User`s guide

Internetwork Monitor
Interpreting the Internetwork View
5967–9446 233
Data Integration, MAC Layer View
To construct the MAC layer view, Internetwork Monitor uses the end-to-
end network-layer conversations to compute intrasegment and segment-
to-segment data values.
End-to-end traffic pairs with both end points on the same segment are
added to the intrasegment traffic data list.
For each traffic pair with network-layer end points residing on different
segments, Internetwork Monitor checks the MAC-layer addresses for the
end points to determine whether the traffic passes through an identifi-
able router. It then creates appropriate intrasegment traffic entries and
assigns the traffic to a segment-to-segment pair. This process is dis-
cussed further below.
Even though the view represents the MAC layer, the internetwork view
is based on network-layer conversations. Consequently, any node running
more than one protocol stack will appear multiple times in the view
(subject to thresholding and filtering). For example, if you have a node
that uses both TCP/IP and IPX, that node will appear twice in the view
(once for each protocol/network address).
Routed Traffic
Internetwork Monitor assumes traffic is routed when:
● The network layer shows a conversation pair’s end points on different
segments. and
● The MAC layer shows the end points on the same segment.
In this case, a MAC-layer end point that does not match the network-
layer end point’s segment is assumed to be a router.
For example:
● The network layer shows node A on segment S1 talking to node C on
segment S2.
● The MAC layer shows node A talking to node R1 on segment S1 and
node C talking to node R2 on segment S2.