As per Relevance of the word february, we have this rfc below:
Network Working Group S.
Request for Comments: 2106 J.
Category: Informational Cisco Systems, Inc
H.
Mitsubishi Electric Corp
February 1997
Data Link Switching Remote Access
Status of this
This memo provides information for the Internet community. This
does not specify an Internet standard of any kind. Distribution
this memo is unlimited
This memo describes the Data Link Switching Remote Access
that is used between workstations and routers to transport SNA
NetBIOS traffic over TCP sessions. Any questions or comments
be sent to drap@cisco.com
1.
Since the Data Link Switching Protocol, RFC 1795, was published,
software vendors have begun implementing DLSw on workstations.
implementation of DLSw on a large number of workstations
several important issues that must be addressed. Scalability is
major concern. For example, the number of TCP sessions to the
router increases in direct proportion to the number of
added. Another concern is efficiency. Since DLSw is a switch-to
switch protocol, it is not efficient when implemented
workstations
DRAP addresses the above issues. It introduces a
structure to resolve the scalability problems. All workstations
clients to the router (server) rather than peers to the router.
creates a client/server model. It also provides a more
protocol between the workstation (client) and the router (server).
Chiang, et. al. Informational [Page 1]
RFC 2106 DLSRAP February 1997
2.
2.1. DRAP Client/Server
+-----------+ +-----------+ +---------+
| Mainframe | | IP Router +- ppp -+ DLSw |
+--+--------+ +-----+-----+ | Work |
| | | Station |
| | +---------+
+--+--+ +-------------+ |
| FEP +- TR -+ DLSw Router +-- IP
+-----+ +-------------+ |
|
|
+-----------+ +---------+
| IP Router +- ppp -+ DLSw |
+-----+-----+ | Work |
| Station |
+---------+
| DLSw Session |
+-------------------------------+
Figure 2-1. Running DLSw on a large number of workstations creates
scalability problem
Figure 2-1 shows a typical DLSw implementation on a workstation.
workstations are connected to the central site DLSw router over
IP network. As the network grows, scalability will become an
as the number of TCP sessions increases due to the growing number
workstations
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+-----------+ +-------+
+-----------+ | DLSw/DRAP | | DRAP |
| Mainframe | | Router +- ppp -+ Client
+--+--------+ +-----+-----+ +-------+
| |
| |
+--+--+ +-------------+ |
| FEP +- TR -+ DLSw Router +-- IP
+-----+ +-------------+ |
|
|
+-----------+ +-------+
| DLSw/DRAP | | DRAP |
| Router +- ppp -+ Client
+-----+-----+ +-------+
| DLSw Session | | DRAP Session |
+--------------+ +--------------+
Figure 2-2. DLSw Remote Access Protocol solves the scalability problem
In a large network, DRAP addresses the scalability problem
significantly reducing the number of peers that connect to
central site router. The workstations (DRAP client) and the
(DRAP server) behave in a Client/Server relationship.
are attached to a DRAP server. A DRAP server has a single
connection to the central site router
2.2. Dynamic Address
In a DLSw network, each workstation needs a MAC address
communicate with a FEP attached to a LAN. When DLSw is implemented
a workstation, it does not always have a MAC address defined.
example, when a workstation connects to a router through a modem
PPP, it only consists of an IP address. In this case, the user
define a virtual MAC address. This is administratively
since each workstation must have an unique MAC address
DRAP uses the Dynamic Address Resolution protocol to solve
problem. The Dynamic Address Resolution protocol permits the
to dynamically assign a MAC address to a client without
configuration
For a client to initiate a session to a server, the workstation
a direct request to the server. The request contains the
MAC address and the destination SAP. The workstation can
specify its own MAC address, or request the server to assign one
it. The server's IP address must be pre-configured on
workstation. If IP addresses are configured for multiple servers at
Chiang, et. al. Informational [Page 3]
RFC 2106 DLSRAP February 1997
workstation, the request can be sent to these servers and the
one to respond will be used
For a server to initiate a session to a client, the server sends
directed request to the workstation. The workstation must pre
register its MAC address at the server. This can be done either
configuration on the server or registration at the server (both
addresses and IP addresses will be registered).
