Migrating X.25 over PSI to XOL

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 Level-2 modulo value supported
At level 2, LLC2 supports only 128 as the Level-2 modulo value. Native LAPB supports 8 or 128 as
the Level-2 modulo values.
Note:
Currently, there is no SAM support for XOL configuration. The X.25
configuration files are edited manually. The X.25 interface must be started
and stopped manually.
Benefits of XOL
Following are the advantages of using XOL instead of X.25 over PSI card:
 Lower hardware cost
Ethernet cards cost less compared to PSI cards. Moreover, the extensive use and large demand for
Ethernet cards is expected to lower the cost of Ethernet cards.
 Lower operational cost
The administration, management, and maintenance costs involved in implementing XOL systems with
Ethernet cards are significantly lesser than the costs involved in implementing X.25 over PSI.
Moreover, skilled Ethernet network administrators are easily available in contrast to administrators
with working knowledge of X.25 over PSI. This reduces the total cost of ownership.
 Higher performance
The maximum throughput of XOL systems using Ethernet cards is 10 Gbps. The maximum throughput
of X.25 systems using PSI cards is only 2 Mbps. Tests show that X.25 applications perform better on
XOL systems than on X.25 systems over PSI. The exact performance improvement metric depends on
the model of Ethernet card used.
 Seamless application migration
Migration of legacy X.25 applications to XOL requires minimal or no application changes.
Migrating X.25 over PSI to XOL
XOL is supported on Ethernet, FDDI and Token Ring LAN cards. However, Ethernet cards are
preferred because they offer high throughput. This section discusses how to migrate X.25 over PSI to
XOL using Ethernet cards. The migration of X.25 over PSI to XOL involves the following:
 Hardware migration
 Configuration migration
 Application migration
Hardware Migration
The following hardware elements, which are a part of the X.25 network, are impacted in the
migration process:
 Cards
 Cables
 Switches and routers