RFC 1841
PPP Network Control Protocol for LAN Extension
Pages: 66
Informational
Informational
Part 2 of 3 – Pages 22 to 45
4.0 Filter MAC Address The host router sends a LEX_RCMD_REQUEST packet with an Option-Type of 0x02 to the LAN extension interface unit to configure the LAN extension interface unit to filter inbound packets by source MAC address. A MAC address filter determines whether or not the LAN extension interface unit forwards packets with a specific source MAC
address to the host router. A MAC address filter consists of MAC address, a MAC address mask, and a permit or deny field. (See the "Option-Data Field Descriptions" section later in this section for more information on these filter fields.) A LEX_RCMD_REQUEST packet can contain 0 to 100 (depending on MTU size) MAC address filters. When a LEX_RCMD_REQUEST packet contains multiple filters, they are concatenated. The LAN extension interface unit applies MAC address filters to each inbound packet's source MAC address in the order in which the filters exist in the filter entry list. A packet must be permitted by one of the filters before the LAN extension interface unit can forward the packet across the serial link. 4.1 LEX RCMD_REQUEST - Filter MAC Address Figure 7 shows a frame format summary of a LEX_RCMD_REQUEST packet for the Filter MAC Address remote command option. The host router transmits the fields from left to right. Figure 7 LEX_RCMD_REQUEST Packet Frame Format - Filter MAC Address 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 Options
<--------------------------------
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MAC Address (48 bits)....
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MAC Address Mask (48 bits)....
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Permit/Deny (16 bits) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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 Options, refer to the "Remote Command Options" section
earlier in this document. Table 4 provides a summary of these fields
when sending a LEX_RCMD_REQUEST packet that configures the LAN
extension interface unit to filter by source MAC address.
Table 4 Field Values for LEX_RCMD_REQUEST Packet - Filter MAC Address
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 = 12 octets
Maximum length = 1412 octets
Option-Type 0x02 (Filter MAC Address)
Option-Flags None
Option-Length Minimum length = 4 octets
Maximum length = 1404 octets
Option-Data Zero or more filters to be applied at the
LAN extension interface unit. See the
following "Option-Data Field Description
section for details.
Option-Data Field Descriptions
The following three Option-Data fields are used in conjunction to
specify a MAC address filter:
* MAC Address
The MAC Address field contains a 48-bit IEEE 802.3 MAC address in
canonical format.
* MAC Address Mask
The MAC Address Mask field contains a "wild card" mask. The mask is a
48-bit hexadecimal number whose ones bits correspond to the MAC
address bits to be ignored during the comparison. The mask excludes
bits from the comparison in the MAC address filter.
* Permit/Deny
The Permit/Deny field determines whether or not a MAC address filter
permits or denies inbound frames of a specific MAC address to pass to
the host router. A permit value is a non-zero value that allows
frames of a specific MAC address to pass to the host router. A deny
value is a zero value that does not allow frames of a specific MAC
address to pass to the host router.
Implementation Notes
Each LEX_RCMD_REQUEST packet is a complete specification of all MAC
address filters and replaces any previously established filters.
A LEX_RCMD_REQUEST packet with an Option-Length field equal to four
(without any filter entries) instructs the LAN extension interface
unit to turn off filtering. All MAC addresses, except local
destination addresses cached in the self-learning filter, are
forwarded.
