diff --git a/README.md b/README.md
index ee782d2..4ad7a8b 100644
--- a/README.md
+++ b/README.md
@@ -4,5 +4,23 @@ not sure how far I will take this but messing around with E1.17 ACN protocol
 ## areas
 - rlp
 - sdt
+  - vectors    
+    - [x] JOIN
+    - [x] JOIN_REFUSE
+    - [x] JOIN_ACCEPT
+    - [x] LEAVING
+    - [x] NAK
+    - [x] REL_WRAP
+    - [x] UNREL_WRAP
+    - [x] GET_SESSIONS
+    - [ ] SESSIONS
+    - [x] ACK
+    - [ ] CHANNEL_PARAMS
+    - [ ] LEAVE
+    - [x] CONNECT
+    - [x] CONNECT_ACCEPT
+    - [x] CONNECT_REFUSE
+    - [x] DISCONNECT
+    - [x] DISCONNECTING
 - dmp
 - ddl
diff --git a/packages/acn/src/enums.ts b/packages/acn/src/enums.ts
new file mode 100644
index 0000000..584f966
--- /dev/null
+++ b/packages/acn/src/enums.ts
@@ -0,0 +1,45 @@
+export enum Protocol {
+  SDT = 1,
+}
+
+export enum SDTVector {
+  REL_WRAP = 1,
+  UNREL_WRAP,
+  CHANNEL_PARAMS,
+  JOIN,
+  JOIN_REFUSE,
+  JOIN_ACCEPT,
+  LEAVE,
+  LEAVING,
+  CONNECT,
+  CONNECT_ACCEPT,
+  CONNECT_REFUSE,
+  DISCONNECT,
+  DISCONNECTING,
+  ACK,
+  NAK,
+  GET_SESSIONS,
+  SESSIONS,
+}
+
+export enum TransportLayerAddressType {
+  SDT_ADDR_NULL = 0,
+  SDT_ADDR_IPV4,
+  SDT_ADDR_IPV6,
+}
+
+export enum SDTReasonCode {
+  NONSPECIFIC = 1,
+  ILLEGAL_PARAMETERS,
+  LOW_RESOURCES,
+  ALREADY_MEMBER,
+  BAD_ADDRESS_TYPE,
+  NO_RECIPROCAL_CHANNEL,
+  CHANNEL_EXPIRED,
+  LOST_SEQUENCE,
+  SATURATED,
+  TRANSPORT_ADDRESS_CHANGING,
+  ASKED_TO_LEAVE,
+  NO_RECIPIENT,
+  ONLY_UNICAST_SUPPORTED,
+}
diff --git a/packages/acn/src/index.ts b/packages/acn/src/index.ts
index 6d508cd..a64b562 100644
--- a/packages/acn/src/index.ts
+++ b/packages/acn/src/index.ts
@@ -1,2 +1,2 @@
-export * from './models';
+export * from './types';
 export * from './udp';
diff --git a/packages/acn/src/models.ts b/packages/acn/src/models.ts
deleted file mode 100644
index a339a25..0000000
--- a/packages/acn/src/models.ts
+++ /dev/null
@@ -1,21 +0,0 @@
-export type Protocols = {
-  SDT: 1;
-};
-
-export type UDPPreamble = {
-  preambleSize: number;
-  postambleSize: number;
-  packetIdentifier: string;
-};
-
-export type ACNPacket<PreambleType, PDUBlockType, PostambleType> = {
-  preamble: PreambleType;
-  pduBlock: PDUBlockType;
-  postamble: PostambleType;
-};
-
-export type RootLayerPDU = {
-  vector: number;
-  header: string;
-  data: Uint8Array;
-};
diff --git a/packages/acn/src/pdu/index.ts b/packages/acn/src/pdu/index.ts
index 58670a5..07a880b 100644
--- a/packages/acn/src/pdu/index.ts
+++ b/packages/acn/src/pdu/index.ts
@@ -1,4 +1,6 @@
 import rlp from './rlp';
+import sdt from './sdt';
 export default {
   rlp,
+  sdt,
 };
diff --git a/packages/acn/src/pdu/rlp.ts b/packages/acn/src/pdu/rlp.ts
index bf8e9dc..4c3d132 100644
--- a/packages/acn/src/pdu/rlp.ts
+++ b/packages/acn/src/pdu/rlp.ts
@@ -1,4 +1,6 @@
-import { RootLayerPDU } from '../models';
+import pdu from '.';
+import { Protocol } from '../enums';
+import { RootLayerPDU, SessionDataTransportPDU } from '../types';
 import { toHex } from '../utils';
 
 function decode(bytes: Uint8Array): RootLayerPDU {
@@ -49,7 +51,22 @@ function decode(bytes: Uint8Array): RootLayerPDU {
   const dataOffset = headerOffset + 16;
   // NOTE(jwetzell): flags/lengthH + lengthL + lengthX + vector + header
   const dataLength = length - (1 + 1 + (lengthFlag ? 1 : 0) + 4 + 16);
-  const data = bytes.subarray(dataOffset, dataOffset + dataLength);
+  let data: SessionDataTransportPDU[] | Uint8Array = bytes.subarray(dataOffset, dataOffset + dataLength);
+
+  if (vector === Protocol.SDT) {
+    const blocks: SessionDataTransportPDU[] = [];
+
+    let blockDataOffset = 0;
+    // TODO(jwetzell): this could blow up so might need some attention later?
