RE: more specific routes in today reality
This however, does not mean though that multiple uplinks to more than one provider gives you more security than mulitple uplinks to one.
I completely disagree with you.
So do I (at least in this little part of the thread, which I haven't had the opportunity to follow at all length). For example, a provider-wide routing (or performance, or whatever) problem would be your problem if homed only to that one provider.
Multiple links may have failure modes in addition to and identical to some of the failure modes of a single connection, but multiple links also removes a complete calls of failure modes associated with a single connection.
This is a pretty fundemental tenet of communications systems in general as is not limited to IP.
mh
Peter
This however, does not mean though that multiple uplinks to more than one provider gives you more security than mulitple uplinks to one.
I completely disagree with you.
So do I (at least in this little part of the thread, which I haven't had the opportunity to follow at all length). For example, a provider-wide routing (or performance, or whatever) problem would be your problem if homed only to that one provider.
If it is a outage and you are running BGP you will need to wait for your router to converge. In worst case you will be dragged into the routing problems. However, I agree with Randy that 90% of outages are due to local-tail problems. I agree that two links to two operators are more reliable, but the real questions are if they are enough MORE reliable to justify the extra routes, and if so how do we implement this? And this should be a general solution all the way down to the residential users... I am not conviced that having multiple upstreams for entrprises, SOHO, residentials or even small ISPs are worth it. - kurtis -
So do I (at least in this little part of the thread, which I haven't had the opportunity to follow at all length). For example, a provider-wide routing (or performance, or whatever) problem would be your problem if homed only to that one provider.
If it is a outage and you are running BGP you will need to wait for your router to converge. In worst case you will be dragged into the routing problems. However, I agree with Randy that 90% of outages are due to local-tail problems.
I agree that two links to two operators are more reliable, but the real questions are if they are enough MORE reliable to justify the extra routes, and if so how do we implement this? And this should be a general solution all the way down to the residential users...
I am not conviced that having multiple upstreams for entrprises, SOHO, residentials or even small ISPs are worth it.
Oh, and BTW. I do think that in the long run we need to address this (among other things) one way to the other, but I don't think that todays routing technologies will scale for it. - kurtis -
Hi, On Mon, Oct 15, 2001 at 12:23:55PM +0100, Hallgren, Michael wrote:
This however, does not mean though that multiple uplinks to more than one provider gives you more security than mulitple uplinks to one.
I completely disagree with you.
So do I (at least in this little part of the thread, which I haven't had the opportunity to follow at all length). For example, a provider-wide routing (or performance, or whatever) problem would be your problem if homed only to that one provider.
Yes. But if one ISP really messes up his routing, he can still blackhole his multi-homed customers as well (like "redistribute IGP into BGP, announce that as more-specifics into the global table and get all the traffic for the netblock in question"). On the other hand: how many "provider wide routing outages" have you seen recently in business provider networks (that haven't been fixed more quickly than a customer would have needed to figure out what's going on and disconnect one upstream to get rid of those problems)? Be realistic about what outage scenarios you're planning for. I still think that for most outages these days, it's sufficient to get multiple uplinks to the same ISP (maybe to different POPs). This will also take care of "the local router at the customer falls down due to BGP table growth and out of memory" (or other BGP related problems), which IS something that a strategy for maximum reliability has to take into account. Gert Doering -- NetMaster -- SpaceNet AG Mail: netmaster@Space.Net Joseph-Dollinger-Bogen 14 Tel : +49-89-32356-0 80807 Muenchen Fax : +49-89-32356-299
participants (3)
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Gert Doering -
Hallgren, Michael -
Kurt Erik Lindqvist KPNQwest