RFC 1841
PPP Network Control Protocol for LAN Extension
Pages: 66
Informational
Informational
Part 3 of 3 – Pages 45 to 66
10.0 Download Request The host router sends a LEX_RCMD_REQUEST packet with an Option-Type of 0x08 to alert the LAN extension interface unit that the host router will be issuing a software download to Flash memory. When the LAN extension interface unit acknowledges the command, the host router starts sending download data.
10.1 LEX RCMD_REQUEST - Download Request Figure 14 shows a summary frame format of a LEX_RCMD_REQUEST packet for a Download Request remote command option. The host router transmits the fields from left to right. Figure 14 LEX_RCMD_REQUEST Packet Frame Format - Download Request PPP Header <--------------------------------------------------------------> 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 0xFF03 | Protocol-Type | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ (2 octets) (2) LAN Extension Interface Protocol Header <--------------------------------------------------------------> 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Code | Identifier | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ (1) (1) (2) LAN Extension Interface Remote Command Option <-------------------------------- 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Option-Type | Option-Flags | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ (1) (1) -----------------------------------------------> 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Option-Length | Option-Data | -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ (2) Where the Option-Data field contains the following fields: 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Block Number (16 bits) | File Size (32 bits).... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Filename (Max. 64 octets)....... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Summary Field Descriptions For a complete description of the fields in the PPP Header, the LAN Extension Interface Protocol Header, and the LAN Extension Interface Remote Command Option, refer to the "Remote Command Options" section earlier in this document. Table 17 provides a summary of these fields when sending a LEX_RCMD_REQUEST packet that informs the LAN extension interface unit of an upcoming software download to Flash memory. Table 17 Field Values for LEX_RCMD_REQUEST Packet - Download Request Field Value Address/Control 0xFF03 (Broadcast address/Unnumbered information) Protocol-Type 0x8041 (Control packet) Code 0x40 (LEX_RCMD_REQUEST packet) Identifier Valid values: 0x01-0xFF Length Variable depending on size of filename in the Filename field. Valid range: Minimum length = 19 octets Maximum length = 82 octets Option-Type 0x08 (Download Request) Option-Flags None Option-Length Variable depending on size of filename in the Filename field. Valid range: Minimum length = 11 octets Maximum length = 74 octets Option-Data Block Number, File Size, and Filename of the code/image to be downloaded. See the following "Option-Data Field Descriptions" section for details. Option-Data Field Descriptions The Option-Data field contains the following fields: * Block Number The Block Number field contains a value that identifies a contiguous group of code bits to be downloaded to the LAN extension interface unit. In the LEX_RCMD_REQUEST packet, the Block Number is always zero. * File Size The File Size field contains the size (in octets) of the code to be downloaded to the LAN extension interface unit.
* Filename The Filename field contains the name of the image to be transferred to the LAN extension interface unit. 10.2 Response Packets - Download Request The following packets are valid responses to a Download Request LEX_RCMD_REQUEST packet: * LEX_RCMD_ACK - Download Request Refer to the "Conditions for Sending PPP-LEX Packets" section earlier in this document for more information on when the LAN extension interface unit sends this packet. * LEX_RCMD_NAK - Download Request The LAN extension interface unit sends a Download Request LEX_RCMD_NAK packet when the LAN Extension interface unit is currently programming Flash, when the File Size field value in the request is greater than the unit's available Flash bytes, when the LAN extension interface unit is out of memory, or when the Block Number field value in the request is not zero. * LEX_RCMD_REJ - Download Request Refer to the "Conditions for Sending PPP-LEX Packets" section earlier in this document for more information on when the LAN extension interface unit sends this packet. Table 18 summarizes the field values of the Download Request LEX_RCMD_ACK, LEX_RCMD_NAK, and LEX_RCMD_REJ packets. Table 18 Field Values for Response Packets - Download Request Field Value Address/Control 0xFF03 (Broadcast address/Unnumbered information) Protocol-Type 0x8041 (Control packet) Code Valid values: * 0x41 (LEX_RCMD_ACK packet) * 0x42 (LEX_RCMD_NAK packet) * 0x43 (LEX_RCMD_REJ packet) Identifier The same value as that sent by the LEX_RCMD_REQUEST packet Length The same value as that sent by the LEX_RCMD_REQUEST packet
Option-Type 0x08 (Download Request)
Option-Flags None
Option-Length The same value as that sent by the
LEX_RCMD_REQUEST packet
Option-Data Block Number, File Size, and Filename of
the code/image to be downloaded.