+    while (blockDataOffset < dataLength) {
+      const blockData = pdu.sdt.decode(bytes.subarray(dataOffset + blockDataOffset));
+      blocks.push(blockData);
+      blockDataOffset += blockData.length;
+    }
+    data = blocks;
+  } else {
+    console.error(`unhandled protocol in RLP: ${vector}`);
+  }
 
   return {
     vector,
diff --git a/packages/acn/src/pdu/sdt.ts b/packages/acn/src/pdu/sdt.ts
new file mode 100644
index 0000000..e87cf7e
--- /dev/null
+++ b/packages/acn/src/pdu/sdt.ts
@@ -0,0 +1,275 @@
+import { Protocol, SDTVector } from '../enums';
+import {
+  SDTAckData,
+  SDTConnectAcceptData,
+  SDTConnectData,
+  SDTConnectRefuseData,
+  SDTDisconnectData,
+  SDTDisconnectingData,
+  SDTGetSessionsData,
+  SDTJoinAcceptData,
+  SDTJoinData,
+  SDTJoinRefuseData,
+  SDTLeavingData,
+  SDTNakData,
+  SDTWrapperData,
+  SessionDataTransportPDU,
+  TransportLayerAddress,
+} from '../types';
+import { toHex } from '../utils';
+
+// TODO(jwetzell): work out flag inheritance, will need previous PDU
+
+export function decode(bytes: Uint8Array): SessionDataTransportPDU {
+  const view = new DataView(bytes.buffer, bytes.byteOffset, bytes.byteLength);
+  const flags = view.getUint8(0) >> 4;
+  const lengthFlag = ((flags >> 3) & 0x1) === 1;
+  const vectorFlag = ((flags >> 2) & 0x1) === 1;
+
+  if (!vectorFlag) {
+    throw new Error('SDT PDU must have a vector');
+  }
+
+  const dataFlag = (flags & 0x1) === 1;
+
+  if (!dataFlag) {
+    // TODO(jwetzell): idk if this is true
+    throw new Error('SDT PDU must have data');
+  }
+
+  const lengthH = view.getUint8(0) & 0x0f;
+  let lengthOffset = 1;
+  const lengthL = view.getUint8(lengthOffset);
+
+  let length = (lengthH << 8) + lengthL;
+  if (lengthFlag) {
+    lengthOffset += 1;
+    const lengthX = view.getUint8(lengthOffset);
+    length = (lengthH << 16) + (lengthL << 8) + lengthX;
+  }
+  let vectorOffset = lengthOffset + 1;
+
+  if (lengthFlag) {
+    vectorOffset += 1;
+  }
+
+  const vector = view.getUint8(vectorOffset);
+
+  const dataOffset = vectorOffset + 1;
+  // NOTE(jwetzell): flags/lengthH + lengthL + lengthX + vector
+  const dataLength = length - (1 + 1 + (lengthFlag ? 1 : 0) + 1);
+  const data = decodeData(vector, bytes.subarray(dataOffset, dataOffset + dataLength));
+
+  return {
+    vector,
+    length,
+    data,
+  };
+}
+
+function decodeClientBlock(bytes: Uint8Array) {
+  if (bytes.byteLength === 0) {
+    return undefined;
+  }
+
+  const view = new DataView(bytes.buffer, bytes.byteOffset, bytes.byteLength);
+  const flags = view.getUint8(0) >> 4;
+  const lengthFlag = ((flags >> 3) & 0x1) === 1;
+  const vectorFlag = ((flags >> 2) & 0x1) === 1;
+
+  if (!vectorFlag) {
+    throw new Error('SDT PDU must have a vector');
+  }
+
+  const dataFlag = (flags & 0x1) === 1;
+
+  if (!dataFlag) {
+    // TODO(jwetzell): idk if this is true
+    throw new Error('SDT PDU must have data');
+  }
+
+  const lengthH = view.getUint8(0) & 0x0f;
+  let lengthOffset = 1;
+  const lengthL = view.getUint8(lengthOffset);
+
+  let length = (lengthH << 8) + lengthL;
+  if (lengthFlag) {
+    lengthOffset += 1;
+    const lengthX = view.getUint8(lengthOffset);
+    length = (lengthH << 16) + (lengthL << 8) + lengthX;
+  }
+  let vectorOffset = lengthOffset + 1;
+
+  if (lengthFlag) {
+    vectorOffset += 1;
+  }
+
+  const memberID = view.getUint16(vectorOffset);
+
+  const headerOffset = vectorOffset + 2;
+  const clientProtocol = view.getUint32(headerOffset);
+  const association = view.getUint16(headerOffset + 4);
+
+  const dataOffset = headerOffset + 6;
+  // NOTE(jwetzell): flags/lengthH + lengthL + lengthX + vector + header