2.3. TCP
The transport used between the client and the server is TCP. Before
TCP session is established between the client and the server,
message can be sent. The default parameters associated with the
connections between the client and the server are as follows
Socket Family AF_INET (Internet protocols
Socket Type SOCK_STREAM (stream socket
Port Number 1973
There is only one TCP connection between the client and the server
It is used for both read and write operations
3. DRAP
3.1. General Frame
The General format of the DRAP frame is as follows
+-------------+-----------+-----------+
| DRAP Header | DRAP Data | User Data |
+-------------+-----------+-----------+
Figure 3-1. DRAP Frame
The DRAP protocol is contained in the DRAP header, which is common
all frames passed between the DRAP client and the server. This
is 4 bytes long. The next section will explain the details
The next part is the DRAP Data. The structure and the size are
on the type of messages carried in the DRAP frame. The DRAP data
used to process the frame, but it is optional
The third part of the frame is the user data, which is sent by
local system to the remote system. The size of this block is
and is included in the frame only when there is data to be sent
the remote system
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RFC 2106 DLSRAP February 1997
3.2. Header
The DRAP header is used to identify the message type and the
of the frame. This is a general purpose header used for each
that is passed between the DRAP server and the client.
information is needed for frames like CAN_U_REACH and I_CAN_REACH
therefore, it is passed to the peer as DRAP data. The structure
the DRAP data depends on the type of frames, and will be discussed
detail in later sections
The DRAP Header is given below
+-------------------------------------------+
| DRAP Packet Header (Each row is one byte) |
+===========================================+
0 | Protocol ID / Version Number |
+-------------------------------------------+
1 | Message Type |
+-------------------------------------------+
2 | Packet Length |
+ - - - - - - - - - - - - - - - - - - - - - +
3 | |
+-------------------------------------------+
Figure 3-2. DRAP Header
o The Protocol ID uses the first 4 bits of this field and is set
"1000".
o The Version Number uses the next 4 bits in this field and is
to "0001".
o The message type is the DRAP message type
o The Total Packet length is the length of the packet including
DRAP header, DRAP data and User Data. The minimum size of
packet is 4, which is the length of the header
3.3. DRAP
Most of the Drap frames are based on the existing DLSw frames
have the same names. The information in the corresponding DRAP
DLSw frames may differ; but the functionalities are the same.
the DLSw State Machine is used to handle these DRAP frames. Some
DRAP frames were created to handle special DRAP functions.
example, the new DRAP frames, I_CANNOT_REACH and START_DL_
provide negative acknowledgment. The DLSw frames not needed for DRAP
are dropped
Chiang, et. al. Informational [Page 5]
RFC 2106 DLSRAP February 1997
The following table lists and describes all available DRAP messages
DRAP Frame Name Code
--------------- ---- --------
CAN_U_REACH 0x01 Find if the station given is
I_CAN_REACH 0x02 Positive response to CAN_U_
I_CANNOT_REACH 0x03 Negative response to CAN_U_
START_DL 0x04 Setup session for given
DL_STARTED 0x05 Session
START_DL_FAILED 0x06 Session Start
XID_FRAME 0x07 XID
CONTACT_STN 0x08 Contact destination to establish
STN_CONTACTED 0x09 Station contacted - SABME mode
DATA_FRAME 0x0A Connectionless Data Frame for a
INFO_FRAME 0x0B Connection oriented I-
HALT_DL 0x0C Halt Data Link
HALT_DL_NOACK 0x0D Halt Data Link session without
DL_HALTED 0x0E Session
FCM_FRAME 0x0F Data Link Session Flow Control
DGRM_FRAME 0x11 Connectionless Datagram Frame for a
CAP_XCHANGE 0x12 Capabilities Exchange
CLOSE_PEER_REQUEST 0x13 Disconnect Peer Connection
CLOSE_PEER_RESPONSE 0x14 Disconnect Peer Connection
PEER_TEST_REQ 0x1D Peer keepalive test
PEER_TEST_RSP 0x1E Peer keepalive
Table 3-1. DRAP
3.4. DRAP Data
The DRAP data is used to carry information required for each
frame. This information is used by the Server or the Client and
does not contain any user data. The DRAP data frame types are
in the following sections. Please note that the sender should set
reserved fields to zero and the receiver should ignore these fields
3.4.1. CAN_U_REACH, I_CAN_REACH, and I_CANNOT_REACH
These frame types are used to locate resources in a network.
