MPLS

os_ken.lib.packet.mpls.label_from_bin(buf)

Converts binary representation label to integer.

Parameters

buf -- Binary representation of label.

Returns

MPLS Label and BoS bit.

os_ken.lib.packet.mpls.label_to_bin(mpls_label, is_bos=True)

Converts integer label to binary representation.

Parameters

• mpls_label -- MPLS Label.

• is_bos -- BoS bit.

Returns

Binary representation of label.

class os_ken.lib.packet.mpls.mpls(label=0, exp=0, bsb=1, ttl=255)

MPLS (RFC 3032) header encoder/decoder class.

NOTE: When decoding, this implementation assumes that the inner protocol is IPv4.

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
label	Label Value
exp	Experimental Use
bsb	Bottom of Stack
ttl	Time To Live

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.