FastTrack Training. "Network Basics". "Basics of routing." Eddie Martin December 2012
About a year ago, I noticed an interesting and fascinating series of lectures by Eddie Martin, which, thanks to its history and real-life examples, as well as its tremendous learning experience, is amazingly comprehensible and allows you to gain an understanding of quite complex technologies.
We continue the cycle of 27 articles based on his lectures:
')
01/02: “Understanding the OSI Model” Part 1 / Part 2
03: "Understanding the Cisco Architecture"
04/05: “The Basics of Switching or Switches” Part 1 / Part 2
06: "Switches from Cisco"
07: "Area of ​​use of network switches, the value of Cisco switches"
08/09: "Basics of a Wireless LAN" Part 1 / Part 2
10: "Products in the field of wireless LAN"
11: The Value of Cisco Wireless LANs
12: Routing Basics
13: "The structure of routers, routing platforms from Cisco"
14: The Value of Cisco Routers
15/16: “The Basics of Data Centers” Part 1 / Part 2
17: "Equipment for data centers"
18: "The Value of Cisco in Data Centers"
19/20/21: "The Basics of Telephony" Part 1 / Part 2 / Part 3
22: "Cisco Collaboration Software"
23: The Value of Collaboration Products from Cisco
24: "The Basics of Security"
25: "Cisco Security Software"
26: "The Value of Cisco Security Products"
27: "Understanding Cisco Architectural Games (Review)"
And here is the twelfth of them.
Today we will talk about routers - what it is, why we need them and what capabilities they have. I will tell you about the bandwidth and things like that. So, routers connect dissimilar networks, but not only networks, they also connect with each other.
Suppose I have a company headquarters, and there is also a data center and switches in this building, and I want to connect them with the company's branch where the employees are located. To do this, I need a service provider called WAN (Wide Area Network) - access to a network that covers large areas and includes a large number of nodes (global computer network).
I take the router, connect it to the WAN provider, and it sends my data to the branch office. On the other side of the WAN, I also place the switch and another router, which is also connected to the provider. What should interest me? How the provider will transfer my data.
Because here, where we have a data center, I use a 10 Gigabit Ethernet with high bandwidth. Relatively speaking, I have here a large pipe through which I pass my data stream. And on the other side, our branch has a pipe of the same diameter. And what is on the side of the provider? Same big pipe? No, he has a small thin tube, that's such a diameter.
This is a good example of how we should analyze the capabilities of the provider in order to provide the necessary bandwidth. Imagine a fire, a huge building that burns, and we call firefighters to extinguish the fire, this requires such a huge pipe, 3 inches in diameter - to let the huge water flow through and extinguish the fire faster. And what do we have with the provider? Straw for cocktail. Its network compared to ours has approximately the same bandwidth.
Do you know what the provider is doing in this case? Every month he gives me a gift, called a bill for services. The more flow I pass through his network, the more “gift” he brings to me. In the end, it costs me more and more.
What do we do? We manage this process and organize QoS routing priority. And the routers act as watchmen, they decide what data to skip out and when, and what not. Such a network can be very, very large. Let us have hundreds of locations associated with the provider. Physically, it looks like this, but logically we have many tunnels from these locations that lead from these locations to our routers via the WAN.
Remember we talked about the fact that the routing process is controlled by L3 routers? We drew it in the form of two L2 level men, who turn to the higher third in order for him to organize the exchange of information. And the third is deciding where and how to send traffic.
All this is mixed up in such a way that the little man at the top can send traffic in all directions - to the main office, to the branch, and to other places. He makes the two lower “guys” exchange information as efficiently as possible, and the routing protocols are used for this. These protocols cover the entire network from the outside and allow you to connect other networks.
Here on the right, I'll draw a new VLAN. Are all routers aware of this? Not really. You need to add another second level guy to the company in the lower half of the circle on this router. And then the job of the L3 guy will be to report this new network to all other routers if someone asks about this new network. That's what routers do.
