diff --git a/openapi/nexus.json b/openapi/nexus.json
index 9e46a92039..a4baa8124f 100644
--- a/openapi/nexus.json
+++ b/openapi/nexus.json
@@ -19797,12 +19797,23 @@
       },
       "Units": {
         "description": "Measurement units for timeseries samples.",
-        "type": "string",
-        "enum": [
-          "count",
-          "bytes",
-          "seconds",
-          "nanoseconds"
+        "oneOf": [
+          {
+            "type": "string",
+            "enum": [
+              "count",
+              "bytes",
+              "seconds",
+              "nanoseconds"
+            ]
+          },
+          {
+            "description": "No meaningful units, e.g. a dimensionless quanity.",
+            "type": "string",
+            "enum": [
+              "none"
+            ]
+          }
         ]
       },
       "User": {
diff --git a/oximeter/impl/src/schema/codegen.rs b/oximeter/impl/src/schema/codegen.rs
index cde67439de..ef686c3cdd 100644
--- a/oximeter/impl/src/schema/codegen.rs
+++ b/oximeter/impl/src/schema/codegen.rs
@@ -515,6 +515,7 @@ fn quote_creation_time(created: DateTime<Utc>) -> TokenStream {
 impl quote::ToTokens for Units {
     fn to_tokens(&self, tokens: &mut TokenStream) {
         let toks = match self {
+            Units::None => quote! { ::oximeter::schema::Units::None },
             Units::Count => quote! { ::oximeter::schema::Units::Count },
             Units::Bytes => quote! { ::oximeter::schema::Units::Bytes },
             Units::Seconds => quote! { ::oximeter::schema::Units::Seconds },
diff --git a/oximeter/impl/src/schema/mod.rs b/oximeter/impl/src/schema/mod.rs
index 83a83e95b2..7743034e31 100644
--- a/oximeter/impl/src/schema/mod.rs
+++ b/oximeter/impl/src/schema/mod.rs
@@ -183,6 +183,8 @@ pub struct TimeseriesDescription {
 // TODO-completeness: Decide whether and how to handle dimensional analysis
 // during queries, if needed.
 pub enum Units {
+    /// No meaningful units, e.g. a dimensionless quanity.
+    None,
     Count,
     Bytes,
     Seconds,
diff --git a/oximeter/oximeter/schema/switch-data-link.toml b/oximeter/oximeter/schema/switch-data-link.toml
new file mode 100644
index 0000000000..fa10759ca9
--- /dev/null
+++ b/oximeter/oximeter/schema/switch-data-link.toml
@@ -0,0 +1,213 @@
+format_version = 1
+
+[target]
+name = "switch_data_link"
+description = "A network data link on an Oxide switch"
+authz_scope = "fleet"
+versions = [
+    { version = 1, fields = [ "rack_id", "sled_id", "sled_model", "sled_revision", "sled_serial", "switch_id", "switch_model", "switch_revision", "switch_serial" ] },
+]
+
+[[metrics]]
+name = "bytes_sent"
+description = "Total number of bytes sent on the data link"
+units = "bytes"
+datum_type = "cumulative_u64"
+versions = [
+    { added_in = 1, fields = [ "port_id", "link_id" ] }
+]
+
+[[metrics]]
+name = "bytes_received"
+description = "Total number of bytes received on the data link"
+units = "bytes"
+datum_type = "cumulative_u64"
+versions = [
+    { added_in = 1, fields = [ "port_id", "link_id" ] }
+]
+
+[[metrics]]
+name = "errors_sent"
+description = "Total number of errors when sending on the data link"
+units = "count"
+datum_type = "cumulative_u64"
+versions = [
+    { added_in = 1, fields = [ "port_id", "link_id" ] }
+]
+
+[[metrics]]
+name = "errors_received"
+description = "Total number of packets for the data link dropped due to any error"
+units = "count"
+datum_type = "cumulative_u64"
+versions = [
+    { added_in = 1, fields = [ "port_id", "link_id" ] }
+]
+
+[[metrics]]
+name = "receive_crc_error_drops"
+description = "Total number of packets for the data link dropped due to CRC errors"
+units = "count"
+datum_type = "cumulative_u64"
+versions = [
+    { added_in = 1, fields = [ "port_id", "link_id" ] }
+]
+
+[[metrics]]
+name = "receive_buffer_full_drops"
+description = "Total number of packets for the data link dropped due to ASIC buffer congestion"