+  const dataLength = length - (1 + 1 + (lengthFlag ? 1 : 0) + 2 + 6);
+  let data: SessionDataTransportPDU | Uint8Array = bytes.subarray(dataOffset, dataOffset + dataLength);
+
+  if (clientProtocol === Protocol.SDT) {
+    data = decode(data);
+  } else {
+    console.error(`SDT client block contains unknown protocol: ${clientProtocol}`);
+  }
+  return {
+    memberID,
+    clientProtocol,
+    association,
+    data,
+  };
+}
+
+function decodeData(
+  vector: SDTVector,
+  bytes: Uint8Array
+):
+  | SDTJoinData
+  | SDTJoinAcceptData
+  | SDTJoinRefuseData
+  | SDTWrapperData
+  | SDTAckData
+  | SDTLeavingData
+  | SDTGetSessionsData
+  | SDTNakData
+  | SDTConnectData
+  | SDTConnectAcceptData
+  | SDTConnectRefuseData
+  | SDTDisconnectData
+  | SDTDisconnectingData
+  | Uint8Array {
+  const view = new DataView(bytes.buffer, bytes.byteOffset, bytes.byteLength);
+  switch (vector) {
+    case SDTVector.JOIN: {
+      const destinationAddress: TransportLayerAddress = {
+        type: view.getUint8(30),
+      };
+
+      // TODO(jwetzell): handle IPv6, type === 2
+      if (destinationAddress.type === 1) {
+        // IPv4
+        destinationAddress.port = view.getUint16(31);
+        destinationAddress.address = bytes.subarray(33, 37).join('.');
+      }
+
+      const adhocExpiry = view.getUint8(45);
+      const joinData = {
+        componentID: toHex(bytes.subarray(0, 16)),
+        memberID: view.getUint16(16),
+        channelNumber: view.getUint16(18),
+        reciprocalChannel: view.getUint16(20),
+        totalSequenceNumber: view.getUint32(22),
+        reliableSequenceNumber: view.getUint32(26),
+        destinationAddress,
+        channelParameters: {
+          expiry: view.getUint8(37),
+          nakOutboundFlag: view.getUint8(38),
+          nakHoldoff: view.getUint16(39),
+          nakModulus: view.getUint16(41),
+          nakMaxWait: view.getUint16(43),
+        },
+        adhocExpiry,
+      };
+      return joinData;
+    }
+    case SDTVector.JOIN_ACCEPT: {
+      const joinData = {
+        leaderComponentID: toHex(bytes.subarray(0, 16)),
+        channelNumber: view.getUint16(16),
+        memberID: view.getUint16(18),
+        reliableSequenceNumber: view.getUint32(20),
+        reciprocalChannel: view.getUint16(24),
+      };
+      return joinData;
+    }
+    case SDTVector.JOIN_REFUSE: {
+      const joinData = {
+        leaderComponentID: toHex(bytes.subarray(0, 16)),
+        channelNumber: view.getUint16(16),
+        memberID: view.getUint16(18),
+        reliableSequenceNumber: view.getUint32(20),
+        refuseCode: view.getUint8(24),
+      };
+
+      return joinData;
+    }
+    case SDTVector.REL_WRAP:
+    case SDTVector.UNREL_WRAP: {
+      const wrapperData: SDTWrapperData = {
+        channelNumber: view.getUint16(0),
+        totalSequenceNumber: view.getUint32(2),
+        reliableSequenceNumber: view.getUint32(6),
+        oldestAvailableWrapper: view.getUint32(10),
+        firstMemberToAck: view.getUint16(14),
+        lastMemberToAck: view.getUint16(16),
+        makThreshold: view.getUint16(18),
+        sdtClientBlock: decodeClientBlock(bytes.subarray(20)),
+      };
+
+      return wrapperData;
+    }
+    case SDTVector.ACK: {
+      return {
+        reliableSequenceNumber: view.getUint32(0),
+      };
+    }
+    case SDTVector.LEAVING: {
+      return {
+        leaderComponentID: toHex(bytes.subarray(0, 16)),
+        channelNumber: view.getUint16(16),
+        memberID: view.getUint16(18),
+        reliableSequenceNumber: view.getUint32(20),
+        reasonCode: view.getUint8(24),
