Re: BCM5341x

[Joel Jaeggli]

Sent from my iPhone

> On Dec 24, 2016, at 15:51, Mike Hammett  wrote:
> 
> I've asked Broadcom directly, but being as though I don't have an intent to 
> buy tens of thousands of chips (or any at all), I don't expect I'll hear 
> back. I was hoping someone here would have some insight. 
> 
> Do any of you know what functionality is available on those chips? That's the 
> chip that powers the Ubiquiti 10G switches and I figured I would limit my 
> most aggressive feature requests to things they can actually deliver with the 
> platform as is. 
> 
> Other than things you just assume a managed switch has like 802.1p and 
> 802.1q, it mentions an advanced ContentAware™ Engine (which means?), IEEE1588 
> (sync over Ethernet), 802.1ag (OAM stuff), "Enhanced DoS attack statistics 
> gathering" (which means?), "IPv4/IPv6 L3 packet classification" (which 
> means?), etc. 
> 
> I'm sure there's an array of things to ask about, but MLAG and S-Flow are at 
> the top of my list at the moment. 

MCLAG is a control plane function. 

Sflow on devices that don't generate it in a distributed fashion is done but 
punting sampled packets to the control-plane for classification by an sflow 
agent. Sample rate is therefore contingent on adequate CPU and control-plane 
bandwidth.

The greyhound switch SOC may be hampered by the amount of CPU available 
locally, but the 2MB packet buffer also is probably cause for caution.

> https://www.broadcom.com/products/ethernet-connectivity/switch-fabric/bcm5341x/
>  
> 
> 
> 
> 
> - 
> Mike Hammett 
> Intelligent Computing Solutions 
> 
> Midwest Internet Exchange 
> 
> The Brothers WISP 
> 
> 

Re: Recent NTP pool traffic increase (update)

[Harlan Stenn]

Hi Fujimura-san,

On 12/24/16 6:11 AM, FUJIMURA Sho wrote:
> Hello,
> 
> I know 133.100.9.2 and 133.100.11.8 are listed.
> The Server Contact is old information.
> So, I sent e-mail to webmas...@ntp.org a few times.
> But, I have't received e-mail from them.
> I'd like them to change the information.
> Is there the person knowing the contact information to ntp.org?

I don't recall seeing the emails you sent to webmaster, but we do have a
new group of folks watching the Servers web.  We would be happy to work
with you to give you access to those entries so you can update them.

-- 
Harlan Stenn 
http://networktimefoundation.org - be a member!

Re: DWDM on 250 Km dark fiber without re-amplification

[Brandon Martin]

On 12/23/2016 07:14 PM, Jeremy wrote:

Hi all,

First, i'm sorry for my english, i'm french and i don't have a good
level in this language. But i want some informations and i'm sure,
someone will be give the good anwser about my question.

So, i'm regarding to rent a dual dark fiber in France, the estimated
distance is 225 Km, but i know there are a lot of optical switching on
the highway where it's fiber is installed (in theory, all 80 Km). So, i
used the bad scenario, in adding 25 Km on my need.

I would like to buy a amplificator and multiplexer DWDM to add some
10Gb/s waves on this dark fiber. I've see that the amplification is
better on 100 Gb/s synchronised ports, but we don't have enoug capacity
on our router to add 100 Gb/s interfaces.

So, someone has installed this type of hardware on a dark fiber without
regeneration  on 250 Km of distance ?
If yes, with what kind of hardware ? If you are commercial for this
hardware, please contact me in private message.



Look up Raman amplification.  The short of what this does is it pumps a 
ton of power into the near end of the fiber span and creates what looks 
somewhat like a typical color-blind amplifier somewhere several dozen km 
out on the span.  You'll also need to dump a ton of power into the span 
at the far end using an EDFA or similar.  Even with both of those, that 
distance is still going to push the raw optical power budget of even 
most state-of-the-art transceivers especially if the fiber is old or of 
low quality (high loss, high dispersion, etc.).


The longest span I've ever gotten a vendor to commit to an engineered 
design for was about 140km, and of course they needed full 
characterization of the span before they'd do it.  At those distances, 
distance alone is no longer sufficient to throw together a design.


It seems highly likely that there's at least one re-gen facility along 
that span.  I'd definitely see if there is one and if you can get some 
space in it.  That will knock you down into the 100-130km range on both 
sides of the re-gen, hopefully, which is perfectly doable.


You are somewhat correct that 100Gb interfaces often handle longer 
distances better, but it's because they are often using coherent 
receivers and carrier-synchronous transmitters rather than raw power 
receivers and ASK pulsed transmitters.  There are vendors that sell 
coherent 10Gb transceivers, too, and they'll be cheaper than 100Gb 
solutions especially if you don't need the extra capacity anyway.  I'd 
definitely check them out for this type of application especially if you 
can't get any dispersion compensation in the middle since coherent 
optics are usually much more tolerant of chromatic dispersion.


The big vendor I've worked with in the past on this sort of stuff is 
Ciena (and they're certainly a juggernaut in the industry) though I have 
no connection to them other than as a satisfied (if occasionally broke 
after a PO or out of breath after seeing a quotation) customer/integrator.


--
Brandon Martin