4.2 Response Packets - Filter MAC Address
The following packets are valid responses to the Filter MAC Address
LEX_RCMD_REQUEST packet:
* LEX_RCMD_ACK - Filter MAC Address The LAN extension interface unit sends a LEX_RCMD_ACK packet in response to a Filter MAC Address LEX_RCMD_REQUEST packet when the LAN extension interface unit correctly receives the Filter MAC Address remote command option and applies the entries to its filter table. All MAC address filter entries are returned in the LEX_RCMD_ACK packet. * LEX_RCMD_NAK - Filter MAC Address The LAN extension interface unit sends a LEX_RCMD_NAK packet in response to the Filter MAC Address LEX_RCMD_REQUEST packet when the request contains an incorrect number of bytes in the filter or when there are no more filter entries available. The LAN extension interface unit continues to use the previous filter table (that is, the filter table that existed prior to the receipt of the request). The host router should signal an error to the user/network administrator. All filter entries are returned in the LEX_RCMD_NAK packet. * LEX_RCMD-REJ - Filter MAC Address See the "Conditions for Sending PPP-LEX Packets" section earlier in this document for more information on this packet type. Table 5 summarizes the field values of Filter MAC Address LEX_RCMD_ACK, LEX_RCMD_NAK, and LEX_RCMD_REJ packets. Table 5 Field Values for Response Packets - Filter MAC Address 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 0x02 (Filter MAC Address) Option-Flags None Option-Length The same value as that sent by the LEX_RCMD_REQUEST packet Option-Data The filter entries sent in the
LEX_RCMD_REQUEST packet
5.0 Set Priority
The host router sends a LEX_RCMD_ REQUEST with an Option-Type of 0x03
to the LAN extension interface unit to establish the sending priority
of different protocol type packets from the LAN extension interface
unit to host router. There are four levels of priority:
* High
* Medium
* Normal
* Low
Packets are classified according to protocol type and then are queued
to one of four output queues on the LAN extension interface unit that
correspond to the above priority levels. When the LAN extension
interface unit is ready to transmit a packet, it scans the priority
queues in order, from the highest to lowest, to find the highest
priority packet.
5.1 LEX RCMD_REQUEST - Set Priority
To establish priority queues for each protocol type, the host router
sends a Set Priority LEX_RCMD_REQUEST packet. Figure 8 shows a frame
format summary of such a LEX_RCMD_REQUEST packet. The host router
transmits the fields from left to right.
Figure 8 LEX_RCMD_REQUEST Packet Frame Format - Set Priority
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 Options
<--------------------------------
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Protocol Type (16 bits) | Protocol Value (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 Options, 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 sets
priority queuing.
Table 6 Field Values for LEX_RCMD_REQUEST Packet - Set Priority
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 = 12 octets
Maximum length = 1028 octets
Option-Type 0x03 (Set Priority)
Option-Flags None
Option-Length Minimum length = 4 octets
Maximum length = 1020 octets
Option-Data Protocol Type and Priority Value. See the
following "Option-Data Field Description"
section for details.
Option-Data Field Descriptions
The following Option-Data fields set the priority queuing of
different protocol type packets.
* Protocol Type
The Protocol Type field contains a 16-bit number that is any Ethernet
type code. See the most recent "Assigned Numbers" RFC for the correct
Ethernet type code.
* Priority Value
The Priority Value field specifies the priority queue for the
protocol type specified in the Protocol Type field. Valid values are
as follows:
- 0 - High priority queue
- 1 - Medium priority queue
- 2 - Normal priority queue
- 3 - Low priority queue
Sending a LEX_RCMD_REQUEST packet with an Option-Length of four (no
priority entries) disables priority queuing. When disabled, the LAN
extension interface unit transfers all packets at a normal (2)
priority level. When a new priority is specified, it overwrites the
previous setting.
5.2 Response Packets - Set Priority
The following packets are valid responses to the Set Priority
LEX_RCMD_REQUEST packet.
* LEX_RCMD_ACK - Set Priority
See the "Conditions for Sending PPP-LEX Packets" section earlier in
this document for more information on this packet type.
* LEX_RCMD_NAK - Set Priority
The LAN extension interface unit sends a LEX_RCMD_NAK packet in
response to the Set Priority LEX_RCMD_REQUEST packet when the request
contains an incorrect number of bytes in the message, when necessary
resources are not available, or when the specified priority is
invalid.
