Window Size Negotiation
Negotiated window sizes are passed transparently from the originating DTE to the destination DTE. However, if the originating DTE does not specify the window size parameter in the call request packet, the X.25 services inserts this facility at the destination. The following table shows the window size negotiation that is implemented by the X.25 services.
| Originator's Request | Originator's Default Remote Window Size | Originator's Default Local Window Size | Action by the X.25 Services |
|---|
| No window size specified | 2 | 2 | The destination Passport 4400 unit issues a call request with window size negotiation parameters based on the originator's default local and remote window sizes (in this case, 2, 2). |
| No window size specified | 2 | 5 | The destination unit issues a call request with window size negotiation parameters based on the originator's default local and remote window sizes (in this case, 2, 5). |
| 3, 7 requested | 2 | 2 | The destination unit issues a call request using the window size parameters requested by the originator (in this case, 3, 7). |
During call accept, the destination DTE may request that the specified window size be negotiated to a lower value. If the originating DTE did not specify window size negotiation, the negotiated size is not communicated to the originator. The window size negotiation process is shown in the following diagram:
