BPDU

Bridge Protocol Data Unit(BPDU, IEEE 802.1D) parser/serializer http://standards.ieee.org/getieee802/download/802.1D-2004.pdf

Configuration BPDUs format

Structure

Octet

Protocol Identifier = 0000 0000 0000 0000

1 - 2

Protocol Version Identifier = 0000 0000

3

BPDU Type = 0000 0000

4

Flags

5
Root Identifier
include - priority

system ID extension MAC address

6 - 13

Root Path Cost

14 - 17
Bridge Identifier
include - priority

system ID extension MAC address

18 - 25
Port Identifier
include - priority

port number

26 - 27

Message Age

28 - 29

Max Age

30 - 31

Hello Time

32 - 33

Forward Delay

34 - 35

Topology Change NotificationBPDUs format

Structure

Octet

Protocol Identifier = 0000 0000 0000 0000

1 - 2

Protocol Version Identifier = 0000 0000

3

BPDU Type = 1000 0000

4

Rapid Spanning Tree BPDUs(RST BPDUs) format

Structure

Octet

Protocol Identifier = 0000 0000 0000 0000

1 - 2

Protocol Version Identifier = 0000 0010

3

BPDU Type = 0000 0010

4

Flags

5
Root Identifier
include - priority

system ID extension MAC address

6 - 13

Root Path Cost

14 - 17
Bridge Identifier
include - priority

system ID extension MAC address

18 - 25
Port Identifier
include - priority

port number

26 - 27

Message Age

28 - 29

Max Age

30 - 31

Hello Time

32 - 33

Forward Delay

34 - 35

Version 1 Length = 0000 0000

36
class os_ken.lib.packet.bpdu.ConfigurationBPDUs(flags=0, root_priority=32768, root_system_id_extension=0, root_mac_address='00:00:00:00:00:00', root_path_cost=0, bridge_priority=32768, bridge_system_id_extension=0, bridge_mac_address='00:00:00:00:00:00', port_priority=128, port_number=0, message_age=0, max_age=20, hello_time=2, forward_delay=15)

Configuration BPDUs(IEEE 802.1D) header encoder/decoder class.

An instance has the following attributes at least. Most of them are same to the on-wire counterparts but in host byte order. __init__ takes the corresponding args in this order.

Attribute

Description

flags
Bit 1: Topology Change flag
Bits 2 through 7: unused and take the value 0
Bit 8: Topology Change Acknowledgment flag

root_priority

Root Identifier priority set 0-61440 in steps of 4096

root_system_id_extension

Root Identifier system ID extension

root_mac_address

Root Identifier MAC address

root_path_cost

Root Path Cost

bridge_priority

Bridge Identifier priority set 0-61440 in steps of 4096

bridge_system_id_extension

Bridge Identifier system ID extension

bridge_mac_address

Bridge Identifier MAC address

port_priority

Port Identifier priority set 0-240 in steps of 16

port_number

Port Identifier number

message_age

Message Age timer value

max_age

Max Age timer value

hello_time

Hello Time timer value

forward_delay

Forward Delay timer value
classmethod parser(buf)

Decode a protocol header.

This method is used only when decoding a packet.

Decode a protocol header at offset 0 in bytearray buf. Returns the following three objects.

  • An object to describe the decoded header.

  • A packet_base.PacketBase subclass appropriate for the rest of the packet. None when the rest of the packet should be considered as raw payload.

  • The rest of packet.

serialize(payload, prev)

Encode a protocol header.

This method is used only when encoding a packet.

Encode a protocol header. Returns a bytearray which contains the header.

payload is the rest of the packet which will immediately follow this header.

prev is a packet_base.PacketBase subclass for the outer protocol header. prev is None if the current header is the outer-most. For example, prev is ipv4 or ipv6 for tcp.serialize.

class os_ken.lib.packet.bpdu.RstBPDUs(flags=0, root_priority=32768, root_system_id_extension=0, root_mac_address='00:00:00:00:00:00', root_path_cost=0, bridge_priority=32768, bridge_system_id_extension=0, bridge_mac_address='00:00:00:00:00:00', port_priority=128, port_number=0, message_age=0, max_age=20, hello_time=2, forward_delay=15)

Rapid Spanning Tree BPDUs(RST BPDUs, IEEE 802.1D) header encoder/decoder class.

An instance has the following attributes at least. Most of them are same to the on-wire counterparts but in host byte order. __init__ takes the corresponding args in this order.

Attribute

Description

flags
Bit 1: Topology Change flag
Bit 2: Proposal flag
Bits 3 and 4: Port Role
Bit 5: Learning flag
Bit 6: Forwarding flag
Bit 7: Agreement flag
Bit 8: Topology Change Acknowledgment flag

root_priority

Root Identifier priority set 0-61440 in steps of 4096

root_system_id_extension

Root Identifier system ID extension

root_mac_address

Root Identifier MAC address

root_path_cost

Root Path Cost

bridge_priority

Bridge Identifier priority set 0-61440 in steps of 4096

bridge_system_id_extension

Bridge Identifier system ID extension

bridge_mac_address

Bridge Identifier MAC address

port_priority

Port Identifier priority set 0-240 in steps of 16

port_number

Port Identifier number

message_age

Message Age timer value

max_age

Max Age timer value

hello_time

Hello Time timer value

forward_delay

Forward Delay timer value
classmethod parser(buf)

Decode a protocol header.

This method is used only when decoding a packet.

Decode a protocol header at offset 0 in bytearray buf. Returns the following three objects.

  • An object to describe the decoded header.

  • A packet_base.PacketBase subclass appropriate for the rest of the packet. None when the rest of the packet should be considered as raw payload.

  • The rest of packet.

serialize(payload, prev)

Encode a protocol header.

This method is used only when encoding a packet.

Encode a protocol header. Returns a bytearray which contains the header.

payload is the rest of the packet which will immediately follow this header.

prev is a packet_base.PacketBase subclass for the outer protocol header. prev is None if the current header is the outer-most. For example, prev is ipv4 or ipv6 for tcp.serialize.

class os_ken.lib.packet.bpdu.TopologyChangeNotificationBPDUs

Topology Change Notification BPDUs(IEEE 802.1D) header encoder/decoder class.

classmethod parser(buf)

Decode a protocol header.

This method is used only when decoding a packet.

Decode a protocol header at offset 0 in bytearray buf. Returns the following three objects.

  • An object to describe the decoded header.

  • A packet_base.PacketBase subclass appropriate for the rest of the packet. None when the rest of the packet should be considered as raw payload.

  • The rest of packet.

class os_ken.lib.packet.bpdu.bpdu

Bridge Protocol Data Unit(BPDU) header encoder/decoder base class.

classmethod parser(buf)

Decode a protocol header.

This method is used only when decoding a packet.

Decode a protocol header at offset 0 in bytearray buf. Returns the following three objects.

  • An object to describe the decoded header.

  • A packet_base.PacketBase subclass appropriate for the rest of the packet. None when the rest of the packet should be considered as raw payload.

  • The rest of packet.

serialize(payload, prev)

Encode a protocol header.

This method is used only when encoding a packet.

Encode a protocol header. Returns a bytearray which contains the header.

payload is the rest of the packet which will immediately follow this header.

prev is a packet_base.PacketBase subclass for the outer protocol header. prev is None if the current header is the outer-most. For example, prev is ipv4 or ipv6 for tcp.serialize.