diff --git a/doc/admin-guide/plugins/cache_range_requests.en.rst b/doc/admin-guide/plugins/cache_range_requests.en.rst
new file mode 100644
index 00000000000..6d11d21121a
--- /dev/null
+++ b/doc/admin-guide/plugins/cache_range_requests.en.rst
@@ -0,0 +1,191 @@
+.. Licensed to the Apache Software Foundation (ASF) under one
+   or more contributor license agreements.  See the NOTICE file
+   distributed with this work for additional information
+   regarding copyright ownership.  The ASF licenses this file
+   to you under the Apache License, Version 2.0 (the
+   "License"); you may not use this file except in compliance
+   with the License.  You may obtain a copy of the License at
+
+      http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing,
+   software distributed under the License is distributed on an
+   "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+   KIND, either express or implied.  See the License for the
+   specific language governing permissions and limitations
+   under the License.
+
+
+.. include:: ../../common.defs
+
+.. _admin-plugins-cache-range-requests:
+
+
+Cache Range Requests Plugin
+***************************
+
+Description
+===========
+
+Most origin servers support HTTP/1.1 range requests (rfc 7233).
+ATS internally handles range request caching in one of 2 ways:
+
+* Don't cache range requests.
+* Only server range requests from a wholly cached object.
+
+This plugin allows you to remap individual range requests so that they
+are stored as individual objects in the ATS cache when subsequent range
+requests are likely to use the same range.  This spreads range requests
+over multiple stripes thereby reducing I/O wait and system load averages.
+
+:program:`cache_range_requests` reads the range request header byte range
+value and then creates a new ``cache key URL`` using the original request
+url with the range value appended to it.  The range header is removed
+where appropriate from the requests and the origin server response code
+is changed from a 206 to a 200 to insure that the object is written to
+cache using the new cache key url.  The response code sent to the client
+will be changed back to a 206 and all requests to the origin server will
+contain the range header so that the correct response is received.
+
+The :program:`cache_range_requests` plugin by itself has no logic to
+efficiently manage overlapping ranges.  It is best to use this plugin
+in conjunction with a smart client that only requests predetermined
+non overlapping cache ranges (request blocking) or as a helper for the
+:program:`slice` plugin.
+
+Only requests which contain the ``Range: <units>=`` GET header
+will be served by the :program:`cache_range_requests` plugin.
+
+If/when ATS implements partial object caching this plugin will
+become deprecated.
+
+*NOTE* Given a multi range request the :program:`cache_range_requests`
+only processes the first range and ignores the rest.
+
+How to run the plugin
+=====================
+
+The plugin can run as a global plugin (a single global instance configured
+using :file:`plugin.config`) or as per-remap plugin (a separate instance
+configured per remap rule in :file:`remap.config`).
+
+Global instance
+---------------
+
+.. code::
+
+  $ cat plugin.config
+  cache_range_request.so
+
+
+Per-remap instance
+------------------
+
+.. code::
+
+  $cat remap.config
+  map http://www.example.com http://www.origin.com \
+      @plugin=cache_range_requests.so
+
+
+If both global and per-remap instance are used the per-remap configuration
+would take precedence (per-remap configuration would be applied and the
+global configuration ignored).
+
+Plugin options
+==============
+
+
+Parent Selection as Cache Key
+-----------------------------
+
+.. option:: --ps-cachekey
+.. option:: -p
+
+Without this option parent selection is based solely on the hash of a
+URL Path a URL is requested from the same upstream parent cache listed
+in parent.config
+
+
+With this option parent selection is based on the full ``cache key URL``
+which includes information about the partial content range.  In this mode,
+all requests (include partial content) will use consistent hashing method
+for parent selection.
+
+
+X-CRR-IMS header support
+------------------------
+
+.. option:: --consider-ims
+.. option:: -c
+
+To support slice plugin self healing an option to force revalidation
+after cache lookup complete was added.  This option is triggered by a
+special header:
+
+.. code::
+
+    X-CRR-IMS: Tue, 19 Nov 2019 13:26:45 GMT
+
+When this header is provided and a `cache hit fresh` is encoutered the
+``Date`` header of the object in cache is compared to this header date
+value.  If the cache date is *less* than this IMS date then the object
+is marked as STALE and an appropriate If-Modified-Since or If-Match
+request along with this X-CRR-IMS header is passed up to the parent.
+
+In order for this to properly work in a CDN each cache in the
+chain *SHOULD* also contain a remap rule with the
+:program:`cache_range_requests` plugin with this option set.
+
+Don't modify the Cache Key
+--------------------------
+
+.. option:: --no-modify-cachekey
+.. option:: -n
+
+With each transaction TSCacheUrlSet may only be called once.  When
+using the `cache_range_requests` plugin in conjunction with the
+`cachekey` plugin the option `--include-headers=Range` should be
+added as a `cachekey` parameter with this option.  Configuring this
+incorrectly *WILL* result in cache poisoning.
+
+.. code::
+
+       map http://ats/ http://parent/ \
+           @plugin=cachekey.so @pparam=--include-headers=Range \
+           @plugin=cache_range_requests.so @pparam=--no-modify-cachekey
+
+*Without this `cache_range_requests` plugin option*
+
+*IF* the TSCacheUrlSet call in cache_range_requests fails, an error is
+generated in the logs and the cache_range_requests plugin will disable
+transaction caching in order to avoid cache poisoning.
