Filters and reality
I'm wondering just how far someone can get ignoring the prefix-length filtering rules used by Sprint/ANS/etc as long as you use Spring/ANS/etc as your provider. The National Archives of Canada has a traditional class B network 142.42. However, instead of advertising the network as 142.42/16, they've elected to advertise only 142.42.242/24. The /24 prefix-length announcement in traditional class B network space wouldn't pass the access-lists some providers use on their inbound BGP sessions. The same providers don't seem to use the same filters on their outbound announcements, leading to customer (and often network engineer) confusion why things don't work to some places but work ok inside the providers own network. Should we continue to poke holes in our filters to let Sprint's customer's customer routes through, or should we keep trying to explain to the Sprint NOC why their customer's customers could use shorter prefix length announcements? Be liberal in what you send, and conservative in what you accept? -- Sean Donelan, Data Research Associates, Inc, St. Louis, MO Affiliation given for identification not representation
[Apologies for an (almost technical) post from outside NA to NANOG] Hi,
Should we continue to poke holes in our filters to let Sprint's customer's customer routes through, or should we keep trying to explain to the Sprint NOC why their customer's customers could use shorter prefix length announcements?
I suppose it depends on what slope you want the graph at http://www.iepg.org/ops/bgptable.html to have. Regardless of whether the filters are a "good idea" or not, they do tend to limit routing table growth and its implications, if for no other reason than smaller sites are "encouraged" to go to their providers for address space due to fear of being filtered. Regards, -drc
At 08:32 AM 8/27/97 +0900, David R. Conrad wrote:
[Apologies for an (almost technical) post from outside NA to NANOG]
Hi,
Should we continue to poke holes in our filters to let Sprint's customer's customer routes through, or should we keep trying to explain to the Sprint NOC why their customer's customers could use shorter prefix length announcements?
I suppose it depends on what slope you want the graph at http://www.iepg.org/ops/bgptable.html to have.
He meant: http://www.telstra.net/ops/bgptable.html
I saw the iepg reference and made it work - either url will reach the same page now. I'd like to jazz it up with an exploder function which lets the viewer magnify parts of the graph, xplot style - does anyone have any good tools which would allow this to happen on a web page? (reply to me - I'll summarise to the list if interest is shown) thanks, Geoff (and no Bill, I'm not a north american this month :-) )
I suppose it depends on what slope you want the graph at http://www.iepg.org/ops/bgptable.html to have.
He meant: http://www.telstra.net/ops/bgptable.html
participants (4)
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Dave Curado -
David R. Conrad -
Geoff Huston -
Sean Donelan