- Direct Known Subclasses:
- GeneralizedLabelEROSubobject, OBSMAINSLabelEROSubobject, WavebandLabelEROSubobject
public abstract class LabelEROSubobject
extends EROSubobject
Label ERO Subobject (RFC 4373).
From RFC 3473:(section 5.1) FIXME COMPLETAR
5.1. Label ERO subobject
The Label ERO subobject is defined as follows:
0 1 2 3
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|L| Type | Length |U| Reserved | C-Type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Label |
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
See [RFC3471] for a description of L, U and Label parameters.
Type
3 Label
Length
The Length contains the total length of the subobject in bytes,
including the Type and Length fields. The Length is always
divisible by 4.
C-Type
The C-Type of the included Label Object. Copied from the Label
Object.
BUSCANDO:
Generalized abeC-Type (2)
Waveband Label uses C-Type (3)
5.1.1. Procedures
The Label subobject follows a subobject containing the IP address, or
the interface identifier [RFC3477], associated with the link on which
it is to be used. Up to two label subobjects may be present, one for
the downstream label and one for the upstream label. The following
SHOULD result in "Bad EXPLICIT_ROUTE object" errors:
o If the first label subobject is not preceded by a subobject
containing an IP address, or an interface identifier [RFC3477],
associated with an output link.
o For a label subobject to follow a subobject that has the L-bit set
o On unidirectional LSP setup, for there to be a label subobject with
the U-bit set
o For there to be two label subobjects with the same U-bit values
To support the label subobject, a node must check to see if the
subobject following its associate address/interface is a label
subobject. If it is, one subobject is examined for unidirectional
LSPs and two subobjects for bidirectional LSPs. If the U-bit of the
subobject being examined is clear (0), then value of the label is
copied into a new Label_Set object. This Label_Set object MUST be
included on the corresponding outgoing Path message.
If the U-bit of the subobject being examined is set (1), then value
of the label is label to be used for upstream traffic associated with
the bidirectional LSP. If this label is not acceptable, a "Bad
EXPLICIT_ROUTE object" error SHOULD be generated. If the label is
acceptable, the label is copied into a new Upstream_Label object.
This Upstream_Label object MUST be included on the corresponding
outgoing Path message.
After processing, the label subobjects are removed from the ERO.
Note an implication of the above procedures is that the label
subobject should never be the first subobject in a newly received
message. If the label subobject is the the first subobject an a
received ERO, then it SHOULD be treated as a "Bad strict node" error.
Procedures by which an LSR at the head-end of an LSP obtains the
information needed to construct the Label subobject are outside the
scope of this document.
- Author:
- Oscar Gonzalez de Dios