* LEX_RCMD-REJ - Set Priority See the "Conditions for Sending PPP-LEX Packets" section earlier in this document for more information on this packet type. Table 7 summarizes the field values of Set Priority LEX_RCMD_ACK, LEX_RCMD_NAK, and LEX_RCMD_REJ packets. Table 7 Field Values for Response Packets - Set Priority 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 A randomly generated value that aids in matching requests with replies Length Minimum length = 12 octets Maximum length = 1028 octets Option-Type 0x03 (Set Priority) Option-Flags None Option-Length Minimum length = 4 octets Maximum length = 1020 octets Option-Data Protocol Type and Priority Value sent in the LEX_RCMD_REQUEST packet 6.0 Disable LAN Extension Ethernet Interface The host router sends a LEX_RCMD_ REQUEST with an Option-Type of 0x04 to the LAN extension interface unit to disable the LAN extension Ethernet interface. This remote command option stops data traffic from the LAN extension interface unit to the host router for troubleshooting or for reconfiguring the LAN extension interface unit. This remote command option only affects data traffic. PPP-LEX control packets can still be transferred over the serial link.
6.1 LEX RCMD_REQUEST - Disable LAN Extension Ethernet Interface Figure 9 shows a frame format summary of a LEX_RCMD_REQUEST packet for the Disable LAN Extension Ethernet Interface remote command option. The host router transmits the fields from left to right. Figure 9 LEX_RCMD_REQUEST Packet Frame Format - Disable LAN Extension Ethernet Interface 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 Options <--------------------------------------------------------------> 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 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 disables the LAN extension interface unit.
Table 8 Field Values for LEX_RCMD_REQUEST Packet -
Disable LAN Extension Ethernet Interface
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 0x04 (Disable LAN Extension Ethernet
Interface)
Option-Flags None
Option-Length 4 octets
Option-Data None
6.2 Response Packets - Disable LAN Extension Ethernet Interface
LEX_RCMD_ACK, LEX_RCMD_NAK, and LEX_RCMD-REJ packets are valid
responses to the Disable LAN Extension Ethernet Interface
LEX_RCMD_REQUEST packet. 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 each of these response
packets. Note that the LAN extension interface unit sends the
LEX_RCMD_ACK packet after shutting down the interface.
Table 9 summarizes the field values of Disable LAN Extension Ethernet
Interface LEX_RCMD_ACK, LEX_RCMD_NAK, and LEX_RCMD_REJ packets.
Table 9 Field Values for Response Packets -
Disable LAN Extension Ethernet Interface
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 12 octets
Option-Type 0x04 (Disable LAN Extension Ethernet
Interface)
Option-Flags None
Option-Length 4 octets
Option-Data None
7.0 Enable LAN Extension Ethernet Interface The host router sends a LEX_RCMD_ REQUEST with an Option-Type of 0x05 to the LAN extension interface unit to enable the LAN extension Ethernet interface. This remote command option allows LAN traffic to flow into the LAN extension interface unit after the interface has been disabled. 7.1 LEX RCMD_REQUEST - Enable LAN Extension Ethernet Interface Figure 10 shows a frame format summary of a LEX_RCMD_REQUEST packet for an Enable LAN Extension Ethernet Interface remote command option. The host router transmits the fields from left to right. Figure 10 LEX_RCMD_REQUEST Packet Frame Format - Enable LAN Extension Ethernet Interface 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 Options <--------------------------------------------------------------> 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 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 10 provides a summary of these fields when sending a LEX_RCMD_REQUEST packet that enables the LAN extension
Ethernet interface.
Table 10 Field Values for LEX_RCMD_REQUEST Packet -
Enable LAN Extension Ethernet Interface
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 12octets
Option-Type 0x05 (Enable LAN Extension Ethernet
Interface)
Option-Flags None
Option-Length 4 octets
Option-Data None
7.2 Response Packets - Enable LAN Extension Ethernet Interface
LEX_RCMD_ACK, LEX_RCMD_NAK, and LEX_RCMD-REJ packets are valid
responses to the Enable LAN Extension Ethernet Interface
LEX_RCMD_REQUEST packet. 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 each of these response
packets. Note that the LAN extension interface unit sends the
LEX_RCMD_ACK packet after enabling the interface.
The frame format of the response packets mirrors that of the request.
