I am in the process of designing an Extranet and am trying to figure out what are the best practices for such a design in general.
In particular is there any standard practice regarding allowing public ip addressing space into the Campus Core.
This has generally not been a good ideal from what I have seen in the past with other designs however I cannot find anything that would substantiate that. The reasons I can think of why it is not good practice to allow public ip addressing into your campus is
- depending on the number of routes it could overwhelm your IGP (that's why you do not export the entire BGP table into your IGP)
- a network that you don't control can cause your routing environment to be unstable for eg. if your internal routing protocol is EIGRP and if you are redistributing this network into EIGRP and this network keeps flapping it could cause SIA issues which could depending on the size of your network cause some devices to age out if they do not receive queries in a timely manner.
Please let me know if these concerns do not apply or if you have any other reasons besides these for not allowing public address space into your network.