Cisco has a really good tech support hot line. I put in a TAC request for a pretty simple question about not being able to configure the serial port.
Create Serial Sub Interface Cisco 2811
"Hi. I can't access the serial port, was trying to configure serial 1/0 on my router cisco 2811 but I guess it does not exist?
The cisco online help says to try
Controller t1 0/0/0
Framing esf
Linecode b8zs
Channel-group 0 timeslots 1-24 speed 64
I did show controllers and all kinds of hardware descriptions pop up but not t1 specifically
The router didn't know what to do with the controller command, I checked the hardware but it does not have a serial port. Is that possible?"
I guess I could pause next time, and give the guy a chance to talk or take notes. Anyway I couldn't immediately provide the serial number on the unit cuz I wasn't logged in and I didn't have the service contract searchable right in front of me. So I mention that I will login and write up the TAC online. While clicking online and trying to find the TAC gui, I stumble upon the link for T1 HWIC cards, like the one that is NOT even plugged into to my unit. There is no WAN interface and link connected, the T1 truly does not exist!
I didn't even have a Cisco T1/ E1 WAN Interface Cards
Anywayz I feel rather silly about calling in the first place but now I have confirmed that the show controller command really works! Once again it is the USER error.
Showing posts with label Cisco Hardware. Show all posts
Showing posts with label Cisco Hardware. Show all posts
Monday, March 5, 2012
Monday, February 20, 2012
Superpowers in the Super Computing Race
Forget the arms race, it's all about supremacy in super computers and math skills. I saw a desktop CRAY computer running the simulations for certain DSP solution for Matlab and Simulink, and it got me thinking, well what if I had a business case and I could ask my boss to buy me one? First off though, I would have to clearly explain what is 786 gigaflops, and if it will run Linux.
A teraflop is a measure of a computer's computing speed or processing power, based on the acronym FLOPS - Floating Operations Per Second. A teraflop is a trillion or 10 to the 12th-power flops (Note the use of the plural, no need for an additional "s"), available on the market for most affordable parallel computing solutions. And of course, within the realm of possibility or imagination is a computer capable of petaflops, a thousand teraflops or a quadrillion (thousand trillion) flops.
Supercomputers are capable of so many amazing tasks, previously to discover new elements, detect dark matter components. simulate nuclear chain reaction or particle collisions. At present, they can model climate change, crack codes, model protein behaviours and drug reactions. Therefore it's obvious that the top buyers include the biosciences, computer aided engineering and defense industries. Hewlett-Packard, Dell and IBM are all competitors in the market. This CRAY system came out in 2008, so I'm a bit 2000-and-late but in this world, by the time you've already built and deployed the number one system, someone has already imagined something 20 times better.
Canada
As of Nov 2011, Canada did not have a system listed within the public top 500 supercomputer list. Boo.
However we do see Supercomputers on the trading floor at the Toronto Stock Exchange (perhaps the server room) called electronic traders. Math geeks design the algorithms (users input parameters like selling or holding thresholds) or dark pools (when trades have to be hidden from algorithms).
Computation resource allocation on the SciNet, another system at the University of Toronto is very competitive though. The Compute Canada's Resource Allocation Committees are in charge of connecting researchers with computational and personnel resources to run calculations for biomedical research, climate change modeling and even galaxy formation simulations.
Japan
Japan ranks number one. As of Nov 2011, the K Computer, based at the Riken Advanced Institute for Computational Science in Japan was the first to clear 10 petaflops, beating its own record. Hardware includes 705,024 Fujitsu Sparc64 processor cores.
Read more: http://news.cnet.com/8301-30685_3-57324194-264/japanese-supercomputer-first-to-clear-10-petaflops/#ixzz1mwp3L6yU
US
The Blue Gen/L can do 0.5 Quadrillion operations per second, the most powerful in 2005-2008. The Blue Gen is deployed at Livermore, San Francisco where 263 supercomputers from the Top 500 list also reside.
The up and coming Sequoia is being built by IBM, for end 2012, capable of 20 quadrillion operations per second, that's 20 petaflops. The main challenges being to write software to run across all the chips amounting to 1.6 million processors 96 racks of 32 slim servers
I like the supercomputer made from many old model Sony PS3's in parallel used by the US Air Force for satellite imagery analysis, demonstrated years ago. Many researchers have already done the same though this is no longer possible with newer generation PS3.
