Changes between Version 13 and Version 14 of Ticket #950


Ignore:
Timestamp:
Oct 29, 2009 12:40:55 AM (15 years ago)
Author:
bennylp
Comment:

Legend:

Unmodified
Added
Removed
Modified

  • Ticket #950 – Description

    v13 v14  
    1 '''QoS Technologies''' 
    2  QoS settings are available for both Layer 2 and Layer 3 of TCP/IP protocols: 
    3  
    4  '''Layer 2: IEEE 802.1p for Ethernet''' 
    5  
    6  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). 
    7  
    8  '''Layer 2: WMM''' 
    9  
    10  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. 
    11  
    12  '''Layer 3: DSCP''' 
    13  
    14  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. 
    15  
    16  '''Layer 3: Other''' 
    17  
    18  Other mechanisms exist (such as RSVP, !IntServ) but this will not be implemented. 
    19  
    20  
    21 '''Availability''' 
    22  
    23  '''Linux''' 
    24  
    25  DSCP is available via IP TOS option.  
    26  
    27  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.  
    28  
    29  WMM is not known to be available. 
    30  
    31  '''MacOS X''' 
    32  
    33  DSCP is available via IP TOS option.  
    34  
    35  '''Windows''' 
    36  
    37  (It's a mess!) 
    38  
    39  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). 
    40  
    41  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.  
    42  
    43  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. 
    44  
    45  '''Symbian S60 3rd Ed''' 
    46  
    47  Both DSCP and WMM is supported via {{{RSocket::SetOpt()}}} with will set both Layer 2 and Layer 3 QoS settings accordingly. 
    48  
    49  
    50 '''Objective''' 
    51  
    52  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. 
    53  
    54  
    55 '''Design''' 
    56  
    57  Based on the above, the following API is proposed. 
    58  
    59  Declare the following "standard" traffic types. 
    60  
    61  {{{ 
    62  typedef enum pj_qos_type 
    63  { 
    64     PJ_QOS_TYPE_BEST_EFFORT, 
    65     PJ_QOS_TYPE_BACKGROUND, 
    66     PJ_QOS_TYPE_VIDEO, 
    67     PJ_QOS_TYPE_VOICE, 
    68     PJ_QOS_TYPE_CONTROL 
    69  } pj_qos_type; 
    70  }}} 
    71  
    72  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: 
    73  
    74  || PJLIB Traffic Type    || IP DSCP || WMM || 802.1p  || 
    75  || BEST_EFFORT || 0x00    || BE (Bulk Effort) ||   0    || 
    76  || BACKGROUND  || 0x08    || BK (Bulk)  ||   2    || 
    77  || VIDEO       || 0x28    || VI (Video)   ||   5    || 
    78  || VOICE       || 0x30    || VO (Voice)   ||   6    || 
    79  || CONTROL     || 0x38    || VO (Voice)   ||   7    || 
    80  
    81  There are two sets of API provided to manipulate the QoS parameters.  
    82  
    83  '''Portable API''' 
    84  
    85  The first set of API is: 
    86  
    87  {{{ 
    88  // Set QoS parameters 
    89  PJ_DECL(pj_status_t) pj_sock_set_qos_type(pj_sock_t sock, 
    90                                            pj_qos_type val); 
    91  
    92  // Get QoS parameters 
    93  PJ_DECL(pj_status_t) pj_sock_get_qos_type(pj_sock_t sock, 
    94                                            pj_qos_type *p_val); 
    95  }}} 
    96  
    97  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. 
    98  
    99  The API above is the recommended use of QoS, since it is the most portable across all platforms. 
    100  
    101  '''Fine Grained Control API''' 
    102  
    103  The second set of API is intended for application that wants to fine tune the QoS parameters. 
    104  
    105  The Layer 2 and 3 QoS parameters are stored in {{{pj_qos_params}}} structure: 
    106  
    107  {{{ 
    108  typedef enum pj_qos_flag 
    109  { 
    110     PJ_QOS_PARAM_HAS_DSCP = 1, 
    111     PJ_QOS_PARAM_HAS_802_1_P = 2, 
    112     PJ_QOS_PARAM_HAS_WMM = 4 
    113  } pj_qos_flag; 
    114  
    115  typedef enum pj_qos_wmm_prio 
    116  { 
    117     PJ_QOS_WMM_TYPE_BULK_EFFORT_PRIO, 
    118     PJ_QOS_WMM_TYPE_BULK_PRIO, 
    119     PJ_QOS_WMM_TYPE_VIDEO_PRIO, 
    120     PJ_QOS_WMM_TYPE_VOICE_PRIO 
    121  } pj_qos_wmm_prio; 
    122  
    123  typedef struct pj_qos_params 
    124  { 
    125     pj_uint8_t      flags;    // Determines which values to  
    126                               // set, bitmask of pj_qos_flag 
    127     pj_uint8_t      dscp_val; // DSCP value to set 
    128     pj_uint8_t      so_prio;  // SO_PRIORITY value 
    129     pj_qos_wmm_prio wmm_prio; // WMM priority value 
    130  } pj_qos_params; 
    131  }}} 
    132  
    133  The second set of API with more fine-grained control over the parameters are: 
    134  
    135  {{{ 
    136  // Retrieve QoS params for the specified traffic type 
    137  PJ_DECL(pj_status_t) pj_qos_get_params(pj_qos_type type,  
    138                                         pj_qos_params *p); 
    139  
    140  // Set QoS parameters to the socket 
    141  PJ_DECL(pj_status_t) pj_sock_set_qos_params(pj_sock_t sock, 
    142                                              const pj_qos_params *p); 
    143  
    144  // Get QoS parameters from the socket 
    145  PJ_DECL(pj_status_t) pj_sock_get_qos_params(pj_sock_t sock, 
    146                                              pj_qos_params *p); 
    147  
    148  }}} 
    149  
    150  '''Important:''' 
    151   
    152  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. 
    153  
    154  
    155  
    156 '''Limitations''' 
    157  
    158  Win32 may not be implemented due to the API mess above. 
    159  
    160 '''References''' 
    161  
    162  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 
    163  2. [http://msdn.microsoft.com/en-us/library/aa916767.aspx WMM (Wi-Fi Multimedia)] (Windows Mobile 6) 
    164  3. [http://wiki.forum.nokia.com/index.php/VoIP_developer_guidelines_for_S60 VoIP developer guidelines for S60] 
    165  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] 
     1Please see [wiki:QoS] for the detailed description.