Currently I have 2 choices as far as I can make out, give them a bit of my /19, break up my nice aggregate and ensure loads of extra announcements (and that probably none of them get routed by anyone applying prefix based filtering), or give them a new /19 all of their own (you've
Suppose you have a customer that needs a /22 and they want to go multi-homed. Suppose you give them that /22 out of your /19 or /16 you got from the RIPE NCC. So they announce their /22 to you and to their other provider. But you keep announcing your /19 or /16. So if anybody were to filter the /22 announcement, your customer only suffers partial loss of connectivity, since you are still announcing an aggregate of their announcemnt (your original /19 or /16).
Problem fixed. Anything else? ;-)
Yes, if you go down, or their line goes down to you, their multi-homing is worthless. Dave -- Dave Siegel President, RTD Systems & Networking, Inc. (520)623-9663 Network Engineer -- Regional/National NSPs (Cisco) dsiegel@rtd.com User Tracking & Acctg -- "Written by an ISP, http://www.rtd.com/~dsiegel/ for an ISP."