11.0 Download Data
Once the host router receives a Download Request LEX_RCMD_ACK packet
from the LAN extension interface unit, the host router downloads the
data to be written to Flash memory by sending a LEX_RCMD_REQUEST
packet with an Option-Type of 0x09. The host router sends multiple
Download Data LEX_RCMD_REQUEST packets, each with 512 octets of
Option-Data containing the binary data to be programmed into Flash
memory.
A packet containing Option-Data with less than 512 octets signals the
end of the download data (that is, the end of tile). If the size of
the file being downloaded is an even multiple of 512 bytes, then the
last packet transferred should have an Option-Length of 6. That is,
the last packet transferred should have Option-Data containing the
Block Number field value but no data. A Block Number field value
without data alerts the LAN extension interface unit that this is the
last block to be transmitted.
11.1 LEX RCMD_REQUEST - Download Data
The frame format for the Download Data LEX_RCMD_REQUEST packet is
similar to a TFTP frame format. Figure 15 shows a summary frame
format. The host router transmits the fields from left to right.
Figure 15 LEX_RCMD_REQUEST Packet Frame Format - Download Data
PPP Header
<-------------------------------------------------------------->
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0xFF03 | Protocol-Type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
(2 octets) (2)
LAN Extension Interface Protocol Header
<-------------------------------------------------------------->
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Code | Identifier | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
(1) (1) (2)
LAN Extension Interface Remote Command Option
<--------------------------------
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Option-Type | Option-Flags |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
(1) (1)
----------------------------------------------->
6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Option-Length | Option-Data |
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
(2)
Where the Option-Data field contains the following fields:
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Block Number (16 bits) | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
| Binary Download Data (Max. 512 octets)..... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Summary Field Descriptions
For a complete descriptions of the fields in the PPP Header, the LAN
Extension Interface Protocol Header, and the LAN Extension Interface
Remote Command Option, refer to the "Remote Command Options" section
earlier in this document. The following table provides a summary of
these fields when sending a LEX_RCMD_REQUEST packet that download
software to the LAN extension interface unit.
Table 19 Field Values for LEX_RCMD_REQUEST Packet - Download Data
Field Value
Address/Control 0xFF03 (Broadcast address/Unnumbered
information)
Protocol-Type 0x8041 (Control packet)
Code 0x40 (LEX_RCMD_REQUEST packet)
Identifier Valid values: 0x01-0xFF
Length Minimum length = 14 octets
Maximum length = 526 octets
Option-Type 0x09 (Download Data)
Option-Flags None
Option-Length Minimum length = 6 octets (signals end of
data transfer for a file with a file size
of an even multiple of 512 bytes)
Maximum length = 518 octets
Option-Data Block Number and Download Data. See the
following "Option-Data Field Descriptions"
section for details.
Option-Data Field Descriptions
The following Option-Data fields provide the LAN extension interface
unit with download data:
* Block Number
The Block Number identifies the contiguous group of code bits to be
downloaded. The host router automatically generates this number. The
first Download Data packet gets a block number of one. The host
router increments this Block Number value by one with every Download
Data LEX_RCMD_REQUEST packet sent to the LAN extension interface
unit. The maximum value of the Block Number is dependent on the
unit's Flash memory size.
* Download Data
The Download Data are the actual code bits being downloaded to the
LAN extension interface unit. A maximum of 512 octets of download
data can sent in one Download Data LEX_RCMD_REQUEST packet.
11.2 Response Packets - Download Data
The following packets are valid responses to a Download Data
LEX_RCMD_REQUEST packet:
* LEX_RCMD_ACK - Download Data
Refer to the "Conditions for Sending PPP-LEX Packets" section earlier
in the document for more information on this packet.