There are several types of routing protocols, we have the RIP protocol for managing small networks (Routing Information Protocol) and the dynamic routing protocol OSPF (Open Shortest Path Firs), based on link state technology and using the shortest path . These are standard protocols that can be used on any of the routers. And there is a maximum form of the protocol, for the largest networks, it is called BGP (Border Gateway Protocol) - a border gateway protocol. It is applied to such a large network like the Internet. All routers connecting to the Internet use BGP protocol. And the routing tables are huge, you know, you need quite a lot of memory for them.
Cisco has another proprietary protocol - EIGRP (Enhanced Interior Gateway Routing Protocol), which means "enhanced internal gateway routing protocol." This is the best protocol of all shown here. It combines the best of RIP and OSPF.
This protocol is very popular with customers, because when they find out that this is Cisco’s own software, our own protocol, they say: “Oh yes, we want it”! And since this is our protocol, who is the only provider of routers that supports it the best way? What is our market share routing? From 70%, closer to 80%, depending on where the routers are used. In fact, here, in the case of the border router of this branch, our share is over 80%, since we are very good at this. And I will show you why soon. Why do you think Cisco has been holding the lead in this market segment for many, many years? Our routers are faster than others? No, you can't say that. But they embody all the innovative technologies, all the modern achievements are in these routers. We enable our routers to do more than just routing. But it's a wan.
There are other networks and other connection paths. Add another network below - the Internet. Where is the Internet? Everywhere! It’s like a cloud, it’s the second global network. And what is the first? PSTN (Public Switched Telephone Network) is a public telephone network. Please note that if I buy a part of the network from a service provider, then I will only be connected to someone else, directly to someone else. So, if I am connected to the Internet, what does my service provider do? He connects me to the cloud and says - go anywhere. I can connect to www.cisco.com or www.ibm.com , I can connect with anyone I want. And it is much cheaper! Because I am directing my traffic to bypass the WAN, I do not need to buy a WAN along the entire route.
Can I connect my business via the Internet? Absolutely. I can use to send traffic on these routes using VPN, virtual private network. So we run our private virtual network over the Internet, what should we do? Provide security! We need to encrypt our data for the entire route. Therefore, it is possible that the requirements for this router should include encryption at the hardware level. When we talked about SDN (software-defined networking) we said that if the traffic goes through our device, then in the case of SDN we need to have a fairly efficient processor to encrypt it on the server side, this is where the hardware chip plays the role. This is probably the biggest disadvantage of SDN, since on the server side it is inefficient to do this.
But this is a VPN, a VPN can be of two kinds. It can be from point to point, or provide remote access. If Eddie starts his VPN client behind this computer, then he connects via the Internet to this router and can enter our network, also bypassing the WAN provider. This is called remote access VPN. How many of you have a CVO (Cisco Virtual Office)? Connecting to CVO is provided using a router that can encrypt your traffic using SSL, it connects to our private network over the Internet using a separate tunnel, while your router will encrypt everything that goes through it. This is the difference between VPN with remote access and VPN SSL. So, we have a point-to-point or site to site VPN and remote VPN access. Point-to-point access can be organized from home if an encrypted router is used to connect to your CVO.
The advantage of this solution in the first place is its low cost, maybe you can even get more traffic. But what do we lose when using a VPN? Unlimited access, we get limited access. What is QoS? Can we guarantee it in this case?
Suppose I sit at home for my laptop and use the cable Internet from Time Warner Calbe, and my VPN stops working, our website cisco.com does not open, there is no access. I dial the provider and I hope that the person will answer me, if it is possible of course. I’m lucky and I tell him that I think that my Internet is “light”. He replies: “Really? I do not see any technical problems in your area. ” “But I can't connect to Cisco.” - "Listen, make me a service, please open your browser, can you enter google.com"? - "Yes, it is loading." What will he say to me? That's right: “Have a nice day, thanks for your call, it's not my problem, it looks like Cisco has it!” What do I have in this case? Technical support, but lost service quality.
If I buy traffic from an ISP, I buy guaranteed bandwidth via WAN between two points, 1 Mbps or 2, and this will be guaranteed. Can I guarantee anything when using a remote access VPN? No I can not. What do I get in this case instead of help? That's right, at best: “Thank you for calling”! And it will be all, but even this is not guaranteed.