+
+Configuration examples
+======================
+
+Global plugin
+-------------
+
+.. code::
+
+    cache_range_requests.so --ps-cachekey --consider-ims --no-modify-cachekey
+
+or
+
+.. code::
+
+    cache_range_requests.so -p -c -n
+
+Remap plugin
+------------
+
+.. code::
+
+    map http://ats http://parent @plugin=cache_range_requests.so @pparam=--ps-cachekey @pparam=--consider-ims @pparam=--no-modify-cachekey
+
+or
+
+.. code::
+
+    map http://ats http://parent @plugin=cache_range_requests.so @pparam=-p @pparam=-c @pparam=-n
diff --git a/doc/admin-guide/plugins/xdebug.en.rst b/doc/admin-guide/plugins/xdebug.en.rst
index fd92bc06b1e..09c0791a4db 100644
--- a/doc/admin-guide/plugins/xdebug.en.rst
+++ b/doc/admin-guide/plugins/xdebug.en.rst
@@ -101,3 +101,9 @@ X-Transaction-ID
 X-Remap
     If the URL was remapped for a request, this header gives the *to* and *from* field from the line in remap.config that caused
     the URL to be remapped.
+
+X-ParentSelection-Key
+    The ``X-ParentSelection-Key`` header contains the URL that is used to
+    determine parent selection for an object in the Traffic Server. This
+    header is particularly useful if a custom parent selection key is
+    being used.
diff --git a/plugins/experimental/cache_range_requests/cache_range_requests.cc b/plugins/experimental/cache_range_requests/cache_range_requests.cc
index b0b61ec1cd1..7ed63d2525b 100644
--- a/plugins/experimental/cache_range_requests/cache_range_requests.cc
+++ b/plugins/experimental/cache_range_requests/cache_range_requests.cc
@@ -41,7 +41,9 @@ typedef enum parent_select_mode {
 } parent_select_mode_t;
 
 struct pluginconfig {
-  parent_select_mode_t ps_mode;
+  parent_select_mode_t ps_mode{PS_DEFAULT};
+  bool consider_ims_header{false};
+  bool modify_cache_key{true};
 };
 
 struct txndata {
@@ -79,18 +81,32 @@ create_pluginconfig(int argc, const char *argv[])
     return nullptr;
   }
 
-  // Plugin uses default ATS selection (hash of URL path)
-  pc->ps_mode = PS_DEFAULT;
-
+  static const struct option longopts[] = {
+    {const_cast<char *>("ps-cachekey"), no_argument, nullptr, 'p'},
+    {const_cast<char *>("consider-ims"), no_argument, nullptr, 'c'},
+    {const_cast<char *>("no-modify-cachekey"), no_argument, nullptr, 'n'},
+    {nullptr, 0, nullptr, 0},
+  };
+  //
   // Walk through param list.
   for (int c = 0; c < argc; c++) {
-    if (strcmp("ps_mode:cache_key_url", argv[c]) == 0) {
-      pc->ps_mode = PS_CACHEKEY_URL;
-      break;
-    }
+  case 'p': {
+    pc->ps_mode = PS_CACHEKEY_URL;
+  } break;
+  case 'c': {
+    DEBUG_LOG("Plugin considers the '%.*s' header", (int)X_IMS_HEADER.size(), X_IMS_HEADER.data());
+    pc->consider_ims_header = true;
+  } break;
+  case 'n': {
+    DEBUG_LOG("Plugin doesn't modify cache key");
+    pc->modify_cache_key = false;
+  } break;
+  default: {
+  } break;
   }
+}
 
-  return pc;
+return pc;
 }
 
 /**
@@ -165,23 +181,41 @@ range_header_check(TSHttpTxn txnp, struct pluginconfig *pc)
             TSfree(req_url);
           }
 
-          // set the cache key.
-          if (TS_SUCCESS != TSCacheUrlSet(txnp, cache_key_url, cache_key_url_length)) {
-            DEBUG_LOG("failed to change the cache url to %s.", cache_key_url);
-          }
+          if (nullptr != pc) {
+            // set the cache key if configured to.
+            if (pc->modify_cache_key && TS_SUCCESS != TSCacheUrlSet(txnp, cache_key_url, cache_key_url_length)) {
+              ERROR_LOG("failed to change the cache url to %s.", cache_key_url);
+              ERROR_LOG("Disabling cache for this transaction to avoid cache poisoning.");
+              TSHttpTxnServerRespNoStoreSet(txnp, 1);
+              TSHttpTxnRespCacheableSet(txnp, 0);
+              TSHttpTxnReqCacheableSet(txnp, 0);
+            }
+
+            // Optionally set the parent_selection_url to the cache_key url or path
+            if (PS_DEFAULT != pc->ps_mode) {
+              TSMLoc ps_loc = nullptr;
+
+              if (PS_CACHEKEY_URL == pc->ps_mode) {
+                const char *start = cache_key_url;
+                const char *end   = cache_key_url + cache_key_url_length;
+                if (TS_SUCCESS == TSUrlCreate(hdr_buf, &ps_loc) &&
+                    TS_PARSE_DONE == TSUrlParse(hdr_buf, ps_loc, &start, end) && // This should always succeed.
+                    TS_SUCCESS == TSHttpTxnParentSelectionUrlSet(txnp, hdr_buf, ps_loc)) {
+                  DEBUG_LOG("Set Parent Selection URL to cache_key_url: %s", cache_key_url);
+                  TSHandleMLocRelease(hdr_buf, TS_NULL_MLOC, ps_loc);
+                }
+              }
+            }
 
-          // Optionally set the parent_selection_url to the cache_key url or path
-          if (nullptr != pc && PS_DEFAULT != pc->ps_mode) {
-            TSMLoc ps_loc = nullptr;
-
-            if (PS_CACHEKEY_URL == pc->ps_mode) {
-              const char *start = cache_key_url;
-              const char *end   = cache_key_url + cache_key_url_length;
-              if (TS_SUCCESS == TSUrlCreate(hdr_bufp, &ps_loc) &&
-                  TS_PARSE_DONE == TSUrlParse(hdr_bufp, ps_loc, &start, end) && // This should always succeed.
