Modelling a large ISP network with C-BGP

Olivier Bonaventure Bonaventure at
Thu Feb 2 16:02:40 UTC 2006

Dear All,

C-BGP is an efficient and open-source simulation tool that allows to 
simulate the behavior of the intra- and interdomain routing protocols in 
large ISP networks. C-BGP is able to simulate networks with thousands of 
routers. A key feature ofco C-BGP compared to other simulators is that 
it is able to support the complex routing policies that are used by ISPs.

Thanks to the support of France Telecom R&D, we have been able to use 
C-BGP to reproduce the behavior of BGP in a large Tier-1 ISP network. 
For this analysis, we have developped several tools to automatically 
convert the BGP configurations of Juniper (JUNOS) and Cisco (IOS) 
routers, the IGP topology and the BGP routes in the C-BGP format. With 
these tools, any network operator can easily build a C-BGP model of 
his/her network. With such a model, it is possible to perform different 
types of analysis on the ISP network, such as :

  - predicting the flow of the traffic through the network or 
determining the traffic matrix based on Netflow data (see article in 
January issue of ACM SIGCOMM Computer Communication Review)
  - predicting the impact of adding a new peering link on the BGP routes 
selected by the routers (see article in Nov/Dec issue of IEEE Network 
  - predicting the impact of link or router failures on the ISP network

You can obtain C-BGP, the conversion tools and several papers describing 
the utilization of C-BGP to model an ISP network or compute traffic 
matrices from :

The website also contains several examples, such as a complete C-BGP 
model of the Abilene Network based on their publically available JUNOS 
configurations files.

We believe that C-BGP could be very useful for ISPs willing to optimise 
the distribution and the selection of the BGP routes in their network. 
Comments, suggestions and questions from network operators are more than 

Best regards,

Bruno Quoitin, Sebastien Tandel and Olivier Bonaventure

CSE Dept. UCL, Belgium -

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