Hi,
I did this tool a few years ago to download and built ASN filter lists
by region automatically:
https://github.com/ipcjk/asnbuilder/releases
The tricky part was to build regular expressions for devices, that don't
understand number ranges.
For some of our routers we (un)select ASNs manually by reading and
comparing CIDR-reports to current Sflow traffic:
E.g.
https://github.com/ipcjk/asnbuilder/blob/master/customASN.txt
will become
https://github.com/ipcjk/asnbuilder/blob/master/saveTheFIB.txt
Jörg
On 17 May 2019, at 10:59, Jared Brown wrote:
There are a few approaches to culling the routing table. You can do it
either statically or dynamically, according to your needs.
1. Filtering based on upstream communities
Slimming down the Internet routing table
https://www.redpill-linpro.com/sysadvent/2016/12/09/slimming-routing-table.html
2. Filtering based on region
BGP filter for North American routes
http://gregsowell.com/?p=5505
Substitute prefixes for applicable region(s). Each region is about
200k prefixes. For more granularity use a geolocation service to
select prefixes and/or ASNs.
3. Using flow information to install only top routes
SDN Internet Router – Part 2
https://labs.spotify.com/2016/01/27/sdn-internet-router-part-2/
https://blog.ipspace.net/2015/01/sdn-router-spotify-on-software-gone-wild.html
4. Aggregate the routing table
According to the weekly routing table report you can aggregate
announcements to about half the number of prefixes. You need to roll
your own software to preprocess the BGP feed. There are some tools out
there, but I couldn't find a blog post about it with a quick search.
If you have one, please share!
Jared