* LEX_RCMD_NAK - Download Data The LAN extension interface unit sends a Download Data LEX_RCMD_NAK packet when the LAN extension interface unit is not in the proper state or when accepting the data will over-run the download buffer. * LEX_RCMD_REJ - Download Data Refer to the "Conditions for Sending PPP-LEX Packets" section earlier in the document for more information on this packet. Table 20 summarizes the field values of the Download Data LEX_RCMD_ACK, LEX_RCMD_NAK, and LEX_RCMD_REJ packets. Table 20 Field Values for Response Packets - Download Data Field Value Address/Control 0xFF03 (Broadcast address/Unnumbered information) Protocol-Type 0x8041 (Control packet) Code Valid values: * 0x41 (LEX_RCMD_ACK packet) * 0x42 (LEX_RCMD_NAK packet) * 0x43 (LEX_RCMD_REJ packet) Identifier The same value as that sent by the LEX_RCMD_REQUEST packet Length 14 octets Option-Type 0x09 (Download Data) Option-Flags None Option-Length 6 octets Option-Data Block Number only 12.0 Download Status Upon completion of a Download Data sequence, the host router issues a LEX_RCMD_REQUEST packet with an Option-Type of 0x0A to request status of the success or failure of the download. A bad checksum of the image or a malfunctioning Flash memory could cause the download to fail.
12.1 LEX RCMD_REQUEST - Download Status Figure 16 shows the frame format summary of a LEX_RCMD_REQUEST packet for a Download Status remote command option. The host router transmits the fields from left to right. Figure 16 LEX_RCMD_REQUEST Packet Frame Format - Download Status PPP Header <--------------------------------------------------------------> 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 0xFF03 | Protocol-Type | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ (2 octets) (2) LAN Extension Interface Protocol Header <--------------------------------------------------------------> 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Code | Identifier | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ (1) (1) (2) LAN Extension Interface Remote Command Option <--------------------------------------------------------------> 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Option-Type | Option-Flags | Option-Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ (1) (1) (2) Summary Field Descriptions For a complete descriptions of the fields in the PPP Header, the LAN Extension Interface Protocol Header, and the LAN Extension Interface Remote Command Option, refer to the "Remote Command Options" section earlier in this document. Table 21 provides a summary of these fields when sending a LEX_RCMD_REQUEST packet that requests the download status of the LAN extension interface unit. Table 21 Field Values for LEX_RCMD_REQUEST Packet - Download Status Field Value Address/Control 0xFF03 (Broadcast address/Unnumbered information) Protocol-Type 0x8041 (Control packet) Code 0x40 (LEX_RCMD_REQUEST packet)
Identifier Valid values: 0x01-0xFF Length 12 octets Option-Type 0x0A (Download Status) Option-Flags None Option-Length 4 octets Option-Data None 12.2 LEX RCMD_REQUEST - Download Status When the LAN extension interface unit correctly receives the Download Status LEX_RCMD_REQUEST packet, it returns a LEX_RCMD_ACK packet containing the appropriate status information in the Option-Data field. Figure 17 shows the frame format for the Download Status LEX_RCMD_ACK packet. The LAN extension interface unit transmits the fields from left to right. Figure 17 LEX_RCMD_ACK Packet Frame Format - Download Status PPP Header <--------------------------------------------------------------> 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 0xFF03 | Protocol-Type | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ (2 octets) (2) LAN Extension Interface Protocol Header <--------------------------------------------------------------> 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Code | Identifier | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ (1) (1) (2)
LAN Extension Interface Remote Command Option
<--------------------------------
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Option-Type | Option-Flags |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
(1) (1)
----------------------------------------------->
6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Option-Length | Option-Data |
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
(2)
Where the Option-Data field contains the following fields:
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Status (16 bits) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Summary Field Descriptions
For a complete descriptions of the fields in the PPP Header, the LAN
Extension Interface Protocol Header, and the LAN Extension Interface
Remote Command Option, refer to the "Remote Command Options" section
earlier in this document. Table 22 provides a summary of these fields
when sending a status information to the host router.
Table 22 Field Values for LEX_RCMD_ACK Packet - Download Status
Field Value
Address/Control 0xFF03 (Broadcast address/Unnumbered
information)
Protocol-Type 0x8041 (Control packet)
Code 0x41 (LEX_RCMD_ACK packet)
Identifier The same value as that sent by the
LEX_RCMD_REQUEST packet
Length 14 octets
Option-Type 0x0A (Download Status)
Option-Flags None
Option-Length 6 octets
Option-Data Status information. See the following
"Option-Data Field Descriptions" section
for details.
Option-Data Field Descriptions
The Option-Data field uses the Status field to send the download
status to the host router. The Status field reports the following
status information:
* 1 - Acknowledgment that no errors occurred
* 3 - Sequence error occurred
* 6 - Flash write error occurred
* 7 - Checksum error
12.3 LEX RCMD_NAK/LEX RCMD_REJ - Download Status
Refer to the "Conditions for Sending PPP-LEX Packets" section earlier
in this document for information on when the LAN extension interface
unit sends a Download Status LEX_RCMD_NAK packet and Download Status
LEX_RCMD_REJ packet.
