IBM SC30-3681-08 X.25 Support Over ISDN BRI D-Channel (X.31), Null Encapsulation, Limitations, Conguration Changes, Conguring Null Encapsulation and Closed User Groups (CUG)

Table48. National Set Parameters (continued)
Paramter DDN Default GTE Default
collision-timer 10 seconds 10 seconds
standard-version 1984 1984
t1-timer 4 seconds 4 seconds
t2-timer 00
truncate-called-addr-size 22
X.25 Support Over ISDN BRI D-Channel (X.31)
X.25 provides the same protocol support over ISDN BRI D-channel (X.31) with the
following restrictions:
vThe packet size must not exceed 256 bytes.
vThe frame extended sequence mode must be enabled.
vX.31 must be configured as a DTE.
See “X.31 Support” on page626 for more information.
Null Encapsulation
Null Encapsulation allows the user to multiplex multiple network layer protocols over
one X.25 circuit. This function may be used to avoid using an unreasonable number
of virtual circuits.
Limitations
Null Encapsulation is not supported for QLLC. This function is supported for
Switched Virtual Circuits (SVCs), but not for Permanent Virtual Circuits (PVCs).
Configuration Changes
The encapsulation option NULL has been added for the following T6 commands:
Under X25 config: add address IP (may input enc type = NULL)
Under X25 config: add address IPX (may input enc type = NULL)
Under X25 config: add address DNA (may input enc type = NULL)
Under X25 config: add address VINES (may input enc type = NULL)
Under X25 config: list addr will show active enc type = NULL if the priority 1
type is NULL.
T5 commands:
Under X25 ıintu: List SVCS will include enc type = NULL
Configuring Null Encapsulation and Closed User Groups (CUG)
Since More than one Protocol can run over one virtual circuit while using Null
Encapsulation, the CUG(s) defined for each protocol over that circuit must be the
same. It is strongly suggested that the user configure multiple Protocols same
destination as follows:
Using the X.25 Network Interface
322 MRS V3.2 Software User’s Guide
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