IBM SC30-3681-08 manual Support Over Isdn BRI D-Channel, Null Encapsulation, Limitations

Using the X.25 Network Interface

Table 48. 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	0	0
truncate-called-addr-size	2	2

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 con®gured as a DTE.

See ªX.31 Supportº on page 626 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).

Con®guration Changes

The encapsulation option NULL has been added for the following T6 commands:

Under X25 con®g: add address IP (may input enc type = NULL)

Under X25 con®g: add address IPX (may input enc type = NULL)

Under X25 con®g: add address DNA (may input enc type = NULL)

Under X25 con®g: add address VINES (may input enc type = NULL)

Under X25 con®g: list addr will show active enc type = NULL if the priority 1

type is NULL.

T5 commands:

Under X25 õintu: List SVCS will include enc type = NULL

Con®guring 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) de®ned for each protocol over that circuit must be the

same. It is strongly suggested that the user con®gure multiple Protocols same

destination as follows:

322MRS V3.2 Software User's Guide