China
In Nov 2010 China was number one with the Tianhe-1A doing 2.5 Quadrillion operations per second
by Dawning Information Industry Ltd. Tianhue means "The Milky Way", although surpassed within six weeks by Japan. Another amazing fact, China owns 74 of the 500 biggest supercomputers in the world
By 2020 the Chinese have something in the works to rival 500x Sequoia and 8x power of Tianhe
Cisco
Anyway it's not supercomputing but here is the fastest Cisco switch ever. http://www.cisco.com/en/US/prod/collateral/switches/ps5718/ps6021/product_data_sheet0900aecd8017a72e.html I'm bringing this up simply because one has to consider connectivity to these super computers and all the glorious applications.
A teraflop is a measure of a computer's computing speed or processing power, based on the acronym FLOPS - Floating Operations Per Second. A teraflop is a trillion or 10 to the 12th-power flops (Note the use of the plural, no need for an additional "s"), available on the market for most affordable parallel computing solutions. And of course, within the realm of possibility or imagination is a computer capable of petaflops, a thousand teraflops or a quadrillion (thousand trillion) flops.
Supercomputers are capable of so many amazing tasks, previously to discover new elements, detect dark matter components. simulate nuclear chain reaction or particle collisions. At present, they can model climate change, crack codes, model protein behaviours and drug reactions. Therefore it's obvious that the top buyers include the biosciences, computer aided engineering and defense industries. Hewlett-Packard, Dell and IBM are all competitors in the market. This CRAY system came out in 2008, so I'm a bit 2000-and-late but in this world, by the time you've already built and deployed the number one system, someone has already imagined something 20 times better.
Canada
As of Nov 2011, Canada did not have a system listed within the public top 500 supercomputer list. Boo.
However we do see Supercomputers on the trading floor at the Toronto Stock Exchange (perhaps the server room) called electronic traders. Math geeks design the algorithms (users input parameters like selling or holding thresholds) or dark pools (when trades have to be hidden from algorithms).
Computation resource allocation on the SciNet, another system at the University of Toronto is very competitive though. The Compute Canada's Resource Allocation Committees are in charge of connecting researchers with computational and personnel resources to run calculations for biomedical research, climate change modeling and even galaxy formation simulations.
Japan
Japan ranks number one. As of Nov 2011, the K Computer, based at the Riken Advanced Institute for Computational Science in Japan was the first to clear 10 petaflops, beating its own record. Hardware includes 705,024 Fujitsu Sparc64 processor cores.
Read more: http://news.cnet.com/8301-30685_3-57324194-264/japanese-supercomputer-first-to-clear-10-petaflops/#ixzz1mwp3L6yU
US
The Blue Gen/L can do 0.5 Quadrillion operations per second, the most powerful in 2005-2008. The Blue Gen is deployed at Livermore, San Francisco where 263 supercomputers from the Top 500 list also reside.
The up and coming Sequoia is being built by IBM, for end 2012, capable of 20 quadrillion operations per second, that's 20 petaflops. The main challenges being to write software to run across all the chips amounting to 1.6 million processors 96 racks of 32 slim servers
I like the supercomputer made from many old model Sony PS3's in parallel used by the US Air Force for satellite imagery analysis, demonstrated years ago. Many researchers have already done the same though this is no longer possible with newer generation PS3.
China
In Nov 2010 China was number one with the Tianhe-1A doing 2.5 Quadrillion operations per second
by Dawning Information Industry Ltd. Tianhue means "The Milky Way", although surpassed within six weeks by Japan. Another amazing fact, China owns 74 of the 500 biggest supercomputers in the world
By 2020 the Chinese have something in the works to rival 500x Sequoia and 8x power of Tianhe
Cisco
Anyway it's not supercomputing but here is the fastest Cisco switch ever. http://www.cisco.com/en/US/prod/collateral/switches/ps5718/ps6021/product_data_sheet0900aecd8017a72e.html I'm bringing this up simply because one has to consider connectivity to these super computers and all the glorious applications.