-                  TS_SUCCESS == TSHttpTxnParentSelectionUrlSet(txnp, hdr_bufp, ps_loc)) {
-                DEBUG_LOG("Set Parent Selection URL to cache_key_url: %s", cache_key_url);
-                TSHandleMLocRelease(hdr_bufp, TS_NULL_MLOC, ps_loc);
+            // optionally consider an X-CRR-IMS header
+            if (pc->consider_ims_header) {
+              TSMLoc const imsloc = TSMimeHdrFieldFind(hdr_buf, hdr_loc, X_IMS_HEADER.data(), X_IMS_HEADER.size());
+              if (TS_NULL_MLOC != imsloc) {
+                time_t const itime = TSMimeHdrFieldValueDateGet(hdr_buf, hdr_loc, imsloc);
+                TSHandleMLocRelease(hdr_buf, hdr_loc, imsloc);
+                if (0 < itime) {
+                  txn_state->ims_time = itime;
+                }
               }
             }
           }
diff --git a/plugins/xdebug/xdebug.cc b/plugins/xdebug/xdebug.cc
index 42e83d8def6..3a2e7a16998 100644
--- a/plugins/xdebug/xdebug.cc
+++ b/plugins/xdebug/xdebug.cc
@@ -35,13 +35,15 @@ static struct {
 } xDebugHeader = {nullptr, 0};
 
 enum {
-  XHEADER_X_CACHE_KEY      = 0x0004u,
-  XHEADER_X_MILESTONES     = 0x0008u,
-  XHEADER_X_CACHE          = 0x0010u,
-  XHEADER_X_GENERATION     = 0x0020u,
-  XHEADER_X_TRANSACTION_ID = 0x0040u,
-  XHEADER_X_DUMP_HEADERS   = 0x0080u,
-  XHEADER_X_REMAP          = 0x0100u,
+  XHEADER_X_CACHE_KEY      = 1u << 2,
+  XHEADER_X_MILESTONES     = 1u << 3,
+  XHEADER_X_CACHE          = 1u << 4,
+  XHEADER_X_GENERATION     = 1u << 5,
+  XHEADER_X_TRANSACTION_ID = 1u << 6,
+  XHEADER_X_DUMP_HEADERS   = 1u << 7,
+  XHEADER_X_REMAP          = 1u << 8,
+  XHEADER_X_PROBE_HEADERS  = 1u << 9,
+  XHEADER_X_PSELECT_KEY    = 1u << 10,
 };
 
 static int XArgIndex             = 0;
@@ -357,6 +359,53 @@ log_headers(TSHttpTxn txn, TSMBuffer bufp, TSMLoc hdr_loc, const char *msg_type)
   TSDebug(DEBUG_TAG_LOG_HEADERS, "%s", ss.str().c_str());
 }
 
+static void
+InjectParentSelectionKeyHeader(TSHttpTxn txn, TSMBuffer buffer, TSMLoc hdr)
+{
+  TSMLoc url = TS_NULL_MLOC;
+  TSMLoc dst = TS_NULL_MLOC;
+
+  struct {
+    char *ptr;
+    int len;
+  } strval = {nullptr, 0};
+
+  TSDebug("xdebug", "attempting to inject X-ParentSelection-Key header");
+
+  if (TSUrlCreate(buffer, &url) != TS_SUCCESS) {
+    goto done;
+  }
+
+  if (TSHttpTxnParentSelectionUrlGet(txn, buffer, url) != TS_SUCCESS) {
+    goto done;
+  }
+
+  strval.ptr = TSUrlStringGet(buffer, url, &strval.len);
+  if (strval.ptr == nullptr || strval.len == 0) {
+    goto done;
+  }
+
+  // Create a new response header field.
+  dst = FindOrMakeHdrField(buffer, hdr, "X-ParentSelection-Key", lengthof("X-ParentSelection-Key"));
+  if (dst == TS_NULL_MLOC) {
+    goto done;
+  }
+
+  // Now copy the parent selection lookup URL into the response header.
+  TSReleaseAssert(TSMimeHdrFieldValueStringInsert(buffer, hdr, dst, 0 /* idx */, strval.ptr, strval.len) == TS_SUCCESS);
+
+done:
+  if (dst != TS_NULL_MLOC) {
+    TSHandleMLocRelease(buffer, hdr, dst);
+  }
+
+  if (url != TS_NULL_MLOC) {
+    TSHandleMLocRelease(buffer, TS_NULL_MLOC, url);
+  }
+
+  TSfree(strval.ptr);
+}
+
 static int
 XInjectResponseHeaders(TSCont /* contp */, TSEvent event, void *edata)
 {
@@ -404,6 +453,10 @@ XInjectResponseHeaders(TSCont /* contp */, TSEvent event, void *edata)
     InjectRemapHeader(txn, buffer, hdr);
   }
 
+  if (xheaders & XHEADER_X_PSELECT_KEY) {
+    InjectParentSelectionKeyHeader(txn, buffer, hdr);
+  }
+
 done:
   TSHttpTxnReenable(txn, TS_EVENT_HTTP_CONTINUE);
   return TS_EVENT_NONE;
@@ -486,7 +539,7 @@ XScanRequestHeaders(TSCont /* contp */, TSEvent event, void *edata)
           TSHttpTxnReenable(txn, TS_EVENT_HTTP_CONTINUE);
           return TS_EVENT_NONE;
         };
-        TSHttpTxnHookAdd(txn, TS_HTTP_SEND_REQUEST_HDR_HOOK, TSContCreate(send_req_dump, nullptr));
+        TSHttpTxnHookAdd(txn, TS_HTTP_SEND_REQUEST_HDR_HOOK, TSContCreate(send_req_dump, nullptr))
 
         // dump on server response
         auto read_resp_dump = [](TSCont /* contp */, TSEvent event, void *edata) -> int {
@@ -501,6 +554,8 @@ XScanRequestHeaders(TSCont /* contp */, TSEvent event, void *edata)
         };
         TSHttpTxnHookAdd(txn, TS_HTTP_READ_RESPONSE_HDR_HOOK, TSContCreate(read_resp_dump, nullptr));
 
+      } else if (header_field_eq("x-parentselection-key", value, vsize)) {
+        xheaders |= XHEADER_X_PSELECT_KEY;
       } else {
         TSDebug("xdebug", "ignoring unrecognized debug tag '%.*s'", vsize, value);
       }
diff --git a/tests/gold_tests/pluginTest/cache_range_requests/cache_range_requests.test.py b/tests/gold_tests/pluginTest/cache_range_requests/cache_range_requests.test.py
new file mode 100644
index 00000000000..49aaf6ed22a
--- /dev/null
+++ b/tests/gold_tests/pluginTest/cache_range_requests/cache_range_requests.test.py
@@ -0,0 +1,340 @@
+'''
+'''
+#  Licensed to the Apache Software Foundation (ASF) under one
+#  or more contributor license agreements.  See the NOTICE file
+#  distributed with this work for additional information
+#  regarding copyright ownership.  The ASF licenses this file
+#  to you under the Apache License, Version 2.0 (the
+#  "License"); you may not use this file except in compliance
+#  with the License.  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+
+import os
+
+Test.Summary = '''
+Basic cache_range_requests plugin test
+'''
+
+## Test description:
+# Preload the cache with the entire asset to be range requested.