The same CVO routers place voice traffic before any other traffic, but until it reaches the final destination, it will not be guaranteed. That is, we cannot provide QoS here, we are only trying to save on traffic. This will work most of the time, but there will be a time when the speed through the Internet will decrease. There have been documented cases where the speed of the Internet has decreased, and in some cases the network has "faded." You heard that a few months ago the Internet on the east coast of the United States was “frozen” for 13 seconds? Imagine what a frozen video looks like! It is "frozen", the connection to the Internet has died. For 13 seconds, the internet was dead. What will happen to your video that you will transmit through the network? It is interrupted. The connection will disappear. A break in service is guaranteed. So, you see what you can get as a result.
We can contact the provider and buy a service called MPLS (Multiprotocol Label Switching) - multi-protocol label switching, a mechanism in a high-performance telecommunications network that transfers data from one network node to another using tags. This service gives you a lot and Cisco loves it very much, because it was our company that created it for network service providers in the mid-90s, theoretically. We are the fathers of MPLS.
MPLS provides you with a channel between points, in this case it connects our headquarters with a branch where you can choose your speed. There are three types of traffic that goes through this network.
The first is data. Suppose I have 2 Mbit / s, of which 1 Mbit / s, I want to allocate a significant portion for data transmission. If the rest of the channel is free, give me the full bandwidth for the data. So, when I transmit data on this "pipe", the provider marks them with a special label, which guarantees me the chosen speed and throughput. And he will charge me for it.
What else can I transmit on this network? That's right, voice. What happens when I make a phone call from headquarters to the branch? It takes little traffic and does not need a large bandwidth, but it needs great speed, the call must be really fast. For this I need only 256 Kbps. I turn to the provider and say that I need to transmit the voice at that speed. And he guarantees that it will be exactly the way I need, marking my voice with another mark. But he says that since this is a different type of traffic and we want to receive it quickly, he needs to make certain “drastic changes” for this to ensure “instantaneousness”. As a result, these 256 Kbps can cost more than 1 Mbit / s. But now, his network will know that this is a voice, and will skip it first of all and quickly, along the entire route.
Perhaps the next should be a video. How can I skip a video on this network? Let me remind you that we still have 768 Mbit / s. For video, I need a lot of speed, because using it helps me to do great things. This is part of my business process, so the video should work!
What properties does the video have? The same as the voice, but it requires more bandwidth. This will require me to pay even more, but I will optimally distribute my network costs. This way I “push” QoS from my networks to this network. Therefore, MPLS is the most useful thing for us.
I worked previously in South Carolina and was selling voice. And when we did it with the help of ancient technologies, the term “sludge” was born, we used Frame Relay and it was awful for us.
A question has been raised regarding the transmission standard T1 - a digital channel using telephone lines that allows you to guarantee speed. But why the provider does not want to provide you with this standard? It also works like a Talbot store selling clothes to my wife. Sells you everything in parts. For if he offers to buy me this entire channel, which we considered, for voice, video and data, for $ 725 together, then I will most likely say: “To hell with this MPLS. Just give me a T1 at 1.5 Mbps. ” But he will not want to do this, he will refuse.
What is the job of a network service provider? How does he make money? You're probably smarter than me, because you guessed it. It sells not bandwidth, but network access. I will give an example to bring you closer to understanding the essence. Recall the very first way you connected to the Internet. This is a dial-up. You went to the provider, paid him money, and for $ 19 a month he provided you with a phone number where you called through the modem. But do you really think that this was your personal modem, and it served only you? No, the provider sold it at least 20 times! He sold this bandwidth one more time, and another, and another. That was his job. Why does he not like to provide a dedicated channel T1? Because he can not resell it! He provides it only to you and no one else and had to reserve this channel for you, even if you do not use your channel at 2 am, it will be assigned to you and it will not be able to sell it to anyone.
And MPLS is different from T1 in that we allow oversell. It's like in Vegas, the correct odds are applied that guarantee casino success. You use the guaranteed full flow, others use it, anyone can use it, and at the same time it is guaranteed to receive it! And what am I doing? I sell it to you with an overcell ratio from 1 to 1.5 or even up to 2-2.5. And you are still able to get a guaranteed channel and continue to pay a premium price.