Wednesday, February 8, 2012
ICND2 Flashcard: VLAN
ICND2 Topic: Implementing VLAN and Trunks, Improving performance with Spanning Tree, Routing between VLANs.
VLAN definition:
Short for Virtual LAN. Each switchport may be assigned to one VLAN, ports in the same VLAN share broadcasts, and there is one IP subnet per VLAN.
Reasons for implementing VLAN
- keep the broadcasts local within the same VLAN, more security
- Inter VLAN traffic can be filtered
- departmental network segmentation for example: Sales, Engineering, Marketing, HR
Static VLAN
Create separate VLAN in the switch by assigning specific ports to VLANs
More secure but no flexibility for moving in the office network
Dynmic VLAN
Permits user to move computer around and still be connected to the department's VLAN
Requires Cisco VLAN Management Policy Server; set up a list of MAC addresses and the VLANs they belong to. User can plug computer into any switch on the LAN (though the NIC card can be removed, less secure).
Trunking VLAN
If two switches have ports with two separate VLANs on both switches, the frames need a frame tag with the VLAN ID. Protocols for trunking:
ISL - Cisco only for fast ethernet or 1 Gig. Spanning Tree works.
802.1q - only one instance of spanning tree runs with 802.1q no matter the number of VLANs
Creating a VLAN and assigning ports.
How does it get added to the vlan.dat in flash, it just does!
usage: conf t
vlan 2 (creates it!)
name Test2 (name optional)
verify: show vlan brief
Assigning a switchport to a VLAN
conf t/ int fa 0/1 usage: switchport access vlan2
Inter VLAN Routing
A router is required to communicate between two different broadcast domains or VLANs. Router will not forward broadcasts, router will forward a unicast with the layer 3 address.
TRUNKING
A trunk is required to carry traffic for multiple VLAN, the IEEE protocol is 802.1q intervlan trunking. There is a practical application for VoIP, using a separate VLAN for IP phone traffic and data traffic.
The VTP or VLAN Trunking Protocol is configured
conf t
int fa 0/0.2
encapsulation dot1q
router rip
network 10.0.0.0
Trunk can carry traffic for mulitple VLANs. The switches tell each other which VLAN they belong to. The administrator has to configure one switch as the VTP Server
VTP Modes:
Server
- default for Cisco Switch
- must be server mode to create, modify or delete a VLAN
- need one switch in server mode
- propogates VLAN information to the whole network
usage: conf t
vtp domain Pod2
vtp mode server
end
Client
- sends and recevies updates about VLAN changes
- Receives information from the VTP server
- cannot modify VLAN
Transparent
- switches just pass alont the VLAN advertisements to other switches
- will not accept or send VLAN information from itself
- can create, modify, delte VLANs for itself
Adding a previously used switch on the network creates a potential issue because switches typical try to sync with a device with a higher revision number. To clean properly clean a switch's flash memory, delete the vlan.dat file. The safest mode to when decommissioning an old switch, and before you plug it back in to avoid damaging or destroying the present VLAN configuration, type the command
usage: vtp mode transparent
usage: show vtp status
VLAN definition:
Short for Virtual LAN. Each switchport may be assigned to one VLAN, ports in the same VLAN share broadcasts, and there is one IP subnet per VLAN.
Reasons for implementing VLAN
- keep the broadcasts local within the same VLAN, more security
- Inter VLAN traffic can be filtered
- departmental network segmentation for example: Sales, Engineering, Marketing, HR
Static VLAN
Create separate VLAN in the switch by assigning specific ports to VLANs
More secure but no flexibility for moving in the office network
Dynmic VLAN
Permits user to move computer around and still be connected to the department's VLAN
Requires Cisco VLAN Management Policy Server; set up a list of MAC addresses and the VLANs they belong to. User can plug computer into any switch on the LAN (though the NIC card can be removed, less secure).
Trunking VLAN
If two switches have ports with two separate VLANs on both switches, the frames need a frame tag with the VLAN ID. Protocols for trunking:
ISL - Cisco only for fast ethernet or 1 Gig. Spanning Tree works.
802.1q - only one instance of spanning tree runs with 802.1q no matter the number of VLANs
Creating a VLAN and assigning ports.
