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RE: Pitfalls of annoucing /24s
What about the /24's that many ISPs (especially tier 2-3) are assigning to multi-homed customers? What about an IX or "critical infrastructure providers" that may be issued a /24 from ARIN (Policy 2001-3)? Although it may be rare that a large aggregate would become unreachable to a "large" network, doesn't the possibility exist that a customer with a /24 would become unreachable (to some) due to the aggregate dropping out even though the /24 should still be reachable? That scenario may not be very likely, but the question of assymetric routing and one's ability to balance traffic become issues. Assigning a lower preference to /24's would be a lot friendlier than just throwing them away. If I am way off base, I fully expect to be corrected (with volume). My flame retardant suit is in place. Michael -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Phil Rosenthal Sent: Wednesday, October 15, 2003 4:47 PM To: John Palmer Cc: [email protected] Subject: Re: Pitfalls of annoucing /24s http://info.us.bb.verio.net/routing.html#PeerFilter That's how Verio does it, and I assume, that's how most people who filter by length do it as well. --Phil On Oct 15, 2003, at 4:40 PM, John Palmer wrote: > > Good question. > > You know there are thousands of legacy /24's out there that were > allocated by > IANA as /24's How can you aggregate them up if all you have is the /24? > > To those who filter out /24's - how is this done - just by the netmask > size? > > ----- Original Message ----- > From: "Jean-Christophe Smith" <[email protected]> > To: <[email protected]> > Sent: Wednesday, October 15, 2003 15:34 > Subject: Pitfalls of annoucing /24s > > >> >> >> In current practice would there be serious jeopardy of portions of the >> internet not being able to reach this address space due to bgp >> filters or >> other restrictions? What is the smallest acceptable block of IPs that >> can be >> announced without adverse or unpredictable results? Verio would most >> likely >> be picking up these routes from us. I don't want to cause a religious >> debate, but I am interested in what the industry consensus is. >> >> I'm just doing some research, any comments would be appreciated. >> >> Thanks, >> Jean-Christophe Smith >> >> > > --Phil Rosenthal ISPrime, Inc.