North American Network Operators Group|
Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical
Re: IPv6 news
Paul Jakma wrote:
On Tue, 18 Oct 2005, Andre Oppermann wrote:As we know from the Internet DFZ the routing table becomes very large.However, it can be confined to that arbitrary area.
Yes, but it's a very cumbersum process. You have to track this stuff for all regions and countries. They all vary how they do it. For example your ComReg publishes a couple of tables now and then with new/changed information. (Look for ComReg 04/35, 03/143R, etc.)
You can forget that X.25 stuff. It's only used for SS7 message routing and doesn't have anything to do with call routing as such.Ah, it was used for everything in that network actually - but that was a very very specialised telco network. (And they had started moving to IP when I last worked with them.)
SS7 over IP is quite popular these days. However call routing != SS7 message routing.
Sure. However this is the main difference between the TDM network and the Internet. Due to this fact many things work on the phone network like carrier pre-selection, phone number portability, etc., that do not work on an IP network.I'm not source how assymetric paths affect portability etc. Also, IP is well capable of that, and makes life easier.
IP routing is not symmetric whereas circuit switching is. In a case of individual IP address portability the return traffic always goes back to the ISP who has that particular prefix. No matter who 'opened' the connection. If I port my static dial-up IP to my new super FTTH ISP then suddenly up to 100Mbit of return traffic have to pass from Dial-Up ISP to FTTH ISP. I'd say this screws the Dial-Up ISP pretty royally. And you too because he most likely doesn't have that much capacity.
On the phone network the prefix information is not dynamically exchanged.Uhm, sure it is.
Nope, it's not. Can you name a phone prefix routing protocol?
There are number portability registries whose data you can download every night or so and then dump it into your own switch or IN platform.The number portability registries can be updated infrequently, yes.
That works differently. In the PSTN you always have multiple routes to a destination. If you have a direct trunk between two CO's then it will fill that first. When the direct trunk is full, the local switch has got an overflow route towards a neighboring or higher switch. It can have multiple overflow routes with different priorities. You can replace full trunk with dead trunk to get your redundancy. However there is no dynamic call routing as we know it from BGP or OSPF. At least not directly. Some switch vendors have developed call optimization software which runs in some sort of central intelligence center in the network and tries to optimize the trunk usage and priorities based on statistical and historical data.
How they figure it out (with or without a regulator) doesn't matter. It just has to be figured out. We don't have IP regulators, so for IP providers would have to figure it out all by themselves obviously. ;)2a. The providers within the area have to figure out how to bill for the difference of this traffic.No. Usually the tariff is set by the regulator based on some fixed interconnection charge and network element usage.
The stumbling block is that all IP packets return to the prefix holder (the old ISP) and the end-user bandwidth is not fixed.
We're discussing what would be possible with area (rather than provider) assigned IP addresses. Ie, this is as possible for IP as PSTN, if $RIR decides to make some allocations in this way.To summarize the differences between PSTN and Internet routing: o PSTN ports numbers only within regions/area codes
$RIR making allocations that way is not sufficient. It would need regulatory backing to enforce IP address portability. Every established carrier is not very interested in porting IP addresses to competitors.
o PSTN routes the return path along the forward path (symetric)I thought you said it didn't? No matter, IP is assymmetric.
IP is asymmetric and PSTN is symmetric. There you have the first major problem with IP in this szenario.
o PSTN calls have pre-determined characteristics and performance (64kbit)
Very much so. See my Dial-Up vs. FTTH ISP example.
The important point is that information to describe number->provider is exchanged betweeen providers in the area only. Whether it's done by dynamic protocols, email or post is an irrelevant detail, all that matters is that we have a way to do same in IP (we do: BGP).o PSTN has static routing with periodic sync from porting database
The differences are far greater. See my description of call routing above.
Indeed, I thought I had emphasised that working out the billing would be a major component of area-allocated IP. ;)o PSTN call forwarding and peering is not free or zero settlement
As you can see in the Dial-Up vs. FTTH ISP case as new ISP you don't have a chance to differentiate yourself through better routing or performance or QOS or whatever from anyone else. If the performance at the old ISP was lousy before it is lousy after porting the IP address because it's still the shitty bandwidth of that old ISP. -- Andre