North American Network Operators Group Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical RE: FW: /8s and filtering
Hello, But how will such an ISP justify this to the RIR? Thanks, Harsha. On Tue, 10 Dec 2002, Brian wrote: > many isps will automatically give a /24 if their client is multihoming, > even if their usage is well below the 254 usable ips allocated by the > above block size. > > Brian > > > On Tue, 10 Dec 2002, Harsha Narayan wrote: > > > > > Hello, > > No, this is not the case. I enquired and it seems multihoming is not a > > justification for a /24 in any RIR. > > > > Does a network have to be able to fully utilize a /26 (25% of /24) in > > order to multihome? > > > > Harsha. > > > > On Tue, 10 Dec 2002, Ejay Hire wrote: > > > > > > > > Having a /24 doesn't indicate you are a network of any particular size, > > > ARIN ratified a policy that allows multihoming as justification for a > > > /24. > > > > > > -ej > > > > > > -----Original Message----- > > > From: N [mailto:[email protected]] > > > Sent: Tuesday, December 10, 2002 1:01 PM > > > To: Forrest > > > Cc: [email protected] > > > Subject: Re: FW: /8s and filtering > > > > > > > > > comments inline > > > > > > On Tue, Dec 10, 2002 at 12:36:39PM -0600, Forrest wrote: > > > > > > > > > > >I was also curious about this - if I am a customer who wants to > > > > > >multihome and can justify only a /24, I would go to an ISP which > > > has an > > > > > >allocation from the Class C space rather than one from the Class A > > > > > >space. > > > > > > > > > > It doesn't matter. For all practical purposes, basement > > > multihomers > > > > > only > > > > > care that their two or three providers have their route. > > > > > > > > > > > > Maybe I'm missing something, but what good would it do for someone to > > > > multihome if only their own providers accept their route, but nobody > > > else > > > > does? I realize that their block should be still announced with their > > > > > > > ISP's larger aggregate, but what good does this do if your ISP goes > > > down > > > > and can't announce the large aggregate. > > > > > > For the assigned block to be part of the same aggregate(of both > > > providers), that implys that the providers sharing the responsibility > > > for the aggregate. It happens, but is rare. In this case, the providers > > > must accept more specific routes from each other, that is within the > > > space being aggregated. If they do not share specifics, one uplink down > > > will cause a large percentage ~50% for the customer. This scenario is > > > valid for load balancing, but redundancy is fragile. The only advantage > > > I see is no limit to prefix length. You can do this with a /28 if you > > > want... given the above caveats are addressed. > > > > > > > If you're a smaller organization, perhaps you'll only have a /23 from > > > your > > > > upstream provider. With the filtering that seems to be in place, it > > > seems > > > > like the only way you can truly multihome with a /23 is if it happens > > > to > > > > be in the old Class C space. Or is this wrong? > > > > > > In today's VLSM world... the old classes have no bearing on filtering in > > > my experience. Prefix length discrimination knows no classfull > > > boundaries. > > > > > > > What seems to be needed is perhaps a /8 set aside by the RIR > > > specifically > > > > to allocate to small organizations that wish to multihome that people > > > > would accept /24 and shorter from. > > > > > > There is value in the current filtering of longest prefixes... Allowing > > > anyone to multihome with BGP, using any network size, is going to double > > > our BGP tables overnight. Perhaps its good that you must be of some size > > > to participate in public BGP. Many providers offer redundancy that is > > > more appropriate for the smaller networks. > > > > > > -- > > > ,N > > > > > > ~Nathan - routing & switching dude/fly-boy/sport biker - San Jose CA~ > > > > > >
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