Router Performance Query

[Mohammed Ashraf Ali]

Hi All,

We have 15 subnets on my Lan side, and the inter subnet routing is done by UTM firewall for now, because of which we are unable to utilize the UTM performnace.

So we have decided to have a router in between Lan and the UTM to handle that intersubnet traffic, and we are looking to have 2901 series of Router,

But before that , i have few Questions.

1. I have seen in the Routerperformance.pdf file,  the Fast/Cef switching , Mbps is 167.42 . So does it means the throughput ?

and if i try to copy data from a PC from one subnet to other subnet PC, i will only get max speed of  167.42 Mbps only ? (remember that all my PCs and switches are having Gigabit ports)

2. Seen the data sheet and other documents of cisco 2900 series of routers , but could not found any details of Max connnections, or Max throughput, So where should i check for these.

First question is very important.

Pls reply soon, implementation is very urgent.

Regards,

Ashraf

[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

BTW - for intra-vlan routing, you might want to consider using a L3 switch (usually much faster than an ISR - also usually much less expensive for its performance).

#1 Yes (to your 1st question) and maybe (to your 2nd question).

#2 Routers generally don't concern themselves with max connections unless they are the logical end point.  Max throughput depends on multiple factors.

I've attached a Cisco whitepaper that better explains (the later model) ISR performance.

[Mohammed Ashraf Ali]

Hi Joseph,

I have actually proposed for L3 switch( C3745 ), but management is not ready to invest as it is atleast 3 times more costlier than 2901 Series of Router.

Just for clerification, do you mean to say, we will not get speed more than 167.42 Mbps if i try to do some transaction (copy) between different subnets in the Lan ?  i have added 1 ip of each subnet as secondary ip address on the router interface, to make router as default gateway for the subnets.

All my computers and switches are of Gigabit ports.

pls clearify...

Regards,

Ashraf

[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

I have actually proposed for L3 switch( C3745 ), but management is not ready to invest as it is atleast 3 times more costlier than 2901 Series of Router.

"L3 switch ( C3745 )"?  Did you note the correct model?  The 3745 I'm aware of is an ISR, previous generation to the 38xx series routers and two generations previous to the 39xx series routers.

I was thinking of the 2960 series (those that support limited static routing) or the 3560 series.

Just for clerification, do you mean to say, we will not get speed more than 167.42 Mbps if i try to do some transaction (copy) between different subnets in the Lan ?

No, I'm not saying you won't exceed 167.42 Mbps.  You may easily exceed that, or you may not even obtain that.  Many variables involved with actual ISR performance.  Much depends on what your traffic "looks like" and your device's configuration.  For example, router performance actually is in packet per seconds, as packet sizes vary you may obtain huge performance differences, in bandwidth transmission, between small packets and large packets.  If your configuration does more "per packet", e.g. large ACLs, packet forwarding slows and so does transmission rate in Mbps.

The document I previouslly provided, notes different performance for different usage situations.

i have added 1 ip of each subnet as secondary ip address on the router interface, to make router as default gateway for the subnets.

Oh?  Normally the preferred setup up is to use different interfaces, as if you use a single interface you're limited to the bandwidth of that one interface for your LANs.  Also, when you do have multiple interfaces on a routers, if your connecting switch supports VLANs, you trunk the VLANs to the routers and define the gateways using subinterfaces.