CAN_U_REACH frame is sent to the server to determine if the
is reachable. The server responds with an I_CAN_REACH frame if it
reach the workstation identified in the CAN_U_REACH frame, or with
I_CANNOT_REACH if the station is not reachable. The server should
send the CAN_U_REACH frame to the clients. When a server receives
explorer whose destination is a known client, the server
respond to it directly
Chiang, et. al. Informational [Page 6]
RFC 2106 DLSRAP February 1997
+---------------+-----------------------+
| Field Name | Information |
+---------------+-----------------------+
| Message Type | 0x01, 0x02, or 0x03 |
+---------------+-----------------------+
| Packet Length | 0x0C |
+---------------+-----------------------+
Figure 3-3. CAN_U_REACH, I_CAN_REACH, and I_CANNOT_REACH
+-----------------------------------+
| Field Name (Each row is one byte) |
+===================================+
0 | Target MAC Address |
+ - - - - - - - - - - - - - - - - - +
1 | |
+ - - - - - - - - - - - - - - - - - +
2 | |
+ - - - - - - - - - - - - - - - - - +
3 | |
+ - - - - - - - - - - - - - - - - - +
4 | |
+ - - - - - - - - - - - - - - - - - +
5 | |
+-----------------------------------+
6 | Source SAP |
+-----------------------------------+
7 | Reserved |
+-----------------------------------+
Figure 3-4. CAN_U_REACH, I_CAN_REACH, and I_CANNOT_REACH
The MAC Address field carries the MAC address of the
workstation that is being searched. This is a six-byte MAC
field. The same MAC Address is returned in the I_CAN_REACH and
I_CANNOT_REACH frames
Byte 6 is the source SAP. The destination SAP is set to zero when
explorer frame is sent to the network
If the sender did not receive a positive acknowledgment within
recommended threshold value of 60 seconds, the destination
considered not reachable
3.4.2. START_DL, DL_STARTED, and START_DL_FAILED
These frame types are used by DRAP to establish a link
(circuit). The START_DL frame is sent directly to the server
responds to the CAN_U_REACH frame. When the server receives
frame, it establishes a link station with the source and
Chiang, et. al. Informational [Page 7]
RFC 2106 DLSRAP February 1997
addresses and saps provided in the START_DL frame. If the
establishment is successful, a DL_STARTED frame is sent back as
response. A failure will result in a START_DL_FAILED response.
server can also send START_DL frames to clients, to
circuits
+---------------+-----------------------+
| Field Name | Information |
+---------------+-----------------------+
| Message Type | 0x04, 0x05, or 0x06 |
+---------------+-----------------------+
| Packet Length | 0x18 |
+---------------+-----------------------+
Figure 3-5. START_DL, DL_STARTED, and START_DL_FAILED
Chiang, et. al. Informational [Page 8]
RFC 2106 DLSRAP February 1997
+-----------------------------------+
| Field Name (Each row is one byte) |
+===================================+
0 | Host MAC Address |
+ - - - - - - - - - - - - - - - - - +
1 | |
+ - - - - - - - - - - - - - - - - - +
2 | |
+ - - - - - - - - - - - - - - - - - +
3 | |
+ - - - - - - - - - - - - - - - - - +
4 | |
+ - - - - - - - - - - - - - - - - - +
5 | |
+-----------------------------------+
6 | Host SAP |
+-----------------------------------+
7 | Client SAP |
+-----------------------------------+
8 | Origin Session ID |
+-----------------------------------+
9 | |
+ - - - - - - - - - - - - - - - - - +
10| |
+ - - - - - - - - - - - - - - - - - +
11| |
+-----------------------------------+
12| Target Session ID |
+ - - - - - - - - - - - - - - - - - +
13| |
+ - - - - - - - - - - - - - - - - - +
14| |
+ - - - - - - - - - - - - - - - - - +
15| |
+-----------------------------------+
16| Largest Frame Size |
+-----------------------------------+
17| Initial Window size |
+-----------------------------------+
18| Reserved |
+ - - - - - - - - - - - - - - - - - +
19| |
+-----------------------------------+
Figure 3-6. START_DL, DL_STARTED, and START_DL_FAILED
The Host MAC address is the address of the target station if
session is initiated from the client, or it is the address of
originating station if the session is initiated from the server
Chiang, et. al. Informational [Page 9]
RFC 2106 DLSRAP February 1997
The next two fields are the Host and Client SAPs. Each is one