Table 11 summarizes the field values of Enable LAN Extension Ethernet
Interface LEX_RCMD_ACK, LEX_RCMD_NAK, and LEX_RCMD_REJ packets.
Table 11 Field Values for Response Packets -
Enable LAN Extension Ethernet Interface
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 12 octets
Option-Type 0x05 (Enable LAN Extension Ethernet
Interface)
Option-Flags None Option-Length 4 octets Option-Data None 8.0 Reboot LAN Extension Interface Unit The host router sends a LEX_RCMD_REQUEST packet with an Option-Type of 0x06 to the LAN extension interface unit to cause the LAN extension interface unit to reboot itself. The Option-Flags field specifies the boot mode for the LAN extension interface unit. There are two boot modes: * The first boot mode (Option-Flag 0x00) is the default. The default boot mode causes the LAN extension interface unit to check for a valid Flash image and to boot from it if it exists. If a valid Flash image does not exist, the default boot mode causes the LAN extension interface unit to boot from the PROM image. Similarly, if the Flash image is bad, then the LAN extension interface unit recovers by booting from the PROM image. * The second boot mode (Option-Flag 0x01) forces the LAN extension interface unit to boot from the PROM image. 8.1 LEX RCMD_REQUEST - Reboot LAN Extension Interface Unit Figure 11 shows a frame format summary of a LEX_RCMD_REQUEST packet for a Reboot LAN Extension Interface Unit remote command option. The host router transmits the fields from left to right. Figure 11 LEX_RCMD_REQUEST Packet Frame Format - Reboot LAN Extension Interface Unit 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 Options
<-------------------------------------------------------------->
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 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 12 provides a summary of these fields
when sending a LEX_RCMD_REQUEST packet that instructs the LAN
extension interface unit to reboot.
Table 12 Field Values for LEX_RCMD_REQUEST Packet -
Reboot LAN Extension Interface Unit
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 0x06 (Reboot LAN Extension Interface Unit)
Option-Flags Valid values:
* 0x00 - Reboot from Flash image if it
exists. If not, reboot from PROM. (This
value does not force the LAN extension
interface unit to reboot from PROM.)
* 0x01 - Reboot from PROM explicitly.
Option-Length 4 octets
Option-Data None
8.2 Response Packets - Reboot LAN Extension Interface Unit
LEX_RCMD_ACK, LEX_RCMD_NAK, and LEX_RCMD-REJ packets are valid
responses to the Reboot LAN Extension Interface Unit LEX_RCMD_REQUEST
packet. 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 each of these response packets. Note
that the LAN extension interface unit reboots after sending the
LEX_RCMD_ACK packet.
The frame format for the response packets mirrors that of the
request. Table 13 summarizes the field values for Reboot LAN
Extension Interface Unit LEX_RCMD_ACK, LEX_RCMD_NAK, and LEX_RCMD_REJ
packets.
Table 13 Field Values for Response Packets -
Reboot LAN Extension Interface Unit
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 in the
LEX_RCMD_REQUEST packet
Length 12 octets
Option-Type 0x06 (Reboot LAN Extension Interface Unit)
Option-Flags Valid values:
* 0x00 - Reboot from Flash image if it
exists. If not, reboot from PROM. (This
value does not force the LAN extension
interface unit to reboot from PROM.)
* 0x01 - Reboot from PROM explicitly.
Option-Length 4 octets
Option-Data None
9.0 Request Statistics
The host router issues a LEX_RCMD_REQUEST packet with an Option-Type
of 0x07 to obtain statistics information from the LAN extension
interface unit. The host router may want statistics information about
the following:
* Serial interface only
* LAN interface only
* Both the serial and LAN interfaces
The host router may also send a Statistics Request LEX_RCMD_REQUEST
packet to reset statistics in the LAN extension interface unit.
9.1 LEX RCMD_REQUEST - Request Statistics
Figure 12 shows a summary frame format of a LEX_RCMD_REQUEST packet
for a Statistics Request remote command option. The host router
transmits the fields from left to right.