+units = "count"
+datum_type = "cumulative_u64"
+versions = [
+    { added_in = 1, fields = [ "port_id", "link_id" ] }
+]
+
+[[metrics]]
+name = "packets_sent"
+description = "Total number of packets sent on the data link"
+units = "count"
+datum_type = "cumulative_u64"
+versions = [
+    { added_in = 1, fields = [ "port_id", "link_id" ] }
+]
+
+[[metrics]]
+name = "packets_received"
+description = "Total number of packets received on the data link"
+units = "count"
+datum_type = "cumulative_u64"
+versions = [
+    { added_in = 1, fields = [ "port_id", "link_id" ] }
+]
+
+[[metrics]]
+name = "link_up"
+description = "Reports whether the link is currently up"
+units = "none"
+datum_type = "bool"
+versions = [
+    { added_in = 1, fields = [ "port_id", "link_id" ] }
+]
+
+[[metrics]]
+name = "link_fsm"
+description = """\
+Total entries into each state of the autonegotation / \
+link-training finite state machine\
+"""
+units = "count"
+datum_type = "cumulative_u64"
+versions = [
+    { added_in = 1, fields = [ "port_id", "link_id", "state" ] }
+]
+
+[[metrics]]
+name = "pcs_bad_sync_headers"
+description = "Total number of bad PCS sync headers on the data link"
+units = "count"
+datum_type = "cumulative_u64"
+versions = [
+    { added_in = 1, fields = [ "port_id", "link_id" ] }
+]
+
+[[metrics]]
+name = "pcs_errored_blocks"
+description = "Total number of PCS error blocks on the data link"
+units = "count"
+datum_type = "cumulative_u64"
+versions = [
+    { added_in = 1, fields = [ "port_id", "link_id" ] }
+]
+
+[[metrics]]
+name = "pcs_block_lock_loss"
+description = "Total number of detected losses of block-lock on the data link"
+units = "count"
+datum_type = "cumulative_u64"
+versions = [
+    { added_in = 1, fields = [ "port_id", "link_id" ] }
+]
+
+[[metrics]]
+name = "pcs_high_ber"
+description = "Total number of high bit-error-rate events on the data link"
+units = "count"
+datum_type = "cumulative_u64"
+versions = [
+    { added_in = 1, fields = [ "port_id", "link_id" ] }
+]
+
+[[metrics]]
+name = "pcs_valid_errors"
+description = "Total number of valid error events on the data link"
+units = "count"
+datum_type = "cumulative_u64"
+versions = [
+    { added_in = 1, fields = [ "port_id", "link_id" ] }
+]
+
+[[metrics]]
+name = "pcs_invalid_errors"
+description = "Total number of invalid error events on the data link"
+units = "count"
+datum_type = "cumulative_u64"
+versions = [
+    { added_in = 1, fields = [ "port_id", "link_id" ] }
+]
+
+[[metrics]]
+name = "pcs_unknown_errors"
+description = "Total number of unknown error events on the data link"
+units = "count"
+datum_type = "cumulative_u64"
+versions = [
+    { added_in = 1, fields = [ "port_id", "link_id" ] }
+]
+
+[fields.rack_id]
+type = "uuid"
+description = "ID of the rack the link's switch is in"
+
+[fields.sled_id]
+type = "uuid"
+description = "ID of the sled managing the link's switch"
+
+[fields.sled_model]
+type = "string"
+description = "Model number of the sled managing the link's switch"
+
+[fields.sled_revision]
+type = "u32"
+description = "Revision number of the sled managing the link's switch"
+
+[fields.sled_serial]
+type = "string"
+description = "Serial number of the sled managing the link's switch"
+
+[fields.switch_id]
+type = "uuid"
+description = "ID of the switch the link is on"
+
+[fields.switch_model]
+type = "string"
+description = "The model number switch the link is on"
+
+[fields.switch_revision]
+type = "u32"
+description = "Revision number of the switch the link is on"
+
+[fields.switch_serial]
+type = "string"
+description = "Serial number of the switch the link is on"
+
+[fields.port_id]
+type = "string"
+description = "Physical switch port the link is on"
+
+[fields.link_id]
+type = "u8"
+description = "ID of the link within its switch port"
+
+[fields.state]
+type = "string"
+description = "Name of the data link FSM state"