Glosssary
61200.070L1-1 Express XL/XLT User Manual 157
U-interface
A twisted pair subscriber loop that connects the NT1 reference point to the
ISDN network, as defined in the I.411 Recommendation. This interface pro-
vides Basic Rate Access with an operating frequency of 160 kbps and an infor-
mation rate of 144 kbps. Under U.S. regulations, this also marks the line of
demarcation between customer-owned equipment and the public network.
ZIP Zone Information Protocol. The AppleTalk session-layer protocol used to
maintain and discover the internet-wide mapping of network number ranges
to zone names.
Zombie Routes
Routes that have been identified by the router to be deleted. They remain in
the router’s route table for a specified amount of time with an infinite metric
so that all other routers will learn of this router’s intention to delete them.