Rings

###Definition

A ring is a looped railroad. A ring is the basic cell of a ByteCart network. There are 53 rings in each region, numerotated from 1 to 53. On a LAN view, a ring is a subnet of the region containing 16 station address (only 15 are usable).

Designing a ring generally consists on building a 2-way railroad and closing its ends to close the loop, then plugging stations in it.

If a router is needed, it will be located at one end of the ring. A second router may be built at the other end. An unlimited number of routers can be attached to the ring.

###Function

A ring has two functions:

1. dispatching local traffic to stations depending on it. This function can be delegated to Extended Rings.
2. transporting non-local traffic from router to router.

###Special rings

• Extended Rings provide only function #1.
• Rings plugged in backbone routers provide only function #2.
• Garbage collector rings provide none of the functions.

###Constraints

• All 15 stations of a ring and its extended rings must have an address in the subnet of the ring and be physically attached to the ring or its extended rings.

• All external traffic to or from another ring or region must pass through a router.

###Extended ring An extended ring is a physical extension plugged in the main ring. All address of an extended ring must meet the Extended Ring requirements. At the intersection between the main ring and an extended ring, a device must manage the direction switch according to destination address, and, optionally, anti-collision policy.

###LAN view

In the LAN topology, rings have a network mask of 63.63.0.