| DCAP, Data Link Switching Client Access Protocol |
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Description | Glossary | RFCs | Publications | Obsolete RFCs |
| Protocol suite: | TCP/IP. |
| Protocol type: | Application layer protocol. |
| Multicast addresses: | 224.0.1.49 (server).
224.0.1.50 (client). 224.0.10.50 (group). |
| Ports: | 1973 (TCP) server. |
| SNMP MIBs: | |
| Working groups: | |
| Links: |
DCAP is used between workstations and routers to transport SNA/ NetBIOS traffic.
| MAC header | IP header | TCP header | DCAP header | Data ::: |
DCAP header:
| 00 | 01 | 02 | 03 | 04 | 05 | 06 | 07 | 08 | 09 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Protocol | Version | Type | Length | ||||||||||||||||||||||||||||
| Data ::: | |||||||||||||||||||||||||||||||
Protocol.
4 bits.
Set to 8.
Version.
4 bits.
Set to 1.
Type.
8 bits.
DCAP message.
| Type | Message | Description |
|---|---|---|
| 1 | CAN_U_REACH. | Find if the station given is reachable. |
| 2 | I_CAN_REACH. | Positive response to CAN_U_REACH. |
| 3 | I_CANNOT_REACH. | Negative response to CAN_U_REACH. |
| 4 | START_DL. | Setup session for given addresses. |
| 5 | DL_STARTED. | Session Started. |
| 6 | START_DL_FAILED. | Session Start failed. |
| 7 | XID_FRAME. | XID Frame. |
| 8 | CONTACT_STN. | Contact destination to establish SABME. |
| 9 | STN_CONTACTED. | Station contacted - SABME mode set. |
| 10 | DATA_FRAME. | Connectionless Data Frame for a link. |
| 11 | INFO_FRAME. | Connection oriented I-Frame. |
| 12 | HALT_DL. | Halt Data Link session. |
| 13 | HALT_DL_NOACK. | Halt Data Link session without ack. |
| 14 | DL_HALTED. | Session Halted. |
| 15 | FCM_FRAME. | Data Link Session Flow Control Message. |
| 17 | DGRM_FRAME. | Connectionless Datagram Frame for a circuit. |
| 18 | CAP_XCHANGE. | Capabilities Exchange Message. |
| 19 | CLOSE_PEER_REQUEST. | Disconnect Peer Connection Request. |
| 20 | CLOSE_PEER_RESPONSE. | Disconnect Peer Connection Response. |
| 29 | PEER_TEST_REQ. | Peer keepalive test request. |
| 30 | PEER_TEST_RSP. | Peer keepalive response. |
Length.
16 bits.
Size of the packet including the DCAP header, DCAP data and user data.
The minimum size of the packet is 4 bytes.
Data. Variable length.
RFCs:
[RFC 2114] Data Link Switching Client Access Protocol.
[RFC 2106] Data Link Switching Remote Access Protocol.
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Description | Glossary | RFCs | Publications | Obsolete RFCs |