Changes between Initial Version and Version 1 of QoS

Timestamp:

Oct 28, 2009 11:45:02 PM (15 years ago)

Author:

bennylp

Comment:

--

QoS

@@ +1 @@
+{{{
+#!html
+<!-- MAIN TABLE START -->
+<table border=0 width="90%" align="center"><tr><td>
+}}}
+
+= Support for QoS (TOS/DSCP, WMM, 802.1p) =
+
+'''Table of Contents'''
+[[PageOutline(2-3,,inline)]]
+
+This article describes the QoS support in PJSIP and how to use it.
+
+[[BR]]
+
+== Introduction on QoS ==
+
+QoS settings are available for both Layer 2 and Layer 3 of TCP/IP protocols:
+
+=== Layer 2: IEEE 802.1p for Ethernet ===
+
+IEEE 802.1p tagging will mark frames sent by a host for prioritized delivery using a 3-bit Priority field in the virtual local area network (VLAN) header of the Ethernet frame. The VLAN header is placed inside the Ethernet header, between the Source Address field and either the Length field (for an IEEE 802.3 frame) or the !EtherType field (for an Ethernet II frame).
+
+=== Layer 2: WMM ===
+
+At the Network Interface layer for IEEE 802.11 wireless, the Wi-Fi Alliance certification for Wi-Fi Multimedia (WMM) defines four access categories for prioritizing network traffic. These access categories are (in order of highest to lowest priority) voice, video, best-effort, and background. Host support for WMM prioritization requires that both wireless network adapters and their drivers support WMM. Wireless access points (APs) must have WMM enabled.
+
+=== Layer 3: DSCP ===
+
+At the Internet layer, you can use Differentiated Services/Diffserv and set the value of the Differentiated Services Code Point (DSCP) in the IP header. As defined in RFC 2472, the DSCP value is the high-order 6 bits of the IP version 4 (IPv4) TOS field and the IP version 6 (IPv6) Traffic Class field.
+
+=== Layer 3: Other ===
+
+Other mechanisms exist (such as RSVP, !IntServ) but this will not be implemented.
+
+
+== Availability ==
+
+=== Linux ===
+
+DSCP is available via IP TOS option. 
+
+Ethernet 802.1p tagging is done by setting {{{setsockopt(SO_PRIORITY)}}} option of the socket, then with the {{{set_egress_map option}}} of the {{{vconfig utility}}} to convert this to set vlan-qos field of the packet. 
+
+WMM is not known to be available.
+
+=== MacOS X ===
+
+DSCP is available via IP TOS option. 
+
+=== Windows and Windows Mobile ===
+
+(It's a mess!)
+
+DSCP is settable with {{{setsockopt()}}} on Windows 2000 or older, but Windows would silently ignore this call on WinXP or later, unless administrator modifies the registry. On Windows 2000, Windows XP, and Windows Server 2003, GQoS (Generic QoS) API is the standard API, but this API may not be supported in the future. On Vista and Windows 7, the is a new QoS2 API, also known as Quality Windows Audio-Video Experience (qWAVE).
+
+IEEE 802.1p tagging is available via Traffic Control (TC) API, available on Windows XP SP2, but this needs administrator access. For Vista and later, it's in qWAVE. 
+
+WMM is available for mobile platforms on Windows Mobile 6 platform and Windows Embedded CE 6, via {{{setsockopt(IP_DSCP_TRAFFIC_TYPE)}}}. qWAVE supports this as well.
+
+=== Symbian S60 3rd Ed ===
+
+Both DSCP and WMM is supported via {{{RSocket::SetOpt()}}} with will set both Layer 2 and Layer 3 QoS settings accordingly.
+
+
+== Objective ==
+
+The objective of this ticket is to add new API to PJLIB socket API to enable manipulation of the QoS parameters above in a uniform and portable manner.
+
+
+== Design ==
+
+Based on the above, the following API is proposed.
+
+Declare the following "standard" traffic types.
+
+ {{{
+ typedef enum pj_qos_type
+ {
+    PJ_QOS_TYPE_BEST_EFFORT,
+    PJ_QOS_TYPE_BACKGROUND,
+    PJ_QOS_TYPE_VIDEO,
+    PJ_QOS_TYPE_VOICE,
+    PJ_QOS_TYPE_CONTROL
+ } pj_qos_type;
+ }}}
+