Figure 12 LEX_RCMD_REQUEST Packet Frame Format - Request Statistics
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 1 2 3 4 5 6 7 8 9 0 1 2
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Option-Type | Option-Flags | Option-Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
(1) (1) (2)
Summary Field Descriptions
For 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 14 provides a summary of these fields
when sending a LEX_RCMD_REQUEST packet that requests statistics of
the LAN extension interface unit.
Table 14 Field Values for LEX_RCMD_REQUEST Packet -
Request Statistics
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 0x07 (Request Statistics)
Option-Flags Valid values:
* 0x01 - Resets serial statistics in the LAN
extension interface unit
* 0x02 - Returns serial statistics from the
LAN extension interface unit
* 0x04 - Returns LAN statistics from the LAN
extension interface unit
* 0x08 - Resets LAN statistics in the LAN
* extension interface unit
If both serial and LAN statistics are
desired, the corresponding bits of this
field should be set (that is, 0x06). The
serial interface statistics appear in the
response packet before the LAN statistics.
Option-Length 4 octets
Option-Data None
9.2 LEX RCMD_ACK - Request Statistics
The normal response to a Statistics Request LEX_RCMD_REQUEST packet
is a LEX_RCMD_ACK packet. This acknowledgment packet has an Option-
Type, an Option-Flags, and an Option-Length field followed by one or
two blocks of statistics data. The value in the Option-Flags field
indicates whether the packet has one or two blocks of statistics. For
more information on these values, see the following "Summary Field
Descriptions" section.
The frame format for the Statistics Request LEX_RCMD_ACK packet
follows. The LAN extension interface unit transmits the fields from
left to right.
Figure 13 LEX_RCMD_ACK Packet Frame Format - Request Statistics
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 Options
<--------------------------------
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 fields contains one or both of the following
statistics blocks:
Serial Interface Statistics Block:
(32 bits)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Serial Line Input, Number of Packets Received |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Serial Line Input, Number of CRC Erros |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Serial Line Input, Number of Framing Errors |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Serial Line Input, Number of Overruns |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Serial Line Input, Number of Packets Dropped |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Serial Line Input, Number of Frame Aborts |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Serial Line Input, Number of Packets in Error |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Serial Line Input, Number of Packets Dropped Due to Lack of |
| Buffer Descriptors |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Serial Line Input, Time of Last Packet Received |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Serial Line Input, Average Data Rate |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Serial Line Input, Average Packet Rate |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Serial Line Input, Number of Octets Received |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Serial Line Input, Number of Packets Dropped Due to No Buffers|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Serial Line Output, Number of Packets Transmitted | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Serial Line Output, Number of Packets with Error Transmissions| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Serial Line Output, Number of Under-run Errors | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Serial Line Output, Number of Packets in Low Priority Queue | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Serial Line Output, Size of Low Priority Queue | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Serial Line Output, Number of Packets Dropped in Low Priority | | Queue | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Serial Line Output, Number of Packets in Normal Priority Queue| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Serial Line Output, Size of Normal Priority Queue | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Serial Line Output, Number of Packets Dropped in Normal | | Priority Queue | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Serial Line Output, Number of Packets in Medium Priority Queue| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Serial Line Output, Size of Medium Priority Queue | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Serial Line Output, Number of Packets Dropped in | | Medium Priority Queue | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Serial Line Output, Number of Packets in High Priority Queue | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Serial Line Output, Size of High Priority Queue | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Serial Line Output, Number of Packets Dropped in High | | Priority Queue | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Serial Line Output, Time of Last Packet Transmitted | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Serial Line Output, Number of Carrier Transitions | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Serial Line Output, Transmitted Data Rate | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Serial Line Output, Number of Octets Transmitted | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Lan Interface Statistics Block:
