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North American Network Operators Group Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical Re: Cable Modem [really good network design]
> On Tue, 26 Jun 2001, Steve Schaefer wrote: > > > On Tue, 26 Jun 2001, Fletcher E Kittredge wrote: > > > > > > You provide frustrating few details and a statement "DHCP alone is not > > > a viable option in this model." Could you restate more concretely > > > what is your design problem which can only be solved by > > > ATM/MPLS/PPPoE? I hesitate to answer for fear that there is some > > > constraint I don't know about. > > > > The constraint is that outbound packets need to go to the right ISP. That > > is, the packets need to go through the carrier network according to the > > business relationship, not according to the destination IP address. > > > > Some method of identifying the ISP associated with each outbound packet is > > necessary. Policy routing, tunnels and PVC's are a few methods. Still vague, and you have the bad habit of specifying implementation mechanisms when asked for requirements. Users who specify implementation methods to engineers end up with bad designs :) With sincere respect, I point out you are asking a question to which you do not know the optimal answer and then supplying your best answer so far as if it is the only answer. You might learn more if you sincerely asked the question and listened... Quick review: ------------- Using an object for a purpose for which it was not designed is almost always a bad idea. Yes, improvisation is a life-saver. But if you get back to home base safely, pop the cowling, have the mechanics remove the duct tape and repair the damage the right way. Same for protocols. Using them for a purpose for which they were not designed almost always results in an inferior design. IP stands for Internet protocol. It was designed to tie disparate physical networks together into one seamless virtual network. The IP suite does not specify any qualities of the physical network. It does specify the end-to-end nature of the virtual Internetwork. It does things like end-to-end security (IPsec.) The Ethernet protocol was designed to adjudicate and route packets internal to one homogeneous, physical network. It handles media access, security, reliablity and routing in that one physical network. It appears to me that your problem here is at the physical network level. You only have one physical network. Your Ethernet hardware should handle the routing to the proper ISP. If it were me, I would also expect my Ethernet hardware to be able to filter, load-balance and meter based on MAC address so that I could gaurantee no ISP could see another's traffic and accurately charge the ISP for bandwidth. I think I hear you saying you must use hardware that does not use Ethernet. In which case, you have steered the conversation away from the original IPoE public network arena. You also have my condolences. I strongly recommend you spend some quality time with the DOCSIS spec... Personally, I think DSL and wireless modems would benefit from using DOCSIS. I have not thought hard about this issue and am interested in other opinions... regards, fletcher
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