Installing and Administering HP FDDI/9000 Software

Chapter 1 27

FDDI Resources

FDDI Concepts

Figure 1-3 FDDI Dual Ring During Normal Operation

By deﬁnition, information is always received by a station from the

nearest station upstream, the Upstream Neighbor (UNA), and

transmitted to the nearest station downstream, the Downstream

Neighbor (DNA). In the example in Figure 1-3, the concentrator with

MAC address 080009001023 receives data from its Upstream Neighbor

at MAC address 080009005034 (see Figure 1-5 for that section of the

network map) and transmits to its Downstream Neighbor, the

concentrator at MAC address 080009004056. In this example, when the

ring is up and functioning normally, the Station State of the

concentrator is listed as Rooted, indicating that the concentrator has

active A, B, or S ports in tree mode, and the Station State of the single-

attached stations is listed as Wrapped indicating the MAC in that

station can transmit data frames on the FDDI network. (Refer to the

fddinet for more information.)

Concentrator (DAC)

Mainframe

CF_State = Thru_A

MAC Address =

080009005067

to SAS

DAS = Dual Attach Station

DAC = Dual Attach Concentrator

A, B, M and S = Port Types

Mainframe (DAS)

CF_State = Thru_A

MAC Address =

080009004056

Concentrator (DAC)

CF_State = Thru_A

MAC Address =

080009001023

Router (DAS)

CF_State = Thru_A

MAC Address =

080009002034

to SAS

MAC

802.3

MAC