+# Reload remap rule with cache_range_requests plugin
+# Request content through the cache_range_requests plugin
+
+Test.SkipUnless(
+    Condition.PluginExists('cache_range_requests.so'),
+    Condition.PluginExists('xdebug.so'),
+)
+Test.ContinueOnFail = False
+Test.testName = "cache_range_requests"
+
+# Define and configure ATS
+ts = Test.MakeATSProcess("ts", command="traffic_server")
+
+# Define and configure origin server
+server = Test.MakeOriginServer("server", lookup_key="{%uuid}")
+
+# default root
+req_chk = {"headers":
+  "GET / HTTP/1.1\r\n" +
+  "Host: www.example.com\r\n" +
+  "uuid: none\r\n" +
+  "\r\n",
+  "timestamp": "1469733493.993",
+  "body": ""
+}
+
+res_chk = {"headers":
+  "HTTP/1.1 200 OK\r\n" +
+  "Connection: close\r\n" +
+  "\r\n",
+  "timestamp": "1469733493.993",
+  "body": ""
+}
+
+server.addResponse("sessionlog.json", req_chk, res_chk)
+
+body = "lets go surfin now"
+
+req_full = {"headers":
+  "GET /path HTTP/1.1\r\n" +
+  "Host: www.example.com\r\n" +
+  "Accept: */*\r\n" +
+  "uuid: full\r\n" +
+  "\r\n",
+  "timestamp": "1469733493.993",
+  "body": ""
+}
+
+res_full = {"headers":
+  "HTTP/1.1 200 OK\r\n" +
+  "Cache-Control: max-age=500\r\n" +
+  "Connection: close\r\n" +
+  'Etag: "772102f4-56f4bc1e6d417"\r\n' +
+  "Last-Modified: Sat, 23 Jun 2018 09:27:29 GMT\r\n" +
+  "\r\n",
+  "timestamp": "1469733493.993",
+  "body": body
+}
+
+server.addResponse("sessionlog.json", req_full, res_full)
+
+block_bytes = 7
+bodylen = len(body)
+
+inner_str = "7-15"
+
+req_inner = {"headers":
+  "GET /path HTTP/1.1\r\n" +
+  "Host: www.example.com\r\n" +
+  "Accept: */*\r\n" +
+  "Range: bytes={}\r\n".format(inner_str) +
+  "uuid: inner\r\n" +
+  "\r\n",
+  "timestamp": "1469733493.993",
+  "body": ""
+}
+
+res_inner = {"headers":
+  "HTTP/1.1 206 Partial Content\r\n" +
+  "Accept-Ranges: bytes\r\n" +
+  "Cache-Control: max-age=500\r\n" +
+  "Content-Range: bytes {0}/{1}\r\n".format(inner_str, bodylen) +
+  "Connection: close\r\n" +
+  'Etag: "772102f4-56f4bc1e6d417"\r\n' +
+  "Last-Modified: Sat, 23 Jun 2018 09:27:29 GMT\r\n" +
+  "\r\n",
+  "timestamp": "1469733493.993",
+  "body": body[7:15]
+}
+
+server.addResponse("sessionlog.json", req_inner, res_inner)
+
+frange_str = "0-"
+
+req_frange = {"headers":
+  "GET /path HTTP/1.1\r\n" +
+  "Host: www.example.com\r\n" +
+  "Accept: */*\r\n" +
+  "Range: bytes={}\r\n".format(frange_str) +
+  "uuid: frange\r\n" +
+  "\r\n",
+  "timestamp": "1469733493.993",
+  "body": ""
+}
+
+res_frange = {"headers":
+  "HTTP/1.1 206 Partial Content\r\n" +
+  "Accept-Ranges: bytes\r\n" +
+  "Cache-Control: max-age=500\r\n" +
+  "Content-Range: bytes 0-{0}/{0}\r\n".format(bodylen) +
+  "Connection: close\r\n" +
+  'Etag: "772102f4-56f4bc1e6d417"\r\n' +
+  "Last-Modified: Sat, 23 Jun 2018 09:27:29 GMT\r\n" +
+  "\r\n",
+  "timestamp": "1469733493.993",
+  "body": body
+}
+
+server.addResponse("sessionlog.json", req_frange, res_frange)
+
+last_str = "-5"
+
+req_last = {"headers":
+  "GET /path HTTP/1.1\r\n" +
+  "Host: www.example.com\r\n" +
+  "Accept: */*\r\n" +
+  "Range: bytes={}\r\n".format(last_str) +
+  "uuid: last\r\n" +
+  "\r\n",
+  "timestamp": "1469733493.993",
+  "body": ""
+}
+
+res_last = {"headers":
+  "HTTP/1.1 206 Partial Content\r\n" +
+  "Accept-Ranges: bytes\r\n" +
+  "Cache-Control: max-age=200\r\n" +
+  "Content-Range: bytes {0}-{1}/{1}\r\n".format(bodylen - 5, bodylen) +
+  "Connection: close\r\n" +
+  'Etag: "772102f4-56f4bc1e6d417"\r\n' +
+  "Last-Modified: Sat, 23 Jun 2018 09:27:29 GMT\r\n" +
+  "\r\n",
+  "timestamp": "1469733493.993",
+  "body": body[-5:]
+}
+
+server.addResponse("sessionlog.json", req_last, res_last)
+
+pselect_str = "1-10"
+
+req_pselect = {"headers":
+  "GET /path HTTP/1.1\r\n" +
+  "Host: parentselect\r\n" +
+  "Accept: */*\r\n" +
+  "Range: bytes={}\r\n".format(pselect_str) +
+  "uuid: pselect\r\n" +
+  "\r\n",
+  "timestamp": "1469733493.993",
+  "body": ""
+}
+
