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New Member

Cisco 3945E Full BGP Table IPv4 and IPv6

I'm looking at Cisco 3945E router to use for our internet edge. Let's say I have two 3945E with 2GB of RAM, and these two are connected to two ISPs with 20-50Mbps of bw and planning to increase it after 3 years.

Network Topology:

ISP1---eBGP---R1---iBGP---R2---ISP2

Objective

1. Receive Full Internet Routing table for IPv4 and IPv6

 

Question

1. Is 3945E with 2GB of memory enough to handle both IPv4 and IPv6 considering the iBGP connection between two 3945Es.

2. Internet routing table is increasing so fast, is it feasible to use 3945E to handle 20-50Mbps of traffic with Full BGP Table.

 

Any suggestions is highly appreciated.

  • WAN Routing and Switching
4 REPLIES

There is an excellent

There is an excellent document that you can download from www.ciscolive365.com, BRKRST-2044 Enterprise Multi-Home Internet Edge Architectures. These figures are from last year but it states the following:

Internet Routing Table size:

IPv4: 451K Routes
IPv6: 12K Routes

Recommended amount of Router DRAM with 2 Internet Feeds: 768MB or More.

Safe for “bgp soft-reconfiguration inbound” and growing IPv4/v6 Tables.

Currently, Full BGP Tables require around 512MB of DRAM.

Don't forget to rate all helpful posts

New Member

I already know this

I already know this information. What I wanted to know is, in real world scenario does 3945E enough to handle this kind of setup, like CEF switching, CPU Load and processing. What is an ideal router to use in ISR G2 platforms?

New Member

Not sure if you already got

Not sure if you already got the information you were looking for, but we are running that same setup with 2 3945e's maxed with 2 gig each, and ibgp between the 3945e's

 

ISP1 100Mbps connection pulling 473K ipv4 routes

ISP2 100Mbps connection pulling 481K ipv4 routes

 

I have never see the cpu go above 10% unless its rebuilding the full table from an ISP which takes about 1 Minute.  

Memory usage is around 33% used.

 

We plan on adding ipv6 this fall

Super Bronze

DisclaimerThe Author of this

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


If your 3945E has sufficient RAM, it should be able to deal with 50 Mbps of traffic with full BGP tables.

 

Although, you need full BGP tables because?  (Yea, I see you have two ISPs.  But what I found works well is just taking a default from ISPs and using OER/PfR to load share and pick best path.  Remember, each ISP should have reachability to any destination [if they don't OER/PfR will notice and not use that ISP] and fewer AS hops don't really guarantee better perfomance.  [You could also just accept BGP destinations in you ISPs' AS.])

 

If you need faster router than the 3945E, now there's the 4451-X between it and the ASR1Ks.

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