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.