Configuring and Managing Host-Based X.25 Links - Edition 5 (36939-90054)

Chapter 3 69

Conﬁguring DTCs Step-by-Step

Modify the Network Management Conﬁguration File

CCITT X.25

Standard Version of the CCITT X.25 standard you are using,

either 1980 or 1984.

Frame size

(N1) The frame size, in bytes, as listed on your

subscription. Note that many network subscription

forms give this value in bits, not bytes. In such cases,

divide the number of bits by 8 to obtain the correct

number of bytes to enter in this ﬁeld.

Range: 23 to 4103 bytes.

Retransmission

timer (T1) Time, in milliseconds, the transmitting node waits

before retransmitting an unacknowledged frame.

The default of 3000 milliseconds is adequate for

most installations.

Range: 1000 to 12000 milliseconds.

Timer (T3) This value is required only if you are using the 1984

CCITT standard. Speciﬁes the time a link will

remain idle before it is automatically reset. The

value of T3 must be greater than T1. The default is

20 seconds.

Range: 0 to 1000 seconds.

Retransmission

count (N2) The number of times a frame is retransmitted before

an error is indicated. The default is 20 times.

Range: 0 to 255.

Unacknowledged

frame number

(K) The maximum number of frames which can be

transmitted without acknowledgment from the

network.

Range: 1 to 7.

Modulo The counting cycle for the send frame sequence

number.

Range: 8 or 128.

Step 10: Conﬁgure X.25 Level 3 and Miscellaneous

NMMGR displays the DTC X.25 Card Conﬁguration — Level 3 &

Miscellaneous screen (Figure 3-9) if you press the

[Go To Level 3] key at

the DTC X.25 Card Conﬁguration screen or the DTC X.25 Card

Conﬁguration — Level 1 and 2 screen. On this screen, you conﬁgure

level 3 values for this X.25 card. You also conﬁgure an X.25 card