Monday, December 29, 2008

OSPF

How OSPF for IPv6 Works



OSPF is a routing protocol for IP. It is a link-state protocol, as opposed to a distance-vector protocol. Think of a link as being an interface on a networking device. A link-state protocol makes its routing decisions based on the states of the links that connect source and destination machines. The state of a link is a description of that interface and its relationship to its neighboring networking devices. The interface information includes the IPv6 prefix of the interface, the network mask, the type of network it is connected to, the routers connected to that network, and so on. This information is propagated in various type of link-state advertisements (LSAs).



A router's collection of LSA data is stored in a link-state database. The contents of the database, when subjected to the Dijkstra algorithm, result in the creation of the OSPF routing table. The difference between the database and the routing table is that the database contains a complete collection of raw data; the routing table contains a list of shortest paths to known destinations via specific router interface ports.



OSPF version 3, which is described in RFC 2740, supports IPv6.


Comparison of OSPF for IPv6 and OSPF Version 2



Much of the OSPF for IPv6 feature is the same as in OSPF version 2. OSPF version 3 for IPv6, which is described in RFC 2740, expands on OSPF version 2 to provide support for IPv6 routing prefixes and the larger size of IPv6 addresses.



In OSPF for IPv6, a routing process does not need to be explicitly created. Enabling OSPF for IPv6 on an interface will cause a routing process, and its associated configuration, to be created.



In OSPF for IPv6, each interface must be enabled using commands in interface configuration mode. This feature is different from OSPF version 2, in which interfaces are indirectly enabled using the router configuration mode.



When using an nonbroadcast multiaccess (NBMA) interface in OSPF for IPv6, users must manually configure the router with the list of neighbors. Neighboring routers are identified by their router ID.



In IPv6, users can configure many address prefixes on an interface. In OSPF for IPv6, all address prefixes on an interface are included by default. Users cannot select some address prefixes to be imported into OSPF for IPv6; either all address prefixes on an interface are imported, or no address prefixes on an interface are imported.



Unlike OSPF version 2, multiple instances of OSPF for IPv6 can be run on a link.


LSA Types for IPv6



The following list describes LSA types, each of which has a different purpose:



  • Router LSAs (Type 1)—Describes the link state and costs of a router's links to the area. These LSAs are flooded within an area only. The LSA indicates if the router is an Area Border Router (ABR) or Autonomous System Boundary Router (ASBR), and if it is one end of a virtual link. Type 1 LSAs are also used to advertise stub networks. In OSPF for IPv6, these LSAs have no address information and are network-protocol-independent. In OSPF for IPv6, router interface information may be spread across multiple router LSAs. Receivers must concatenate all router LSAs originated by a given router when running the SPF calculation.

  • Network LSAs (Type 2)—Describes the link-state and cost information for all routers attached to the network. This LSA is an aggregation of all the link-state and cost information in the network. Only a designated router tracks this information and can generate a network LSA. In OSPF for IPv6, network LSAs have no address information and are network-protocol-independent.

  • Interarea-prefix LSAs for ABRs (Type 3)—Advertises internal networks to routers in other areas (interarea routes). Type 3 LSAs may represent a single network or a set of networks summarized into one advertisement. Only ABRs generate summary LSAs. In OSPF for IPv6, addresses for these LSAs are expressed as prefix, prefix length instead of address, mask. The default route is expressed as a prefix with length 0.

  • Interarea-router LSAs for ASBRs (Type 4)—Advertise the location of an ASBR. Routers that are trying to reach an external network use these advertisements to determine the best path to the next hop. ASBRs generate Type 4 LSAs.

  • Autonomous system external LSAs (Type 5)—Redistributes routes from another AS, usually from a different routing protocol into OSPF. In OSPF for IPv6, addresses for these LSAs are expressed as prefix, prefix length instead of address, mask. The default route is expressed as a prefix with length 0.

  • Link LSAs (Type 8)—Have local-link flooding scope and are never flooded beyond the link with which they are associated. Link LSAs provide the link-local address of the router to all other routers attached to the link, inform other routers attached to the link of a list of IPv6 prefixes to associate with the link, and allow the router to assert a collection of Options bits to associate with the network LSA that will be originated for the link.

  • Intra-Area-Prefix LSAs (Type 9)—A router can originate multiple intra-area-prefix LSAs for each router or transit network, each with a unique link-state ID. The link-state ID for each intra-area-prefix LSA describes its association to either the router LSA or the network LSA and contains prefixes for stub and transit networks.



An address prefix occurs in almost all newly defined LSAs. The prefix is represented by three fields: PrefixLength, PrefixOptions, and Address Prefix. In OSPF for IPv6, addresses for these LSAs are expressed as prefix, prefix length instead of address, mask. The default route is expressed as a prefix with length 0. Type 3 and Type 9 LSAs carry all IPv6 prefix information that, in IPv4, is included in router LSAs and network LSAs. The Options field in certain LSAs (router LSAs, network LSAs, interarea-router LSAs, and link LSAs) has been expanded to 24 bits to provide support for OSPF in IPv6.



In OSPF for IPv6, the sole function of link-state ID in interarea-prefix LSAs, interarea-router LSAs, and autonomous-system external LSAs is to identify individual pieces of the link-state database. All addresses or router IDs that are expressed by the link-state ID in OSPF version 2 are carried in the body of the LSA in OSPF for IPv6.



The link-state ID in network LSAs and link LSAs is always the interface ID of the originating router on the link being described. For this reason, network LSAs and link LSAs are now the only LSAs whose size cannot be limited. A network LSA must list all routers connected to the link, and a link LSA must list all of the address prefixes of a router on the link.


NBMA in OSPF for IPv6



On NBMA networks, the designated router (DR) or backup DR (BDR) performs the LSA flooding. On point-to-point networks, flooding simply goes out an interface directly to a neighbor.



