Hmmm...seems everyone wants to either be a smart*** or overanalyze this.
First off: It appears that he is working with the local cable company, so, actually, he has already defined what sort of issues and designs he will have with this.
Dark fiber from a cable company means a point to point link. If he has multiple offices, this will generally mean that there will be a hub and spoke design on the fiber from a central location to the edge sites. In addition, the local cable co will most certainly provide the distances and loss budget for the fiber, making selection of equipment an act of trivia.
The only thing not defined was the type of network he really wants, but in this case, it is also probably completely irrelevant. If you can't put all your services over TCP/IP, then you shouldn't be maintaining a network.
First off, gear selection. I work for a Cisco-centric company, so most of my experience is with Cisco, but I have worked with Foundry and Nortel and a few others. If you want reliable, Cisco is certainly acceptable, and you can always put a contract on it to meet your needs.
Second, protocol selection. Well, he wants TCP/IP. This will certainly be easy enough. Engineer the backend properly (IP addressing 101, and get a router for the links, your done. If you need to convert Analog Video to H.323, there are plenty of vendors who can do this. If you need COS, again, there are plenty of solutions.
Layer 2 Selection. My recommendation would be to go with GigE. This is certainly cheaper than going with outdated FX technology if you buy new, and more reliable. When you have the distances and loss budget of the fiber links, you can select the appropriate GBIC's for the link, and if you get light at both ends, you have a network.
In Cisco terms, I'd go with a 3550-12G at the core if you have more than 2 locations. This will be a reasonable fiber concentrator ($9,999 list) and also does QOS, policing, and routing (both packet and protocols, such as EIGRP).
At the edge, depending on how much intelligence you need, you can put in Cisco 3550-24's, either EMI or SMI flavor. The EMI boxes are routers (same code as the 3550-12G. The SMI boxes have port routing in the newest code, but won't run routing protocols. These boxes will allow you to converge your network (data, VOIP, and video) and really don't have a horrible price tag. The SMI lists at $2,999 and the EMI at $4,999. This doesn't include GBIC's but the max cost on those is long-haul (Cisco ZX) which lists at $5,995. The intermediate reach LX is only $995. Don't mess around with MMF (SX GBIC's) if you don't have to. Even if you do short haul, this will be a more stable solution and will allow you to repurpose gear in the future.
The big gotcha with this is support of the fiber. Most of the time Cable dark fiber contracts mean that the customer is responsible for paying for repair of the fiber. Find out who is responsible for the fiber, and make sure you budget appropriately if the cable company is going to charge you for repairs on the lines. If they won't do it, find someone who can (check the contractors who already work with the cable company, they already know the systems and people) and get them on retainer or whatever. Many schools and governments have ended up shocked because they had to find someone in the middle of the night with a fusion splicer to fix a damaged link. Or the cable company sent them an outrageous bill for repair after the fact. This sucks, because it is hard to budget for an 18-wheeler gone awry in an ice storm.
If you do it this way, you can treat the fiber just like Ethernet, and be done with it. You don't have to relearn protocols, and you will have a decent growth path for the future. My networks (that look just like this!) are WAN's that I treat like LAN's, and they are easy to support.
Gybrwe
Disclaimer: I work for a large cable company. However, I spent my last 5 years running startup ISP technical operations, and I was a cable modem customer long before I started with my current company.
Having spent close to the last year working for a large cable company, I have to say that the reality of providing data over the cable system is a little different than the comments that I've seen here today seem to indicate.
First of all, the scarce resource for a cable company is not internet bandwidth. In the local network, my employer currently has 3 OC-3's to the Internet, and is converting those to OC-48's as I type this. Outside bandwidth is certainly cheap these days, and until the glut of dark fiber in the ground works itself out, this probably won't stop anytime soon. However, the scarce resource for the cable company is the RF spectrum on the coaxial cable plant itself. Essentially, each service/channel resides in its own RF band on the cable plant. For my provider, we have a 6mhz downstream frequency and a 1.6mhz (currently being migrated to 3.2mhz) upstream frequency dedicated for every 4 nodes on our network that share these RF spectrums. Needless to say, this is *THE* bottle neck to providing higher bandwidth to our customers. Remember also: all of our services are shared within the 850mhz range that is carried by our system. Currently we have the following services on our system: Analog cable: 75 channels, each one takes 1 6mhz carrier Digital cable: 100+ channels, 6 channels per carrier Cable modems: 1 6 mhz channel Telephony: 1 6mhz channel Video on Demand: 32 channels (sorry, I don't know how many carriers it takes, but I suspect a decent amount. Reverse carriers: 50 mhz total spectrum, all communications to our systems (upstream cable modem, pay-per-view orders, VOD orders, telephony) within these carriers.