How does it get added to the vlan.dat in flash, it just does!
usage: conf t
vlan 2 (creates it!)
name Test2 (name optional)
verify: show vlan brief
Assigning a switchport to a VLAN
conf t/ int fa 0/1 usage: switchport access vlan2
Inter VLAN Routing
A router is required to communicate between two different broadcast domains or VLANs. Router will not forward broadcasts, router will forward a unicast with the layer 3 address.
TRUNKING
A trunk is required to carry traffic for multiple VLAN, the IEEE protocol is 802.1q intervlan trunking. There is a practical application for VoIP, using a separate VLAN for IP phone traffic and data traffic.
The VTP or VLAN Trunking Protocol is configured
conf t
int fa 0/0.2
encapsulation dot1q
router rip
network 10.0.0.0
Trunk can carry traffic for mulitple VLANs. The switches tell each other which VLAN they belong to. The administrator has to configure one switch as the VTP Server
VTP Modes:
Server
- default for Cisco Switch
- must be server mode to create, modify or delete a VLAN
- need one switch in server mode
- propogates VLAN information to the whole network
usage: conf t
vtp domain Pod2
vtp mode server
end
Client
- sends and recevies updates about VLAN changes
- Receives information from the VTP server
- cannot modify VLAN
Transparent
- switches just pass alont the VLAN advertisements to other switches
- will not accept or send VLAN information from itself
- can create, modify, delte VLANs for itself
Adding a previously used switch on the network creates a potential issue because switches typical try to sync with a device with a higher revision number. To clean properly clean a switch's flash memory, delete the vlan.dat file. The safest mode to when decommissioning an old switch, and before you plug it back in to avoid damaging or destroying the present VLAN configuration, type the command
usage: vtp mode transparent
usage: show vtp status
Tuesday, February 7, 2012
VPN in a Nutshell
Not sure if this topic is for the CCNA Exam, ICND1, or ICND2 Exam but it was covered peripherally in the CCNA Bootcamp course and is offered as a separate course or certification for Cisco VPNs.
What is a VPN?
Definition: Virtual Private Network, for creating a private network tunneling over a public network, while maintaining confidentiality and security. It's a way to communicate through a dedicated server securely to a corporate network over the Internet. Windows NT, 2000 and XP offer native VPN support. The Cisco Router IOS has to support VPN.
VPN Client can also be setup on a Linux platform, the first of its kind. Download the network-manager-vpnc package. http://www.linuxplanet.com/linuxplanet/tutorials/6773/1
What are the Components of a VPN?
How to make VPN's secure?
VPNs are inherently secure. In fact, there are certain totalitarian regimes in the world today where VPN's are absolutely banned! I suppose it is because the added security prevents the government from spying on its own people plotting a revolt. Now what I want to know is, how does the government know if someone is using a VPN, where it starts and where it ends? How do you even see a VPN signature?
VPN's are secure by virtue of encapsulation or tunneling, by transmitting data transparently from network to another through a shared infrastructure. Encryption is also used to code data into a format using a shared secret key, and then decode encrypted data into the original unencrypted format
Read more about Encryption Standards
Setting up or Connecting to the VPN
Hardware
Cisco ASA 5500 Series offers both IPSec and SSL VPN, application inspection firewall and intrusion prevention services.
Cisco 7600 Series/ Catalyst 6500 Series IPSec VPN, requires a shared port adapter. Did I read correctly, it runs AES encryption and can carry up to 8,000 IPSec tunnels?
Configuration Commands
Here is a mishmash of commands I have to reorder in the right sequence because it is supposed to work on a Cisco 2811. It's not an actual configuration file but notes I wrote to myself as comments for things to include. Sample config file coming soon, when I can prove that it works!
It's tricky but there is useful information on HOW TO configure an IPSEC encrypted tunnel with Cisco. A lot of helpful pages on cisco.com as well.
% Prerequisites
% ip cef or ip cef distributed
% configure loopback interface
% enable SNMP notifications of L2TP session up/down; snmp-server enable traps l2tunnel session
% xconnect applied to which interface
% ip pmtu command configures the pseudowire class
% L2TPv3 data encapsulation directly over IP port 115, sessions between the same Layer 2 protocols.