Routers that share a common segment (Layer 2 link between two interfaces) become neighbors on that segment. OSPF uses the Hello protocol, periodically sending hello packets out each interface. Routers become neighbors when they see themselves listed in the neighbor's hello packet. After two routers become neighbors, they may proceed to exchange and synchronize their databases, which creates an adjacency. Not all neighboring routers have an adjacency.



On point-to-point and point-to-multipoint networks, the software floods routing updates to immediate neighbors. There is no DR or BDR; all routing information is flooded to each networking device.



On broadcast or NBMA segments only, OSPF minimizes the amount of information being exchanged on a segment by choosing one router to be a DR and one router to be a BDR. Thus, the routers on the segment have a central point of contact for information exchange. Instead of each router exchanging routing updates with every other router on the segment, each router exchanges information with the DR and BDR. The DR and BDR relay the information to the other routers.



The software looks at the priority of the routers on the segment to determine which routers will be the DR and BDR. The router with the highest priority is elected the DR. If there is a tie, then the router with the higher router ID takes precedence. After the DR is elected, the BDR is elected the same way. A router with a router priority set to zero is ineligible to become the DR or BDR.



When using NBMA in OSPF for IPv6, you cannot automatically detect neighbors. On an NBMA interface, you must configure your neighbors manually using interface configuration mode.


Force SPF in OSPF for IPv6



When the process keyword is used with the clear ipv6 ospf command, the OSPF database is cleared and repopulated, and then the shortest path first (SPF) algorithm is performed. When the force-spf keyword is used with the clear ipv6 ospf command, the OSPF database is not cleared before the SPF algorithm is performed.


Load Balancing in OSPF for IPv6



When a router learns multiple routes to a specific network via multiple routing processes (or routing protocols), it installs the route with the lowest administrative distance in the routing table. Sometimes the router must select a route from among many learned via the same routing process with the same administrative distance. In this case, the router chooses the path with the lowest cost (or metric) to the destination. Each routing process calculates its cost differently and the costs may need to be manipulated in order to achieve load balancing.



OSPF performs load balancing automatically in the following way. If OSPF finds that it can reach a destination through more than one interface and each path has the same cost, it installs each path in the routing table. The only restriction on the number of paths to the same destination is controlled by the maximum-paths command. The default maximum paths is 16, and the range is from 1 to 64.


Importing Addresses into OSPF for IPv6



When importing the set of addresses specified on an interface on which OSPF for IPv6 is running into OSPF for IPv6, users cannot select specific addresses to be imported. Either all addresses are imported, or no addresses are imported.


OSPF for IPv6 Customization



You can customize OSPF for IPv6 for your network, but you likely will not need to do so. The defaults for OSPF in IPv6 are set to meet the requirements of most customers and features. If you must change the defaults, refer to the IPv4 configuration guide and the IPv6 command reference to find the appropriate syntax.







Caution Be careful when changing the defaults. Changing defaults will affect your OSPF for IPv6 network, possibly adversely.



How to Implement OSPF for IPv6



This section contains the following procedures:



Enabling OSPF for IPv6 on an Interface



This task explains how to enable OSPF for IPv6 routing and configure OSPF for IPv6 on each interface. By default, OSPF for IPv6 routing is disabled and OSPF for IPv6 is not configured on an interface.


SUMMARY STEPS

1. enable


2. configure terminal


3. interface type number


4. ipv6 ospf process-id area area-id [instance instance-id]


5. exit


DETAILED STEPS



































Command or Action

Purpose
Step 1

enable



Example:



Router> enable


Enables privileged EXEC mode.



  • Enter your password if prompted.


Step 2

configure terminal



Example:



Router# configure terminal


Enters global configuration mode.


Step 3

interface type number



Example:



Router(config)# interface ethernet 0/0


Specifies an interface type and number, and places the router in interface configuration mode.


Step 4

ipv6 ospf process-id area area-id [instance
instance-id]



Example:



Router(config-if)# ipv6 ospf 1 area 0


Enables OSPF for IPv6 on an interface.


Step 5

exit



Example:



Router(config-if)# exit


Exits interface configuration mode, and returns the router to global configuration mode.







Configuring NBMA Interfaces



You can customize OSPF for IPv6 in your network to use NBMA interfaces. OSPF for IPv6 cannot automatically detect neighbors over NBMA interfaces. On an NBMA interface, you must configure your neighbors manually using interface configuration mode.


Prerequisites



Before you configure NBMA interfaces, you must perform the following tasks:



  • Configure your network to be an NBMA network

  • Identify each neighbor


Restrictions



You cannot automatically detect neighbors when using NBMA interfaces. You must manually configure your router to detect neighbors when using an NBMA interface.


SUMMARY STEPS

1. enable


2. configure terminal


3. interface type number


4. frame-relay map ipv6 ipv6-address dlci [broadcast] [cisco] [ietf] [payload-compression {packet-by-packet frf9 stac [hardware-options] data-stream stac [hardware-options]}]


5. ipv6 ospf neighbor ipv6-address [priority number] [poll-interval seconds] [cost number] [database-filter all out]


6. exit


DETAILED STEPS







































Command or Action

Purpose
Step 1

enable



Example:



Router> enable


Enables privileged EXEC mode.



  • Enter your password if prompted.


Step 2

configure terminal



Example:



Router# configure terminal


Enters global configuration mode.


Step 3

interface type number



Example:



Router(config)# interface serial 0


Specifies an interface type and number, and places the router in interface configuration mode.


Step 4

frame-relay map ipv6 ipv6-address dlci
[broadcast] [cisco] [ietf] [payload-compression
{packet-by-packet frf9 stac
[hardware-options] data-stream stac
[hardware-options]}]


Example:



Router(config-if)# frame-relay map ipv6
FE80::A8BB:CCFF:FE00:C01 120


Defines the mapping between a destination IPv6 address and the data-link connection identifier (DLCI) used to connect to the destination address.



  • In this example, the NBMA link is frame relay. For other kinds of NBMA links, different mapping commands are used.


