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BGP Internet Router Sizing

rmck2003
Level 4
Level 4

I am looking for two new routers to be used to connect to two ISPs for internet connectivity.  The basic design requirements are below:

  - dual, multi-homed BGP design.

  - 100 Mbps per ISP, so an aggregate of 200 Mbps.

  - Each router will connect to both ISPs, we plan to receive a default and partial routes from each ISP, BGP will load balance traffic across these two links.  We receive partial updates from one of these ISPs already and only a default route from another and BGP is currently only using about 70 Mb of memory.

  - HSRP will be configured to provide first hop redundancy across the two routers.

 

My question is, will two 2911 routers with 1.5 GB of RAM each be sufficient for this design.  It appears that it would be able to handle the load, but I do not want to "under-size" my recommendation.  Also, is there any specific IOS level that is needed to support this design, or will the base license be capable?  Would the security license be recommended since this will be an internet edge router?

Thank you,

Rick

7 Replies 7

Joseph W. Doherty
Hall of Fame
Hall of Fame

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

So each router will have 100 Mbps to each ISP?  If so, Cisco would recommend a 3925E for 250 Mbps of WAN bandwidth.  (The 3945 is recommended for 150 Mbps, which is 50 Mbps less than your 200.)

I'm not too familiar with licensing 29xx/39xx, so I cannot comment on that.

Regrading you question about specific IOS level, that would depend on what features you need.  From what you've described, any IOS version for a 29xx/39xx would probably provide what you need, but you'll want to insure so too does the feature set (or feature license).

Thank you for the replies.  

I looked up the specs on the 3925E and I also had a quick discussion with a reseller about this and they recommend the ISR 4431 router instead of the 3925E.  It is a 1U form-factor with 4 GE interfaces, dual-power supplies, can handle 500-1000 Mbps of WAN bandwidth and its list price is $4000 less than the 3925E.

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

Nothing wrong with the new 4K ISRs, however Cisco lists the performance of a 4431 at 100 Mbps (upgradable to 300 Mbps).  (I think, unlike the recommendations I noted for the 3925E, the 4K performance bandwidths are aggregate, i.e. half what Cisco means by "WAN" bandwidths for the 29xx/39xx ISRs.)

PS:

Be careful of retailer recommendations.  Cisco documents an 890 can handle up to 1.4 gig, but they only recommend it for 15 Mbps.

I've attached a Cisco whitepaper that explains ISR performance, unfortunately, it doesn't include the 4K series.

According to the spec sheet in the link below, the 4331 has a native bandwidth capacity of 100 Mbps and the 4431 has 500 Mbps.  It also shows the bandwidth of the 800 series routers.  Even if the actual bandwidth of the 4431 is half of the reported 500 Mbps, then I should still be covered.

http://www.cisco.com/c/dam/en/us/products/collateral/routers/4000-series-integrated-services-routers-isr/enterprise-routing-portfolio-poster.pdf

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

My 4331 performance stats matches your reference.  You didn't mention the 4431 before, but yes, its non-upgraded 500 Mbps aggregate bandwidth should be about the same as the 3925E's 250 Mbps WAN bandwidth.  If so, is should be fine too, unknown whether it too is $4,000 less than a 3935E (like you note the 4331 is).

4451 is always better interms of pricing and throughput if compaired with 3945E.

johnlloyd_13
Level 9
Level 9

hi,

i would agree with joseph. we're also using 3925 for our BGP/internet edge routers.

if it's just for purely BGP peering/internet edge, just use the default IP base license and 512MB RAM.

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