Hardware for network load balancing between two WANs

[eric0000111]

Hi,

I'm new to Cisco hardware ecosystem and feel a bit amongst so many devices. I'm a network administrator, and I do most of my work with Linux-based routers (ipfilter et al.)

The design I'm busy with ATM is a small office with 10+ desktop computers, Wi-Fi available for visitors, 2 100Mbps-WAN to the internet, 1 mysql/apache/samba server. Attached is a diagram of the proposed design.

I need to balance network load to the internet between the 2 100Mbps-WAN connections. The intranet should be all GigaEthernet.

From what I've read so far, the adequate router/switch would be a 1921 or a 1941 or is it overkilled ?

What expansion cards should I add to the 1921/1941 to achieve the proposed design?

Is there a way I can mount 8 GigaEthernet LAN ports AND 2 FastEthernet WAN ports on the same device?

Thanks in advance for your help.

Eric.

[Joseph W. Doherty]

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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

Dual 100 Mbps duplex?  If so, a 19xx will be inadequate.  Cisco recommends those for 15 and 25 Mbps, respectively.  For 200 Mbps, you're in the ballpark of a 3945 or 3925E (150 and 250 Mbps).

Also keep in mind, if you expect to do LAN routing, the forgoing performance numbers also apply (note 1 - LAN routing should perform a little higher - note 2 - if doing both LAN and WAN routing, you need to allow for the aggregate of the two).

Regarding your question about 8 gig LAN ports, and two FE WAN port - on the 19xx series, no.  On the 29xx and 39xx series, there's the SM-X-ES3-16 or SM-ES3G-16-P [which also does routing]).

[eric0000111]

AFAIU, this is not full duplex. We have 2 FTTH lines 100/10Mbps that we want to balance the network load through
 

[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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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

Ok, that would be the equivalent of 110 (WAN), so that's the ballpark of a 3925 (recommended for 100 Mbps). 19xx is still way too small.

[eric0000111]

We actually have 2 of those lines, so following your arithmetic, that'd be 220Mbps.

Do you mean I have to spend $6000+ on a router just to balance network traffic between 2 FTTH lines ?

[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

Yes, that's correct, 220 Mbps total aggregate.  However, the particular Cisco performance recomendations I'm quoting from is for the non-duplex bandwidth (what they call WAN bandwidth, which normally is always full duplex - e.g. a T3, has 45 Mbps, but 90 Mbps duplex).  So, I divide the 220 Mbps in half to get the equivalent "WAN" bandwidth of 110 Mbps.

No, you don't need to speed $6K to get a router to balance 2 line, your $6K is for a Cisco ISR that supports the total possible aggregate bandwidth; number of lines doesn't really matter, nor does load balancing - at least for router forwarding performance.

Now, if you don't want to have a router that can handle all your bandwidth, allowing pretty much any configuration, you can go smaller.  For example, the 1921 has a maximum throughput documented as close to 2.8 Gbps.  This though is for a configuration that is just packet forwarding of 1500 byte packets.

I'm attaching the Cisco document I'm quoting from.  In it, you can see the performance of the different ISR models under different usage situations.  You know you maximum bandwidths.  If you know your expected traffic load and what kind of supporting configuration you'll need, you might well chose a smaller router.