Step 5

ipv6 ospf neighbor ipv6-address [priority
number
] [poll-interval seconds] [cost number]
[database-filter all out]


Example:



Router(config-if) ipv6 ospf neighbor FE80::A8BB:CCFF:FE00:C01


Configures an OSPF for IPv6 neighboring router.


Step 6

exit



Example:



Router(config-if)# exit


Exits interface configuration mode, and returns the router to global configuration mode.







Forcing an SPF Calculation



This task explains how to start the SPF algorithm without first clearing the OSPF database.


SUMMARY STEPS

1. enable


2. clear ipv6 ospf [process-id] {process force-spf redistribution counters [neighbor [neighbor-interface]]}
























Command or Action

Purpose
Step 1

enable



Example:



Router> enable


Enables privileged EXEC mode.



  • Enter your password if prompted.


Step 2

clear ipv6 ospf [process-id] {process
force-spf
redistribution counters [neighbor
[neighbor-interface]]}


Example:



Router# clear ipv6 ospf force-spf


Clears the OSPF state based on the OSPF routing process ID.







Verifying OSPF for IPv6 Configuration and Operation



This task explains how to display information to verify the configuration and operation of OSPF for IPv6.


SUMMARY STEPS

1. enable


2. show ipv6 ospf [process-id] [area-id] interface [interface-type interface-number]


3. show ipv6 ospf [process-id] [area-id]


DETAILED STEPS



























Command or Action

Purpose
Step 1

enable



Example:



Router> enable


Enables privileged EXEC mode.



  • Enter your password if prompted.


Step 2

show ipv6 ospf [process-id] [area-id] interface
[interface-type interface-number]


Example:



Router# show ipv6 ospf interface


Displays OSPF-related interface information.


Step 3

show ipv6 ospf [process-id] [area-id]


Example:



Router# show ipv6 ospf


Displays general information about OSPF routing processes.







What to Do Next



For output examples of the commands used to verify OSPF for IPv6 configuration and operation, refer to the IPv6 for Cisco IOS Command Reference.


Configuration Examples for Implementing OSPF for IPv6



This section provides the following configuration examples:



Enabling OSPF for IPv6 on an Interface Configuration Example



The following example configures an OSPF routing process 109 to run on the interface and puts it in area 1:



ipv6 ospf 109 area 1

Configuring NBMA Interfaces Configuration Example



The following example configures an OSPF neighboring router with the IPv6 address of FE80::A8BB:CCFF:FE00:C01.



interface serial 0

ipv6 enable

ipv6 ospf 1 area 0

encapsulation frame-relay

frame-relay map ipv6 FE80::A8BB:CCFF:FE00:C01 120

ipv6 ospf neighbor FE80::A8BB:CCFF:FE00:C01

Forcing SPF Configuration Example



The following example triggers SPF to redo the SPF and repopulate the routing tables:



clear ipv6 ospf force-spf

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Sunday, November 30, 2008

Top Ten Cisco IOS Tip

When O'Reilly asked me to write a collection of hints and tips about Cisco routers, I knew that it would be difficult to come up with a list that would do justice to all the various features of a Cisco IOS device.
In hopes of making the list smaller and more useful, I decided to list ten tips that discuss situations I have encountered either through my own experience or that were sparked by other people's questions. Some of these hints are simple while others a little more advanced. Whether you are a novice or an expert, I hope you will find them useful.
1. Commands take effect right away.
If you are an experienced Cisco router user, you probably just groaned. However, I find that this concept escapes new users.
As you type commands into the configuration mode, they immediately take effect. For example, if we change the router's name, we see that the very next line contains the new router name:

Router1#config terminal
Enter configuration commands, one per line. End with CNTL/Z.
Router1(config)#hostname MyRouter
MyRouter(config)#^Z
MyRouter#
As you can see, we changed the router's name to MyRouter, which was immediately processed. This concept applies to everything in the router's configuration mode.
2. Use all the descriptions you can.
In the router's configuration, there are certain commands that let you document various portions of a configuration. For example, the interface description command, an access-list remark command, or a banner message. All of these commands stay within the router configuration, which helps greatly when you are trying to configure or troubleshoot a router.
Here's an example of a description on an interface:

! Here is an interface description.
! Document as much about the interface as possible
interface Serial0
description Connection To Irvine: Wan ID [23499]
The available banner messages are the message of the day, or MOTD, login, incoming, and exec. Consult the documentation or Cisco IOS in a Nutshell for a description of each. Here is an example of the MOTD banner, which is the first message a person sees when connecting to the device:

MyRouter(config)#banner motd #
Enter TEXT message. End with the character '#'.
Welcome to MyRouter.
Some legalese should go here about unauthorized access.
#
The remark statement in an access-list is a relatively new feature. It first appeared in version 12.0(2)T of the IOS. This handy command allows you to make an entry in your access-list that describes what you are trying to accomplish. The comment can be up to 100 characters in length. <>statements work for both numbered and named access-lists.