+      };
+    }
+    case SDTVector.GET_SESSIONS: {
+      return {
+        componentID: toHex(bytes.subarray(0, 16)),
+      };
+    }
+    case SDTVector.NAK: {
+      return {
+        leaderComponentID: toHex(bytes.subarray(0, 16)),
+        channelNumber: view.getUint16(16),
+        memberID: view.getUint16(18),
+        reliableSequenceNumber: view.getUint32(20),
+        firstMissedSequence: view.getUint32(24),
+        lastMissedSequence: view.getUint32(28),
+      };
+    }
+    case SDTVector.DISCONNECT:
+    case SDTVector.CONNECT:
+    case SDTVector.CONNECT_ACCEPT: {
+      return {
+        protocolID: view.getUint32(0),
+      };
+    }
+    case SDTVector.CONNECT_REFUSE: {
+      return {
+        protocolID: view.getUint32(0),
+        refuseCode: view.getUint8(4),
+      };
+    }
+    case SDTVector.DISCONNECTING: {
+      return {
+        protocolID: view.getUint32(0),
+        reasonCode: view.getUint8(4),
+      };
+    }
+    default:
+      console.error(`unhandled SDT vector: ${vector}`);
+      return bytes;
+  }
+}
+
+export default {
+  decode,
+};
diff --git a/packages/acn/src/types.ts b/packages/acn/src/types.ts
new file mode 100644
index 0000000..5398bac
--- /dev/null
+++ b/packages/acn/src/types.ts
@@ -0,0 +1,141 @@
+import { TransportLayerAddressType, SDTVector, SDTReasonCode } from './enums';
+
+export type UDPPreamble = {
+  preambleSize: number;
+  postambleSize: number;
+  packetIdentifier: string;
+};
+
+export type ACNPacket<PreambleType, PDUBlockType, PostambleType> = {
+  preamble: PreambleType;
+  pduBlock: PDUBlockType;
+  postamble: PostambleType;
+};
+
+export type RootLayerPDU = {
+  vector: number;
+  header: string;
+  data: SessionDataTransportPDU[] | Uint8Array;
+};
+
+export type SDTChannelParams = {
+  expiry: number;
+  nakOutboundFlag: number;
+  nakHoldoff: number;
+  nakModulus: number;
+  nakMaxWait: number;
+};
+
+export type TransportLayerAddress = {
+  type: TransportLayerAddressType;
+  port?: number;
+  address?: string;
+};
+
+export type SDTJoinData = {
+  componentID: string;
+  memberID: number;
+  channelNumber: number;
+  reciprocalChannel: number;
+  totalSequenceNumber: number;
+  reliableSequenceNumber: number;
+  destinationAddress: TransportLayerAddress;
+  channelParameters: SDTChannelParams;
+  adhocExpiry: number;
+};
+
+export type SDTJoinAcceptData = {
+  leaderComponentID: string;
+  channelNumber: number;
+  memberID: number;
+  reliableSequenceNumber: number;
+  reciprocalChannel: number;
+};
+
+export type SDTJoinRefuseData = {
+  leaderComponentID: string;
+  channelNumber: number;
+  memberID: number;
+  reliableSequenceNumber: number;
+  refuseCode: SDTReasonCode;
+};
+
+export type SDTLeavingData = {
+  leaderComponentID: string;
+  channelNumber: number;
+  memberID: number;
+  reliableSequenceNumber: number;
+  reasonCode: SDTReasonCode;
+};
+
+export type SDTWrapperData = {
+  channelNumber: number;
+  totalSequenceNumber: number;
+  reliableSequenceNumber: number;
+  oldestAvailableWrapper: number;
+  firstMemberToAck: number;
+  lastMemberToAck: number;
+  makThreshold: number;
+  sdtClientBlock?: SDTClientBlock;
+};
+
+export type SDTAckData = {
+  reliableSequenceNumber: number;
+};
+
+export type SDTNakData = {
+  leaderComponenetID: string;
+  channelNumber: number;
+  memberID: number;
+  reliableSequenceNumber: number;
+  firstMissedSequence: number;
+  lastMissedSequence: number;
+};
+
+export type SDTConnectData = {
+  protocolID: number;
+};
+
+export type SDTConnectAcceptData = SDTConnectData;
+export type SDTConnectRefuseData = {
+  protocolID: number;
