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.
https://www.broadcom.com/products/ethernet-connectivity/switch-fabric/bcm5341x/
The chip really doesn't even function as an Ethernet switch by itself...all
of the behavior is software driven. It's the ... actualization of "software
defined networking" -- It provides a lot of low level constructs inside the
hardware to support your application, but it's really a software defined
switch.
It has many programmable offload functions the idea being you do not handle
packets on the onboard CPU.
ContentAware is their term for L4-L7 I believe I don't think it's much more
than simple pattern matching in the hardware and can be used to apply as
ACL or drive QoS decisions.
The chip can do things like handle limited v4/v6 lookups and routing (but
it's not going to do ARP response... nor LACP...)
It has a huge number of integrated hardware counters, lots are built in but
you can count basically anything the hardware can match (which is basically
anything you can describe in a stateless manner).
So s-flow... probably in hardware it can be programmed to do most or all of
it as it's largely copying a buffer into a header but I don't have the data
sheets so couldn't say for sure.
MCLAG/MLAG, sure, that's software directed and behaves exactly like LACP
or static lag down at the hardware. Really the hardware doesn't much care
as that all exists above it in the control plane.
I'm not clear at all what depth of v4/v6 classification they support - but
that's usually the basics of QoS and calling it out specifically is
marketing wankery I think.
How big the tables can get I don't know. Nearly two decades ago they had 2k
in the L3 space with 8K in L2 on 24x100+2x1G ... so I can't imagine it's
less than that for table sizes 
probably like 8k/4K entries range as the
RAMs and TCAMs haven't scaled up in speed very well.
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.
Mike, Another practical question (for what you are seeking) is how much of
the control plane software (for features you seek) does Broadcom provide
with their reference design and how much must Ubiquiti write?
Thanks,
Brough
Brough Turner
netBlazr Inc. – Free your Broadband!
Mobile: 617-285-0433 Skype: brough
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