From: Brett D. Watson[SMTP:bwatson@genuity.net] Sent: Saturday, September 14, 1996 11:12 AM
this is what i was getting at in my note a week ago or so. it appears that many more networks are being announced by 2+ as's. so i'm assuming we're sort of doomed to poor aggregation as more and more people dual-home to providers.
This is a trend (multi-homing) which will not only continue, but will definitely accelerate. -- Jim
There is no question that more people are needing more reliable connections to the net. With some education, tools, and the right pricing models, people can be encouraged to get backup connectivity in a manner that doesn't impact the size of the routing table. Specifically, they should not announce any routes on their backup connection unless their primary is down. ISPs should provide good prices on backups connections (ie, connections that almost never get any traffic). Contrast this to some ISPs which say you pay for your connection whether you use it or not. This causes the customer to want to load balance (and announce all routes all the time).
This is a trend (multi-homing) which will not only continue, but will definitely accelerate.
There is no question that more people are needing more reliable connections to the net. With some education, tools, and the right pricing models, people can be encouraged to get backup connectivity in a manner that doesn't impact the size of the routing table. Specifically, they should not announce any routes on their backup connection unless their primary is down. ISPs should provide
Is there some trick here or are you saying that a duel homed ISP should manually update their announcements when their primay pipe is down? I think that, in theory, your statement makes sense, but I don't know how one accomplishes it in practice. Outbound traffic is easy, but if one is duel homed and wishes to have inbound traffic find their network "quickly" and dynamically when their primary pipe is down, I believe it is necessary to advertise ones routes via ones backup at all times. Jim
--> -->> -->> -->> There is no question that more people are needing more reliable -->> connections to the net. With some education, tools, and the right -->> pricing models, people can be encouraged to get backup connectivity in -->> a manner that doesn't impact the size of the routing table. -->> Specifically, they should not announce any routes on their backup -->> connection unless their primary is down. ISPs should provide --> -->Is there some trick here or are you saying that a duel homed ISP should -->manually update their announcements when their primay pipe is down? I -->think that, in theory, your statement makes sense, but I don't know how -->one accomplishes it in practice. Outbound traffic is easy, but if one is -->duel homed and wishes to have inbound traffic find their network "quickly" -->and dynamically when their primary pipe is down, I believe it is necessary -->to advertise ones routes via ones backup at all times. --> -->Jim --> You might be able to set the backup interface in backup mode or standby mode or whatever cisco calls it, I don't remember. Anyway, if your primary line drops, the backup line would come up. Since the backup line would come up, you would begin peering with the backup peer. At this time, you would probably want to decide how much of a backup you want your backup to be. At what point do you declair an emergency and begin routing via your backup? I agree with the person who stated it earlier, the one saying that he'd rather use a backup all the time so he'd know whether a problem would come up when he needed his backup the most. Where this gets nasty is when your main ISP is having trouble peering at the peer points and so your connection is not down. At this time, I don't see how you could only announce to one peer at a time without a change in software. -- ------------------------------------------- | Jeremy Hall Network Engineer | | ISDN-Net, Inc Office +1-615-371-1625 | | Nashville, TN and the southeast USA | | jhall@isdn.net Pager +1-615-702-0750 | -------------------------------------------
Certainly not manually, but automatically. This does require some type of "if/then" logic in your router (ie, if you don't see this route from this source, then announce these routes to xxx). If your router can't do this, then you need to talk to your router vendor*. One needs to define quickly, but the time it takes to propogate a route isn't that long. * - tell them they need to do things like this and build a router that will handle several 100k routes.
There is no question that more people are needing more reliable connections to the net. With some education, tools, and the right pricing models, people can be encouraged to get backup connectivity in a manner that doesn't impact the size of the routing table. Specifically, they should not announce any routes on their backup connection unless their primary is down. ISPs should provide
Is there some trick here or are you saying that a duel homed ISP should manually update their announcements when their primay pipe is down? I think that, in theory, your statement makes sense, but I don't know how one accomplishes it in practice. Outbound traffic is easy, but if one is duel homed and wishes to have inbound traffic find their network "quickly" and dynamically when their primary pipe is down, I believe it is necessary to advertise ones routes via ones backup at all times.
Jim
participants (4)
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Jim Browning -
Jim Van Baalen -
jon＠branch.com -
Mr. Jeremy Hall