Re: Feasible to implement a router on a system on a chip?
- From: Keith M <keithvz@xxxxxxxxxxxxxxxxxxxxxxxxxx>
- Date: Thu, 27 Mar 2008 23:37:43 GMT
dspfun wrote:
Is it feasible, or even possible to implement a complete router on a
system on a chip (i.e. on one FPGA)?
While I'm new to FPGA's, I'm not new to routers. I don't think this is possible. There's a reason Cisco routers are large and expensive, and it's not because there's a single chip inside. :) (of course it's because their NAME is on it!!) Cisco, or one of the other companies, would have distilled it down to one chip, if they could. I don't disagree that FPGA's and/or ASICs are used in the designs, they most certainly are -- I just think you need more supporting components (processor, big memories, interface chips, etc)
The router should be able to handle BGP and OSPF (i.e. traditional
router functionality).
Depends on the class of router. SOHO routers most certainly don't support BGP or OSPF --- normally those routing protocols are supported in mid-to-high end routers. BGP tables can get very big, with full internet tables being 200k+ routes. Calling BGP and OSPF traditional features might be assuming a little much.
For example, which of the following routers would be feasible/possible
to implment on a system on a chip (the router should be able to
forward the packets at full speed according to the interface
speed) ? :
Most routers have limited processing power --- even large routers. They normally get rated in terms of packets per second. The thing most vendors play around with is this: how big are the packets that we're talking about? 64 bytes? 128 bytes? full 1500-ish byte packets? This gets complicated when you start talking about access-lists, firewalls, NAT, etc because depending on what deep-packet inspection/modification is going on can REALLY slow things down.
Many router vendors lie like dogs when it comes to performance. I'd be surprised if there are routers out there that can truly handle multiple single gig ports with any type of reasonable throughput. Outside of Internet 2, there aren't many needs for such products.
Most gigabit routing solutions end up being LOCAL routing, between multiple local LANs, and then Layer-3 switches end up picking up the task. But then, you lose many capabilities in terms of filtering, etc --- which of course would limit the speed again.
-A router with four 1 Gbps Ethernet interfaces?
No.
-A router with ten 1 Gbps Ethernet interfaces?
No.
-A router with four 10 Gbps Ethernet interfaces?
Definitely no.
-A router with ten 10 Gbps Ethernet interfaces?
Are you crazy??
Or does it sound completely undoable?
Yup. Undeniably undoable.
A couple 10mbps ethernet ports in a SOHO application? Maybe.
Keith
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