% choose static or dynamic L2TPv3 sessions
% set mtu; use ipdfbit set and ip pmtu accordingly
What is a VPN?
Definition: Virtual Private Network, for creating a private network tunneling over a public network, while maintaining confidentiality and security. It's a way to communicate through a dedicated server securely to a corporate network over the Internet. Windows NT, 2000 and XP offer native VPN support. The Cisco Router IOS has to support VPN.
VPN Client can also be setup on a Linux platform, the first of its kind. Download the network-manager-vpnc package. http://www.linuxplanet.com/linuxplanet/tutorials/6773/1
What are the Components of a VPN?
- A real network with servers and workstations
- An Internet connection
- VPN gateways are endpoints to establish, maintain and control VPN connections; these could be routers, firewalls, VPN concentrators and ASA (Adaptive Security Applicance)
- Software to manage the VPN tunnels
- Cisco IOS software that supports VPN
How to make VPN's secure?
VPNs are inherently secure. In fact, there are certain totalitarian regimes in the world today where VPN's are absolutely banned! I suppose it is because the added security prevents the government from spying on its own people plotting a revolt. Now what I want to know is, how does the government know if someone is using a VPN, where it starts and where it ends? How do you even see a VPN signature?
VPN's are secure by virtue of encapsulation or tunneling, by transmitting data transparently from network to another through a shared infrastructure. Encryption is also used to code data into a format using a shared secret key, and then decode encrypted data into the original unencrypted format
Read more about Encryption Standards
Setting up or Connecting to the VPN
- IPSEC gateway: the hostname or IP of the VPN server
- IPSEC ID: the groupname
- IPSEC secret: the shared password for the group
- your username
- your password
Hardware
Cisco ASA 5500 Series offers both IPSec and SSL VPN, application inspection firewall and intrusion prevention services.
Cisco 7600 Series/ Catalyst 6500 Series IPSec VPN, requires a shared port adapter. Did I read correctly, it runs AES encryption and can carry up to 8,000 IPSec tunnels?
Configuration Commands
Here is a mishmash of commands I have to reorder in the right sequence because it is supposed to work on a Cisco 2811. It's not an actual configuration file but notes I wrote to myself as comments for things to include. Sample config file coming soon, when I can prove that it works!
It's tricky but there is useful information on HOW TO configure an IPSEC encrypted tunnel with Cisco. A lot of helpful pages on cisco.com as well.
% Prerequisites
% ip cef or ip cef distributed
% configure loopback interface
% enable SNMP notifications of L2TP session up/down; snmp-server enable traps l2tunnel session
% xconnect applied to which interface
% ip pmtu command configures the pseudowire class
% L2TPv3 data encapsulation directly over IP port 115, sessions between the same Layer 2 protocols.
% choose static or dynamic L2TPv3 sessions
% set mtu; use ipdfbit set and ip pmtu accordingly
Friday, February 3, 2012
Cisco ICND1 Flashcard: WAN Hardware and Encapsulation
ICND1: PPP
ICND2: Frame Relay
Wide Area Networks
A LAN will cover an area in the same building or vicinity; a WAN spans a much larger geographically connected sites. Setting up and maintain a WAN is very expensive, most private companies would rather purchase a WAN connection from the ISP, who will manage the WAN infrastructure and back-end network backbone. Services include T1, T3, E1 and E3, DSL, cable, frame-relay and ATM.
WAN operations cover the Layer 2 Data Link Layer (Metro Ethernet, MPLS, frame-relay, ATM, HDLC)and Layer 1 Physical Layer components (electrical, mechanical, operational connections).
WAN Devices
Equipment required includes a modem CSU/DSU to connect to the service provider, and edge devices modify the Ethernet encapsulation to the serial WAN
Modem - modulates an analog carrier signal to encode the digital signal, and modulates the carrier signal to decode the transmitted information.
CSU/ DSU - Channel Service Unit/ Data Service Unit. CSU is termination for the digital signal ensures integrity, error correction, and line monitoring. DSU converts T Carrier line frames into LAN frames. Provides a clocking signal to the customer equipment interface from the DSU, terminate the channelized transport media of the carrier on the CSU. CSU also provides a loopback test diagnostic.
