Before we get too much closer to J-Inet, I want to point out that I'm going to be using a single network model for continuity between posts. I've worked out IP addressing (v4 & v6), consistent routing policies, and a topology that should suffice for many posts. I've got several posts lined up that should help show at least one path to building a scalable network.
The Interconnects
J-Inet has two transit providers (Transit 1 & 2), three customers (Customer A, B, & C), and a single Peer (Peer 1). Customer C is a bit of stretch for this conversation. They aren't an autonomous system, but we'll look at them anyway, as it may lead some readers to revelations they might not have otherwise.
J-Inet has four Points of Presence (POPs) where equipment is housed. Most customers of J-Inet are like Customer C. They simply buy transit from J-Inet. These customers actually make up the bulk of J-Inet's revenue. But they're pretty boring from an network perspective.
The Network, Prefixes, and Policy
The network itself is pretty simple, and looks like this:
Over view J-Inet's network and interconnects. Click on it for more detail |
J-Inet has two blocks of address space it uses internally, that we will advertise to anyone that interconnects. Those prefixes are: 172.16.32.0/21 and 192.168.92.0/22
Customer A uses 172.16.36.0/24. That block comes from J-Inet's prefixes, but they are allowed to use it as long as they are a customer of J-Inet. J-Inet also allows Customer A to advertise this prefix across any interconnects they may have with other networks. J-Inet will pass all of the prefixes it knows about to Customer A.
Customer B uses 10.193.32.0/22, which was allocated to them from their Regional Internet Registry. They advertise this prefix to us, and any other interconnects they have according to their own routing policy. J-Inet will pass advertise all routes to Customer B.
Customer C uses 192.168.93.112/28. They don't have any other interconnects, so they aren't really an autonomous system (AS). They're in this mix as a kind of anti-example -- a customer that really only acts as an extension of J-Inet's network and routing policy. Neither Customer C nor J-Inet will advertise prefixes to one another.
Peer 1 is another ISP that happens to have equipment in the same building that houses POP 1. J-Inet and the Peer 1 decided that they should interconnect directly. They will be announcing 172.16.34.0/24 to J-Inet. J-Inet will pass internal and customer prefixes to Peer 1, but will not send any routes learned from transit providers.
Customer B uses 10.193.32.0/22, which was allocated to them from their Regional Internet Registry. They advertise this prefix to us, and any other interconnects they have according to their own routing policy. J-Inet will pass advertise all routes to Customer B.
Customer C uses 192.168.93.112/28. They don't have any other interconnects, so they aren't really an autonomous system (AS). They're in this mix as a kind of anti-example -- a customer that really only acts as an extension of J-Inet's network and routing policy. Neither Customer C nor J-Inet will advertise prefixes to one another.
Peer 1 is another ISP that happens to have equipment in the same building that houses POP 1. J-Inet and the Peer 1 decided that they should interconnect directly. They will be announcing 172.16.34.0/24 to J-Inet. J-Inet will pass internal and customer prefixes to Peer 1, but will not send any routes learned from transit providers.
Transit 1 and Transit 2 are networks that have customers and other interconnects. Since they are transit providers, they have promised to get traffic to any destination. However, they bouth announce prefixes to us, J-Inet can make an informed decision about which network should be used for any given prefix. J-Inet will announce internal routes and customer routes to both transit providers. J-Inet will not advertise routes learned from Peer1. Lastly, J-Inet will not advertise any transit routes back to either transit provider. (i.e. J-Inet will not allow transit to the these providers.)
At this point, we have a pretty good idea of J-Inet's network topology and how it interconnects with customers, peers and transit providers. In our next installment, we'll look at some of the internal housekeeping of J-Inet's network is put together, and later use this internal configuration to make our interconnects simpler.