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Label_Set and Channel_Set in draft-ietf-ccamp-gmpls-dcsc-channel-ext-01.txt
One question about a Label_Set containing Channel_Set labels:
Let's consider the following LABEL_SET object. Labels are assumed to
be two bytes Generalized labels (type 2) - such as the EVPL Generalized
Label format defined in draft-ietf-ccamp-gmpls-ether-svcs-03.txt.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Length | Class-Num (36)| C-Type (1) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Action(0) | Reserved | Label Type(4) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Action(2) |Num Subchannels(2) | Label Type(2) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Subchannel 1(100) | Subchannel 2(200) |
|-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Action(2) |Num Subchannels(2) | Label Type(2) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Subchannel 1(300) | Subchannel 2(400) |
|-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
I can see two different interpretation of this LABEL_SET:
1. This LABEL_SET specifies a single subchannel, which uses the format
of a Channel_Set label.The Channel_Set label consists of two ranges:
100..200 and 300..400. The purpose of this LABEL_SET would be to force
the downstream node to send back a LABEL object that consists of range
100..200 AND range 300..400.
2. This LABEL_SET specifies two subchannels, both using the format of a
Channel_Set label. The first channel is the range 100..200; the second
one is the range 300..400. The purpose of this LABEL_SET would be to
force the downstream node to send back a LABEL object that consists
either of range 100..200 OR range 300..400
Which interpretation is the correct one? am I misunderstanding something?
One way to remove the ambiguity would be to consider that the
LABEL_SET object can contain only one Channel_Set label (case 1 is then
the correct interpretation). And it would be possible (if needed) to
handle case 2 by using two LABEL_SET objects in a Path message.
Rémi