AIS AI2524 user manual Configure Additional Routing Features

AI2524 Router Card User’s Manual

Configuration for Router Y

service tcp-keepalives-in service tcp-keepalives-out interface ethernet 0

ip address 172.20.1.2 255.255.255.0

!

interface serial 0 x25 ltc 5

x25 pvc 1 tunnel 172.20.1.1 interface serial 0 pvc 2 x25 pvc 2 tunnel 172.20.1.1 interface serial 1 pvc 2

Configure

Additional X.25

Routing Features

To configure other, less common X.25 routing features, perform these tasks:

zConfigure XOT to Use Interface Default Flow Control Values

zSubstitute Addresses in a Local X.25 Rout

zConfigure XOT Alternate Destinations

Configure XOT to Use Interface Default Flow Control Values

When setting up a connection, the source and destination XOT imple- mentations need to cooperate to determine the flow control values that apply to the SVC. The source XOT ensures cooperation by encoding the X.25 flow control facilities (the window sizes and maximum packet sizes) in the X.25 Call packet. The far host's XOT implementa- tion can then correctly negotiate the flow control values at the destina- tion interface and, if needed, indicate the final values in the X.25 Call Confirm packet.

The versions of XOT prior to Release 9.1(4.1) software will not, how- ever, ensure that these flow control values are encoded in the X.25 Call packet. When XOT receives a call that leaves one or both flow control values unspecified, it supplies the values. The values supplied are a window size of 2 packets and maximum packet size of 128 bytes; ac cording to the standards, any SVC can be negotiated to use these val- ues. Thus, when XOT receives a call from an older XOT implementation, it can specify in the Call Confirm packet that thes flow control values must revert to the lowest common denominator.

What the older XOT implementations required was that the source and destination XOT router use the same default flow control values on the two X.25 interfaces that connect the SVC. Consequently, connections with mismatched flow control values were created when this assump-

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