+res_pselect = {"headers":
+  "HTTP/1.1 206 Partial Content\r\n" +
+  "Accept-Ranges: bytes\r\n" +
+  "Cache-Control: max-age=200\r\n" +
+  "Content-Range: bytes {}/19\r\n".format(pselect_str) +
+  "Connection: close\r\n" +
+  'Etag: "772102f4-56f4bc1e6d417"\r\n' +
+  "Last-Modified: Sat, 23 Jun 2018 09:27:29 GMT\r\n" +
+  "\r\n",
+  "timestamp": "1469733493.993",
+  "body": body[1:10]
+}
+
+server.addResponse("sessionlog.json", req_pselect, res_pselect)
+
+# cache range requests plugin remap
+ts.Disk.remap_config.AddLines([
+  'map http://www.example.com http://127.0.0.1:{}'.format(server.Variables.Port) +
+    ' @plugin=cache_range_requests.so',
+  'map http://parentselect http://127.0.0.1:{}'.format(server.Variables.Port) +
+    ' @plugin=cache_range_requests.so @pparam=ps_mode:cache_key_url',
+])
+
+# cache debug
+ts.Disk.plugin_config.AddLine('xdebug.so')
+
+# minimal configuration
+ts.Disk.records_config.update({
+  'proxy.config.diags.debug.enabled': 1,
+  'proxy.config.diags.debug.tags': 'cache_range_requests',
+  'proxy.config.http.cache.http': 1,
+  'proxy.config.http.wait_for_cache': 1,
+})
+
+curl_and_args = 'curl -s -D /dev/stdout -o /dev/stderr -x localhost:{} -H "x-debug: x-cache"'.format(ts.Variables.port)
+
+# 0 Test - Fetch whole asset into cache
+tr = Test.AddTestRun("full asset cache miss bypass")
+ps = tr.Processes.Default
+ps.StartBefore(server, ready=When.PortOpen(server.Variables.Port))
+ps.StartBefore(Test.Processes.ts, ready=When.PortOpen(ts.Variables.port))
+ps.Command = curl_and_args + ' http://www.example.com/path -H "uuid: full"'
+ps.ReturnCode = 0
+ps.Streams.stdout = "gold/full.stdout.gold"
+ps.Streams.stderr = "gold/full.stderr.gold"
+tr.StillRunningAfter = ts
+
+# test inner range
+# 1 Test - Fetch range into cache
+tr = Test.AddTestRun("inner range cache miss")
+ps = tr.Processes.Default
+ps.Command = curl_and_args + ' http://www.example.com/path -r {} -H "uuid: inner"'.format(inner_str)
+ps.ReturnCode = 0
+ps.Streams.stdout = "gold/inner.stdout.gold"
+ps.Streams.stderr = "gold/inner.stderr.gold"
+ps.Streams.stdout.Content = Testers.ContainsExpression("X-Cache: miss", "expected cache miss")
+tr.StillRunningAfter = ts
+
+# 2 Test - Fetch from cache
+tr = Test.AddTestRun("inner range cache hit")
+ps = tr.Processes.Default
+ps.Command = curl_and_args + ' http://www.example.com/path -r {}'.format(inner_str)
+ps.ReturnCode = 0
+ps.Streams.stdout = "gold/inner.stdout.gold"
+ps.Streams.stderr = "gold/inner.stderr.gold"
+ps.Streams.stdout.Content = Testers.ContainsExpression("X-Cache: hit", "expected cache hit")
+tr.StillRunningAfter = ts
+
+# full range
+
+# 3 Test - 0- request
+tr = Test.AddTestRun("0- request miss")
+ps = tr.Processes.Default
+ps.Command = curl_and_args + ' http://www.example.com/path -r {} -H "uuid: frange"'.format(frange_str)
+ps.ReturnCode = 0
+ps.Streams.stdout = "gold/frange.stdout.gold"
+ps.Streams.stderr = "gold/frange.stderr.gold"
+ps.Streams.stdout.Content = Testers.ContainsExpression("X-Cache: miss", "expected cache miss")
+tr.StillRunningAfter = ts
+
+# 4 Test - 0- request
+tr = Test.AddTestRun("0- request hit")
+ps = tr.Processes.Default
+ps.Command = curl_and_args + ' http://www.example.com/path -r {}'.format(frange_str)
+ps.ReturnCode = 0
+ps.Streams.stdout = "gold/frange.stdout.gold"
+ps.Streams.stderr = "gold/frange.stderr.gold"
+ps.Streams.stdout.Content = Testers.ContainsExpression("X-Cache: hit", "expected cache hit")
+tr.StillRunningAfter = ts
+
+# end range
+
+# 5 Test - -5 request miss
+tr = Test.AddTestRun("-5 request miss")
+ps = tr.Processes.Default
+ps.Command = curl_and_args + ' http://www.example.com/path -r {} -H "uuid: last"'.format(last_str)
+ps.ReturnCode = 0
+ps.Streams.stdout = "gold/last.stdout.gold"
+ps.Streams.stderr = "gold/last.stderr.gold"
+ps.Streams.stdout.Content = Testers.ContainsExpression("X-Cache: miss", "expected cache miss")
+tr.StillRunningAfter = ts
+
+# 6 Test - -5 request hit
