[j-nsp] MX104 capabilities question

[Adam Vitkovsky]

> Ross Halliday
> Sent: Tuesday, June 07, 2016 10:01 PM
> To: Saku Ytti
> Cc: juniper-nsp at puck.nether.net
> Subject: Re: [j-nsp] MX104 capabilities question
>
> Hi Saku,
>
> > I don't see how this makes it any less of a box, in my mind this makes
> > it superior box. You lost single PFE/linecard, which happens to be
> > only linecard you have.
> > In my mind fabricless single-linecard design is desirable, as it
> > reduces delay and costs significantly. Not only can you omit fabric
> > chip, but you can get >2x the ports on faceplate, as no capacity is
> > wasted on fabric side.
>
> This is a good point but kind of tangential to what I was getting at. Before we
> were really familiar with the MX104, we went on sales and marketing
> material that talked about "the little" MXes and "MXes with multiple slots".
> It's very misleading. Even JUNOS MX documentation talks about FPCs being
> separate in control and forwarding plane operations, when in reality there's
> only AFEB0 and that's the whole box. No isolation, and "slot diversity" is
> basically only a little bit better than adjacent ports... Again, contrary to what
> the popular advice about "multi-slot MX routers" is. The MX104 is not really a
> multi-slot router in the traditional sense, it just takes more MICs.
>
One thing I'm not clear about MX104 and MX80 is, are there two TRIO chips or just one?


> > Regarding PR1031696, years ago I had bunch of 3rd party SFPs which
> > would crash MX PFE. I practically begged JTAC to fix it. The issue was
> > caused by SFP being sluggish to answer to I2C polling, and the code
> > which was expecting an answer crashed when it couldn't receive I2C
> > answer fast enough. I tried to explain to them, it's only matter of
> > time before original SFP develops I2C error, at which point you'll see
> > this from customer buying 1st party optics. JTAC was unconvinced, told
> > me to re-open if I see it on 1st party.
> > I used many channels to complain, but no avail. To me this was
> > absolutely appalling and short-sighted behaviour.
>
> Yes, and then it crashes every single SFP... brilliant design backed with
> brilliant support... give me a break!
>
> > But all platforms can have all kind of problems, and if you would have
> > multiple linecards, sure, in this case you'd only crash one of them.
> > But just having multiple linecards won't help that much, you can still
> > crash all linecards due to RE problem, so you're still going to need
> > second router for proper redundancy, at which point it becomes
> > immaterial if you have this 'linecard redundancy' or not.
>
> All kinds of problems happen, yes the only "real" safeguard is to put every
> customer on their own PE. You might remember a previous conversation we
> had regarding the DDoS Protection mechanism. This thing is a major thorn in
> my side. Thanks to this "faster" design, when one of these filters kicks in, any
> traffic matching that class on the ENTIRE box is blackholed. I don't think this is
> appropriate behaviour: In my experience, it actually *creates* a DoS
> situation on these boxes.
>
Hmm that's a good point actually, haven’t realised that.
Since the first level at which the policers are applied is per LU that really makes a difference whether the box has just one or two LUs.

I really feel like cisco dropped the ball with RSP2 for ASR903 -heck if they would allow at least 2M of routes it would be no brainer, compared to MX104.


adam







        Adam Vitkovsky
        IP Engineer

T:      0333 006 5936
E:      Adam.Vitkovsky at gamma.co.uk
W:      www.gamma.co.uk

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