Demarcation Point, the point where a service provider considers the services delivered, such as the CSU/DSU on customer's premises to the provider's Central Office.
Access Server - I'll check my notes what that is for.
WAN Switch - used in carrier networks to carry Frame Relay, ATM, X.25 and PSTN in the cloud
Router - The router can be a WAN connection device, with serial interface ports to connect to the service provider and the internetwork for the LAN. Basically a router will connect to the POP router of the ISP
Core Router - needs explaining
CPE - Customer Premise Equipment that includes a DCE/ DTE.
DCE - Data Circuit-terminating Equipment or Data Communications Equipment, the device that ports data on the local loop.Configure the clock rate for the DCE interface.
DTE - Data Terminal Equipment, customer equipment that passes data to the DCE such as the routers. Synchronizes to the clock rate.
There is a lengthy description of EIA/ TIA connectors, but the most important part is the router end of the shielded serial transition cable which has a DB-60 connector. The DB-60 port on a serial WAN interface car is a 5 in 1 port. There is a new type of cable called a Smart Serial Cable.
Summary of WAN Links Hierarchy
Three main WAN types: Dedicated, Circuit Switched and Packet Switched.
DEDICATED
Leased Lines: T1/ E1
For companies who constantly send traffic, expensive.
SWITCHED
Circuit Switched: PSTN, ISDN, analog modem
For companies who send occassional traffic, least expensive.
Packet Switched: Frame Relay, x.25
Ideal for companies requiring a minimum constant service without the cost of dedicated lines.
Cell Switched: ATM
INTERNET
Broadband:VPN
Other: DSL Cable, Broadband, Wireless
The Last Mile
This refers to the local loop, the last mile connection that defines how the local user gets to the ISP perhaps? One example is for example, installing a new fiber optic cable from the exchange outside the building into the networking lab perhaps. Another example could be a satellite hop.
Long Range Connectivity
The protocols SONET and Synchronous Digital Hierarchy (SDH) have been around for ages. These are used to move large amounts of data over great distances through fiber optic cables, mostly refering to voice and data. A newer optical technology, Dense Wavelength Division Multiplex (DWDM) provides extremely long range communications by assigning a specific frequency (or wavelength) of light to incoming signals. Equipment can amplify the wavelength to boost signal strength. A single DWDM fiber can have more than 80 different wavelengths or channels multiplexed, each channel carrying up to 10 Gb/s. The other important feature is that DWDM can carry IP, SONET, ATM at the same time on the same optical fiber.
At the receiving end, the router needs the right optical SFP.
Related Topics: PPP Encapsulation, ISDN
Next Topic: DSL two types-ADSL and SDSL
Followed by: Cisco IPSec VPN
ICND2: Frame Relay
Wide Area Networks
A LAN will cover an area in the same building or vicinity; a WAN spans a much larger geographically connected sites. Setting up and maintain a WAN is very expensive, most private companies would rather purchase a WAN connection from the ISP, who will manage the WAN infrastructure and back-end network backbone. Services include T1, T3, E1 and E3, DSL, cable, frame-relay and ATM.
WAN operations cover the Layer 2 Data Link Layer (Metro Ethernet, MPLS, frame-relay, ATM, HDLC)and Layer 1 Physical Layer components (electrical, mechanical, operational connections).
WAN Devices
Equipment required includes a modem CSU/DSU to connect to the service provider, and edge devices modify the Ethernet encapsulation to the serial WAN
 |
| Wan Ecapsulation Answer Hack. Is this legal? |
Modem - modulates an analog carrier signal to encode the digital signal, and modulates the carrier signal to decode the transmitted information.
CSU/ DSU - Channel Service Unit/ Data Service Unit. CSU is termination for the digital signal ensures integrity, error correction, and line monitoring. DSU converts T Carrier line frames into LAN frames. Provides a clocking signal to the customer equipment interface from the DSU, terminate the channelized transport media of the carrier on the CSU. CSU also provides a loopback test diagnostic.
Demarcation Point, the point where a service provider considers the services delivered, such as the CSU/DSU on customer's premises to the provider's Central Office.
Access Server - I'll check my notes what that is for.