access-list 1 remark Permit our private network through the list
access-list 1 permit 10.1.1.0 0.0.0.255
access-list 1 remark Just deny everything else
access-list 1 deny any
You might be wondering about commenting a configuration with the "!" symbol.
Yes, you can comment a configuration with a "!" as I have done in the above examples. However, these comments do not stay in the router configuration. They are great when you are working on a configuration offline in a text editor. (Where you plan to upload the configuration to a router.)
However, these "!" comments will get lost when you send the configuration to the router because the router ignores them.
3. The reload command can get you out of a jam.
Related Reading
Cisco IOS in a NutshellBy James BoneyDecember 2001Table of ContentsIndexSample ExcerptFull Description
4. No matter how well you plan an upgrade, you are eventually going to need to change a router configuration remotely. If you make a mistake and can no longer get to the router because of the change you made, you have to make the embarrassing call to someone to go "hit the power." The power cycle takes the router back to the original starting configuration because your change was never saved. In other words, since you lost connection, you couldn't type "copy run start" to save your changes.
5. One of the classic mistakes (I know because I have done it myself a number of times) is to incorrectly update an access-list on an interface when you are connected to the device remotely. And suddenly, the Telnet connection is dropped to the router because of a forgotten list entry that would permit your incoming connection.
6. There is another way. When you are doing something tricky, you can use the following feature of the reload command, which causes the router to reboot in a certain number of minutes. For example, let's tell the router to reboot in three minutes.
7.
8. MyRouter#reload in 3
9. Reload scheduled in 3 minutes
10. Proceed with reload? [confirm]y
11. Now, we have three minutes to do what we need to do. Let's say we are applying an access-list to serial0.
12.
13. MyRouter#config terminal
14. Enter configuration commands, one per line. End with CNTL/Z.
15. MyRouter(config)#interface serial0
16. MyRouter(config-if)#ip access-group 110 in
17. MyRouter(config-if)#^Z
18. MyRouter#
19. We made the change and everything still works. (Well, at least our connection wasn't dropped.) Now all we have to do cancel the impending reload with the following command:
20.
21. MyRouter#reload cancel
22. Or, if our access-list update did destroy our connection to the router, all we need to do is wait three minutes (plus the router's reload time) before the router is back online. After the reload, the router uses the original saved configuration before our access-list change.
23. Don't forget to add either an enable password or an enable secret password.
If you are planning to telnet into your router remotely, you need to add an enable password or enable secret password, or the router will not allow you to go to enable mode. Of course, it goes without saying that adding an enable password is always a good thing.

! Enable service password-encryption if it isn't already.
service password-encryption
! Here is our enable password, which is ok
! but not too secure.
enable password 7 141B171F01012325
! Here is our enable secret, much better.
enable secret 5 $1$99Jc$dxVXUkwMM3Edvj7f0SUrL/
Don't forget that "enable secret" overrides the "enable" password. Just be safe and use the enable secret command. The enable secret uses a better encryption method to encode the password.
24. Stopping the router from trying to telnet.
This is often an annoying problem. Mistype a command and the router thinks you just typed a hostname. For example:

MyRouter#shwo
Translating "shwo"...domain server (10.1.1.2)
% Unknown command or computer name, or unable to find computer address
MyRouter#
Here, we just mistyped the word show. We didn't want to telnet to a device named "shwo." The way to handle this is to change the preferred transport method:

! Console port
line con 0
transport preferred none
! VTY Ports
line vty 0 5
transport preferred none
The output shows the lack of a failed connection based on our mistyped keyword:

MyRouter#shwo
^
% Invalid input detected at '^' marker.

6. Two common access-list pitfalls.
The first common access-list problem I have seen is not allowing some ICMP (Internet Control Message Protocol) traffic through a gateway firewall.
For example, you just configured an access-list on your DSL link for your home router. All of the sudden, when you send big transmissions like a large email attachment, you find your connections timing out or closing unexpectedly. Unsure, you take the access-list off and the problem goes away. When you put the access-list back on, the problem reappears. You ask yourself what happened as you review the access-list. Well, the problem is as simple as not permitting ICMP through your list.
As I say in Cisco IOS in a Nutshell, people often think of ICMP as the hacker's tool. But in reality, it plays a very important role. In the problem I just described, it sounds like an MTU (Maximum Transmission Unit) or source-quench problem, which means the ICMP information isn't getting through the access-list. Either way, add the following commands to your access-list and your problems might go away:

! allow pings into the network
access-list 110 permit icmp any any echo
! allow ping responses
access-list 110 permit icmp any any echo-reply
! allow ICMP source-quench
access-list 110 permit icmp any any source-quench
! allow path MTU discovery
access-list 110 permit icmp any any packet-too-big
! allow time-exceeded, which is useful for traceroute
access-list 110 permit icmp any any time-exceeded
! deny all other ICMP packets
access-list 110 deny icmp any any
A second common access-list pitfall is when people forget to allow DNS (Domain Name Servers) from their internal network to the provider's DNS servers. Mainly this is a problem on home or small office routers where you might not have an internal DNS server running.
The following command allows DNS access from your hosts to the outside DNS server. In this example, our outside DNS servers are 172.16.1.1 and 172.30.1.1

access-list 110 permit udp host 172.16.1.1 eq domain any gt 1023
access-list 110 permit udp host 172.30.1.1 eq domain any gt 1023
7. Useful show commands.
Configuration of a router is only half the battle. Without a good toolbox of show commands, configuring your router properly will be very difficult. Throughout the tutorial section of my book, I tried to include the appropriate show commands for each topic.
But here are some of the most useful show commands that you should have at a minimum. Of course, the bias here is towards IP.
show ip arp
Displays the entire ARP (Address Resolution Protocol)table, which is the MAC-to-IP resolution table.
show version
This command gives a good amount of information; the IOS version you are running, the available interfaces, the system uptime, the last reload reason, and the configuration register setting.
show ip protocols
Displays information about the currently running routing protocols.
show ip route
The old standby, which displays the entire IP route table.
show ip route summary
Gives a very useful summary of the IP route table.
show ip interface
Gives a summary of each interface from the IP level.
show ip interface brief
A very brief summary of each interface.
show ip traffic
An extensive summary of IP traffic statistics on the router.
show access-list
This useful command not only shows the all the currently configured access-lists, but it also shows you the number of hits each line has received. You can use this information to better troubleshoot your access-lists.
show cdp neighbors
Assuming you have CDP enabled, this command gives you a report of all Cisco devices that the current device is connected to. CDP stands for Cisco Discovery Protocol, which can be an invaluable tool.
show cdp neighbors detail
This command gives even more information about CDP neighbors.
8. Learn the command-line editing keys.
When spending time on a Cisco IOS device, it is good to know some of the hot keys. People are always surprised (so it seems) that these editing keys even exist. If you are familiar with Unix, these commands will also look familiar. (The Bash shell, for example, uses a very similar list of keys.)
The entire list is included in Cisco IOS in a Nutshell. But here are a few to get you started:

