Routing and optical boxes
We know that routers often interface or hand off their IP signals to an optical box, such as an optical switch (electrical backplane) or a multiservice box that also supports DWDM. Does the optical box have to run routing protocols such as OSPF, RIP, BGP, ISIS...or is that taken care of by the routers who simply use the optical boxes as transport boxes?
Yes, routers can either connect directly to a fiber network with a fiber interface card installed into the router or can connect to an optical switch. The standard routing protocols you?ve listed above don?t really apply once the data enters the fiber network. The fiber switch will encapsulate the IP packet into a protocol packet consistent with the switch, such as ATM, or FDDI. In an ATM switched network for example, the router would send the IP packet to the ATM (fiber) switch, then the switch would encapsulate that packet into an ATM packet and send it to another ATM switch, which would remove the IP packet from the ATM packet and send it to another router at which point you are back to IP. ATM is designed to transport anything voice, data, etc. regardless of protocol in a standard size packet called an octet. FDDI is another one of many choices. So to say it simply, yes, routers use the optical boxes as transport boxes.
This was first published in October 2001