+The traffic classes above will determine how the Layer 2 and 3 QoS settings will be used. The standard mapping between the classes above to the corresponding Layer 2 and 3 settings are as follows:
+
+ || PJLIB Traffic Type    || IP DSCP || WMM || 802.1p  ||
+ || BEST_EFFORT || 0x00    || BE (Bulk Effort) ||   0    ||
+ || BACKGROUND  || 0x08    || BK (Bulk)  ||   2    ||
+ || VIDEO       || 0x28    || VI (Video)   ||   5    ||
+ || VOICE       || 0x30    || VO (Voice)   ||   6    ||
+ || CONTROL     || 0x38    || VO (Voice)   ||   7    ||
+
+There are two sets of API provided to manipulate the QoS parameters. 
+
+=== Portable High Level API ===
+
+The first set of API is:
+
+ {{{
+ // Set QoS parameters
+ PJ_DECL(pj_status_t) pj_sock_set_qos_type(pj_sock_t sock,
+                                           pj_qos_type val);
+
+ // Get QoS parameters
+ PJ_DECL(pj_status_t) pj_sock_get_qos_type(pj_sock_t sock,
+                                           pj_qos_type *p_val);
+ }}}
+
+The API will set the traffic type according to the DSCP class, for '''both''' Layer 2 and Layer 3 QoS settings, where it's available. If any of the layer QoS setting is not settable, the API will silently ignore it. If '''both''' layers are not setable, the API will return error.
+
+The API above is the recommended use of QoS, since it is the most portable across all platforms.
+
+=== Fine Grained Control API ===
+
+The second set of API is intended for application that wants to fine tune the QoS parameters.
+
+The Layer 2 and 3 QoS parameters are stored in {{{pj_qos_params}}} structure:
+
+ {{{
+ typedef enum pj_qos_flag
+ {
+    PJ_QOS_PARAM_HAS_DSCP = 1,
+    PJ_QOS_PARAM_HAS_802_1_P = 2,
+    PJ_QOS_PARAM_HAS_WMM = 4
+ } pj_qos_flag;
+
+ typedef enum pj_qos_wmm_prio
+ {
+    PJ_QOS_WMM_TYPE_BULK_EFFORT_PRIO,
+    PJ_QOS_WMM_TYPE_BULK_PRIO,
+    PJ_QOS_WMM_TYPE_VIDEO_PRIO,
+    PJ_QOS_WMM_TYPE_VOICE_PRIO
+ } pj_qos_wmm_prio;
+
+ typedef struct pj_qos_params
+ {
+    pj_uint8_t      flags;    // Determines which values to 
+                              // set, bitmask of pj_qos_flag
+    pj_uint8_t      dscp_val; // DSCP value to set
+    pj_uint8_t      so_prio;  // SO_PRIORITY value
+    pj_qos_wmm_prio wmm_prio; // WMM priority value
+ } pj_qos_params;
+ }}}
+
+The second set of API with more fine-grained control over the parameters are:
+
+ {{{
+ // Retrieve QoS params for the specified traffic type
+ PJ_DECL(pj_status_t) pj_qos_get_params(pj_qos_type type, 
+                                        pj_qos_params *p);
+
+ // Set QoS parameters to the socket
+ PJ_DECL(pj_status_t) pj_sock_set_qos_params(pj_sock_t sock,
+                                             const pj_qos_params *p);
+
+ // Get QoS parameters from the socket
+ PJ_DECL(pj_status_t) pj_sock_get_qos_params(pj_sock_t sock,
+                                             pj_qos_params *p);
+
+ }}}
+
+ '''Important:'''
+ 
+ The {{{pj_sock_set/get_qos_params()}}} APIs are not portable, and it's probably only going to be implemented on Linux. Application should always try to use {{{pj_sock_set_qos_type()}}} instead.
+
+
+
+== Limitations ==
+
+Win32 may not be implemented due to the API mess above.
+
+== References ==
+
+ 1. [http://technet.microsoft.com/en-gb/magazine/2007.02.cableguy.aspx QoS Support in Windows] - good intro for QoS on Windows and in general
+ 2. [http://msdn.microsoft.com/en-us/library/aa916767.aspx WMM (Wi-Fi Multimedia)] (Windows Mobile 6)
+ 3. [http://wiki.forum.nokia.com/index.php/VoIP_developer_guidelines_for_S60 VoIP developer guidelines for S60]
+ 4. [http://blogs.msdn.com/wndp/archive/2006/06/30/WiFi_QoS_Support_in_Windows_Vista_part_2.aspx WiFi QoS Support in Windows Vista: WMM part 2]
+
+
+
+{{{
+#!html
+<!-- MAIN TABLE END -->
+</td></tr></table>
+}}}
+