Control A Goes to the beginning of the line
Control E Goes to the end of the line
Control K Deletes everything to the right of the cursor
Control P Recalls the previous command in the history buffer
Control N Recalls the next command in the history buffer
9. A common frame-relay misunderstanding.
The encapsulation type on the physical interface must be set to frame-relay before any sub-interfaces can be created. The default encapsulation type is usually HDLC (High-level Data Link Control).
So, before starting to create our frame-relay sub-interfaces, we need to first set the encapsulation type to frame-relay on the physical interface:

interface serial0
encapsulation frame-relay
Now we can create our sub-interfaces:

interface serial0.1 point-to-point
description This is our first sub interface for serial1
10. Setting the bandwidth on serial links.
Setting the bandwidth on a serial interface has nothing to do with the actual link speed. Rather, it provides the value that some routing protocols use in calculating routing metrics. The default bandwidth is 1.544mps, which is the speed of a T1 link.
However, if you aren't using a T1, setting your bandwidth on serial links is always a good (and sometimes forgotten) idea.

interface serial0
description This is a 56k link
bandwidth 56
That's it for now. I hope these tips will help you avoid some of the common pitfalls of dealing with Cisco IOS devices.
James Boney is a consultant specializing in a wide variety of subjects, including network design, network management, Unix administration, and programming.

Friday, November 28, 2008

Getting Your Dream Job


Essentially, a letter of application should be brief and to the point. In terms of length, it should not exceed a single page. And to make it more effective in serving its purpose, the letter should meet the following three objectives:1. Express interest in the job for which you are applying.2. Brie�ly show how your background and work experience qualify you for the job. 3. Ask for an interview. As we found out in earlier chapters, when the application letter >>>>>>>>>>>>>>>>>>

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Thursday, November 27, 2008

welcome Fedora 10


As always, Fedora continues to develop (http://www.fedoraproject.org/wiki/RedHatContributions) and integrate the latest free and open source software (http://www.fedoraproject.org/wiki/Features.) The following sections provide a brief overview of major changes from the last release of Fedora. For more details about other features that are included in Fedora 10, refer to their individual wiki pages that detail feature goals and progress:
http://www.fedoraproject.org/wiki/Releases/10/FeatureList
Throughout the release cycle, there are interviews with the developers behind key features giving out the inside story:
http://www.fedoraproject.org/wiki/Interviews
The following are major features for Fedora 10:
Wireless connection sharing enables ad hoc network sharing -- http://www.fedoraproject.org/wiki/Features/ConnectionSharing
Better setup and use of printers through improved management tools -- http://www.fedoraproject.org/wiki/Features/BetterPrinting
Virtualization storage provisioning for local and remote connections now simplified -- http://www.fedoraproject.org/wiki/Features/VirtStorage
SecTool is a new security audit and intrusion detection system -- http://www.fedoraproject.org/wiki/Features/SecurityAudit
RPM 4.6 is a major update to the powerful, flexible software management libraries -- http://www.fedoraproject.org/wiki/Features/RPM4.6
Some other features in this release include:
Glitch free audio and better performance is achieved through a rewrite of the PulseAudio sound server to use timer-based audio scheduling -- http://www.fedoraproject.org/wiki/Features/GlitchFreeAudio
Improved webcam support -- http://www.fedoraproject.org/wiki/Features/BetterWebcamSupport
Better support for infrared remote controls makes them easier to connect and work with many applications -- http://www.fedoraproject.org/wiki/Features/BetterLIRCSupport
The paths /usr/local/sbin:/usr/sbin:/sbin have been added to the PATH for normal users, to simplify command-line administration tasks -- http://fedoraproject.org/wiki/Features/SbinSanity
The online account service provides applications with credentials for online accounts listed on http://online.gnome.org/ or stored in GConf -- http://www.fedoraproject.org/wiki/Features/OnlineAccountsService
Download Gnome
Download KDE

IT Essentials & Wirless OnLine Curriculum



IT Essentials









Wireless LAN (WLAN) Fundamentals



CCNP OnLine Curriculum

Cisco Network Academy


Advanced Routing



Implementing Secure Cisco Wide Area Networks



Multilayer Switched Networks



Optimizing Network Technologies (ONT or OCN)

Wednesday, November 26, 2008

CCNA Exploration OnLine Curriculum


CIS 81 Networking Fundamentals



CIS 82 Routing Protocols, Concepts, and Theory



CIS 83 LANs, Switching, and WANS



CCNA Discovery OnLine Curriculum


(Introductory Level Curriculum - Not used in CNSA courses)


CCNA 1 version 4.0

CCNA 2 version 4.0

CCIE vLecture Seminar Series


The vLecture Seminar Series offers focused online discussions led by the renowned CCIE-certified instructors at IPexpert. Each seminar concentrates on a specific topic related to CCIE or CCDE preparation, including individual protocols and technologies listed on the lab blueprint, as well as test-taking strategies!
CCIE vLecture Seminar Series Details
All vLecture sessions are conducted by one of the industry-recognized instructors at IPexpert.
Each seminar lasts approximately one to two hours.

Interested in attending a vLecture?
To view the schedule of upcoming vLectures and to register for free, click here.

View Previous vLectures Free
CCIE Related Topics: All Tracks
The Psychology of the CCIE lab and how to plan an attack.
CCIE R&S Related Topics
Basic Multicast Design/Operations
Frame Relay
OSPF
Layer 2 Tunneling Techniques
Spanning-Tree
Troubleshooting on the CCIE Lab
Multicast- Anycast RP
Binary Math: Subnetting / access-lists
CCIE Voice Related Topics
SRST
Unity
H323 Gatekeeper Basics
IPMA
WAN QoS
Digit Manipulation on CallManager 4.1(3) & CME 3.3
Troubleshooting in the CCIE Lab
Advanced Call Routing
Unity, Unity Express, & VPIM
Basic-ACD: Part 1, Part 2
Campus QOS
CCIE Security Related Topics
DMVPN
Binary Math: Subnetting / access-lists
CCIE Service Provider Related Topics
ATM Operations and Configuration

Cisco To Shut Down For 4 Days At Year End


Updated with Cisco Confirmation: If you want to know how bad it is going to get for all of us in Silicon Valley, just look at Cisco Systems. For first time in its history the company is going to shut down for four days at the end of the year, according to a report by UBS Research. Remember when such shutdowns were associated with industrial era companies? Well, this is the new past as they say. I heard that a major internal annual event has been put on hold as well.

