Cogent Layer 2

Thu Oct 15 23:27:35 UTC 2020

On 10/15/20 6:15 PM, Robert Blayzor wrote:
> On 10/14/20 1:56 PM, Shawn L via NANOG wrote:
>> When I last spoke to them, it sounded like they were using a bunch of
>> LAG groups based on ip address because they _really_ wanted to know how
>> many ip addresses we had and what kind of traffic we would be expecting
>> (eyeball networks, big data transport, etc).
> 
> 
> Not why IP addresses are even an issue on an a "Layer 2" service. But
> then again, this is Cogent we're talking about here.
> 

Hashing on LAGs within their core.  Even otherwise fairly braindead 
Ethernet switches often hash on L3 to try and get more entropy.

I hope they hash on L2 MAC, as well, but a pretty common scenario for an 
L2 interconnect only has one MAC on each end of the link, so that 
doesn't help much.  They reeeeallly don't want all your traffic ending 
up on one side of a LAG.
-- 
Brandon Martin