And the beauty of MPLS is that it is worldwide. Take the people from Perth, Australia’s west coast, it's at the opposite end of Sydney, the business people are there, the other business people live in Melbourne. So, if I want to connect to a valley in North Carolina, I will definitely contact AT & T or any other provider and say that we need an MPLS channel in Perth, because I want to open a new office there. And he provides us with MPLS. Can we use Frame relay instead of MPLS? Not. Do not even try, you will not get anything except a headache. I tried to do this many times, tried to transfer all the necessary technologies there, but nothing came of it.
Tell me, what is SIP? That's right, this is a session establishment protocol. Where did he come from, why did it happen? SIP helped to move from the traditional T1 RPI (Primary Rate Interface) line, which we used for voice transmission, to VOIP technology. And I could go to the same service provider and ask me to sell more band to forward SIP as well. But this did not reduce the price of his services. However, you could certainly send this signal along the same line.
How is bandwidth guaranteed on a non-guaranteed network that is resold several times? It's very simple, users do not press the keys on their keyboard at the same time. Because the chance that you will not get your channel is close to 0. However, T1 meant that I would definitely take 1.5 Mbit / s from others. T1 is actually the transmission of the first level, in Europe use its equivalent of E1, it is almost the same. We use 24 channels of 64 Kbps, which gives a total of 1.5 Mbps. We can talk about this a bit more in detail when we talk about telephony, but in fact this 1.5 Mbit / s bandwidth was used to support 24 phone calls, which we did - it essentially removed the separation between them. So think about it again when your channel is - no one else can use it.
MPLS is a great thing for us, people! She is really good! It is used by all providers and all users. The main reason why I go so deep into the details is that I know 3 partners, 3 people who came to Cisco, and two of them created these technologies right before my eyes. Service providers call this MPLS, but the provider also calls it differently - VPN. , VPN – , , , , , VPN. ? , .
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Question. Cisco ? , . , :) , , . , , - , , . , . . , CocaCola . . EIGRP, . , : « OSPF, Cisco, OSPF , , EIGRP ».
Continued:
FastTrack Training. "Network Basics". "The structure of routers, routing platforms from Cisco." Eddie Martin December 2012
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We continue the cycle of 27 articles based on his lectures:
')
01/02: “Understanding the OSI Model” Part 1 / Part 2
03: "Understanding the Cisco Architecture"
04/05: “The Basics of Switching or Switches” Part 1 / Part 2
06: "Switches from Cisco"
07: "Area of ​​use of network switches, the value of Cisco switches"
08/09: "Basics of a Wireless LAN" Part 1 / Part 2
10: "Products in the field of wireless LAN"
11: The Value of Cisco Wireless LANs
12: Routing Basics
13: "The structure of routers, routing platforms from Cisco"
14: The Value of Cisco Routers
15/16: “The Basics of Data Centers” Part 1 / Part 2
17: "Equipment for data centers"
18: "The Value of Cisco in Data Centers"
19/20/21: "The Basics of Telephony" Part 1 / Part 2 / Part 3
22: "Cisco Collaboration Software"
23: The Value of Collaboration Products from Cisco
24: "The Basics of Security"
25: "Cisco Security Software"
26: "The Value of Cisco Security Products"
27: "Understanding Cisco Architectural Games (Review)"
And here is the twelfth of them.
FastTrack Training. "Network Basics". "Basics of routing." Eddie Martin December 2012
Today we will talk about routers - what it is, why we need them and what capabilities they have. I will tell you about the bandwidth and things like that. So, routers connect dissimilar networks, but not only networks, they also connect with each other.
Suppose I have a company headquarters, and there is also a data center and switches in this building, and I want to connect them with the company's branch where the employees are located. To do this, I need a service provider called WAN (Wide Area Network) - access to a network that covers large areas and includes a large number of nodes (global computer network).
I take the router, connect it to the WAN provider, and it sends my data to the branch office. On the other side of the WAN, I also place the switch and another router, which is also connected to the provider. What should interest me? How the provider will transfer my data.
