacity router rather than a small regional one).

Configuration Example:

London(config)# ip route 192.168.20.0 255.255.255.0 192.168.10.1 permanent

London(config)# ip route 192.168.20.0 255.255.255.0 Fastethernet 0 permanent

In both the above examples, packets destined for 192.168.20. network will go to the connected route described in connected routes above. The word permanent means the static routes are kept in the routing table if the interface goes down and saves time rediscovering if the interface comes back up again.

Dynamic Routes:

This is the crux of the matter. Dynamic routes are populated in a routers tables using a routing protocol. such as RIP, IGRP EIGRP and OSPF. This will be discussed later. Dynamic also means Automatic network discovery if the protocol is set up correctly. The best path to a network is determined using routing protocols if a static or connected route cannot be found.

The 3 laws of ~~Robotics~~ Routing

1. Routers make decisions alone, based on the information in the routing table.

2. If one router has some information, it doesn't mean they all do.

3. Routing information to a destination doesn't mean it can get back.

CCNA Basic router Config

2010-05-02T08:57:00.000-07:00

From turning on a router without any any kind of configuration it try to go through a basic configuration. It isnt recommended to go thought the auto-configuration utility so at the first question you say no.

Here is the configuration in my router so far (note: no routing procols yet!)

London#show run
Building configuration...

Current configuration : 1057 bytes
!
version 12.4
service timestamps debug datetime msec
service timestamps log datetime msec
service password-encryption this gives basic level encryption, but better than nothing.
!
hostname London Always recommend giving you router names as you can then see where you are telnetting from one to another.
!
!
!
no ip domain lookup stops the router trying to translat wrongly inputted commands
!
!
!
!
interface FastEthernet0
ip address 192.168.10.1 255.255.255.0
duplex auto
speed auto
!
!
line con 0
privilege level 15
password 7 030752180500
logging synchronous when the router gives an update, the line you are typing is repeated so it easier to carry on.
login
line aux 0
line vty 0 4
privilege level 15 This automatically puts a telnetter into enable mode when they dial into the router
password 7 13061E010803
login If login command isn't set then noone can telnet into this machine.
!
end

London(config)#

This isnt an exaustive list, just some of the basics.

CCNA Routers, internals and boot

2010-05-01T08:37:00.000-07:00

This is a quick list of the internals and what they are used for:

RAM:

The working IOS that has been loaded from flash.

The running configuration

IP Routing tables

ARP Cache, IP to MAC tables

Packet Buffering

ROM:

Bootstrap instructions

Basic Diagnostic software

basic version of IOS for disaster recovery.

FLASH Memory:

IOS

NVRam:

Backup configuration file (aka Startup config)

BOOT ORDER:

1. Post

2. Executes Bootstrap loader

3. Locate the IOS

4. Load the IOS

5 Locate Startup Config

6. Load Startup config

Above is my router, London. Show Version gives me my flash file name and its location.

Disclaimer: These are my notes and intended as my on-line quick reference, Thanks.

CCNA - New course, new apps

2010-02-06T09:44:00.000-08:00

I'm getting to grips with the course, but nearly every lab needs a workaround to get it to work with Linux.

Firstly, Cisco Packet tracer. It does work natively but the fonts made it look horrible and unusable for a 9 month course. The fonts supplied are poor so its better to make them default to the Ubuntu ones. Within the /usr/local/PacketTracer51/packet tracer start-up script you can # out the packages fonts.
# export LD_LIBRARY_PATH=$PTDIR/lib
When you next restart, the application defaults to make a much more workable program.

The packet tracer also has a bug, where in simulation mode the simulation panel flutters (changes size along the vertical axis) constantly many times a second. Fortunately the simulation pane is movable and once done the problem seems to go.

Secondly, The course is recommending Neotrace. Wireshark does the same thing and again is natively run. The only thing i am not happy with is you have to run with root permissions (e.g. sudo wireshark) to be able to monitor the packets on the Ethernet. I've had a look further in the course, and this isn't used often so I have some time to find a workaround.

Finally, I have a number of routers I want to connect to physically at home to practice on. cutecom and minicom both installed but not able to see tty0 the serial port, but GTKterm (which reports itself as a hyper-terminal replacement) works perfectly....

right. Back to the course.
STG

Twinview and Ubuntu

2010-02-06T02:24:00.001-08:00

The course i'm doing involves two applications and browsers and the content so it was a good excuse to double viewing capability!

