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Cisco ASR 9000 Series Aggregation Services Router Getting Started Guide
OL-28417-02
Chapter
terabyte
A unit of computer memory or data storage capacity equal to 1024 gigabytes (2
40
bytes).
Approximately 1 trillion bytes.
TFTP
Trivial File Transfer Protocol. A simplified version of FTP that allows files to be transferred from one
computer to another over a network, usually without the use of client authentication (for example,
username and password).
Note: some TFTP servers (such as Sun Solaris) may not support file sizes larger that 32 MB.
trap
Message sent by an SNMP agent to an NMS, a console, or a terminal to indicate the occurrence of a
significant event, such as a specifically defined condition or a threshold that was reached.
tunnel
Secure communication path between two peers, such as two routers.
Tx
The transmitter end of a fabric link. All links are unidirectional. See also Rx.
U
UDP
User Datagram Protocol. Connectionless transport layer protocol in the TCP/IP protocol stack. UDP is
a simple protocol that exchanges datagrams without acknowledgments or guaranteed delivery,
requiring that error processing and retransmission be handled by other protocols. UDP is defined in
RFC 768.
unicast
Message sent to a single network destination.
unicast
transmission
A unicast transmission sends one copy of each packet to each member of the group. This method is
inefficient because the same information must be carried multiple times, requiring extra bandwidth.
V
VCSEL
vertical cavity surface emitting laser.
vm
A vm file is a Cisco IOS XR software file that can be installed from ROM Monitor mode. A vm file is
typically used to install the Cisco
IOS XR software when the software has not yet been installed or has
been corrupted.
VPN
Virtual Private Network. Enables IP traffic to travel securely over a public TCP/IP network by
encrypting all traffic from one network to another. A VPN uses “tunneling” to encrypt all information
at the IP level.
W
WRED
Weighted Random Early Detection. Queueing method that ensures that high-precedence traffic has
lower loss rates than other traffic during times of congestion.