(32 bits)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LAN Input, Number of Packets Received |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LAN Input, Number of Packets Received with CRC Errors |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LAN Input, Number of Packets Received with Framing Errors |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LAN Input, Number of Overruns |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LAN Input, Number of Packets Dropped Due to Congestion |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LAN Input, Number of Frame Aborts |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LAN Input, Number of Broadcast Packets Received |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LAN Input, Number of Packets Received with Errors |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LAN Input, Number of Packets Dropped Due to Lack of Buffer |
| Descriptors |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LAN Input, Number of Runts (Too Small Packets) Received |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LAN Input, Time of Last Packet Received |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LAN Input, Average Data Rate |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LAN Input, Average Packet Rate |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LAN Input, Number of Octets Received |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LAN Input, Number of Packets Dropped Due to Lack of Buffers |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LAN Output, Number of Packets Transmitted |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LAN Output, Number of Packets Transmitted with Errors |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LAN Output, Number of Under-runs |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LAN Output, Number of Collisions (Ethernet) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LAN Output, Number of Packets in Queue |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LAN Output, Queue Size | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | LAN Output, Number of Packets Dropped in Queue | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | LAN Output, Time of Last Packet Transmitted | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | LAN Output, Transmit Data Rate | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | LAN Output, Transmit Packet Rate | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | LAN Output, Number of Octets Transmitted | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | LAN, Number of Interface Resets | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Note: Counts are cumulative since last counter reset. Time stamps are in milliseconds since last given event. Packet rates are in packets per second (averaged). Summary Field Descriptions For complete descriptions of the fields in the PPP Header, the LAN Extension Protocol Header, and the LAN Extension Remote Command Option, refer to the "Remote Command Options" section earlier in this document. The following table provides a summary of these fields for a LEX_RCMD_ACK packet that sends statistics to the host router. Table 15 Field Values for LEX_RCMD_ACK Packet - Request Statistics 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 Minimum length = 120 octets Maximum length = 140 octets Option-Type 0x07 (Request Statistics) Option-Flags The LAN extension interface unit always sets this field to reflect the actions taken in response to the LEX_RCMD_ACK packet. Valid values: * 0x01 - Reset serial statistics in the LAN extension interface unit * 0x02 - Return serial statistics from the LAN extension interface unit * 0x04 - Return LAN statistics from the LAN
extension interface unit
* 0x08 - Reset LAN statistics in the LAN
extension interface unit
If both serial and LAN statistics are
returned, the corresponding bits of this
field should are set (that is, 0x06). The
serial interface statistics appear in the
response packet before the LAN statistics.
Option-Length Minimum length = 116 octets
Maximum length = 136 octets
Option-Data The Serial Interface Statistics Block, the
LAN Interface Statistics Block, or both the
Serial Interface and LAN Interface
Statistics blocks. When the Option-Data
contains both blocks, the Serial Interface
Block precedes the LAN Interface Block.
Statistics values that the LAN extension
interface unit does not collect/support
are retuned with a value of zero.
Implementation Notes
If the LAN extension interface unit does not implement the capability
of sending the serial and LAN interface statistics blocks separately,
the implementation may always return both statistics blocks (with the
Option-Flags and Option-Length fields containing the appropriate
corresponding values).
An implementation, such as a Token Ring LAN implementation, can
collect a different set of statistics than shown above by defining a
new statistics request type remote command option.
9.3 LEX RCMD_NAK/LEX RCMD_REJ - Request Statistics
The LAN extension interface unit sends a LEX_RCMD_NAK packet when the
Statistics Request LEX_RCMD_REQUEST packet did not specify the type
of statistics the host router wants. That is, the request's Option-
Flags field equals zero.
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 Request Statistics LEX_RCMD_REJ packet.
The frame format for the LEX_RCMD_NAK and LEX_RCMD_REJ packets is the
same as that of the Statistics Request LEX_RCMD_REQUEST packet. Table
16 summarizes the appropriate field values for the Statistics Request
LEX_RCMD_NAK and LEX_RCMD_REJ packets.
Table 16 Field Values for LEX_RCMD_NAK/LEX_RCMD_REJ Packets -
Request Statistics
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 0x07 (Request Statistics)
Option-Flags The same value as that sent by the
LEX_RCMD_REQUEST packet
Option-Length 4 octets
Option-Data None
(page 45 continued on part 3)