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North American Network Operators Group Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical Re: all the mails on Filtering
Hi Harsha, this occurs quite often as a topic for discussion here.. the answer is they do it because they can and unless you have an RIR allocation theres no guarantees and to be fair the RIRs do state that. and good/bad agree/disagree some ISPs filter more than others and theres not a lot you can do! providing you connect to the provider who gave you the prefix you wont have any issues.... Steve On Wed, 13 Nov 2002, Harsha Narayan wrote: > > Hi, > But it appears that there are many cases where customers prefer to take > a prefix from the ISP rather than an RIR even if it is a /19 or a /20 - > for example from the /11 of a big ISP, there are 50 /19s and /20s which > are multihoming assignments. > > I was told that this saves the cost of RIR membership for the customer. > > Moreover, how do we know the RIR makes multihoming assignments from a > separate /8 - atleast in the case of RIPE it does not I think (in the case > of APNIC it does). If we are of sure of this - i.e. that a multihoming > assignment from an RIR comes from a separate section of the address space > - we can't filter. > > Harsha. > On Wed, 13 Nov 2002, Jared Mauch wrote: > > > If you're multihomed you can generally obtain provider indepdent > > space from your RIR. > > > > Most people who do this filtering do it on the RIR boundaries > > for their minimum allocation. > > > > If you are annoucing your provider assigned space > > as a /24, they tend to announce the (/14 - /rir-minimum) > > so your packets will follow the aggregate. If they > > are not announcing their aggregate then you will have > > problems. Most people in that case would blame > > the provider for not announcing their space. > > > > - Jared > > > > On Wed, Nov 13, 2002 at 10:25:53AM -0800, Harsha Narayan wrote: > > > > > > Hi, > > > > > > So what happens to multihoming assignments made by the ISP? That means > > > the multihoming assignment can't be used as a backup. If the customer's > > > connection to the ISP which made the multihoming assignment gets lost, > > > then it can't use its multihoming assignments (say a /24) to get traffic > > > from some other ISP?! > > > > > > Thanks to all, > > > Harsha. > > > > > > On Wed, 13 Nov 2002, Buddy Bagga wrote: > > > > > > > Greets, > > > > > > > > Look at <http://www.nanog.org/filter.html>. If I remember correctly, Verio > > > > used to filter prefixes longer than /19s in classful A range. Apparently > > > > this isn't the case anymore. But it would be naive to think that ISP only > > > > filter prefixes longer than /24. > > > > > > > > Cheers, > > > > > > > > On Wed, 13 Nov 2002, Harsha Narayan wrote: > > > > > > > > > Are there some ISPs who filter prefixes longer than /19 or a /20?. I > > > > > thought they filtered only prefixes which are longer than /24? > > > > > > > > ~ > > > > Buddy Bagga > > > > Genuity | BBN > > > > > > > > > > > -- > > Jared Mauch | pgp key available via finger from [email protected] > > clue++; | http://puck.nether.net/~jared/ My statements are only mine. > > > >
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