+  refuseCode: SDTReasonCode;
+};
+
+export type SDTDisconnectData = SDTConnectData;
+export type SDTDisconnectingData = {
+  protocolID: number;
+  reasonCode: SDTReasonCode;
+};
+
+export type SDTGetSessionsData = {
+  componentID: string;
+};
+
+export type SessionDataTransportPDU = {
+  vector: SDTVector;
+  length: number;
+  // TODO(jwetzell): cleanup these types
+  data:
+    | SDTJoinData
+    | SDTJoinAcceptData
+    | SDTJoinRefuseData
+    | SDTWrapperData
+    | SDTAckData
+    | SDTLeavingData
+    | SDTGetSessionsData
+    | SDTNakData
+    | SDTConnectData
+    | SDTConnectAcceptData
+    | SDTConnectRefuseData
+    | SDTDisconnectData
+    | SDTDisconnectingData
+    | Uint8Array;
+};
+
+export type SDTClientBlock = {
+  memberID: number;
+  clientProtocol: number;
+  association: number;
+  data: SessionDataTransportPDU | Uint8Array;
+};
diff --git a/packages/acn/src/udp.ts b/packages/acn/src/udp.ts
index 8e1a8b5..0877fae 100644
--- a/packages/acn/src/udp.ts
+++ b/packages/acn/src/udp.ts
@@ -1,4 +1,4 @@
-import { ACNPacket, RootLayerPDU, UDPPreamble } from './models';
+import { ACNPacket, RootLayerPDU, UDPPreamble } from './types';
 import pdu from './pdu';
 
 // ANSI E1.17 - 2015 (R2020) EPI 17
diff --git a/packages/acn/src/utils.ts b/packages/acn/src/utils.ts
index cd0b88d..5747042 100644
--- a/packages/acn/src/utils.ts
+++ b/packages/acn/src/utils.ts
@@ -1,7 +1,7 @@
-export function toHex(bytes: Uint8Array): string{
-    let hex = '';
-    bytes.forEach((byte)=>{
-        hex += byte.toString(16).padStart(2,'0')
-    }) 
-    return hex;
-}
\ No newline at end of file
+export function toHex(bytes: Uint8Array): string {
+  let hex = '';
+  bytes.forEach((byte) => {
+    hex += byte.toString(16).padStart(2, '0');
+  });
+  return hex;
+}
diff --git a/packages/acn/tests/udp-decode.test.js b/packages/acn/tests/udp-decode.test.js
index fe1602b..026cec7 100644
--- a/packages/acn/tests/udp-decode.test.js
+++ b/packages/acn/tests/udp-decode.test.js
@@ -20,10 +20,33 @@ const goodTests = [
       pduBlock: {
         vector: 1,
         header: 'b0abd82a20d24240a7cd3e49d999a4e5',
-        data: new Uint8Array([
-          112, 50, 4, 73, 136, 131, 52, 255, 255, 74, 69, 176, 66, 102, 183, 33, 235, 216, 155, 0, 1, 244, 136, 0, 0, 0,
-          0, 244, 136, 0, 0, 244, 136, 1, 67, 216, 239, 192, 220, 207, 5, 0, 0, 2, 0, 10, 0, 20, 1, 44,
-        ]),
+        data: [
+          {
+            vector: 4,
+            length: 50,
+            data: {
+              componentID: '49888334ffff4a45b04266b721ebd89b',
+              memberID: 1,
+              channelNumber: 62600,
+              reciprocalChannel: 0,
+              totalSequenceNumber: 62600,
+              reliableSequenceNumber: 62600,
+              destinationAddress: {
+                type: 1,
+                port: 17368,
+                address: '239.192.220.207'
+              },
+              channelParameters: {
+                expiry: 5,
+                nakOutboundFlag: 0,
+                nakHoldoff: 2,
+                nakModulus: 10,
+                nakMaxWait: 20
+              },
+              adhocExpiry: 1,
+            }
+          }
+        ],
       },
       postamble: undefined,
     },
@@ -71,7 +94,9 @@ const badTests = [
 describe('ACN Message Decoding Pass', () => {
   goodTests.forEach((messageTest) => {
     it(messageTest.description, () => {
+      console.log(JSON.stringify(messageTest.expected))
       const decoded = acn.decode(messageTest.bytes);
+      console.log(JSON.stringify(decoded))
       deepEqual(decoded, messageTest.expected);
     });
   });