+tr = Test.AddTestRun("-5 request hit")
+ps = tr.Processes.Default
+ps.Command = curl_and_args + ' http://www.example.com/path -r {}'.format(last_str)
+ps.ReturnCode = 0
+ps.Streams.stdout = "gold/last.stdout.gold"
+ps.Streams.stderr = "gold/last.stderr.gold"
+ps.Streams.stdout.Content = Testers.ContainsExpression("X-Cache: hit", "expected cache hit")
+tr.StillRunningAfter = ts
+
+# Ensure 404's aren't getting cached
+
+# 7 Test - 404
+tr = Test.AddTestRun("404 request 1st")
+ps = tr.Processes.Default
+ps.Command = curl_and_args + ' http://www.example.com/404 -r 0-'
+ps.Streams.stdout = "gold/404.stdout.gold"
+ps.Streams.stdout.Content = Testers.ContainsExpression("X-Cache: miss", "expected cache miss")
+tr.StillRunningAfter = ts
+
+# 8 Test - 404
+tr = Test.AddTestRun("404 request 2nd")
+ps = tr.Processes.Default
+ps.Command = curl_and_args + ' http://www.example.com/404 -r 0-'
+ps.Streams.stdout = "gold/404.stdout.gold"
+ps.Streams.stdout.Content = Testers.ContainsExpression("X-Cache: miss", "expected cache miss")
+tr.StillRunningAfter = ts
+
+curl_and_args = 'curl -s -D /dev/stdout -o /dev/stderr -x localhost:{} -H "x-debug: x-parentselection-key"'.format(ts.Variables.port)
+
+# 9 Test - cache_key_url request
+tr = Test.AddTestRun("cache_key_url request")
+ps = tr.Processes.Default
+ps.Command = curl_and_args + ' http://parentselect/path -r {} -H "uuid: pselect"'.format(pselect_str)
+ps.ReturnCode = 0
+ps.Streams.stdout = "gold/pselect.stdout.gold"
+ps.Streams.stdout.Content = Testers.ContainsExpression(
+  "X-ParentSelection-Key: .*-bytes=",
+  "expected bytes in parent selection key",
+)
+tr.StillRunningAfter = ts
+tr.StillRunningAfter = server
+
+# 10 Test - non cache_key_url request ... no X-ParentSelectionKey
+tr = Test.AddTestRun("non cache_key_url request")
+ps = tr.Processes.Default
+ps.Command = curl_and_args + ' http://www.example.com/path -r {} -H "uuid: inner"'.format(inner_str)
+ps.ReturnCode = 0
+ps.Streams.stdout = "gold/pselect_none.stdout.gold"
+tr.StillRunningAfter = ts
+tr.StillRunningAfter = server
diff --git a/tests/gold_tests/pluginTest/cache_range_requests/cache_range_requests_cachekey.test.py b/tests/gold_tests/pluginTest/cache_range_requests/cache_range_requests_cachekey.test.py
new file mode 100644
index 00000000000..2622694a04e
--- /dev/null
+++ b/tests/gold_tests/pluginTest/cache_range_requests/cache_range_requests_cachekey.test.py
@@ -0,0 +1,198 @@
+'''
+'''
+#  Licensed to the Apache Software Foundation (ASF) under one
+#  or more contributor license agreements.  See the NOTICE file
+#  distributed with this work for additional information
+#  regarding copyright ownership.  The ASF licenses this file
+#  to you under the Apache License, Version 2.0 (the
+#  "License"); you may not use this file except in compliance
+#  with the License.  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+
+import os
+import time
+
+Test.Summary = '''
+cache_range_requests with cachekey
+'''
+
+## Test description:
+# Preload the cache with the entire asset to be range requested.
+# Reload remap rule with cache_range_requests plugin
+# Request content through the cache_range_requests plugin
+
+Test.SkipUnless(
+    Condition.PluginExists('cache_range_requests.so'),
+    Condition.PluginExists('cachekey.so'),
+    Condition.PluginExists('xdebug.so'),
+)
+Test.ContinueOnFail = False
+Test.testName = "cache_range_requests_cachekey"
+
+# Define and configure ATS, enable traffic_ctl config reload
+ts = Test.MakeATSProcess("ts", command="traffic_server")
+
+# Define and configure origin server
+server = Test.MakeOriginServer("server", lookup_key="{%uuid}")
+
+# default root
+req_chk = {"headers":
+  "GET / HTTP/1.1\r\n" +
+  "Host: www.example.com\r\n" +
+  "uuid: none\r\n" +
+  "\r\n",
+  "timestamp": "1469733493.993",
+  "body": ""
+}
+
+res_chk = {"headers":
+  "HTTP/1.1 200 OK\r\n" +
+  "Connection: close\r\n" +
+  "\r\n",
+  "timestamp": "1469733493.993",