The frame format for these two response packets mirror the frame
format of the Download Status LEX_RCMD_REQUEST packet. Table 23
summarizes the field values of the Download Status LEX_RCMD_NAK and
LEX_RCMD_REJ packets.
Table 23 Field Values for LEX_RCMD_NAK/LEX_RCMD_REJ Packets - Download
Status
Field Value
Address/Control 0xFF03 (Broadcast address/Unnumbered
information)
Protocol-Type 0x8041 (Control packet)
Code Valid values:
* 0x42 (LEX_RCMD_NAK packet)
* 0x43 (LEX_RCMD_REJ packet)
Identifier The same value as that sent by the
LEX_RCMD_REQUEST packet
Length 12 octets
Option-Type 0x0A (Download Status)
Option-Flags None
Option-Length 4 octets
Option-Data None
13.0 Inventory Request
The host router sends a LEX_RCMD_REQUEST packet with an Option-Type
of 0x0B to the LAN extension interface unit to request inventory
information. The host router may use this remote command option to
accomplish the following:
* Distinguish between different versions of the LAN extension
interface unit for determining their capabilities
* Determine whether a new version of Flash code should be downloaded
13.1 LEX RCMD_REQUEST - Inventory Request
Figure 18 shows the frame format for a LEX_RCMD_REQUEST packet with
an Inventory Request remote command option. The host router transmits
the fields from left to right.
Figure 18 LEX_RCMD_REQUEST Packet Frame Format - Inventory Request
PPP Header
<-------------------------------------------------------------->
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0xFF03 | Protocol-Type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
(2 octets) (2)
LAN Extension Interface Protocol Header
<-------------------------------------------------------------->
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Code | Identifier | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
(1) (1) (2)
LAN Extension Interface Remote Command Option
<-------------------------------------------------------------->
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Option-Type | Option-Flags | Option-Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
(1) (1) (2)
Summary Field Descriptions
For a complete description of the fields in the PPP Header, the LAN
Extension Interface Protocol Header, and the LAN Extension Interface
Remote Command Option, refer to the "Remote Command Options" section
earlier in this document. Table 24 provides a summary of these fields
when sending a LEX_RCMD_REQUEST packet that requests inventory
information.
Table 24 Field Values for LEX_RCMD_REQUEST Packet-Inventory Request
Field Value
Address/Control 0xFF03 (Broadcast address/Unnumbered
information)
Protocol-Type 0x8041 (Control packet)
Code 0x40 (LEX_RCMD_REQUEST packet)
Identifier Valid values: 0x01-0xFF
Length 12 octets
Option-Type 0x0B (Inventory Request)
Option-Flags None
Option-Length 4 octets
Option-Data None
13.2 LEX RCMD_ACK - Inventory Request
When it correctly receives the Inventory Request remote command
option and retrieves the inventory information, the LAN extension
interface unit responds with an acknowledgment. This acknowledgment
contains the requested inventory information in the Option-Data
field.
Figure 19 shows the frame format for the Inventory Request
LEX_RCMD_ACK packet.
Figure 19 LEX_RCMD_ACK Packet Frame Format - Inventory Request
PPP Header
<-------------------------------------------------------------->
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0xFF03 | Protocol-Type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
(2 octets) (2)
LAN Extension Interface Protocol Header
<-------------------------------------------------------------->
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Code | Identifier | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
(1) (1) (2)
LAN Extension Interface Remote Command Option
<--------------------------------
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Option-Type | Option-Flags |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
(1) (1)
----------------------------------------------->
6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Option-Length | Option-Data |
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
(2)
Where the Option-Data field contains the following fields:
(32 bits)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flash Size |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Serial Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| HW Version | PROM Major Ver| PROM Minor Ver|Flash Major Ver|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Flash Minor Ver| FLAGS | RAM Major Ver | RAM Minor Ver |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ Mac Address (6 octets) +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Summary Field Descriptions
For a complete description of the fields in the PPP Header, the LAN
Extension Interface Protocol Header, and the LAN Extension Interface
Remote Command Option, refer to the "Remote Command Options" section
earlier in this document. Table 25 provides a summary of these fields
when acknowledging a LEX_RCMD_REQUEST packet that requests inventory
information.
