Need Opinions

[mark shuford]

Here is an over view of our network design:

We use Metero Ethernet.

           ISP

            |

        2800 Series Router

            |

         ASA

            |

       3750G (Central Office) Internal IP Routing

            |

       3750G (Multiple Remote sites) IP Routing

Yesterday a Network Engineer from AT&T visited our site and suggested that we would probably get faster throughput to the ISP if we replaced the 2800 series router with another 3750G and allowed it to route the traffic to the ISP. I don't know enough about 3750 and 2800 to agree or disagree with his assessment so I would like to get opinions from the knowledgable folks on this board. Do you guys agree with him and why?

Thanks for the help.

Mark

[pompeychimes · Accepted solution]

I would tend to agree with this statement. I can't back it up with numbers, only personal experience. I prefer to terminate Ethernet hand-offs on Switches and in some cases ASA's.

James

[Giuseppe Larosa · Accepted solution]

Hello Mark,

if your C2800 is not doing NAT or other software bases features you can have a performance gain in using a multilayer switch instead of the ISR router.

you can see raw performance of routers in the attached pdf a C2800 can handle 50 to 100 Mbps of traffic in total so it is not able to handle a true 100 Mbps handoff

A C3750G can do

• 32-Gbps switching fabric

• Stack-forwarding rate of 38.7 mpps for 64-byte packets

http://www.cisco.com/en/US/prod/collateral/switches/ps5718/ps5023/product_data_sheet0900aecd80371991.html

obviusly the next bottle neck will be the ASA.

Hope to help

Giuseppe

[Jon Marshall · Accepted solution]

Mark

In terms of throughput the engineer was right ie. you will get more from a L3 switch such as the 3750 than you will with the 2821. However the router can provide more functions than the L3 switch, NAT being one of them as Giuseppe mentioned. Equally important is QOS where a router has a much more fully featured toolset than a switch. Often on Metro ethernet connections you need to shape the bandwidth and switches in general do not support shaping.

So it is a tradeoff. If you don't need the extra features provided by a router then yes go for a switch although it would be interesting to know what ASA model you have in terms of throughput as the switch might not be much of a gain. Bear in mind also that Cisco do a 3750 ME switch (ME = Metro Ethernet) which has more QOS features than the standard 3750.

Jon

[mark shuford]

Jon,

We have an  ASA 5550.

[mark shuford]

Jon I made a mistake when I said the ASA model was a 5550, it is in fact a 5510. Do you think it may be a bottleneck as well?

Mark

[Jon Marshall]

mshuford1 wrote:
Jon I made a mistake when I said the ASA model was a 5550, it is in fact a 5510. Do you think it may be a bottleneck as well?
Mark

Mark

No, you should be fine. I have just checked the datasheet from the 5510 and it supports up to 300Mbps of clear text throghput and up to 170Mbps of VPN throughput so it shouldn't be a bottleneck.

Jon

[pompeychimes]

Mark,

By using the ASA you've saved the company money by not buying a switch. You've freed up a router for another project (Or your lab). And you've regained some of the features you would've lost by moving to a switch.

I'd be approaching mgmt for a raise!

James

[mark shuford]

Good stuff guys. I really appreciate your help.

Mark

[pompeychimes]

Dont forget to rate helpful posts. Thanks.