Because here, where we have a data center, I use a 10 Gigabit Ethernet with high bandwidth. Relatively speaking, I have here a large pipe through which I pass my data stream. And on the other side, our branch has a pipe of the same diameter. And what is on the side of the provider? Same big pipe? No, he has a small thin tube, that's such a diameter.
This is a good example of how we should analyze the capabilities of the provider in order to provide the necessary bandwidth. Imagine a fire, a huge building that burns, and we call firefighters to extinguish the fire, this requires such a huge pipe, 3 inches in diameter - to let the huge water flow through and extinguish the fire faster. And what do we have with the provider? Straw for cocktail. Its network compared to ours has approximately the same bandwidth.
Do you know what the provider is doing in this case? Every month he gives me a gift, called a bill for services. The more flow I pass through his network, the more “gift” he brings to me. In the end, it costs me more and more.
What do we do? We manage this process and organize QoS routing priority. And the routers act as watchmen, they decide what data to skip out and when, and what not. Such a network can be very, very large. Let us have hundreds of locations associated with the provider. Physically, it looks like this, but logically we have many tunnels from these locations that lead from these locations to our routers via the WAN.
Remember we talked about the fact that the routing process is controlled by L3 routers? We drew it in the form of two L2 level men, who turn to the higher third in order for him to organize the exchange of information. And the third is deciding where and how to send traffic.
All this is mixed up in such a way that the little man at the top can send traffic in all directions - to the main office, to the branch, and to other places. He makes the two lower “guys” exchange information as efficiently as possible, and the routing protocols are used for this. These protocols cover the entire network from the outside and allow you to connect other networks.
Here on the right, I'll draw a new VLAN. Are all routers aware of this? Not really. You need to add another second level guy to the company in the lower half of the circle on this router. And then the job of the L3 guy will be to report this new network to all other routers if someone asks about this new network. That's what routers do.
There are several types of routing protocols, we have the RIP protocol for managing small networks (Routing Information Protocol) and the dynamic routing protocol OSPF (Open Shortest Path Firs), based on link state technology and using the shortest path . These are standard protocols that can be used on any of the routers. And there is a maximum form of the protocol, for the largest networks, it is called BGP (Border Gateway Protocol) - a border gateway protocol. It is applied to such a large network like the Internet. All routers connecting to the Internet use BGP protocol. And the routing tables are huge, you know, you need quite a lot of memory for them.
Cisco has another proprietary protocol - EIGRP (Enhanced Interior Gateway Routing Protocol), which means "enhanced internal gateway routing protocol." This is the best protocol of all shown here. It combines the best of RIP and OSPF.
This protocol is very popular with customers, because when they find out that this is Cisco’s own software, our own protocol, they say: “Oh yes, we want it”! And since this is our protocol, who is the only provider of routers that supports it the best way? What is our market share routing? From 70%, closer to 80%, depending on where the routers are used. In fact, here, in the case of the border router of this branch, our share is over 80%, since we are very good at this. And I will show you why soon. Why do you think Cisco has been holding the lead in this market segment for many, many years? Our routers are faster than others? No, you can't say that. But they embody all the innovative technologies, all the modern achievements are in these routers. We enable our routers to do more than just routing. But it's a wan.
There are other networks and other connection paths. Add another network below - the Internet. Where is the Internet? Everywhere! It’s like a cloud, it’s the second global network. And what is the first? PSTN (Public Switched Telephone Network) is a public telephone network. Please note that if I buy a part of the network from a service provider, then I will only be connected to someone else, directly to someone else. So, if I am connected to the Internet, what does my service provider do? He connects me to the cloud and says - go anywhere. I can connect to www.cisco.com or www.ibm.com , I can connect with anyone I want. And it is much cheaper! Because I am directing my traffic to bypass the WAN, I do not need to buy a WAN along the entire route.
Can I connect my business via the Internet? Absolutely. I can use to send traffic on these routes using VPN, virtual private network. So we run our private virtual network over the Internet, what should we do? Provide security! We need to encrypt our data for the entire route. Therefore, it is possible that the requirements for this router should include encryption at the hardware level. When we talked about SDN (software-defined networking) we said that if the traffic goes through our device, then in the case of SDN we need to have a fairly efficient processor to encrypt it on the server side, this is where the hardware chip plays the role. This is probably the biggest disadvantage of SDN, since on the server side it is inefficient to do this.
