

Tech startups best positioned to strike engineering gold - taylorbuley
http://blog.linkedin.com/2012/05/17/top-10-tech-engineering-startups/

======
mrmaddog
I was surprised at how few web/consumer companies there were on this list--
perhaps that is mostly a function of LinkedIn's demographic.

Anyhow, I work at Arista Networks, and would be more than happy to answer any
questions you guys have about us, our technology, or our engineering culture.
(P.S. If Santa Clara isn't your thing, we just opened a SF office!)

~~~
nanijoe
A little off topic..I had never heard of Arista Networks until just now. I did
go and check out the product line, and one of those products promises low
latency switching at the same speeds for both layer 2 and layer 3!! How is it
possible to process routed and no-routed traffic at the same speed? I'm
genuinely interested...Designing networks is part of what I do for a living.

~~~
aaronbee
Every packet goes through special switching hardware or ASIC. This ASIC has a
pipeline for processing packets like a CPU has a pipeline for processing
instructions. The ASIC also contains very fast tables optimized for storing
and looking up MAC and IP addresses.

One part of the pipeline checks if the destination MAC matches the switch's
MAC. If it does then the packet is routed and the ASIC will read the
destination IP address from the packet. The dest IP is looked up in the
routing table to figure out which port the next hop lives on and what it's MAC
address is. If the destination MAC is for another host, then the MAC table is
checked to see what port to send the mac.

Modern ASICs are designed to handle both cases very quickly.

~~~
nanijoe
So for a layer 2 packet, the routing table does not get consulted.. In effect,
the time to forward a layer 3 packet is = time to forward layer 2 packet +
time to look up routing table (no matter how quickly). ie Layer 3 packets take
longer to forward than Layer 2 packets

------
drcode
Thanks taylorbuley, this HN post made me a nice sum of money (only publicly
traded company in the post <http://www.google.com/finance?q=splk> )