Two 19" screens, one graphics card and ubuntu.

After sudo-ing my xorg.conf file, both screens recognised and working perfectly.

STG

Norton Antivirus

2010-02-03T14:35:00.000-08:00

My wifes laptop contains the itunes folder, we both use and enjoy our ipods and its one of the things that has kept the familiar windows startup sound in the house.

Windows needs anti-virus, its a fact of life. Our old isp gave us Norton free. Its great at what it does, intuitive, easy to use and when we changed providers to sky, a bloody nightmare to remove off the laptop. I thought I'd got it all, and installed AVG at the recommendation of a friend. All was well, until Norton pop-ups continually appeared stating we were at risk. With increasing frequency, the tool bar would say unprotected.

I'm hunt through the hard disk and now thing alls gone, but no. At this point i had NO internet connection at all through the laptop, wired or wireless. Norton produces a product that not just hard to remove, but actually requires you to download the 'Norton software removal tool'!

Its now gone.

AVG seems quite happy alone.

I'm off to run a quick spy-bot search and destroy scan, set off an antivirus scan, check the firewall, pass the laptop back to my better half and go back to my Linux machine where i never worry about such things. I call it my happy place.

STG

16th December 2009

2009-12-13T06:51:00.000-08:00

Two great things for the 16th :
1. Hoping to get the results for M366 final exam.
2. Me and Mrs TheGeek are going for a scan on the expected baby (hereinafter referred to as MiniGeek).

Crossing fingers all is well.

Update:
1. Passed M366, Chuffed and 1 last year to go!.
2. Scan went really well, minigeek is tiny and looking forward to next july!

STG

Linux test Machine

2009-12-09T06:57:00.000-08:00

I want a machine to 'play with' and look into settings and scripts but cannot afford a separate machine to try out programs or even have to play with settings so am going to try out VirtualBox and create a virtual installation of a few of the Linux distros and another of Ubuntu 9.10 for testing out terminal commands, bash scripting etc

I've grown fond of Ubuntu and the current set-up of my home pc so its off to virtual land to ensure nothing gets corrupt.

STG

The End User Licence Agreement

2009-12-03T10:01:00.000-08:00

I've just read an article in Micro Mart about end user licence agreements (EULA's), and it really shocked me how the large companies are a law unto themselves. Only for research, I've just have a quick look at the Microsoft XP EULA. Its 5000 words of the worst legalise. Some of it is in French and most not understandable! Who has the time to read and understand every eula they come across in a windows world!. Amazing. There is a EULA hall of shame if your so inclined.

I'm going to continue with my adventures in Linux
STG

Wedding

2009-12-02T06:49:00.001-08:00

I was really lucky this year to get married to my wonderfully tolerant wife. We've been planning this for a few years and in may we and some family fly out to Antigua for the wedding and we went onto Granada for the honeymoon. We spent 3 weeks chilling by the pool, reading, catching up on all the podcasts I'd been saving for the trip.

I'd recommend the Caribbean to anyone looking to swim, enjoy the sun and relax. The people were so friendly and food fantastic. its about the only time in my adult life I've has the chance to forget completely about work and home. more importantly, it was a wonderful place to get married and we loved every minute. there was even a web-cam for the family who couldn't make it!

Its been a good 6 months since we got back and still trying to sort out all the photos and videos.

STG

Itunes and linux

2009-12-01T05:54:00.001-08:00

Wow, its almost as though itunes and apple don't want you to sync an ipod with anything open source! Like they have some rights, perhaps digital in some way to stop you using with Linux! I'm happy with Rhythm-box and it never fails to download all the podcasts, but still having trouble with ipod.

I installed gtkpod, and after adjusting the settings I got a one way sync with the data coming onto the pc. It then tried to put 20Gb of data onto a 8Gb ipod and failed. Even the podcasts it put on weren't recognised.

Trying a different tac, I tried installing itunes 6.0, then 7.2 and they both failed to install. I've ran the mods requires but no luck. The installs fail before getting to the end.

I'm back to plan b. Work laptop, itunes and windows. I feel dirty, but this is only a temporary measure. The ipod project is going on the back burner until after Christmas. The better halfs' birthday, finishing the bathroom and a few glasses of baileys takes priority!

I have a sneaking feeling Santa is bringing me the new trek movie!

