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Add 16-bit Sink Indication field to INT header #57

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Add 16-bit Sink Indication field to INT header #57

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48 changes: 36 additions & 12 deletions telemetry/specs/INT.mdk
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Original file line number Diff line number Diff line change
Expand Up @@ -757,9 +757,9 @@ INT Metadata Header and Metadata Stack:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Ver |Rep|C|E|M| Reserved | Hop ML |RemainingHopCnt|
| Ver |Rep|C|E|M|S| Reserved | Hop ML |RemainingHopCnt|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Instruction Bitmap | Reserved |
| Instruction Bitmap | Sink Indication |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| INT Metadata Stack (Each hop inserts Hop ML * 4B of metadata) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Expand Down Expand Up @@ -821,7 +821,11 @@ The original packet must have C bit set to 0.
switch(es) set the M bit based on knowledge of the network topology
and "Switch ID, Ingress port ID, Egress port ID" tuples in the INT
metadata stack.
- R: Reserved bits.
- S (1b): Sink Indication Present
- When set, this flag indicates that the Sink Indication field has been set
by the source and should be updated by transit switches.
- R: Reserved bits. Must be set to zero upon transmission and ignored upon
reception.
- Hop ML (5b): Per-hop Metadata Length, the length of metadata in 4-Byte words
to be inserted at each INT hop.
- While the largest value of Per-hop Metadata Length is 31, an INT-capable
Expand All @@ -844,6 +848,24 @@ The original packet must have C bit set to 0.
- When a packet is received with the Remaining Hop Count equal to 0, the
device must ignore the INT instruction, pushing no new metadata onto
the stack, and the device must set the E bit.
- Sink Indication (16b): This field is used by the source and transit switches
as an indication to the sink switch.
- While INT allows network state to be collected on a per packet basis,
for many packets the network state may not differ significantly from the
state collected in previous packets belonging to the same flow. The sink
may choose to report only a subset of packets, or it may choose to
aggregate the collected network state.
- The Sink Indication allows the source and transit switches to notify the
sink switch about the collected network state in a concise manner. This
lets the sink switch look at only one field when deciding how to process
the telemetry information from the packet, without having to scrape over
each field added at each hop, just to decide whether and how to process
the collected network state.
- The Sink Indication is initially set by the source switch, and is updated
by each transit switch, taking into account the received value as well as
the local state added by that transit switch.
- When the S bit is set to zero, the Sink Indication must be set to zero at
the source and ignored at transit and sink switches.
* INT instructions are encoded as a bitmap in the 16-bit INT Instruction field:
each bit corresponds to a specific standard metadata as specified in Section 3.
- bit0 (MSB): Switch ID
Expand Down Expand Up @@ -937,6 +959,7 @@ port ID)
- C = 0
- E = 0 (Max Hop Count not exceeded)
- M = 0 (MTU not exceeded at any switch)
- S = 0 (Sink Indication is not used)
- Per-hop Metadata Length = 2 (for switch id & queue occupancy)
- Remaining hop count starts at 8, decremented by 1 at each hop
that inserts INT metadata
Expand Down Expand Up @@ -1003,7 +1026,7 @@ INT Metadata Header and Metadata Stack, followed by TCP payload:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Ver=1 | 0 |0|0|0| Reserved | HopML=2 |RemainingHopC=6|
| Ver=1 | 0 |0|0|0|0| Reserved | HopML=2 |RemainingHopC=6|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|1 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0| Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Expand Down Expand Up @@ -1058,7 +1081,7 @@ INT Metadata Header and Metadata Stack:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Ver=1 | 0 |0|0|0| Reserved | HopML=2 |RemainingHopC=5|
| Ver=1 | 0 |0|0|0|0| Reserved | HopML=2 |RemainingHopC=5|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|1 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0| Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Expand Down Expand Up @@ -1115,7 +1138,7 @@ INT Metadata Header and Metadata Stack:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Ver=1 | 0 |0|0|0| Reserved | HopML=2 |RemainingHopC=5|
| Ver=1 | 0 |0|0|0|0| Reserved | HopML=2 |RemainingHopC=5|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|1 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0| Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Expand Down Expand Up @@ -1172,15 +1195,16 @@ header int_header_t {
bit<1> c;
bit<1> e;
bit<1> m;
bit<7> rsvd1;
bit<1> s;
bit<6> rsvd1;
bit<3> rsvd2;
bit<5> hop_metadata_len;
bit<8> remaining_hop_cnt;
bit<4> instruction_mask_0003;
bit<4> instruction_mask_0407;
bit<4> instruction_mask_0811;
bit<4> instruction_mask_1215;
bit<16> rsvd3;
bit<16> sink_indication;
}

/* INT meta-value headers - different header for each value type */
Expand Down Expand Up @@ -1497,14 +1521,14 @@ parser EgressParserImpl(packet_in packet,
ck.subtract({
hdr.int_header.ver, hdr.int_header.rep,
hdr.int_header.c, hdr.int_header.e,
hdr.int_header.m, hdr.int_header.rsvd1,
hdr.int_header.m, hdr.int_header.s, hdr.int_header.rsvd1,
hdr.int_header.rsvd2, hdr.int_header.hop_metadata_len,
hdr.int_header.remaining_hop_cnt,
hdr.int_header.instruction_mask_0003,
hdr.int_header.instruction_mask_0407,
hdr.int_header.instruction_mask_0811,
hdr.int_header.instruction_mask_1215,
hdr.int_header.rsvd3
hdr.int_header.sink_indication
});
meta.fwd_metadata.checksum_state = ck.get_state();
transition accept;
Expand Down Expand Up @@ -1559,14 +1583,14 @@ control EgressDeparserImpl(packet_out packet,
ck.add({
hdr.int_header.ver, hdr.int_header.rep,
hdr.int_header.c, hdr.int_header.e,
hdr.int_header.m, hdr.int_header.rsvd1,
hdr.int_header.m, hdr.int_header.s, hdr.int_header.rsvd1,
hdr.int_header.rsvd2, hdr.int_header.hop_metadata_len,
hdr.int_header.remaining_hop_cnt,
hdr.int_header.instruction_mask_0003,
hdr.int_header.instruction_mask_0407,
hdr.int_header.instruction_mask_0811,
hdr.int_header.instruction_mask_1215,
hdr.int_header.rsvd3
hdr.int_header.sink_indication
});
}

Expand Down