But this is a VPN, a VPN can be of two kinds. It can be from point to point, or provide remote access. If Eddie starts his VPN client behind this computer, then he connects via the Internet to this router and can enter our network, also bypassing the WAN provider. This is called remote access VPN. How many of you have a CVO (Cisco Virtual Office)? Connecting to CVO is provided using a router that can encrypt your traffic using SSL, it connects to our private network over the Internet using a separate tunnel, while your router will encrypt everything that goes through it. This is the difference between VPN with remote access and VPN SSL. So, we have a point-to-point or site to site VPN and remote VPN access. Point-to-point access can be organized from home if an encrypted router is used to connect to your CVO.
The advantage of this solution in the first place is its low cost, maybe you can even get more traffic. But what do we lose when using a VPN? Unlimited access, we get limited access. What is QoS? Can we guarantee it in this case?
Suppose I sit at home for my laptop and use the cable Internet from Time Warner Calbe, and my VPN stops working, our website cisco.com does not open, there is no access. I dial the provider and I hope that the person will answer me, if it is possible of course. I’m lucky and I tell him that I think that my Internet is “light”. He replies: “Really? I do not see any technical problems in your area. ” “But I can't connect to Cisco.” - "Listen, make me a service, please open your browser, can you enter google.com"? - "Yes, it is loading." What will he say to me? That's right: “Have a nice day, thanks for your call, it's not my problem, it looks like Cisco has it!” What do I have in this case? Technical support, but lost service quality.
If I buy traffic from an ISP, I buy guaranteed bandwidth via WAN between two points, 1 Mbps or 2, and this will be guaranteed. Can I guarantee anything when using a remote access VPN? No I can not. What do I get in this case instead of help? That's right, at best: “Thank you for calling”! And it will be all, but even this is not guaranteed.
The same CVO routers place voice traffic before any other traffic, but until it reaches the final destination, it will not be guaranteed. That is, we cannot provide QoS here, we are only trying to save on traffic. This will work most of the time, but there will be a time when the speed through the Internet will decrease. There have been documented cases where the speed of the Internet has decreased, and in some cases the network has "faded." You heard that a few months ago the Internet on the east coast of the United States was “frozen” for 13 seconds? Imagine what a frozen video looks like! It is "frozen", the connection to the Internet has died. For 13 seconds, the internet was dead. What will happen to your video that you will transmit through the network? It is interrupted. The connection will disappear. A break in service is guaranteed. So, you see what you can get as a result.
We can contact the provider and buy a service called MPLS (Multiprotocol Label Switching) - multi-protocol label switching, a mechanism in a high-performance telecommunications network that transfers data from one network node to another using tags. This service gives you a lot and Cisco loves it very much, because it was our company that created it for network service providers in the mid-90s, theoretically. We are the fathers of MPLS.
MPLS provides you with a channel between points, in this case it connects our headquarters with a branch where you can choose your speed. There are three types of traffic that goes through this network.
The first is data. Suppose I have 2 Mbit / s, of which 1 Mbit / s, I want to allocate a significant portion for data transmission. If the rest of the channel is free, give me the full bandwidth for the data. So, when I transmit data on this "pipe", the provider marks them with a special label, which guarantees me the chosen speed and throughput. And he will charge me for it.
What else can I transmit on this network? That's right, voice. What happens when I make a phone call from headquarters to the branch? It takes little traffic and does not need a large bandwidth, but it needs great speed, the call must be really fast. For this I need only 256 Kbps. I turn to the provider and say that I need to transmit the voice at that speed. And he guarantees that it will be exactly the way I need, marking my voice with another mark. But he says that since this is a different type of traffic and we want to receive it quickly, he needs to make certain “drastic changes” for this to ensure “instantaneousness”. As a result, these 256 Kbps can cost more than 1 Mbit / s. But now, his network will know that this is a voice, and will skip it first of all and quickly, along the entire route.