Cisco’s four-day shutdown is part of an effort by the company to save $1 billion. It might be more than just cost savings because Cisco (and many of us) doesn’t have visibility into 2009. Cisco, as a company has just seen Wall Street, a major customer shrink in size. At the same time it is facing low-cost competition from Dell, HP and Huawei. The New York Times is correct in identifying HP’s ProCurve businesses as slowly becoming a major competitor to Cisco. “HP is a much more formidable challenger to Cisco, and it has sent an obvious message,” Nikos Theodosopoulos, an analyst at UBS Securities told The Times.

Cisco has confirmed the shutdown and other cuts in a blog posting pointing out that it had started talking about these initiatives following its Q1 2009 earnings release

We will be target reductions in travel and discretionary-related expenses, including offsites, outside services, equipment, events, trade shows, marketing and other activities. As part of this effort, we will also implement a year-end shutdown of the US-Canada theater from December 29, 2008, through January 2, 2009 (note that January 1 is already a holiday). There will be some exceptions for targeted business-critical teams including technical assistance services and channel partner and customer product ordering services.

While this is not our first year-end shutdown as we followed this longstanding Silicon Valley practice in our early years as a company, it is our first in over a decade. Given the difficult macroeconomic conditions, we believe our cost control focus at this time is appropriate while still providing our partners and customers with critical services over the holiday period.

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Tuesday, November 25, 2008

ATI CrossFire


"Crossfire" redirects here. For other uses, see Crossfire (disambiguation).
CrossFire (also CrossFire X after release of the Spider desktop platform on November 19, 2007) is a brand name for ATI Technologies' multi-GPU solution, which competes with Scalable Link Interface (SLI) from NVIDIA. The technology allows up to four graphics cards to be used in a single computer to improve graphics performance. Although only recently announced for consumer level hardware, similar technology known as AMR has been used for some time in professional grade cards for flight simulators and similar applications available from Evans & Sutherland, ATI had also previously released a similar dual RAGE 128 consumer card called the Fury MAXX.

Contents

1 Configurations
1.1 First-generation
1.2 Second-generation (Software CrossFire)
1.3 Current generation (CrossFire X)
2 Comparisons to NVIDIA SLI
2.1 Advantages
2.2 Disadvantages
3 See also
4 References
5 External links



Configurations

First-generation
CrossFire was first made available to the public on September 27, 2005.[1]

The system required a CrossFire-compliant motherboard with a pair of ATI Radeon PCI Express (PCIe) graphics cards. Radeon x800s, x850s, x1800s and x1900s came in a regular edition, and a 'CrossFire Edition' which has 'master' capability built into the hardware. 'Master' capability is a term used for 5 extra image compositing chips, which combine the output of both cards.[2] One had to buy a Master card, and pair it with a regular card from the same series. The Master card would have shipped with a proprietary DVI Y-dongle, which would plug into the primary DVI ports from both cards, and into the monitor cable. This dongle serves as the main link between both cards, sending incomplete images between them, and complete images to the monitor. Low-end Radeon x1300 and x1600 cards have no 'CrossFire Edition' but are enabled via software, with communication forwarded via the standard PCI Express slots on the motherboard. ATI currently has not created the infrastructure to allow FireGL cards to be set up in a CrossFire configuration. The 'slave' graphics card needed to be from the same family as the 'master'.

An example of a limitation in regard to a Master-card configuration would be the first-generation CrossFire implementation in the Radeon X850 XT Master Card. Because it used a compositing chip from Silicon Image (SiI 163B TMDS), the maximum resolution on an X850 CrossFire setup was limited to 1600×1200 at 60 Hz, or 1920×1440 at 52 Hz. This was considered a problem for CRT owners wishing to use CrossFire to play games at high resolutions, or owners of Widescreen LCD monitors. As many people found a 60 Hz refresh rate with a CRT to strain ones eyes, the practical resolution limit became 1280×1024, which did not push CrossFire enough to justify the cost.[3] The next generation of CrossFire, as employed by the X1800 Master cards, used two sets of compositing chips and a custom double density dual-link DVI Y-dongle to double the bandwidth between cards, raising the maximum resolution and refresh rate to far higher levels.


Second-generation (Software CrossFire)
When used with ATI's "CrossFire Xpress 3200" motherboard chipset, the 'master' card is no longer required for every "CrossFire Ready" card (with the exception of the Radeon X1900 series). With the CrossFire Xpress 3200, two normal cards can be run in a Crossfire setup, using the PCI-E bus for communications. This is similar to X1300 CrossFire, which also uses PCI Express, except that the Xpress 3200 had been built for low-latency and high-speed communication between graphics cards.[4] While performance was impacted, this move was viewed as an overall improvement in market strategy, due to the fact that Crossfire Master cards were expensive, in very high demand, and largely unavailable at the retail level.

Although the CrossFire Xpress 3200 chipset is indeed capable of CrossFire through the PCI-e bus for every Radeon series below the X1900s, the driver accommodations for this CrossFire method has not yet materialized for the X1800 series. ATI has said that future revisions of the Catalyst driver suite will contain what is required for X1800 dongleless CrossFire, but has not yet mentioned a specific date.


