Another neat thing about 400 and 800GE is that you can get MPO optics that
allow splitting a single 4x100 or 8x100 into individual 100G feeds. Good
for port density and/or adding capacity to processing/Edge/Appliances

Now there are decent ER optics for 100G you can now do 40-70KM runs of each
100G link without additional active electronics on the path or going to and
optical transport route.

On Thu, 16 Apr 2020 at 08:57, Michael Richardson <mcr@sandelman.ca> wrote:

>
> Mikael Abrahamsson via Cerowrt-devel wrote:
>     > Backbone ISPs today are built with lots of parallel links (20x100GE
> for
>     > instance) and then we do L4 hashing for flows across these. This
> means
>
> got it. inverse multiplexing of flows across *links*
>
>     > We're now going for 100 gigabit/s per lane (it's been going up from
> 4x2.5G
>     > for 10GE to 1x10G, then we went for lane speeds of 10G, 25G, 50G and
> now
>     > we're at 100G per lane), and it seems the 800GE in your link has 8
> lanes of
>     > that. This means a single L4 flow can be 800GE even though it's in
> reality
>     > 8x100G lanes, as a single packet bits are being sprayed across all
> the
>     > lanes.
>
> Here you talk about *lanes*, and inverse multiplexing of a single frame
> across *lanes*.
> Your allusion to PCI-E is well taken, but if I am completing the analogy,
> and
> the reference to DWDM, I'm thinking that you are talking about 100
> gigabit/s
> per lambda, with a single frame being inverse multiplexed across lambdas
> (as lanes).
>
> Did I understand this correctly?
>
> I understand a bit of "because we can".
> I also understand that 20 x 800GE parallel links is better than 20 x 100GE
> parallel links across the same long-haul (dark) fiber.
>
> But, what is the reason among ISPs to desire enabling a single L4 flow to
> use more
> than 100GE?  Given that it seems that being able to L3 switch 800GE is
> harder
> than switching 8x flows of already L4 ordered 100GE. (Flowlabel!), why pay
> the extra price here?
>
> While I can see L2VPN use cases, I can also see that L2VPNs could generate
> multiple flows themselves if they wanted.
>
> --
> ]               Never tell me the odds!                 | ipv6 mesh
> networks [
> ]   Michael Richardson, Sandelman Software Works        |    IoT
> architect   [
> ]     mcr@sandelman.ca  http://www.sandelman.ca/        |   ruby on
> rails    [
>
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