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

76 Chapter3

Conﬁguring DTCs Step-by-Step

Modify the Network Management Conﬁguration File

The following factors must be considered in

determining how many SVCs to allow:

• The total number of SVCs which an X.25 board

can establish depends on the packet size

conﬁgured in the X.25 level 3 conﬁguration.

Upper limits for each DTC48 and DTC72MX card

are:

• 256 for packet sizes of 512 or less.

• 150 for 1024 byte packets.

• 100 for 2048 byte packets.

• 54 for 4096 byte packets.

Note that these limits are not affected by

packet size negotiation. That is, if you have

conﬁgured a packet size of 4096, and a packet

size of 128 has been negotiated, you are still

limited to the 54 SVCs supported with 4096

byte packets.

• If you are also conﬁguring PAD connections on

this card, remember that PAD connections use

SVCs out of the pool of available SVCs. You will

need to balance your PAD support requirements

with your system-to-system requirements to ﬁnd

the optimum conﬁguration for your network.

• The total number of SVCs available may also be

limited by your PSN subscription.

System X.25

address This is the X.25 address of the X.25 card, to be used

for system-to-system connections. In most cases, this

will be the same as the address entered on the

Level 3 & Miscellaneous screen. If, however, your

network application requires the address used for

X.25 system-to-system communications to be

different from the address used for PAD connections,

enter a different address here. For most connections

to public data networks, this will be the DTC/X.25

Network Access card address plus a unique

subaddress for the host system.

Note that with certain networks (such as Transpac,

in France) the called address is removed from

incoming call packets and the calling address is

added to outgoing call packets by the network. For

these networks, enter only the subaddress in this

ﬁeld, not the full X.25 address.