+  "body": ""
+}
+
+server.addResponse("sessionlog.json", req_chk, res_chk)
+
+body = "lets go surfin now"
+bodylen = len(body)
+
+# this request should work
+req_full = {"headers":
+  "GET /path HTTP/1.1\r\n" +
+  "Host: www.example.com\r\n" +
+  "Accept: */*\r\n" +
+	"uuid: full\r\n" +
+  "\r\n",
+  "timestamp": "1469733493.993",
+  "body": ""
+}
+
+res_full = {"headers":
+  "HTTP/1.1 206 Partial Content\r\n" +
+  "Accept-Ranges: bytes\r\n" +
+  'Etag: "foo"\r\n' +
+  "Cache-Control: public, max-age=500\r\n" +
+  "Connection: close\r\n" +
+  "\r\n",
+  "timestamp": "1469733493.993",
+  "body": body
+}
+
+server.addResponse("sessionlog.json", req_full, res_full)
+
+# this request should work
+req_good = {"headers":
+  "GET /path HTTP/1.1\r\n" +
+  "Host: www.example.com\r\n" +
+  "Accept: */*\r\n" +
+  "Range: bytes=0-\r\n" +
+	"uuid: range_full\r\n" +
+  "\r\n",
+  "timestamp": "1469733493.993",
+  "body": ""
+}
+
+res_good = {"headers":
+  "HTTP/1.1 206 Partial Content\r\n" +
+  "Accept-Ranges: bytes\r\n" +
+  'Etag: "foo"\r\n' +
+  "Cache-Control: public, max-age=500\r\n" +
+  "Content-Range: bytes 0-{0}/{0}\r\n".format(bodylen) +
+  "Connection: close\r\n" +
+  "\r\n",
+  "timestamp": "1469733493.993",
+  "body": body
+}
+
+server.addResponse("sessionlog.json", req_good, res_good)
+
+# this request should fail with a cache_range_requests asset
+req_fail = {"headers":
+  "GET /path HTTP/1.1\r\n" +
+  "Host: www.fail.com\r\n" +
+  "Accept: */*\r\n" +
+  "Range: bytes=0-\r\n" +
+	"uuid: range_fail\r\n" +
+  "\r\n",
+  "timestamp": "1469733493.993",
+  "body": ""
+}
+
+res_fail = {"headers":
+  "HTTP/1.1 206 Partial Content\r\n" +
+  "Accept-Ranges: bytes\r\n" +
+  'Etag: "foo"\r\n' +
+  "Cache-Control: public, max-age=500\r\n" +
+  "Content-Range: bytes 0-{0}/{0}\r\n".format(bodylen) +
+  "Connection: close\r\n" +
+  "\r\n",
+  "timestamp": "1469733493.993",
+  "body": body
+}
+
+server.addResponse("sessionlog.json", req_fail, res_fail)
+
+# cache range requests plugin remap, working config
+ts.Disk.remap_config.AddLine(
+  'map http://www.example.com http://127.0.0.1:{}'.format(server.Variables.Port) +
+    ' @plugin=cachekey.so @pparam=--include-headers=Range' +
+    ' @plugin=cache_range_requests.so @pparam=--no-modify-cachekey',
+)
+
+# improperly configured cache_range_requests with cachekey
+ts.Disk.remap_config.AddLine(
+  'map http://www.fail.com http://127.0.0.1:{}'.format(server.Variables.Port) +
+    ' @plugin=cachekey.so @pparam=--static-prefix=foo'
+    ' @plugin=cache_range_requests.so',
+)
+
+# cache debug
+ts.Disk.plugin_config.AddLine('xdebug.so')
+
+# minimal configuration
+ts.Disk.records_config.update({
+  'proxy.config.diags.debug.enabled': 1,
+  'proxy.config.diags.debug.tags': 'cache_range_requests',
+  'proxy.config.http.cache.http': 1,
+  'proxy.config.http.wait_for_cache': 1,
+})
+
+curl_and_args = 'curl -s -D /dev/stdout -o /dev/stderr -x localhost:{} -H "x-debug: x-cache"'.format(ts.Variables.port)
+
+# 0 Test - Fetch full asset into cache (ensure cold)
+tr = Test.AddTestRun("full asset fetch")
+ps = tr.Processes.Default
+ps.StartBefore(server, ready=When.PortOpen(server.Variables.Port))
+ps.StartBefore(Test.Processes.ts, ready=When.PortOpen(ts.Variables.port))
+ps.Command = curl_and_args + ' http://www.example.com/path -H "uuid: full"'
+ps.ReturnCode = 0
+ps.Streams.stdout.Content = Testers.ContainsExpression("X-Cache: miss", "expected cache miss for load")
+tr.StillRunningAfter = ts
+
+# 1 Test - Fetch whole asset into cache via range request (ensure cold)
+tr = Test.AddTestRun("0- asset fetch")
+ps = tr.Processes.Default
+ps.Command = curl_and_args + ' http://www.example.com/path -r 0- -H "uuid: range_full"'
+ps.ReturnCode = 0
+ps.Streams.stdout.Content = Testers.ContainsExpression("X-Cache: miss", "expected cache miss for load")
+tr.StillRunningAfter = ts
+
+# 2 Test - Ensure assert happens instead of possible cache poisoning.
