On 22/Oct/16 23:59, Marian Ďurkovič wrote:
The question here is, whether MPLS is the *optimal* solution for campus needs.
The same functionality could be obviously achived by multiple technologies, and while MPLS is well supported on high-end SP routers, various limitations appear when people try to use it on commodity ASICs which typically empower today's ethernet switches - one of them being e.g. limited ability to effectively load-balance traffic over multiple parallel links.
Yes, in theory we could build all campus LANs using high-end SP routers, but when 100GE backbone is desired (which is often the case in EDU/NREN sector), the costs of such solution jump to unacceptable heights.
Thus we looked for another technology, which doesn't have the usual L2 problems and is able to provide services we need (including L2 extensions to remote campuses) at reasonable costs and with enough simplicity.
To avoid typical L2 problems, you clearly need a solution based on L3 routing. And TRILL is exactly that - although it maintains L2 interface to the outside world, internally it performs dynamic L3 routing by IS-IS protocol with all safety belts like TTL check, RPF check etc.
IMHO, TRILL is much better fit for campus needs, since it was specifically designed for this networking space - and our 6-months production fully confirms that view (of course, YMMV).
I don't consider the ASR920 or CES2000 to be particularly high-end routers, but YMMV. True, merchant silicon presents a number of data plane challenges that may, at first, seem non-trivial or completely go unnoticed. That is why we stay away from the ACX5000, for example. I expect improvements to come with newer-generation ASIC's/NP's, but that tests one's patience. But, like I said, I have not run TRILL myself, so I'm not going to tell you that it's not an ideal technology for this use-case. All I'll say is that MPLS is not limited to high-end platforms, even when custom silicon is involved. Mark.