[ixpmanager] Fwd: Re: Peering Matrix

[Nick Hilliard]

Carlos Saura wrote:
> Hello!
>> My main concern is that these sflow flows come from a switch and
>> therefore I can only see the mac addresses and I think I will not be
>> able to see the bgp sessions. We have a switch connected to all our
>> clients and I do not have access to my clients' team. My goal is to
>> see in the neutral point who makes peering with whom. Can I simply
>> with the level 2 flows build a matrix?

sflow includes the layer 3 and payer 4 packet headers. The
sflow-detect-ixp-bgp-sessions script (located in the
"tools/runtime/sflow" directory) will parse BGP packets that are picked
up by sflow, and will insert potential peering relationships into the
bgpsessiondata table in the database.

The peering relationships are only created for IPv4 and IPv6 addresses
visible in the IP address table in the database, i.e. the script will
ignore multihop BGP sessions running over the exchange and will only
provide visibility into bilateral bgp sessions on the IXP.

After a couple of days running, this is usually enough to give enough
information to build up a peering matrix.  This is a slow process
because sflow is sampled at low rates, e.g. 1:4096 or higher.  This
means that if there's only one in 4000 packets visible, it will take a
while before all BGP sessions are identified.

Nick