Current generation (CrossFire X)
With the release of the Radeon X1950 Pro (RV570 GPU), ATI has completely revised CrossFire's connection infrastructure to further eliminate the need for past Y-dongle/Master card and slave card configurations for CrossFire to operate. ATI's CrossFire connector is now a ribbon-like connector attached to the top of each graphics adapter, similar to nVidia's SLi bridges, but different in physical and logical natures.[5] As such, Master Cards no longer exist, and are not required for maximum performance. Two dongles can be used per card; these were put to full use with the release of CrossFire X. Radeon HD 2900 and HD 3000 series cards use the same ribbon connectors, but the HD 3800 series of cards only require one ribbon connector, to facilitate CrossFire X.[6] Unlike older series of Radeon cards, different HD 3800 series cards can be combined in CrossFire, each with separate clock control.

Since the release of the codenamed Spider desktop platform from AMD on November 19, 2007, the CrossFire setup has been updated with support for a maximum of four video cards with the 790FX chipset; the CrossFire branding was then changed to "ATI CrossFire X". The setup, according to internal testing by AMD, will bring at least 3.2x performance increase in several games and applications which required massive graphics capabilities of the computer system, the setup is targeted to the enthusiast market. A later development include a dual GPU solution that was released in early 2008, the "ATI Radeon HD 3870 X2", featuring only one CrossFire connector for dual card, four GPU scalability.


Comparisons to NVIDIA SLI

Advantages
ATI has opened the Crossfire architecture to Intel, allowing CrossFire to be enabled on certain Intel chipsets which boast two 16x PCI-E slots. SLI, however, requires a motherboard which is SLI certified (usually based on nForce chipset, such as the nForce 590 SLI, nForce 680i SLI, and nForce 790i.
On the codenamed Spider platform, utilizing CrossFireX with AMD 790FX chipset and Radeon HD 3800 series video cards, the user can use multiple displays and maintain CrossFire functionality while SLI and previous generation CrossFire setups are limited to one display only.[7]

Disadvantages
If an OpenGL game does not have a Crossfire profile, the Catalyst AI system will set the rendering mode to Scissor by default, with no way to change it to a more suitable or faster mode, such as AFR. However SLI allows the rendering mode to be set for each application manually, even for games which do not have an existing profile. It should be noted that setting Catalyst AI to 'Advanced' allows manual mode setting for Direct 3D games, but not OpenGL games, to AFR.
The first generation CrossFire implementations (the Radeon X800 to X1900 series) require an external y-cable/dongle to operate in CrossFire mode due to the PCI-e bus not being able to provide enough bandwidth to run CrossFire without losing a significant amount of performance.
Application support for Crossfire is not very good, meaning many games may see little to no added benefit of adding a second card, where games that support it may see up to 100% increase

Friday, November 21, 2008

Windows Desktop History

1985: Windows 1.0
The first version of Windows provided a new software environment for developing and running applications that use bitmap displays and mouse pointing devices. Before Windows, PC users relied on the MS-DOS® method of typing commands at the C prompt (C:\). With Windows, users moved a mouse to point and click their way through tasks, such as starting applications.
In addition, Windows users could switch among several concurrently running applications. The product included a set of desktop applications, including the MS-DOS file management program, a calendar, card file, notepad, calculator, clock, and telecommunications programs, which helped users manage day-to-day activities.


1987: Windows 2.0
Windows 2.0 took advantage of the improved processing speed of the Intel 286 processor, expanded memory, and inter-application communication capabilities made possible through Dynamic Data Exchange (DDE). With improved graphics support, users could now overlap windows, control screen layout, and use keyboard combinations to move rapidly through Windows operations. Many developers wrote their first Windows–based applications for this release.
The follow-up release, Windows 2.03, took advantage of the protected mode and extended memory capabilities of the Intel 386 processor. Subsequent Windows releases continued to improve the speed, reliability, and usability of the PC as well as interface design and capabilities.


1990: Windows 3.0
The third major release of the Windows platform from Microsoft offered improved performance, advanced graphics with 16 colors, and full support of the more powerful Intel 386 processor. A new wave of 386 PCs helped drive the popularity of Windows 3.0, which offered a wide range of useful features and capabilities, including:

Program Manager, File Manager, and Print Manager.

A completely rewritten application development environment.

An improved set of Windows icons.
The popularity of Windows 3.0 grew with the release of a new Windows software development kit (SDK), which helped software developers focus more on writing applications and less on writing device drivers. Widespread acceptance among third-party hardware and software developers helped fuel the success of Windows 3.0.


1993: Windows NT 3.1
When Microsoft Windows NT® was released to manufacturing on July 27, 1993, Microsoft met an important milestone: the completion of a project begun in the late 1980s to build an advanced new operating system from scratch. "Windows NT represents nothing less than a fundamental change in the way that companies can address their business computing requirements," Microsoft Chairman Bill Gates said at its release.
That change is represented in the product's name: "NT" stands for new technology. To maintain consistency with Windows 3.1, a well-established home and business operating system at the time, the new Windows NT operating system began with version 3.1. Unlike Windows 3.1, however, Windows NT 3.1 was a 32-bit operating system.
Windows NT was the first Windows operating system to combine support for high-end, client/server business applications with the industry's leading personal productivity applications. It was initially available in both a desktop (workstation) version and a server version called Windows NT Advanced Server. The desktop version was well received by developers because of its security, stability, and Microsoft Win32® application programming interface (API)—a combination that made it easier to support powerful programs. The result was a strategic business platform that could also function as a technical workstation to run high-end engineering and scientific applications.


1993: Windows for Workgroups 3.11
A superset of Windows 3.1, Windows for Workgroups 3.11 added peer-to-peer workgroup and domain networking support. For the first time, Windows–based PCs were network-aware and became an integral part of the emerging client/server computing evolution.
Windows for Workgroups was used in local area networks (LANs) and on standalone PCs and laptop computers. It added features of special interest to corporate users, such as centralized configuration and security, significantly improved support for Novell NetWare networks, and remote access service (RAS).