long. The Host SAP is the SAP used by the station with the Host
address. The Client SAP is the SAP used by the client
The Origin Session ID, is the ID of the originating station
initiates the circuit. The originating station uses this ID
identify the newly created circuit. Before the START_DL frame is
to the target station, the originating station sets up a
block for the circuit. This link station information is set
DRAP does not use a three-way handshake for link
establishment. In the DL_STARTED and the START_DL_FAILED messages
the Origin Session ID is returned as received in the START_DL frame
The Target Session ID is set by the target station and returned
the DL_STARTED message
The Target Session ID is not valid for the START_DL and
START_DL_FAILED frame, and should be treated as Reserved fields.
the DL_STARTED frame, it is the session ID that is used to set
this circuit by the target station
The Largest Frame Size field is used to indicate the maximum
size that can be used by the client. It is valid only when it is
by the server. The Largest Frame Size field must be set to zero
a frame is sent by the client. Both START_DL and DL_STARTED use
Largest Frame Size field and only its rightmost 6 bits are used.
format is defined in the IEEE 802.1D Standard, Annex C, Largest
Bits (LF). Bit 3 to bit 5 are base bits. Bit 0 to bit 2 are
bits. The Largest Frame Size field is not used in the START_DL_
frame and must be set to zero
bit 7 6 5 4 3 2 1 0
r r b b b e e
Figure 3-7. Largest Frame
Please note that if the client is a PU 2.1 node, the client
use the maximum I-frame size negotiated in the XID3 exchange
The Initial window size in the START_DL frame gives the
window size on the originating side, and the target DRAP
returns its receive window size in the DL_STARTED frame. The field
reserved in the START_DL_FAILED frame. The usage of the window
is the same as the one used in DLSw. Please refer to RFC 1795
details
The last two bits are reserved for future use. They must be set
zero by the sender and ignored by the receiver
Chiang, et. al. Informational [Page 10]
RFC 2106 DLSRAP February 1997
If the sender of the START_DL frame did not receive a START_DL_
frame within a recommended threshold value of 60 seconds,
connection is considered unsuccessful
3.4.3. HALT_DL, HALT_DL_NOACK, and DL_HALTED
These frame types are used by DRAP to disconnect a link station.
HALT_DL frame is sent directly to the remote workstation to
that the sender wishes to disconnect. When the receiver receives
frame, it tears down the session that is associated with the
Session ID and the Target Session ID provided in the HALT_DL frame
The receiver should respond with the DL_HALTED frame. The DL_
frame should use the same Session ID values as the received HALT_
message without swapping them. The HALT_DL_NOACK frame is used
the response is not required
+---------------+-----------------------+
| Field Name | Information |
+---------------+-----------------------+
| Message Type | 0x0C, 0x0D, or 0x0E |
+---------------+-----------------------+
| Packet Length | 0x10 |
+---------------+-----------------------+
Figure 3-8. HALT_DL, HALT_DL_NOACK, and DL_HALTED
Chiang, et. al. Informational [Page 11]
RFC 2106 DLSRAP February 1997
+-----------------------------------+
| Field Name (Each row is one byte) |
+===================================+
0 | Sender Session ID |
+ - - - - - - - - - - - - - - - - - +
1 | |
+ - - - - - - - - - - - - - - - - - +
2 | |
+ - - - - - - - - - - - - - - - - - +
3 | |
+-----------------------------------+
4 | Receiver Session ID |
+ - - - - - - - - - - - - - - - - - +
5 | |
+ - - - - - - - - - - - - - - - - - +
6 | |
+ - - - - - - - - - - - - - - - - - +
7 | |
+-----------------------------------+
8 | Reserved |
+ - - - - - - - - - - - - - - - - - +
9 | |
+ - - - - - - - - - - - - - - - - - +
10| |
+ - - - - - - - - - - - - - - - - - +
11| |
+-----------------------------------+
Figure 3-9. START_DL, DL_STARTED, and START_DL_FAILED
3.4.4. XID_FRAME, CONTACT_STN, STN_CONTACTED, INFO_FRAME, FCM_FRAME
and DGRM_
These frame types are used to carry the end-to-end data or
a circuit. The Destination Session ID is the Session ID created
the START_DL frame or the DL_STARTED frame by the receiver. The
of the flow control flag is the same as the one used in DLSw.