So, do the math: what causes our bandwidth headaches? Analog video. These 75 channels account for well over half the total RF spectrum we have.
Can we get rid of it? Not until every one of our users gives up their analog cable boxes and stops complaining that the digital boxes cost 3x as much (3.95 for analog, 8.95 for digital). Also not until our franchise agreements are changed in many cases to allow digital only transmission to customers.
Would we absolutely kill and die to get rid of analog and be able to do more for our customers? You bet. In a heartbeat. Personally, I'd love to have DS-3 speeds (which is what DOCSIS will currently support) at my house cheap, plus 4 extra phone lines at a price cheaper than the local ILEC can provide. But until we are able to migrate our customers to the latest and greatest, there is nothing we can do.
Incidentally, some of the service problems caused by wide open cable systems (@Home, for one) are based on the fact that the RF spectrum is shared. If you open everyone up, one person can conceivably trash the entire node. Also, I was peripherally involved with an @Home conversion. One of the things we discovered on the routers that @Home maintained for us was the fact that they allowed the end cable modem connect at their maximum speeds, but they rate limited the network between the routers and the Internet drain during prime time to keep each router from overwhelming the DS-3's that they maintained for Internet access. Kinda dirty, letting users *THINK* they had infinite bandwidth, but barely letting more bandwidth through on the backend that a few cable modems.
I would suggest (very politely) that you find out the details of how the cable system works before whacking the cable provider over these issues.
Having been Director of Operations for 3 different dot.bomb ISP's, I thoroughly understand the differences between the two. The way I tell people the difference between a traditional ISP and a cable provider is this: When I was with the ISP's, it was like playing in an orchestra that only played music in C Major. When I moved over to the cable provider, I moved to an orchestra that only played in D Minor. It's still music, but the differences are both amazing and subtle.
Slashdot Mirror
Hmmm...seems everyone wants to either be a smart*** or overanalyze this. First off: It appears that he is working with the local cable company, so, actually, he has already defined what sort of issues and designs he will have with this. Dark fiber from a cable company means a point to point link. If he has multiple offices, this will generally mean that there will be a hub and spoke design on the fiber from a central location to the edge sites. In addition, the local cable co will most certainly provide the distances and loss budget for the fiber, making selection of equipment an act of trivia. The only thing not defined was the type of network he really wants, but in this case, it is also probably completely irrelevant. If you can't put all your services over TCP/IP, then you shouldn't be maintaining a network. First off, gear selection. I work for a Cisco-centric company, so most of my experience is with Cisco, but I have worked with Foundry and Nortel and a few others. If you want reliable, Cisco is certainly acceptable, and you can always put a contract on it to meet your needs. Second, protocol selection. Well, he wants TCP/IP. This will certainly be easy enough. Engineer the backend properly (IP addressing 101, and get a router for the links, your done. If you need to convert Analog Video to H.323, there are plenty of vendors who can do this. If you need COS, again, there are plenty of solutions. Layer 2 Selection. My recommendation would be to go with GigE. This is certainly cheaper than going with outdated FX technology if you buy new, and more reliable. When you have the distances and loss budget of the fiber links, you can select the appropriate GBIC's for the link, and if you get light at both ends, you have a network. In Cisco terms, I'd go with a 3550-12G at the core if you have more than 2 locations. This will be a reasonable fiber concentrator ($9,999 list) and also does QOS, policing, and routing (both packet and protocols, such as EIGRP). At the edge, depending on how much intelligence you need, you can put in Cisco 3550-24's, either EMI or SMI flavor. The EMI boxes are routers (same code as the 3550-12G. The SMI boxes have port routing in the newest code, but won't run routing protocols. These boxes will allow you to converge your network (data, VOIP, and video) and really don't have a horrible price tag. The SMI lists at $2,999 and the EMI at $4,999. This doesn't include GBIC's but the max cost on those is long-haul (Cisco ZX) which lists at $5,995. The intermediate reach LX is only $995. Don't mess around with MMF (SX GBIC's) if you don't have to. Even if you do short haul, this will be a more stable solution and will allow you to repurpose gear in the future. The big gotcha with this is support of the fiber. Most of the time Cable dark fiber contracts mean that the customer is responsible for paying for repair of the fiber. Find out who is responsible for the fiber, and make sure you budget appropriately if the cable company is going to charge you for repairs on the lines. If they won't do it, find someone who can (check the contractors who already work with the cable company, they already know the systems and people) and get them on retainer or whatever. Many schools and governments have ended up shocked because they had to find someone in the middle of the night with a fusion splicer to fix a damaged link. Or the cable company sent them an outrageous bill for repair after the fact. This sucks, because it is hard to budget for an 18-wheeler gone awry in an ice storm. If you do it this way, you can treat the fiber just like Ethernet, and be done with it. You don't have to relearn protocols, and you will have a decent growth path for the future. My networks (that look just like this!) are WAN's that I treat like LAN's, and they are easy to support. Gybrwe
Disclaimer: I work for a large cable company. However, I spent my last 5 years running startup ISP technical operations, and I was a cable modem customer long before I started with my current company.