Merry Crimbo
STG

Podcasts

2009-11-26T11:12:00.001-08:00

My wife bought me my first ipod for my birthday last year. I downloaded itunes and promptly copied my whole music collection (its not a prolific collection) and moved them across. Its a 3rd gen model, and has always performed its job without fuss or foul.

A couple of months into ownership, i looked at the menu and saw an option for podcasts. Looking at the itunes site, i saw one of the options was free 'podcasts'. It took me a while to realise that i could pick any subject i wanted there would probably be a podcast about it. The quality of some were terrible and made me regret the bandwidth to download them even if the subject and hosts were good. Life is a bit too short to listen to rattling and tinny conversations.

Its now a year and a half later, most of the original podcasts have gone by the wayside but i think the ones that have remained are worth recommending:

1. Simply Syndicated. This isn't strictly one podcast, its a whole family of shows. The have been going years and still produce many shows a week on a huge variety of subjects from movies you should see, the definitive word, masters of none, starbase 66, etc. At the last count there were 18 regularly produced shows, of great quality and i will continue to listen and support because of the shear amount of entertainment they give.

2. The BBC produce and distribute what they call podcasts. I don't think this is strictly true, they seem to be more downloadable versions of shows that have has any copy-written material removed. This should not put you off though, as many of the shows are entertaining, informative and accessible to people who arent next to a radio when their on! Its worth checking out Kermode and Mayo film review.

3. My last is a recent discovery. As you may (or may not) have read, I'm now using Linux as my main home OS, and the Going Linux podcast has been a great resource for all things Linux.

I spend my day driving between sites and have a lot of time on the road. Luckily my car has a mp3 playing stereo, i burn the cd's and catchup every week on these shows. It takes away a lot of the monotony of being on the road and drowns out the voices :)

I am constantly amazed at the quality of the shows produced by the non-bbc guys and amazed they have enough hours in the day to record, edit and distribute.

If you get a chance, give them a go. If you like them, then consider donating or buying from their stores to support them.

All the Best
STG

Open university

2009-11-24T13:08:00.001-08:00

I'm between open university courses at the moment. Just finished M366 artificial intelligence (waiting for the result around Christmas) and beginning my new one, T216 Cisco CCNA.

Firstly, M366. Its a great course that covers biology, AI history, maths, programming and more. It has more theories and definitions than any other course I've done. It seems to 'jump' in some way. Flitting from point to the next, but the points within each section are related. The tmas took more time than they should have and they were pretty tough too. The material covered was interesting, and made references to other articles both included and on-line. You, as a student, are encouraged to for your own opinions as you go, which i enjoyed.

Secondly, The exam. I crammed for a month and am not sure i did enough! It was a tough 3 hours. A few obscure points from the course came up and i don't think anyone was truly prepared (but this might be misery loves company).

Overall, i think this should have been 45 points at level 3 (perhaps more). Many people I've spoken to after the exam would be happy with a level 4 pass. I tend to agree. It might be that the course is simply too ambitious for itself and tries to cover too much material or it should be broken into two course (level 2 then 3), progressing. I really hope i pass, because I don't know if i have the energy or compulsion to repeat this exam, and might consider moving onto another course instead! I enjoyed the course, found the topics covered interesting, found they challenged me and enjoyed it. The tutor i had was great, and gave honest and valuable feedback.

The cisco course is one I've been waiting for for a couple of years and its the last course to complete my degree. The OU has given me a second chance to get my degree, having unsuccessfully attempted when younger!

One last year....well, i say 1 last year, but i'm a bit addicted. we'll see.

STG

First rambling of a geek

2009-11-24T05:07:00.000-08:00

ahhh....my first post.

Well, writing this on Ubuntu (Koala) and the upgrade to 9.10 a few days ago. Everything seems to be working fine. Nothing lost but I wasn't really worried as this is the 3rd update. I'm hoping to stay with 9.10 as its the lts version. (Does anyone out there know how to stop getting the 'Want to upgrade?' messages?)

A few months ago i bought world of goo but it never ran right. There was no sound and the graphic were juddering and painfully slow. Koala didn't resolve it as i hoped, but after stumbling through system>administration>hardware drivers i found the nVidia drivers for the mainboard I've got and all the bugs have gone, even the slight screen misalignment that been a minor nuisance for the last few months.

I'm impressed with Linux, specifically Ubuntu. It's worked out of the box and every program i need i can either substitute or run under wine. The old problem of printers didn't even show its head. The hp site had the Linux downloads and has worked flawlessly.

Next to get my ipod working!.....

Cheers
STG