1994: Windows NT Workstation 3.5
The Windows NT Workstation 3.5 release provided the highest degree of protection yet for critical business applications and data. With support for the OpenGL graphics standard, this operating system helped power high-end applications for software development, engineering, financial analysis, scientific, and business-critical tasks.
The product also offered 32-bit performance improvements and better application support, including support for NetWare file and print servers. Other improved productivity features included the capability to use friendlier, long file names of up to 255 characters.


1995: Windows 95
Windows 95 was the successor to the three existing general-purpose desktop operating systems from Microsoft—Windows 3.1, Windows for Workgroups, and MS-DOS. Windows 95 integrated a 32-bit TCP/IP (Transmission Control Protocol/Internet Protocol) stack for built-in Internet support, dial-up networking, and new Plug and Play capabilities that made it easy for users to install hardware and software.
The 32-bit operating system also offered enhanced multimedia capabilities, more powerful features for mobile computing, and integrated networking.


1996: Windows NT Workstation 4.0
This upgrade to the Microsoft business desktop operating system brought increased ease of use and simplified management, higher network throughput, and tools for developing and managing intranets. Windows NT Workstation 4.0 included the popular Windows 95 user interface yet provided improved networking support for easier and more secure access to the Internet and corporate intranets.
In October 1998, Microsoft announced that Windows NT would no longer carry the initials NT and that the next major version of the business operating system would be called Windows 2000.

1998: Windows 98
Windows 98 was the upgrade from Windows 95. Described as an operating system that "Works Better, Plays Better," Windows 98 was the first version of Windows designed specifically for consumers.
With Windows 98, users could find information more easily on their PCs as well as the Internet. Other ease-of-use improvements included the ability to open and close applications more quickly, support for reading DVD discs, and support for universal serial bus (USB) devices.

1999: Windows 98 Second Edition
Windows 98 SE, as it was often abbreviated, was an incremental update to Windows 98. It offered consumers a variety of new and enhanced hardware compatibility and Internet-related features.
Windows 98 SE helped improve users' online experience with the Internet Explorer 5.0 browser technology and Microsoft Windows NetMeeting® 3.0 conferencing software. It also included Microsoft DirectX® API 6.1, which provided improved support for Windows multimedia, and offered home networking capabilities through Internet connection sharing (ICS). Windows 98 SE was also the first consumer operating system from Microsoft capable of using device drivers that also worked with the Windows NT business operating system.

2000: Windows Millennium Edition (Windows Me)
Designed for home computer users, Windows Me offered consumers numerous music, video, and home networking enhancements and reliability improvements.
For example, to help consumers troubleshoot their systems, the System Restore feature let users roll back their PC software configuration to a date or time before a problem occurred. Windows Movie Maker provided users with the tools to digitally edit, save, and share home videos. And with Microsoft Windows Media® Player 7 technologies, users could find, organize, and play digital media easily.
Windows Me was the last Microsoft operating system to be based on the Windows 95 code base. Microsoft announced that all future operating system products would be based on the Windows NT and Windows 2000 kernel.

2000: Windows 2000 Professional
More than just the upgrade to Windows NT Workstation 4.0, Windows 2000 Professional was also designed to replace Windows 95, Windows 98, and Windows NT Workstation 4.0 on all business desktops and laptops. Built on top of the proven Windows NT Workstation 4.0 code base, Windows 2000 added major improvements in reliability, ease of use, Internet compatibility, and support for mobile computing.
Among other improvements, Windows 2000 Professional simplified hardware installation by adding support for a wide variety of new Plug and Play hardware, including advanced networking and wireless products, USB devices, IEEE 1394 devices, and infrared devices.

2001: Windows XP
With the release of Windows XP in October 2001, Microsoft merged its two Windows operating system lines for consumers and businesses, uniting them around the Windows 2000 code base.
The "XP" in Windows XP stands for "experience," symbolizing the innovative experiences that Windows can offer to personal computer users. With Windows XP, home users can work with and enjoy music, movies, messaging, and photos with their computer, while business users can work smarter and faster, thanks to new technical-support technology, a fresh user interface, and many other improvements that make it easier to use for a wide range of tasks.

2001: Windows XP Professional
Windows XP Professional brings the solid foundation of Windows 2000 to the PC desktop, enhancing reliability, security, and performance. With a fresh visual design, Windows XP Professional includes features for business and advanced home computing, including remote desktop support, an encrypting file system, and system restore and advanced networking features. Key enhancements for mobile users include wireless 802.1x networking support, Windows Messenger, and Remote Assistance.

2001: Windows XP Home Edition
Windows XP Home Edition offers a clean, simplified visual design that makes frequently used features more accessible. Designed for home users, the product offers such enhancements as the Network Setup Wizard, Windows Media Player, Windows Movie Maker, and enhanced digital photo capabilities.

2001: Windows XP 64-bit Edition

Windows XP 64-Bit Edition satisfies the needs of power users with workstations that use the Intel Itanium 64-bit processor. The first 64-bit client operating system from Microsoft, Windows XP 64-Bit Edition is designed for specialized, technical workstation users who require large amounts of memory and floating point performance in areas such as movie special effects, 3D animation, engineering, and scientific applications.

2002: Windows XP Media Center Edition

For home computing and entertainment, Microsoft released the Windows XP Media Center Edition operating system in October 2002 for specialized media center PCs.
With all the benefits of Windows XP Professional, Media Center Edition adds fun digital media and entertainment options, enabling home users to browse the Internet, watch live television, communicate with friends and family, enjoy digital music and video collections, watch DVDs, and work from home.

2002: Windows XP Tablet PC Edition

The long-held industry vision of mainstream pen-based computing became a reality when Microsoft unveiled the Windows XP Tablet PC Edition in November, 2002. The logical evolution of notebook computers, Tablet PCs include a digital pen for handwriting recognition capabilities, yet can be used with a keyboard or mouse, too.
In addition, users can run their existing Windows XP applications. The result is a computer that is more versatile and mobile than traditional notebook PCs.

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