Hi Lads, I Used to Filter based on AS paths and reject any prefix that had private or reserved AS numbers in the AS Path, I have to say that my experience is that on Software routers such as Mikrotik, even on fast x86 processor based routers that it increased convergence times by up to 5x in some case, and 8x/ 10x on Cloud core versions of Mikrotik Hardware,
in short the benefit of removing prefixes whos as path appears to be non standard conforming, was far , by fa,r out weighed, by the cost of the time it took my routers to recover from a blip or even just starndard regular maintainence, I would agree (now that I learned the hard way) with all those who say filtering via AS Path and Reg ex is not such a hot idea... I hope this helps, Tom Smyth On Wed, Nov 4, 2015 at 11:09 AM, James Bensley <jwbens...@gmail.com> wrote: > > On 31 Oct 2015 18:59, "Nick Hilliard" <n...@foobar.org> wrote: > > > > um, apologies for the tactlessness of this email, which didn't come out > at > > all as intended, oops :-/ > > > > -n > > No problems. If I wasn't clear, I'm not saying prefixes and AS paths are > the same. See earlier post about being in mobile and multi-AS consolidation > work. > > I have 5 full table provides, if someone is sending me a prefix with AS > path that contains XYZ-AS which I'd a private AS, someone has made a boo > boo somewhere and I don't want that to become my best path as that operator > potentially has a network full of problems. Nuking the prefix with a bad AS > path then allows me to learn it from somewhere else. > > Yes, caveat corner cases for a customer with single upstream somewhere so > we will see their prefixes the same via all my transit providers. I have > taken a dump of the full table, I'll be scanning it. Off the top of my > head, I'm confident that they're few and far between enough that it's no > problems for me. > > James > -- Kindest regards, Tom Smyth Mobile: +353 87 6193172 --------------------------------- PLEASE CONSIDER THE ENVIRONMENT BEFORE YOU PRINT THIS E-MAIL This email contains information which may be confidential or privileged. The information is intended solely for the use of the individual or entity named above. If you are not the intended recipient, be aware that any disclosure, copying, distribution or use of the contents of this information is prohibited. If you have received this electronic transmission in error, please notify me by telephone or by electronic mail immediately. Any opinions expressed are those of the author, not the company's .This email does not constitute either offer or acceptance of any contractually binding agreement. Such offer or acceptance must be communicated in writing. You are requested to carry out your own virus check before opening any attachment. Thomas Smyth accepts no liability for any loss or damage which may be caused by malicious software or attachments.