[j-nsp] MX304 reliability

[Andrey Kostin]

Thank you both, Aaron and Saku for your feedback.

I can only guess that there isn't a problem with high failure rates as 
happened before with some linecards.
Regarding Saku's note about pure single chip design, MX301 is a single 
Trio system, but it has the same number of ports available for network 
connectivity because Trio6 has two slices that act as independent 
forwarding engines, so theirs fabric lanes connect them together and no 
additional ports can be gained there.
https://community.juniper.net/blogs/david-roy/2025/11/24/mx301-deepdive

Regards,
Andrey

Saku Ytti писал(а) 2026-05-05 02:53:
> Not contributing much here, rambling mostly.
> 
> MX304 from product marketing follows MX80, MX104, MX204, but
> technically it's very different.
> 
> Previously from the WAN+LAN side of Trio connected WAN ports, that is,
> the Trio had 2xports compared to fabric ports, because no capacity was
> used for fabric. This of course means the smallest average packet size
> at 100% is twice as large, because PPS remains the same, but port
> count doubles, which I can't recall anyone actually suffering from, as
> the PPS budget is still good enough.
> 
> MX304 has up-to 3 Trio YT, so it needs fabric to connect them, and
> we're missing 'true 304' which would be single YT, with all WAN ports.
> This single YT MX304 would still be 2/3 of the port density of MX304,
> which almost no one exceeds, because most buy it with RE redundancy.
> So the box would be basically third of the CAPEX with in practice
> similar port-density had it followed the 80/104 design.
> 
> In practice it may be impossible to do this in YT, because YT is
> really two Trio in a package, and those Trios still need fabric to
> talk to each other. But even this seems like huge omission, because
> they actually have shared memory between the Trio chip, so you're
> using fabric to loopback the packet back to the same physical memory,
> because you're lacking some magic signal to tell 'pick up packet from
> memory address X', it has to come from fabric. I think this omission
> is fixed in next-gen Trio and it can do local switching between the
> package instances(?) and I hope MX404 or whatever follows will again
> deliver true pizzabox design. And perhaps people in this list who talk
> to Juniper remind them that they want a simple and cost efficient
> single Trio box.
> 
> I can't stop wondering what would have happened if Juniper tried to
> sell Trio-PCI in newegg with open spec, let people build their linux
> edge boxes with NPUs, NVIDIA style. I did suggest it repeatedly to
> Juniper, because I was worried about their small unit numbers shipped
> and thought it would be good to try something. I don't think there is
> almost any overlap between the companies who'd build Trio-PCI edge box
> and companies who'd buy MX, so it feels weird not to try.
> 
> On Mon, 4 May 2026 at 23:42, Aaron1 via juniper-nsp
> <juniper-nsp at puck.nether.net> wrote:
>> 
>> I have a few 304’a doing a lot of ENNI/EVC/CBH/Carrier Ethernet.  Been 
>> solid.  I dug through email, and came across an initial issue with 
>> Juno’s upgrades, I recall related to these PR’s.
>> 
>> PR1792524
>> PR1721421
>> 
>> Aaron
>> 
>> > On May 4, 2026, at 1:15 PM, Andrey Kostin via juniper-nsp <juniper-nsp at puck.nether.net> wrote:
>> >
>> > Hello, juniper-nsp readers.
>> >
>> > From the article https://www.juniper.net/documentation/us/en/software/junos26.1/chassis/topics/topic-map/chassis-guide-tm-fabric-plane-mngmnt.html :
>> > Limitations
>> >
>> > • MX304 routers have only one built-in SFB and one FPC. Hence there is no fabric redundancy support.
>> >
>> > Does anybody encountered MX304 HW failures that required a chassis replacement and how real is the risk of such a failure?
>> >
>> > Kind regards,
>> > Andrey
>> > _______________________________________________
>> > juniper-nsp mailing list juniper-nsp at puck.nether.net
>> > https://puck.nether.net/mailman/listinfo/juniper-nsp
>> 
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-- 
С уважением,

Андрей Костин

http://mx-sport.ru/