nanog mailing list archives
RE: FW: /8s and filtering
From: Harsha Narayan <hnarayan () cs ucsd edu>
Date: Tue, 10 Dec 2002 11:31:33 -0800 (PST)
Hello, I asked if the multihomer has to be able to fully utilize a /26=25% of /24 to be able to multihome. I am sorry but the link doesn't help. Harsha. On Tue, 10 Dec 2002, Ejay Hire wrote:
Interesting. Perhaps your source hasn't read the policy updates. Here is the link to ARIN's site, and I have successfully used this as justification for a customer. http://www.arin.net/policy/2001_2.html -ej -----Original Message----- From: Harsha Narayan [mailto:hnarayan () cs ucsd edu] Sent: Tuesday, December 10, 2002 1:15 PM To: Ejay Hire Cc: nanog () merit edu Subject: RE: FW: /8s and filtering 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 particularsize,ARIN ratified a policy that allows multihoming as justification for a /24. -ej -----Original Message----- From: N [mailto:nathan () stonekitty net] Sent: Tuesday, December 10, 2002 1:01 PM To: Forrest Cc: nanog () merit edu 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 whichhas anallocation from the Class C space rather than one from the ClassAspace.It doesn't matter. For all practical purposes, basementmultihomersonly care that their two or three providers have their route.Maybe I'm missing something, but what good would it do for someonetomultihome if only their own providers accept their route, but nobodyelsedoes? I realize that their block should be still announced withtheirISP's larger aggregate, but what good does this do if your ISP goesdownand 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, theprovidersmust accept more specific routes from each other, that is within the space being aggregated. If they do not share specifics, one uplinkdownwill cause a large percentage ~50% for the customer. This scenario is valid for load balancing, but redundancy is fragile. The onlyadvantageI 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 /23fromyourupstream provider. With the filtering that seems to be in place, itseemslike the only way you can truly multihome with a /23 is if ithappenstobe in the old Class C space. Or is this wrong?In today's VLSM world... the old classes have no bearing on filteringinmy experience. Prefix length discrimination knows no classfull boundaries.What seems to be needed is perhaps a /8 set aside by the RIRspecificallyto allocate to small organizations that wish to multihome thatpeoplewould accept /24 and shorter from.There is value in the current filtering of longest prefixes...Allowinganyone to multihome with BGP, using any network size, is going todoubleour BGP tables overnight. Perhaps its good that you must be of somesizeto 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~
Current thread:
- RE: FW: /8s and filtering, (continued)
- RE: FW: /8s and filtering Harsha Narayan (Dec 10)
- RE: FW: /8s and filtering Brian (Dec 10)
- Re: FW: /8s and filtering bmanning (Dec 10)
- RE: FW: /8s and filtering Alec H. Peterson (Dec 10)
- RE: FW: /8s and filtering Alec H. Peterson (Dec 10)
- RE: FW: /8s and filtering Harsha Narayan (Dec 10)
- RE: FW: /8s and filtering Alec H. Peterson (Dec 10)
- RE: FW: /8s and filtering Harsha Narayan (Dec 10)
- RE: FW: /8s and filtering Harsha Narayan (Dec 10)
- RE: FW: /8s and filtering Harsha Narayan (Dec 10)
- Re: FW: FW: /8s and filtering Marshall Eubanks (Dec 10)
- Re: FW: FW: /8s and filtering william (Dec 10)