Network Instruments WAN Probe Kit - Manual (Page 38)

32 Analyzing a WAN Link with Observer
pie, graph and dial views. The display setup dialog (click Settings to access), lets you
choose what ports to display as well as color and scale options.
The Bandwidth Utilization display is not subject to any filters as it compares
the actual activity on the network to the network’s theoretical capacity.
WAN Vital Signs by DLCI
In WAN Observer, the Network Vital Signs display is replaced by the WAN Vital Signs by
DLCI mode. This mode provides a summary of the errors occurring on a WAN link
(E1/T1/DS3/E3).
You can choose what portion of traffic you wish to view from the list box in the upper left
corner of the window: DCE, DTE, or Summary.
DTE (Data Terminal Equipment), in the context of a WAN link, refers to the DSU/CSU.
DCE (Data Circuit-terminating equipment) refers to the WAN switch (which may reside
remotely at the line provider's site). Summary view shows a concatenation of traffic from
both ends of the link.
List View
The following statistics are shown, broken down by DLCIs (which are listed in the
leftmost column). You can change the sort order by clicking on any of the column
headings:
Column Description
DLCI Data Link Connection Identifier of the statistics that follow.
DCE KBits/s Max The maximum bit rate sensed so far from the DCE side of this DLCI, in
Kbits per second.
DTE KBits/s Max The maximum bit rate sensed so far from the DTE side of this DLCI, in
Kbits per second.
DCE Kbits/s Avg The average bit rate sensed on the DCE side of this DLCI, in Kbits per
second.
DTE Kbits/s Avg The average bit rate sensed on the DTE side of this DLCI, in Kbits per
second.
DCE FECN
under CIR The number of packets seen on the DCE side of the link that had the
Forward Explicit Congestion Notification bit set, even though the
bandwidth usage was within the Committed Information Rate (CIR).
Normally this number should be zero. If bandwidth usage exceeds CIR,
congestion is expected.