refer to RFC 1795 for details
+---------------+----------------------------+
| Field Name | Information |
+---------------+----------------------------+
| Message Type | Based on Message type |
+---------------+----------------------------+
| Packet Length | 0x0C + length of user data |
+---------------+----------------------------+
Figure 3-10. Generic DRAP
Chiang, et. al. Informational [Page 12]
RFC 2106 DLSRAP February 1997
+-----------------------------------+
| Field Name (Each row is one byte) |
+===================================+
0 | Destination Session ID |
+ - - - - - - - - - - - - - - - - - +
1 | |
+ - - - - - - - - - - - - - - - - - +
2 | |
+ - - - - - - - - - - - - - - - - - +
3 | |
+-----------------------------------+
4 | Flow Control Flags |
+-----------------------------------+
5 | Reserved |
+ - - - - - - - - - - - - - - - - - +
6 | |
+ - - - - - - - - - - - - - - - - - +
7 | |
+-----------------------------------+
Figure 3-11. Generic DRAP Data
3.4.5. DATA_
This frame type is used to send connectionless SNA and
Datagram (UI) frames that do not have a link station associated
the source and destination MAC/SAP pair. The difference
DGRM_FRAME and DATA_FRAME is that DGRM_FRAME is used to send
frames received for stations that have a link station opened,
DATA_FRAME is used for frames with no link station established
+---------------+-----------------------------+
| Field Name | Information |
+---------------+-----------------------------+
| Message Type | 0x0A |
+---------------+-----------------------------+
| Packet Length | 0x10 + Length of user data |
+---------------+-----------------------------+
Figure 3-12. DATA_FRAME
Chiang, et. al. Informational [Page 13]
RFC 2106 DLSRAP February 1997
+-----------------------------------+
| Field Name (Each row is one byte) |
+===================================+
0 | Host MAC Address |
+ - - - - - - - - - - - - - - - - - +
1 | |
+ - - - - - - - - - - - - - - - - - +
2 | |
+ - - - - - - - - - - - - - - - - - +
3 | |
+ - - - - - - - - - - - - - - - - - +
4 | |
+ - - - - - - - - - - - - - - - - - +
5 | |
+-----------------------------------+
6 | Host SAP |
+-----------------------------------+
7 | Client SAP |
+-----------------------------------+
8 | Broadcast Type |
+-----------------------------------+
9 | Reserved |
+ - - - - - - - - - - - - - - - - - +
10| |
+ - - - - - - - - - - - - - - - - - +
11| |
+-----------------------------------+
Figure 3-13. DATA_FRAME Data
The definition of the first 8 bytes is the same as the START_
frame. The Broadcast Type field indicates the type of
frames in use; Single Route Broadcast, All Route Broadcast,
Directed. The target side will use the same broadcast type. In
case of Directed frame, if the RIF information is known, the
peer can send a directed frame. If not, a Single Route
frame is sent
3.4.6. CAP_XCHANGE
In DRAP, the capability exchange frame is used to exchange
client's information, such as its MAC address, with the server. If
DRAP client has its own MAC address defined, it should put it in
MAC address field. Otherwise, that field must be set to zero
When the DRAP server receives the CAP_XCHANGE frame, it should
the MAC address if it is non zero. The DRAP server also verifies
the MAC address is unique. The server should return a CAP_
response frame with the MAC address supplied by the client if the
Chiang, et. al. Informational [Page 14]
RFC 2106 DLSRAP February 1997
address is accepted. If a client does not have its own MAC address
the server should assign a MAC address to the client and put
address in the CAP_XCHANGE command frame
A client should record the new MAC address assigned by the server
return a response with the assigned MAC address. If the client
accept the assigned MAC address, another CAP_XCHANGE command with
MAC address field set to zero should be sent to the server.
