Mikrotik Cloud Core Router and BGP real life experiences?

Justin Wilson lists at mtin.net
Fri Dec 27 18:01:03 UTC 2013


	The issues I see are because of routers versions.  The Cloud core routers
are a fairly new platform. As such, the software isn¹t as stable as it
should be.  The OS is up to version 6.7.  There were some betas before 6.0
was released.  However, almost every version that has been released
addresses issues with the cloud core.  The cloud cores only run Version 6.

	We did se BGP issues early on accepting more than one full routing table.
We saw other issues but they were fixed with subsequent OS software
releases.

	Justin

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Justin Wilson <j2sw at mtin.net>
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-----Original Message-----
From: Jim Shankland <nanog at shankland.org>
Date: Friday, December 27, 2013 at 11:26 AM
To: <nanog at nanog.org>
Subject: Re: Mikrotik Cloud Core Router and BGP real life experiences?

>On 12/27/13 6:40 AM, matt kelly wrote:
>> They can not handle a full routing table. The load balancing doesn't
>>work.
>> They can not properly reassemble fragmented packets, and therefore drop
>>all
>> but the first "piece". They can not reliably handle traffic loads over
>> maybe 200 Mbps, we needed 4-6 Gbps capacity. They can not hold a gre
>>tunnel
>> connection.
>>
>>
>Can't say anything about MicroTik specifically, but I've used Linux as a
>routing platform for many years, off and on, and took a reasonably close
>look at performance about a year ago, in the previous job, using
>relatively high-end, but pre-Sandy Bridge, generic hardware.  We were
>looking to support ca. 8 x 10 GbE ports with several full tables, and
>the usual suspects wanted the usual 6-figure amounts for boxes that
>could do that (the issue being the full routes -- 8 x 10 GbE with
>minimal routing is a triviality these days).
>
>Routing table size was completely not an issue in our environment; we
>were looking at a number of concurrent flows in the high-5 to
>low-6-digit range, and since Linux uses a route cache, it was that
>number, rather than the number of full tables we carried, that was
>important. Doing store-and-forward packet processing, as opposed to
>cut-through switching, took about 5 microseconds per packet, and
>consumed about that much CPU time. The added latency was not an issue
>for us; but at 5 us, that's 200Kpps per CPU.  With 1500-byte packets,
>that's about 2.4 Gb/s total throughput; but with 40-byte packets, it's
>only 64 Mb/s (!).
>
>But that's per CPU.  Our box had 24 CPUs (if you count a hyperthreaded
>pair as 2), and this work is eminently parallelizable.  So a theoretical
>upper bound on throughput with this box would have been 4.8 Mpps -- 57.6
>Gb/s with 1500-byte packets, 1.5 Gb/s with 40-byte packets.
>
>The Linux network stack (plus RSS on the NICs) seemed to do quite a good
>job of input-side parallelism - but we saw a lot of lock contention on
>the output side. At that point, we abandoned the project, as it was
>incidental to the organization's mission. I think that with a little
>more work, we could have gotten within, say, a factor of 2 of the limits
>above, which would have been good enough for us (though surely not for
>everybody). Incrementally faster hardware would have incrementally
>better performance.
>
>OpenFlow, which marries cheap, fast, and dumb ASICs with cheap, slower,
>and infinitely flexible generic CPU and RAM, seemed, and still seems,
>like the clearly right approach. At the time, it didn't seem ready for
>prime time, either in the selection of OpenFlow-capable routers or in
>the software stack. I imagine there's been some progress made since.
>Whether the market will allow it to flourish is another question.
>
>Below a certain maximum throughput, routing with generic boxes is
>actually pretty easy.  Today, I'd say that maximum is roughly in the
>low-single-gigabit range. Higher is possible, but gets progressively
>harder to get right (and it's not a firm bound, anyway, as it depends on
>traffic mix and other requirements). Whether it's worth doing really
>depends on your goals and skill. Most people will probably prefer a
>canned solution from a vendor. People who grow and eat their own food
>surely eat better, and more cheaply, than those who buy at the
>supermarket; but it's not for everybody.
>
>Jim Shankland
>
>





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