Explain a feature of a 2921 ISR please.

[Eric Daoust]

High Performance with Integrated Services

• The Cisco 2900 Series enables deployment in high speed WAN environments with concurrent services enabled up to 75 Mbps. • A multigigabit fabric (MGF) enables high-bandwidth module-to-module communication without compromising routing performance.

Does that mean that the total bandwith coming from my wan into the 2921 will never be able to go over 75Mbps?

just standard data over vpn is what i am using it for

[paolo bevilacqua]

Yes, approximatively.

Beside that, there is also a limitation dicated by US export regulation, of 85 Mbps, that requires additional licensing to be be removed.

[Eric Daoust]

So why bother with the HSEC license if the device cannot go over 75Mbps anyways? Also why bother with gig ports?

This is quite dissapointing that a router of this caliber cannot do more that 75Mbps...

[paolo bevilacqua]

That 75 Mbps is just indicative, however it is a branch/access router not made for high speeds. If you need more performance you can refer to the attached document to choose.

[Joseph W. Doherty · Accepted solution]

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Posting

The 75 Mbps is from Cisco's WAN bandwidth recommendation for a 2951 (the fastest model of the series).

From the same document, a 2921 is recommend for up to 50 Mbps of WAN bandwidth (i.e. this would be 50 Mbps duplex, with a "typical" full feature configuration [NAT, QoS, ACLs up to 75% CPU]).  Depending on configurations, and what the traffic looks like, higher performance is possible.  A 2921 is documented as being capable of forwarding 3.5 Gbps (aggregate).

[Eric Daoust]

Ah so if i use it only for vpn tunnels with no QOS and limited ACL's i might be able to get faster that 75Mbps..

but i should prob get 3925 if i want to guarantee it.

thanks again guys.

[paolo bevilacqua]

For simple IPSEC of up to 150 Mbps (75 x 2) you can use as small as a 1921, check table 2.

Thank you for the nice rating and good luck!

[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

Table 7, in the document reference Paolo provided, would indicate a 2921 could provide 72 Mbps of IMIX IPSec bandwidth, which is probably close enough to your 75 Mbps if you mean 75 Mbps aggregate.  If you mean 75 Mbps duplex, then from the same table, yes, it appears you would want a 3925.

But as for actual guarantees - when dealing with performance, your individual configuration and your actual traffic can result in performance possibly much better or much worse than what the performance tables show.

For an example, an issue with VPN tunnels is whether you'll also have to deal with IP fragmentation.

If you needed to, I doubt the Cisco performance tables account for the any IP fragmentation performance reduction.  (NB: For TCP, the mss adjust command often avoids IP fragmentation.)

So for a true guarantee, you either need to buy much larger than you might actually need, or need the seller allow a trial or exchange to insure the device you select really is "right" for your needs.

[Eric Daoust]

"So for a true guarantee, you either need to buy much larger than you might actually need"

Which is what i will do by buying the 3925E.. thanks again guys.