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Re: Sprint BGP filters in 207.x.x.x?
> Aside from what Daniel says about Sprint and MCI's routing policy > mismatch, this statement is interesting on another level. For Dan says: > MCI aggregates all its customer's routes into /19's. This is new is it > not? Also it says *MCI* does the aggregating and not the customer. > Would someone please explain how this differs from what I understand to > be Sprints policy which says (i believe) that it is the CUSTOMER's > responsibility to aggregate the routes they present to sprint??? > > Why would MCI do the aggregating? Is such mci policy good for mci or > good for the customer or equally good for both? If one gets a /19 and redistributes it to 8 new ISP customers, it is your responsibility to make sure that you only redistribute that /19 - and not any more specifics. If you *know* what those /19s, /18s, ... are, you can put specific aggregate statements into the peering routers. It's trickier when you have some contiguous space (customer X announces a /23 to you and customer Y announces a /23 - and the two /23s can be merged into a /22) that comes from customer's space allocations. You have to detect that aggregation is possible and then statically insert it - and check that it won't break anything (i.e. that customer X doesn't need only the /23 announced because he wants it to override a larger /22). But certainly when you are directly allocated address space, you have a responsibility to aggregate announcements from your customers who are in that space yourself. It doesn't hurt the customer, since the space is administratively yours - if they want to multi-home, their other provider (who obviously does not own the same /19 or /18 or ...) will announce the more specific /22 route and things will be fine for that customer (except that if it's newer address space, Sprintlink customers won't see the second provider's path to that /22 unless the second provider *is* Sprintlink). Avi