Table 25 Field Values for LEX_RCMD_ACK Packet - Inventory Request
Field Value
Address/Control 0xFF03 (Broadcast address/Unnumbered
information)
Protocol-Type 0x8041 (Control packet)
Code 0x41 (LEX_RCMD_ACK packet)
Identifier The same value as that sent by
LEX_RCMD_REQUEST packet
Length 34 octets
Option-Type 0x0B (Inventory Request)
Option-Flags None
Option-Length 26 octets
Option-Data Inventory data. See the following
"Option-Data Field Descriptions" section
for details.
Option-Data Field Descriptions
The Option-Data field of the LEX_RCMD_ACK packet uses the following
fields to send inventory data to the host router about the LAN
extension interface unit.
* Flash Size
This field contains the LAN extension interface unit's Flash size in
bytes.
* Serial Number
This field provides the LAN extension interface unit's serial number.
This is an unassigned, 32-bit number.
* HW Version
This field contains the version number of the LAN extension interface
hardware unit.
* PROM Major Ver
This field contains part of the version number of the PROM image.
"Major" indicates which major software release this revision belongs
to. For example, if the PROM version number is 1.2, then the major
version number is 1.
* PROM Minor Ver
This field contains part of the version number of the PROM image.
"Minor" indicates which minor software release this revision belongs
to. For example, if the PROM version number is 1.2, then the minor
version number is 2.
* Flash Major Ver This field contains the "major" version number of the Flash image. For example, if the Flash image version number is 1.2, then the major version number is 1. * Flash Minor Ver This field contains the "minor" version number of the Flash image. For example, if the Flash image version number is 1.2, then the minor version number is 2. * FLAGS FLAGS report the boot status of the LAN extension interface unit. The flags are as follows: - 0x01 - Running PROM image - 0x02 - Running Flash image - 0x04 - PROM image passed checksum - 0x08 - Flash image passed checksum * RAM Major Ver This field contains the "major" version number of the running image in RAM. For example, if the RAM image version number is 1.2, then the major version number is 1. * RAM Minor Ver This field contains the "minor" version number of the running image in RAM. For example, if the RAM image version number is 1.2, then the minor version number is 2. * MAC Address The MAC Address is the LAN extension interface unit's burned-in MAC address in canonical format. This field is six octets. 13.3 LEX RCMD_NAK/LEX RCMD_REJ - Inventory Request Refer to the "Conditions for Sending PPP-LEX Packets" section earlier in this document for information on when the LAN extension interface unit sends an Inventory Request LEX_RCMD_NAK packet and Inventory Request LEX_RCMD_REJ packet. The frame format of these two response packets mirrors that of the request. Table 26 summarizes the field values for such Inventory
Request LEX_RCMD_NAK/LEX_RCMD_REJ packets.
Table 26 Field Values for LEX_RCMD_NAK/LEX_RCMD_REJ Packets -
Inventory Request
Field Value
Address/Control 0xFF03 (Broadcast address/Unnumbered
information)
Protocol-Type 0x8041 (Control packet)
Code Valid values:
* 0x42 (LEX_RCMD_NAK packet)
* 0x43 (LEX_RCMD_REJ packet)
Identifier The same value as that sent by the
LEX_RCMD_REQUEST packet
Length 12 octets
Option-Type 0x0B (Inventory Request)
Option-Flags None
Option-Length 4 octets
Option-Data None
14.0 LAN Extension Interface Protocol Data Packets
When the PPP-LEX NCP is in an "opened" state, the LAN extension
interface unit and the host router also exchange PPP-LEX data packets
(as well as control packets). There is only one type of PPP-LEX data
packet. This data packet is a subset of the PPP-BCP packet format.
The format subsetting is such that a PPP-BCP implementation will
successfully process a LAN extension interface protocol packet. The
differences are as follows:
* LAN ID field will not be present.
* LAN FCS field will never be present (that is, the F flag will
always be off [=0]).
* LAN ID flag (I) will always be off.
* Pad field for the serial link will never be present, and the
count field will be 0.
For detailed information on PPP-BCP packets, refer to the "PPP
Bridging Control Protocol (BCP)" RFC. (References, [2])
14.1 Frame Format
Figure 20 shows the frame format for a PPP-LEX data packet. The MAC
frame is transferred except for the FCS field. The LAN extension
interface unit computes the FCS for packets transferred to the LAN
and strips the FCS for packets destined for the host router.