server should allocate a new MAC address for this client
During the capability exchange, both the client and the server
send command frames. The process stops when either side sends
CAP_XCHANGE response frame. When the response frame is sent, the
address in the CAP_XCHANGE frame should be the same as the one in
previous received command. The sender of the CAP_XCHANGE
agrees to use the MAC address defined in the previous command
The number of CAP_XCHANGE frames that need to be exchanged
determined by the client and the server independently. When
number of exchange frames has exceeded the pre-defined number set
either the server or the client, the session should be brought down
The flag is used to show the capability of the sender. The
list shows the valid flags
0x01 NetBIOS support. If a client sets this bit on, the server
pass all NetBIOS explorers to this client. If this bit is
set, only SNA traffic will be sent to this client
0x02 TCP Listen Mode support. If a client supports TCP listen mode
the server will keep the client's MAC and IP addresses
after the TCP session is down. The cached information will
used for server to connect out. If a client does not
TCP listen mode, the cache will be deleted as soon as the
session is down
0x04 Command/Response. If this bit is set, it is a command
otherwise, it is a response
The values 0x01 and 0x02 are used only by the client. When a
sends the command/response to a client, the server does not
these values
Starting with the Reserved field, implementors can
implement the Capability Exchange Control Vector. Each
Exchange Control Vector consists of three fields: Length (1 byte),
Type (1 byte), and Data (Length - 2 bytes). Two types of
Vectors are defined: SAP_LIST and VENDOR_CODE (described below).
Chiang, et. al. Informational [Page 15]
RFC 2106 DLSRAP February 1997
ensure compatibility, implementors should ignore the unknown
Vectors instead of treating them as errors
0x01 SAP_LIST. Length: 2+n bytes, where n ranges from 1 to 16.
This control vector lists the SAPs that the client can support
The maximum number of SAPs a client can define is 16. Therefore
the length of this Control Vector ranges from 3 to 18. If
SAP_LIST is not specified in the capability exchange, the
assumes that the client can support all the SAP values.
example, if a client can only support SAP 4 and 8, then
following Control Vectors should be sent: "0x04, 0x01, 0x04,
0x08". The first byte indicates the length of 4. The second
indicates the control vector type of SAP_LIST. The last two
indicate the supported SAP values; 0x04 and 0x08. This
Vector is used only by the client. If the server accepts
Control Vector, it must return the same Control Vector to
client
0x02 VENDOR_CODE. Length: 6 bytes
Each vendor is assigned a vendor code that identifies the vendor
This Control Vector does not require a response
After the receiver responds to a Control Vector, if the
exchange is not done, the sender does not have to send the
Control Vector again
+---------------+-----------------------+
| Field Name | Information |
+---------------+-----------------------+
| Message Type | 0x12 |
+---------------+-----------------------+
| Packet Length | 0x1C |
+---------------+-----------------------+
Figure 3-14. CAP_XCHANGE
Chiang, et. al. Informational [Page 16]
RFC 2106 DLSRAP February 1997
+-----------------------------------+
| Field Name (Each row is one byte) |
+===================================+
0 | MAC Address |
+ - - - - - - - - - - - - - - - - - +
1 | |
+ - - - - - - - - - - - - - - - - - +
2 | |
+ - - - - - - - - - - - - - - - - - +
3 | |
+ - - - - - - - - - - - - - - - - - +
4 | |
+ - - - - - - - - - - - - - - - - - +
5 | |
+-----------------------------------+
6 | Flag |
+-----------------------------------+
7 | Reserved |
+-----------------------------------+
