[mirror-admin] please use ASNs, delete redundant netblocks

[Matt Domsch]

On Thu, Mar 04, 2010 at 12:13:11PM -0500, Chuck Anderson wrote:
> On Thu, Mar 04, 2010 at 10:43:47AM -0600, Matt Domsch wrote:
> > Hi all.  For a few months now, Fedora's MirrorManager instance has had
> > the ability for mirrors to specify the BGP ASN of your network, in
> > addition to separately listing your netblocks.
> > 
> > Some sites have quite a few netblock entries, which are all covered
> > now by the single ASN.  As the lookups on each client request must go
> > through all of the netblock entries in the database to some extent,
> > the now-redundant netblock entries only serve to slow things down,
> > even if it's just a little bit.
> > 
> > Please review your Host entries in MirrorManager, and if you have set
> > an ASN, and if your netblock lists are completely covered by your ASN
> > setting, please delete your netblock entries.
> 
> I would also make sure that your ASN is actually visible to 
> MirrorManager before doing that.  Especially if you are usihg IPv6 
> prefixes, hierarchical summarization of IPv6 routing may hide the view 
> of your ASN from the global routing table and hence MirrorManager 
> might not see it.  But the same thing could happen with IPv4 if you 
> are using PA address space from your ISP.  Even if you announce your 
> separate prefix to a different ISP, there is no guarantee that your 
> longer prefix route (and hence ASN) will be visible at the point of 
> observation by MirrorManager.

Ah, I always forget that part...

OK, here's what I do to test.  For each netblock, look it up in
asn.routeviews.org:

$ dig txt 0.0.166.143.asn.routeviews.org

;; ANSWER SECTION:
0.0.166.143.asn.routeviews.org.	86400 IN TXT	"3614" "143.166.0.0" "16"

tells me that netblock 143.166.0.0/16 is in ASN 3614.  Do likewise for
all your netblocks.  If they're all in the same ASN, as visible to
routeviews.org, you're OK to remove the netblocks from your Hosts and
just rely on the ASN.

Thanks,
Matt

-- 
Matt Domsch
Technology Strategist, Dell Office of the CTO
linux.dell.com & www.dell.com/linux

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