Building a Network

[highspeedvideo]

Hello, and thank you for reviewing my post.

I am rebuilding my companies' WAN network structure because we have a new half gig ethernet handoff (electric). Currently the 2801 and 1841 I have in place only have 10/100 fast ports, so I am going to pick up a 3845 to replace them.  One of the GB interfaces will connect to my new upstream, the other to a switch feeding my lan/subnets. My question is this:  I also have a cable modem that I would like to use for redundant traffic. I know how to configure the routing for what I would like to achieve, but I'm not sure which interface would be the most economical/practical for me to purchase to get the job done.  I see the 3845 supports both HWIC-2FE, NM-2FE2W & NM-2W, it also supports a few 4 port switches. I would at minimum require an interface that is routable/addressable so I can divert certain traffic out the backup line.  I know the 3845 has the onboard available SFP port, but if I recall correctly, using that would negate one of my onboard GB interfaces.  Does anyone have any suggestions? My cable modem only requires a fastethernet connection so adding another GE port would be costly and overkill.

Best Regards,

Mike

[cflory · Accepted solution]

FYI, according to below link, the 3845 will only support 256Mb throughput (Fast/CEF switching):

http://www.cisco.com/web/partners/downloads/765/tools/quickreference/routerperformance.pdf

So, you may choke the router if you're going to get close to the half Gb you're talking about.  Any of the modules you've listed should work.  I've used a couple of them before.

-Chris

[highspeedvideo]

Thanks for the tip Chris,

I had just assumed the upgrade to a 3800 series would be enough horsepower to handle the routing through the gigabit ports.

I also have 2 vxr7206 chassis' collecting dust, maybe I will look into a 7200-NPE-G1 engine on the used market as an alternative. (I think that'd run me about the same as a 3845 and a gigabit hwic) and give me double the performance.

[Joseph W. Doherty]

Disclaimer

The  Author of this posting offers the information contained within this  posting without consideration and with the reader's understanding that  there's no implied or expressed suitability or fitness for any purpose.  Information provided is for informational purposes only and should not  be construed as rendering professional advice of any kind. Usage of this  posting's information is solely at reader's own risk.

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Posting

Actually the -G1 has 2x the PPS rate of a 3845, as can be seen in the document reference Chris provided.  Also note, when looking at the performance "bandwidth" on that data sheet, you need to half for full duplex.  You also don't want to run a box at 100%, so halving again avoids this.  I.e. the 256 Mbps Chris notes, should be consider only 64 Mbps for general usage.

[highspeedvideo]

Thanks Joseph and Chris for your input. It's an interesting situation I have. My company paid for 100/100 metro style ethernet. I'm not sure if it requires too much resource for our provider to rateshape bandwidth past a certain point, but when I run speed tests plugged directly from the handoff i get 98 down and 500 up.  (a friend of mine in that company said they have a problem limiting from their cores).  I never imagined a 3845 would choke on half a gig since my cheapo Linksys RVS4000 was giving me 400 up in tests.  I know the RVS was not doing routing, but I assumed the NAT running on it would provide just as much overhead when switching to the 192 network.  If I was running just NAT/PAT on the 3845 instead of CEF switching would it be able to pass the full 500mb? The main usage of our upstream will be to provide streaming video which can be handled by a simple port forward.

[Joseph W. Doherty]

Disclaimer

The Author of this posting offers the information contained within this posting without consideration and with the reader's understanding that there's no implied or expressed suitability or fitness for any purpose. Information provided is for informational purposes only and should not be construed as rendering professional advice of any kind. Usage of this posting's information is solely at reader's own risk.

Liability Disclaimer

In no event shall Author be liable for any damages whatsoever (including, without limitation, damages for loss of use, data or profit) arising out of the use or inability to use the posting's information even if Author has been advised of the possibility of such damage.

Posting

On the older routers, Cisco doesn't normally document performance using different services.  On the latest routers, they have provided much more extensive performance documentation.  You could compare a 500Kpps 3845 against a newer router (i.e. 2921 - 2951) with about the same raw performance.  Although this is a bit of comparing "apples to oranges", the performance hit for various services, like NAT/PAT, might be similar.