Figure 3-15. CAP_XCHANGE Data
3.4.7. CLOSE_PEER_REQ
This frame is used for peer connection management and contains
reason code field. The following list describes the valid
codes
0x01 System shutdown. This indicates shutdown in progress
0x02 Suspend. This code is used when there is no traffic between
server and the client, and the server or the client wishes
suspend the TCP session. When the TCP session is suspended,
circuits should remain intact. The TCP session should be re
established when new user data needs to be sent. When the
session is re-established, there is no need to send
CAP_XCHANGE frame again
0x03 No MAC address available. This code is sent by the server
there is no MAC address is available from the MAC address pool
+---------------+-----------------------+
| Field Name | Information |
+---------------+-----------------------+
| Message Type | 0x13 |
+---------------+-----------------------+
| Packet Length | 0x08 |
+---------------+-----------------------+
Figure 3-16. CLOSE_PEER_REQ
Chiang, et. al. Informational [Page 17]
RFC 2106 DLSRAP February 1997
+-----------------------------------+
| Field Name (Each row is one byte) |
+===================================+
0 | Reason Code |
+-----------------------------------+
1 | Reserved |
+ - - - - - - - - - - - - - - - - - +
2 | |
+ - - - - - - - - - - - - - - - - - +
3 | |
+-----------------------------------+
Figure 3-17. CLOSE_PEER_REQ Data
3.4.8. CLOSE_PEER_RSP, PEER_TEST_REQ, and PEER_TEST_RSP
These three frames are used for peer connection management. There
no data associated with them
o CLOSE_PEER_
CLOSE_PEER_RSP is the response for CLOSE_PEER_REQ
o PEER_TEST_REQ and PEER_TEST_
PEER_TEST_REQ and PEER_TEST_RSP are used for peer level keepalive
Implementing PEER_TEST_REQ is optional, but PEER_TEST_RSP must
implemented to respond to the PEER_TEST_REQ frame. When
PEER_TEST_REQ frame is sent to the remote station, the
expects to receive the PEER_TEST_RSP frame in a predefined
interval (the recommended value is 60 seconds). If
PEER_TEST_RSP frame is not received in the predefined
interval, the sender can send the PEER_TEST_REQ frame again. If
predefined number of PEER_TEST_REQ frames is sent to the
station, but no PEER_TEST_RSP frame is received (the
number is 3), the sender should close the TCP session with
remote station and terminate all associated circuits
+---------------+-----------------------+
| Field Name | Information |
+---------------+-----------------------+
| Message Type | 0x14, 0x1D, or 0x1E |
+---------------+-----------------------+
| Packet Length | 0x04 |
+---------------+-----------------------+
Figure 3-18. CLOSE_PEER_RSP, PEER_TEST_REQ, and PEER_TEST_RSP
Chiang, et. al. Informational [Page 18]
RFC 2106 DLSRAP February 1997
4.
[1] Wells, L., Chair, and A. Bartky, Editor, "DLSw: Switch-to-
Protocol", RFC 1795, October 1993.
[2] IEEE 802.1D Standard
Authors'
Steve T.
InterWorks Business
Cisco Systems, Inc
170 Tasman
San Jose, CA 95134
Phone: (408) 526-5189
EMail: schiang@cisco.
Joseph S.
InterWorks Business
Cisco Systems, Inc
170 Tasman
San Jose, CA 95134
Phone: (408) 526-5232
EMail: jolee@cisco.
Hideaki
System Product
Network Products
Network Software Products Section
Mitsubishi Electric Corp
Information Systems Engineering
325, Kamimachiya Kamakura Kanagawa 247,
Phone: +81-467-47-2120
EMail: yasuda@eme068.cow.melco.co.
Chiang, et. al. Informational [Page 19]
if you see any problems within the linking, don't worry be happy,
this is version 0.1 of the Relevance System and you gotta expect some crappy subroutines sometimes,
just be content we did not write this in Java, which would have made this "bigger and better" HAHAHHA.
RFC documents can be found at I.E.T.F.
Relevance System Copyright © 2002 Spectrum WorldResearch
other technical nosh by ServerMasters Corporation
collaboration of BobX