+tr = Test.AddTestRun("Attempt poisoning")
+ps = tr.Processes.Default
+ps.Command = curl_and_args + ' http://www.fail.com/path -r 0- -H "uuid: range_fail"'
+ps.ReturnCode = 0
+tr.StillRunningAfter = ts
+
+ts.Disk.diags_log.Content = Testers.ContainsExpression("ERROR", "error condition hit")
+ts.Disk.diags_log.Content = Testers.ContainsExpression("failed to change the cache url", "ensure failure for misconfiguration")
+ts.Disk.diags_log.Content = Testers.ContainsExpression("Disabling cache for this transaction to avoid cache poisoning", "ensure transaction caching disabled")
diff --git a/tests/gold_tests/pluginTest/cache_range_requests/gold/404.stdout.gold b/tests/gold_tests/pluginTest/cache_range_requests/gold/404.stdout.gold
new file mode 100644
index 00000000000..f188050f072
--- /dev/null
+++ b/tests/gold_tests/pluginTest/cache_range_requests/gold/404.stdout.gold
@@ -0,0 +1,8 @@
+HTTP/1.1 404 Not Found
+Server: ``
+Date: ``
+Age: 0
+Transfer-Encoding: chunked
+Proxy-Connection: ``
+X-Cache: miss
+``
diff --git a/tests/gold_tests/pluginTest/cache_range_requests/gold/frange.stderr.gold b/tests/gold_tests/pluginTest/cache_range_requests/gold/frange.stderr.gold
new file mode 100644
index 00000000000..24ad29c1a82
--- /dev/null
+++ b/tests/gold_tests/pluginTest/cache_range_requests/gold/frange.stderr.gold
@@ -0,0 +1 @@
+lets go surfin now``
diff --git a/tests/gold_tests/pluginTest/cache_range_requests/gold/frange.stdout.gold b/tests/gold_tests/pluginTest/cache_range_requests/gold/frange.stdout.gold
new file mode 100644
index 00000000000..6dae639a9c3
--- /dev/null
+++ b/tests/gold_tests/pluginTest/cache_range_requests/gold/frange.stdout.gold
@@ -0,0 +1,11 @@
+HTTP/1.1 206 Partial Content
+Accept-Ranges: bytes
+Cache-Control: max-age=500
+Content-Range: bytes 0-18/18
+Etag: "772102f4-56f4bc1e6d417"
+Last-Modified: Sat, 23 Jun 2018 09:27:29 GMT
+Content-Length: 18
+Date: ``
+Server: ``
+X-Cache: ``
+``
diff --git a/tests/gold_tests/pluginTest/cache_range_requests/gold/full.stderr.gold b/tests/gold_tests/pluginTest/cache_range_requests/gold/full.stderr.gold
new file mode 100644
index 00000000000..24ad29c1a82
--- /dev/null
+++ b/tests/gold_tests/pluginTest/cache_range_requests/gold/full.stderr.gold
@@ -0,0 +1 @@
+lets go surfin now``
diff --git a/tests/gold_tests/pluginTest/cache_range_requests/gold/full.stdout.gold b/tests/gold_tests/pluginTest/cache_range_requests/gold/full.stdout.gold
new file mode 100644
index 00000000000..a485d263577
--- /dev/null
+++ b/tests/gold_tests/pluginTest/cache_range_requests/gold/full.stdout.gold
@@ -0,0 +1,9 @@
+HTTP/1.1 200 OK
+Cache-Control: max-age=500
+Etag: "772102f4-56f4bc1e6d417"
+Last-Modified: Sat, 23 Jun 2018 09:27:29 GMT
+Content-Length: 18
+Date: ``
+Server: ``
+X-Cache: miss
+``
diff --git a/tests/gold_tests/pluginTest/cache_range_requests/gold/inner.stderr.gold b/tests/gold_tests/pluginTest/cache_range_requests/gold/inner.stderr.gold
new file mode 100644
index 00000000000..1b0ef57a044
--- /dev/null
+++ b/tests/gold_tests/pluginTest/cache_range_requests/gold/inner.stderr.gold
@@ -0,0 +1 @@
+ surfin``
diff --git a/tests/gold_tests/pluginTest/cache_range_requests/gold/inner.stdout.gold b/tests/gold_tests/pluginTest/cache_range_requests/gold/inner.stdout.gold
new file mode 100644
index 00000000000..0628bfad209
--- /dev/null
+++ b/tests/gold_tests/pluginTest/cache_range_requests/gold/inner.stdout.gold
@@ -0,0 +1,11 @@
+HTTP/1.1 206 Partial Content
+Accept-Ranges: bytes
+Cache-Control: max-age=500
+Content-Range: bytes 7-15/18
+Etag: "772102f4-56f4bc1e6d417"
+Last-Modified: Sat, 23 Jun 2018 09:27:29 GMT
+Content-Length: 7
+Date: ``
+Server: ``
+X-Cache: ``
+``
diff --git a/tests/gold_tests/pluginTest/cache_range_requests/gold/last.stderr.gold b/tests/gold_tests/pluginTest/cache_range_requests/gold/last.stderr.gold
new file mode 100644
index 00000000000..9e4c8c43d82
--- /dev/null
+++ b/tests/gold_tests/pluginTest/cache_range_requests/gold/last.stderr.gold
@@ -0,0 +1 @@
+n now``
diff --git a/tests/gold_tests/pluginTest/cache_range_requests/gold/last.stdout.gold b/tests/gold_tests/pluginTest/cache_range_requests/gold/last.stdout.gold
new file mode 100644
index 00000000000..5e2da0005c8
--- /dev/null
+++ b/tests/gold_tests/pluginTest/cache_range_requests/gold/last.stdout.gold
@@ -0,0 +1,11 @@
+HTTP/1.1 206 Partial Content
+Accept-Ranges: bytes
+Cache-Control: max-age=500
+Content-Range: bytes 12-18/18
+Etag: "772102f4-56f4bc1e6d417"
+Last-Modified: Sat, 23 Jun 2018 09:27:29 GMT
+Content-Length: 5
+Date: ``
+Server: ``
+X-Cache: ``
+``
diff --git a/tests/gold_tests/pluginTest/cache_range_requests/gold/pselect.stdout.gold b/tests/gold_tests/pluginTest/cache_range_requests/gold/pselect.stdout.gold
new file mode 100644
index 00000000000..11902d7ec3d
--- /dev/null
+++ b/tests/gold_tests/pluginTest/cache_range_requests/gold/pselect.stdout.gold
@@ -0,0 +1,11 @@
+HTTP/1.1 206 Partial Content
+Accept-Ranges: bytes
+Cache-Control: max-age=500
+Content-Range: bytes 1-10/18
+Etag: "772102f4-56f4bc1e6d417"
+Last-Modified: Sat, 23 Jun 2018 09:27:29 GMT
+Content-Length: 9
+Date: ``
+Server: ``
+X-ParentSelection: ``
+``
diff --git a/tests/gold_tests/pluginTest/cache_range_requests/gold/pselect_none.stdout.gold b/tests/gold_tests/pluginTest/cache_range_requests/gold/pselect_none.stdout.gold
new file mode 100644
index 00000000000..dc9b1559778
--- /dev/null
+++ b/tests/gold_tests/pluginTest/cache_range_requests/gold/pselect_none.stdout.gold
@@ -0,0 +1,10 @@
+HTTP/1.1 206 Partial Content
+Accept-Ranges: bytes
+Cache-Control: ``
+Content-Range: ``
+Etag: ``
+Last-Modified: ``
+Content-Length: ``
+Date: ``
+Server: ``
+``