WAN Switch - used in carrier networks to carry Frame Relay, ATM, X.25 and PSTN in the cloud
Router - The router can be a WAN connection device, with serial interface ports to connect to the service provider and the internetwork for the LAN. Basically a router will connect to the POP router of the ISP
Core Router - needs explaining
CPE - Customer Premise Equipment that includes a DCE/ DTE.
DCE - Data Circuit-terminating Equipment or Data Communications Equipment, the device that ports data on the local loop.Configure the clock rate for the DCE interface.
DTE - Data Terminal Equipment, customer equipment that passes data to the DCE such as the routers. Synchronizes to the clock rate.
There is a lengthy description of EIA/ TIA connectors, but the most important part is the router end of the shielded serial transition cable which has a DB-60 connector. The DB-60 port on a serial WAN interface car is a 5 in 1 port. There is a new type of cable called a Smart Serial Cable.
Summary of WAN Links Hierarchy
Three main WAN types: Dedicated, Circuit Switched and Packet Switched.
DEDICATED
Leased Lines: T1/ E1
For companies who constantly send traffic, expensive.
SWITCHED
Circuit Switched: PSTN, ISDN, analog modem
For companies who send occassional traffic, least expensive.
Packet Switched: Frame Relay, x.25
Ideal for companies requiring a minimum constant service without the cost of dedicated lines.
Cell Switched: ATM
INTERNET
Broadband:VPN
Other: DSL Cable, Broadband, Wireless
The Last Mile
This refers to the local loop, the last mile connection that defines how the local user gets to the ISP perhaps? One example is for example, installing a new fiber optic cable from the exchange outside the building into the networking lab perhaps. Another example could be a satellite hop.
Long Range Connectivity
The protocols SONET and Synchronous Digital Hierarchy (SDH) have been around for ages. These are used to move large amounts of data over great distances through fiber optic cables, mostly refering to voice and data. A newer optical technology, Dense Wavelength Division Multiplex (DWDM) provides extremely long range communications by assigning a specific frequency (or wavelength) of light to incoming signals. Equipment can amplify the wavelength to boost signal strength. A single DWDM fiber can have more than 80 different wavelengths or channels multiplexed, each channel carrying up to 10 Gb/s. The other important feature is that DWDM can carry IP, SONET, ATM at the same time on the same optical fiber.
At the receiving end, the router needs the right optical SFP.
Related Topics: PPP Encapsulation, ISDN
Next Topic: DSL two types-ADSL and SDSL
Followed by: Cisco IPSec VPN
Monday, January 23, 2012
FREE Long Distance Calling
Of course it's free if you Do It Yourself! And I'm not talking about a Magic Jack (see it on the scrolling slideshow). This is a VoIP network I setup while my guy was posted overseas. We were able to stay connected through a homegrown VoIP service. Everytime that phone rang, I called it the "Bat" phone cuz I envision this to be the service Batman himself must be using, right? If I missed the call, the voice mail was sent as a wav file to my email! The service was provided by ICONSA.CA
How to set up a VoIP network
Plug and play, what else can I say? Seriously, though when connecting a VoIP phone to the network, you can buy a wired VoIP phone that connects directly to the switch or a wireless VoIP phone that is connected to the switch via an access point. I found this one online recently and it simplifies completely the setup I used to own. For example, http://www.voiplink.com/Cisco_
Well that is presuming I have a Cisco Catalyst switch, which offers a separate voice VLAN to overlay the voice topology onto the data network. Once again this is plug and play, because the voice VLAN feature is usually automatically configured. Simply plug the phone into the switch, and the switch provides the phone with the necessary VLAN information. Make sure you choose a model that supports PoE (power of Ethernet) to avoid having another power cord to contend with.
However, back to the home network which requires something less costly than a smart Cisco Catalyst switch but a bit more wiring. I presume this is the same equipment my grandma uses for her "land-line" that is a VoIP phone connected to her internet service.
Here is the Cisco Linksys VoIP Internet Phone Adapter I eventually sold on ebay for only $19.99.
The PAP2T offers the benefits of high-quality voice over IP (VoIP) without the need to upgrade your existing analog phones. The following weblink has more specs from the manufacture...
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