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Old 01-13-2011, 11:18 PM   #1
badkuk
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Using multi-core/multiprocessor pc routers, vpn routers


Hello All,

Does it really make sense to use a multi-core processor(2,3,6 cores) on a pc router? At least in the routing functions, are there any differences between a true SMP pc, and one that has a single multi-core processor?


i read somewhere that the number of processors doesn't really matter, that for pc routers the main bottleneck is the interface between the processor and the network card..and how good/bad the chipset being used on the card.


What if VPNs are in play? Shouldn't the processor matter in this case, since some significant number-crunching is involved?

tia
 
Old 01-14-2011, 12:38 PM   #2
mauirixxx
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in my opinion, if all you're doing is JUST routing, a single core CPU should be more then sufficient. However, if you're looking at a full blown router distro that does ... everything (VPN, routing, anti-spam, anti-virus, and some even provide web/ftp/email services, like ClearOS for instance), then the more cores, the better, *especially* once antivirus comes into play.
 
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Old 01-14-2011, 03:04 PM   #3
jefro
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I would use a dedicated hardware device. They tend to be a single use device that is made to be fast and have the options a user would need.

What can take up processing is checksum computations. If one offloads checksums to the nic's it would reduce the load. Then the load tends to be any other minor work. If you had 10 gigabyte cards in and rocking you may need a quad core or more. There have been others here who posted some real life stats on their system.

As mauirixxx points out there are other tasks that need to be monitored.
 
Old 01-15-2011, 01:09 AM   #4
Nominal Animal
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Quote:
Originally Posted by badkuk View Post
Does it really make sense to use a multi-core processor(2,3,6 cores) on a pc router?
No. You don't need a lot of CPU to do routing at full gigabit speeds.

Quote:
Originally Posted by badkuk View Post
i read somewhere that the number of processors doesn't really matter, that for pc routers the main bottleneck is the interface between the processor and the network card..and how good/bad the chipset being used on the card.
Right. PCI Express cards usually have the needed bandwidth. If you use more than one NIC, check the motherboard PCIe details: many have more connectors than they have bandwidth to.

Quote:
Originally Posted by badkuk View Post
What if VPNs are in play? Shouldn't the processor matter in this case, since some significant number-crunching is involved?
If it's an endpoint, then yes; but see here for some benchmarks. Using Blowfish CBC or AES CBC ciphers a 2.16GHz Core 2 (single core) can encrypt/decrypt over 50 MB/s (400 MBit/s). For a 100Mbit/s network, an atom processor should suffice; just configure your VPNs to use either AES or Blowfish ciphers.

I don't recommend offloading any of it to the NIC. Such cards cost much more, but their benefits are marginal; usually they just increase the latencies. The exception is multi-port NICs, that can do routing and filtering directly on the NIC, but they tend to be very expensive.
Nominal Animal

Last edited by Nominal Animal; 03-21-2011 at 03:08 AM.
 
Old 01-15-2011, 06:55 AM   #5
Dani1973
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Quote:
Originally Posted by badkuk View Post
... i read somewhere that the number of processors doesn't really matter, that for pc routers the main bottleneck is the interface between the processor and the network card..and how good/bad the chipset being used on the card.
The bottleneck can be even worse then your NIC if you are using the machine as a internet router since the bottleneck will most probably be your internet connection in that case.

One thing I also consider when choosing a box for a router is energy efficiency because the machine will be up 24/7.
Some older and slower CPUs use more power while recent versions might draw less power unless they are stressed (which doesn't happen in a router setup).
 
  


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