Having spent close to the last year working for a large cable company, I have to say that the reality of providing data over the cable system is a little different than the comments that I've seen here today seem to indicate.
First of all, the scarce resource for a cable company is not internet bandwidth. In the local network, my employer currently has 3 OC-3's to the Internet, and is converting those to OC-48's as I type this. Outside bandwidth is certainly cheap these days, and until the glut of dark fiber in the ground works itself out, this probably won't stop anytime soon.
However, the scarce resource for the cable company is the RF spectrum on the coaxial cable plant itself. Essentially, each service/channel resides in its own RF band on the cable plant. For my provider, we have a 6mhz downstream frequency and a 1.6mhz (currently being migrated to 3.2mhz) upstream frequency dedicated for every 4 nodes on our network that share these RF spectrums. Needless to say, this is *THE* bottle neck to providing higher bandwidth to our customers.
Remember also: all of our services are shared within the 850mhz range that is carried by our system.
Currently we have the following services on our system:
Analog cable: 75 channels, each one takes 1 6mhz carrier
Digital cable: 100+ channels, 6 channels per carrier
Cable modems: 1 6 mhz channel
Telephony: 1 6mhz channel
Video on Demand: 32 channels (sorry, I don't know how many carriers it takes, but I suspect a decent amount.
Reverse carriers: 50 mhz total spectrum, all communications to our systems (upstream cable modem, pay-per-view orders, VOD orders, telephony) within these carriers.
So, do the math: what causes our bandwidth headaches? Analog video. These 75 channels account for well over half the total RF spectrum we have.
Can we get rid of it? Not until every one of our users gives up their analog cable boxes and stops complaining that the digital boxes cost 3x as much (3.95 for analog, 8.95 for digital). Also not until our franchise agreements are changed in many cases to allow digital only transmission to customers.
Would we absolutely kill and die to get rid of analog and be able to do more for our customers?
You bet. In a heartbeat. Personally, I'd love to have DS-3 speeds (which is what DOCSIS will currently support) at my house cheap, plus 4 extra phone lines at a price cheaper than the local ILEC can provide. But until we are able to migrate our customers to the latest and greatest, there is nothing we can do.
Incidentally, some of the service problems caused by wide open cable systems (@Home, for one) are based on the fact that the RF spectrum is shared. If you open everyone up, one person can conceivably trash the entire node. Also, I was peripherally involved with an @Home conversion. One of the things we discovered on the routers that @Home maintained for us was the fact that they allowed the end cable modem connect at their maximum speeds, but they rate limited the network between the routers and the Internet drain during prime time to keep each router from overwhelming the DS-3's that they maintained for Internet access. Kinda dirty, letting users *THINK* they had infinite bandwidth, but barely letting more bandwidth through on the backend that a few cable modems.
I would suggest (very politely) that you find out the details of how the cable system works before whacking the cable provider over these issues.
Having been Director of Operations for 3 different dot.bomb ISP's, I thoroughly understand the differences between the two. The way I tell people the difference between a traditional ISP and a cable provider is this: When I was with the ISP's, it was like playing in an orchestra that only played music in C Major. When I moved over to the cable provider, I moved to an orchestra that only played in D Minor. It's still music, but the differences are both amazing and subtle.