I usually place a document version number on the cover page of my article/document. Later, I may wish to use that value in say a footer or header. So many times I’ve been caught with “Version 2.1” vritten on the cover, only to find “Version 1.5” written in the footer, because I forgot to update the version number in the footer field. |
Dividing IP networks into subnets is as easy as pie. All you need to do is remember one simple rule about how to cut the pie. Download my Guide to IP Subnetting using Pies The BGP synchronization rule states that if an AS provides transit service to another AS, BGP should not advertise a route until all of the routers within the AS have learned about the route via an IGP. Consider the following scenario: |
Adapted from http://www.cisco.com/en/US/docs/internetworking/case/studies/icsbgp4.html When an AS provides transit service to other ASs when there are non-BGP routers in the AS, transit traffic might be dropped if the intermediate non-BGP routers have not learned routes for that traffic via an IGP. The BGP synchronization rule states that if an AS provides transit service to another AS, BGP should not advertise a route until all of the routers within the AS have learned about the route via an IGP. Forget the bitwise operations. Here's how I do subnets. In my head! Any subnet, any mask in 30 seconds or less. |
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