Perhaps the next should be a video. How can I skip a video on this network? Let me remind you that we still have 768 Mbit / s. For video, I need a lot of speed, because using it helps me to do great things. This is part of my business process, so the video should work!
What properties does the video have? The same as the voice, but it requires more bandwidth. This will require me to pay even more, but I will optimally distribute my network costs. This way I “push” QoS from my networks to this network. Therefore, MPLS is the most useful thing for us.
I worked previously in South Carolina and was selling voice. And when we did it with the help of ancient technologies, the term “sludge” was born, we used Frame Relay and it was awful for us.
A question has been raised regarding the transmission standard T1 - a digital channel using telephone lines that allows you to guarantee speed. But why the provider does not want to provide you with this standard? It also works like a Talbot store selling clothes to my wife. Sells you everything in parts. For if he offers to buy me this entire channel, which we considered, for voice, video and data, for $ 725 together, then I will most likely say: “To hell with this MPLS. Just give me a T1 at 1.5 Mbps. ” But he will not want to do this, he will refuse.
What is the job of a network service provider? How does he make money? You're probably smarter than me, because you guessed it. It sells not bandwidth, but network access. I will give an example to bring you closer to understanding the essence. Recall the very first way you connected to the Internet. This is a dial-up. You went to the provider, paid him money, and for $ 19 a month he provided you with a phone number where you called through the modem. But do you really think that this was your personal modem, and it served only you? No, the provider sold it at least 20 times! He sold this bandwidth one more time, and another, and another. That was his job. Why does he not like to provide a dedicated channel T1? Because he can not resell it! He provides it only to you and no one else and had to reserve this channel for you, even if you do not use your channel at 2 am, it will be assigned to you and it will not be able to sell it to anyone.
And MPLS is different from T1 in that we allow oversell. It's like in Vegas, the correct odds are applied that guarantee casino success. You use the guaranteed full flow, others use it, anyone can use it, and at the same time it is guaranteed to receive it! And what am I doing? I sell it to you with an overcell ratio from 1 to 1.5 or even up to 2-2.5. And you are still able to get a guaranteed channel and continue to pay a premium price.
And the beauty of MPLS is that it is worldwide. Take the people from Perth, Australia’s west coast, it's at the opposite end of Sydney, the business people are there, the other business people live in Melbourne. So, if I want to connect to a valley in North Carolina, I will definitely contact AT & T or any other provider and say that we need an MPLS channel in Perth, because I want to open a new office there. And he provides us with MPLS. Can we use Frame relay instead of MPLS? Not. Do not even try, you will not get anything except a headache. I tried to do this many times, tried to transfer all the necessary technologies there, but nothing came of it.
Tell me, what is SIP? That's right, this is a session establishment protocol. Where did he come from, why did it happen? SIP helped to move from the traditional T1 RPI (Primary Rate Interface) line, which we used for voice transmission, to VOIP technology. And I could go to the same service provider and ask me to sell more band to forward SIP as well. But this did not reduce the price of his services. However, you could certainly send this signal along the same line.
How is bandwidth guaranteed on a non-guaranteed network that is resold several times? It's very simple, users do not press the keys on their keyboard at the same time. Because the chance that you will not get your channel is close to 0. However, T1 meant that I would definitely take 1.5 Mbit / s from others. T1 is actually the transmission of the first level, in Europe use its equivalent of E1, it is almost the same. We use 24 channels of 64 Kbps, which gives a total of 1.5 Mbps. We can talk about this a bit more in detail when we talk about telephony, but in fact this 1.5 Mbit / s bandwidth was used to support 24 phone calls, which we did - it essentially removed the separation between them. So think about it again when your channel is - no one else can use it.
MPLS is a great thing for us, people! She is really good! It is used by all providers and all users. The main reason why I go so deep into the details is that I know 3 partners, 3 people who came to Cisco, and two of them created these technologies right before my eyes. Service providers call this MPLS, but the provider also calls it differently - VPN. , VPN – , , , , , VPN. ? , .
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Continued:
FastTrack Training. "Network Basics". "The structure of routers, routing platforms from Cisco." Eddie Martin December 2012
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