Figure 20 PPP-LEX Data Packet Frame Format
(8 bits) (8 bits) (8 bits) (8 bits)
+-+-+-+-+-+-+-+-+
| HDLC FLAG |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0xFF | 0x03 | 0x0041 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| F|I|Z|0| Pad | Mac Type | Destination MAC Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Destination MAC Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Source MAC Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Source MAC Address | Length/Type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LLC Data |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| (Serial) HDLC CRC | HDLC FLAG |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
14.2 Summary Field Descriptions
HDLC FLAG
HDLC Frame delimiter.
0xFF
This Address field contains the broadcast address.
0x03
This Control field contains unnumbered information.
0x0041
This field contains the IETF-assigned protocol type value for a
PPP-LEX data packet. In this case this field will always contain
0x0041.
Flags
The flags F, I, Z, 0 have the following meanings:
* F: Set bit F if the LAN FCS field is present. Because PPP-LEX
data packets do not contain the LAN FCS field, this bit should
not be set (field=0).
* I: Set bit I if the LAN ID field is present. Because PPP-LEX
data packets do not contain the field, this bit should not be
set (field=0).
* Z: Set bit Z if IEEE 802.3 Pad must be zero filled to minimum
size.
* 0: Reserved, must be zero.
Pad
Any PPP frame may have padding inserted in the Optional Data Link
Layer Padding field. The value tells the receiving system how many
pad octets to strip off. The LAN extension interface protocol does
not support the Optional Data Link Layer Padding field, so the
value of this field should be zero.
MAC Type
This field contains the most up-to-date value of the MAC type as
specified in the most recent "Assigned Numbers" RFC. The current
value is as follows:
* 1: IEEE 802.3/Ethernet with canonical addresses
Destination MAC Address
This field is 6 octets and contains the MAC address of the
destination system as defined by IEEE. The MAC Type field defines
the bit ordering.
Source MAC Address
This field is 6 octets and contains the MAC address of the
destination system as defined by IEEE. The MAC Type field defines
the bit ordering.
Length/Type
This field is any Ethernet protocol type (See RFC 1700 in the
references "Assigned Numbers"). For IEEE 802.3 frames, this is a
length field.
LLC Data This field is the remainder of the MAC frame which is (or would be if it were present) protected by the LAN FCS. (Serial) HDLC CRC This is a 16 bit Cyclic Redundancy Check field. For complete information on the above fields and their relationship to PPP-BCP packets, refer to the "PPP Bridging Control Protocol (BCP)" RFC. (References, [2]) Notes 1. The LAN extension interface protocol does allow the segmentation of individual LAN packets across the serial link. Each LAN packet must be transmitted across the serial link as one PPP-LEX encapsulation. 2. MAC addresses in PPP-LEX packets should be in canonical format. References [1] Simpson, W., "The Point-To-Point Protocol (PPP) for the Transmission of Multi-protocol Datagrams over Point-To-Point Links", RFC 1331, Daydreamer, May 1992. [2] Baker, F., and R. Bowen, "PPP Bridging Control Protocol (BCP)", RFC 1638, ACC, IBM, June 1994. [3] Lloyd, B., and W. Simpson, "PPP Authentication Protocols", RFC 1334, Lloyd & Associates, Daydreamer, October 1992. [4] Reynolds, J., and J. Postel, "Assigned Numbers", STD 2, RFC 1700, USC/Information Sciences Institute, October 1994. [5] Reynolds, J., and J. Postel, "Standard for the transmission of IP datagrams over IEEE 802 networks", RFC 1042, USC/Information Sciences Institute, February 1988.
Security Considerations Security issues are not discussed in this memo. Authors' Addresses Joelle Bafile Chapman, Technical Writer Cisco Systems, Inc. 170 West Tasman Drive San Jose, CA 95134-1706 EMail: joelle@cisco.com Dave Coli, Software Engineer Cisco Systems, Inc. 170 West Tasman Drive San Jose, CA 95134-1706 EMail: dcoli@cisco.com Andy Harvey, Software Engineer Cisco Systems, Inc. 170 West Tasman Drive San Jose, CA 95134-1706 EMail: agh@cisco.com Bent Jensen, Engineering Manager Cisco Systems, Inc. 170 West Tasman Drive San Jose, CA 95134-1706 EMail: bent@cisco.com Kevin Rowett, Software Engineer Cisco Systems, Inc. 170 West Tasman Drive San Jose, CA 95134-1706 EMail: krowett@cisco.com