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Á¦¸ñ LTE QoS (1Æí) - EPS Bearer¿Í SDF
ÀÛ¼ºÀÏÀÚ 2014-08-20

À¯¼±Åë½Å¸ÁÀÌ´ø ¹«¼±Åë½Å¸ÁÀÌ´ø ¸ðµÎ Ç¥ÁØ(IETF RFC, IEEE 802, 3GPP, NWGµî)¿¡ ±â¹ÝÇÑ QoS ±â´ÉÀ» Á¦°øÇÕ´Ï´Ù. Åë½Å ¹æ½Ä(À¯¼± Ethernet/IP/MPLS, ¹«¼± LTE/WiBro/Wi-Fi)¿¡ µû¶ó ±× Ç¥ÁØ°ú ¹æ½ÄÀÇ Â÷ÀÌÁ¡Àº ÀÖ°ÚÀ¸³ª QoS´Â °á±¹ (1) µ·À» ¸¹À̳½ °¡ÀÔÀÚÀÇ Æ®·¡ÇÈÀº ±× Ç°ÁúÀ» º¸ÀåÇØ ÁÖ°Ú´Ù. (2) Áß¿äÇÑ ¼­ºñ½º Æ®·¡ÇÈÀº ±× Ç°ÁúÀ» º¸ÀåÇØ ÁÖ°Ú´Ù(Voice³ª Video Æ®·¡ÇÈÀº Internet Æ®·¡ÇȺ¸´Ù ¼ÒÁßÇϴϱî...). ÀÔ´Ï´Ù.



»ç½Ç (1)¹øÀº ±×¸® ÀϹÝÀûÀÌÁö ¾ÊÀ» °Í °°±¸¿ä(¿ì¸®°¡ Åë½Å»ç¾÷ÀÚ¿¡ ¼­ºñ½º °¡ÀÔÇÒ¶§ µ· ¸¹ÀÌ ³»¸é QoS º¸ÀåÇØ ÁÖ°Ú´Ù´Â »óÇ°Àº ¾øÀݾƿä). º¸Åë Åë½Å»ç¾÷ÀÚ´Â (2)¹øÀ» À§ÇØ QoS¸¦ »ç¿ëÇÕ´Ï´Ù. À¯¼±¸Á¿¡¼­ °¡Àå ÀϹÝÀûÀ¸·Î QoS°¡ Àû¿ëµÇ´Â °ÍÀÌ ¾Æ¸¶µµ VoIP³ª IPTV ¼­ºñ½º ÀÏ°ÍÀÔ´Ï´Ù. ÀúÈñ ÁýÀº KT IPTV¸¦ ÀÌ¿ëÇÏ°í Àִµ¥¿ä. KT´Â ÀÎÅÍ³Ý Æ®·¡ÇÈ¿¡ ºñÇؼ­ IPTV(Live & VoD) Æ®·¡ÇÈÀÇ QoS µî±ÞÀ» ´õ ³ô¿©¼­(L2 ±¸°£¿¡¼­´Â 802.1p·Î, IP ±¸°£¿¡¼­´Â DSCP·Î, MPLS ±¸°£¿¡¼­´Â MPLS headerÀÇ EXP Çʵ带 ÀÌ¿ëÇÏ¿© Â÷º°È­ÇÔ) ÀÎÅÍ³Ý Æ®·¡ÇÈÀÌ ¾Æ¹«¸® ¸¹¾Æµµ IPTV Æ®·¡ÇÈÀÇ Ç°ÁúÀ» º¸ÀåÇÕ´Ï´Ù. ±×·¡¼­ Àú´Â ²÷±è¾øÀÌ ¸ðÀÚÀÌÅ© ¾øÀÌ ¼Ò³à½Ã´ë¸¦ Àß º¼ ¼ö ÀÖ¾ú½À´Ï´Ù. ^^*



ÀÚ ÀÌÁ¦ ¹«¼±Åë½Å¼­ºñ½ºÀÎ LTE¿¡¼­ÀÇ QoS¸¦ »ìÆì º¸µµ·Ï ÇÏ°Ú½À´Ï´Ù. ¿À´ÃÀº LTE QoS¿¡ ±âº»ÀûÀÎ ¼³¸í¸¸ µå¸®±¸¿ä, ÀÌÈÄ ÈļÓÆí¿¡¼­ LTE QoS¿¡ ´ëÇØ ½Éµµ±í°Ô ±â¼úµéÀ» ¼³¸í µå¸®µµ·Ï ÇÏ°Ù½À´Ï´Ù.






 

Àü¿¡µµ ¼³¸íµå¸° ¹Ù¿Í °°ÀÌ UE°¡ LTE ¸Á¿¡ Á¢¼ÓÀ» Çϸé UEºÎÅÍ P-GW±îÁö(UE - eNB - S-GW - P-GW) EPS Bearer¶ó´Â°Ô »ý¼ºÀÌ µË´Ï´Ù(GTP ¹æ½ÄÀÇ ÅͳÎ). ±×¸®°í ÀÌ EPS Bearer´Â UE´ç Çϳª¸¸ »ý¼ºµÇÁö ¾Ê°í °¢ ¼­ºñ½º Ư¼º¿¡ µû¶ó ¿©·¯°³°¡ »ý¼ºÀÌ µÉ ¼öµµ ÀÖ½À´Ï´Ù(¿¹¸¦ µé¾î, Internet¿ë EPS Bearer, IPTV¿ë EPS Bearer, VoIP¿ë EPS Bearer.... ÀÌ°Ç Åë½Å»ç¾÷ÀÚÀÇ Á¤Ã¥ÀÔ´Ï´Ù.). ÀÌ EPS Bearer´Â »ý¼ºµÇ´Â ½ÃÁ¡¿¡ µû¶ó 2°¡Áö Á¾·ùÀÇ Bearer°¡ Á¸ÀçÇÕ´Ï´Ù.



Default EPS Bearer

  • ´Ü¸»(UE)ÀÌ LTE¸Á¿¡ Á¢¼ÓÇÏ¸é ¹«Á¶°Ç ÇϳªÀÇ EPS Bearer°¡ »ý¼ºµÇ¾î¾ß Çϸç, ÀÌ Bearer¸¦ "Default EPS Bearer"¶ó°í ÇÕ´Ï´Ù. ±×¸®°í ÀÌ Bearer´Â UE°¡ ¸Á¿¡¼­ ºüÁ®³ª¿À±â(Detach) Àü±îÁö À¯ÁöµË´Ï´Ù.
  • Default EPS BearerÀÇ QoS Ư¼ºÀº Non-GBR(Non-Guaranteed Bit Rate) ÀÔ´Ï´Ù. Áï, Best Effort (Ç°ÁúÀ» º¸ÀåÇÒ ¼ö ¾ø´Â) Ư¼ºÀ» °¡Áý´Ï´Ù.

 

Dedicated EPS Bearer

  • Default EPS Bearer°¡ »ý¼ºµÈ ÈÄ¿¡ Ãß°¡ÀûÀ¸·Î ÇÊ¿ä½Ã »ý¼ºµÇ´Â Bearer¸¦ Dedicated EPS Bearer¶ó°í ÇÕ´Ï´Ù. ¿¹¸¦ µé¾î, óÀ½ LTE ¸Á¿¡¼­ Á¢¼ÓÇÑ UE´Â Internet¿ëÀ¸·Î Default EPS Bearer¸¸ »ý¼ºÀÌ µË´Ï´Ù. ±×·±µ¥ ÀÌÈÄ UE°¡ Voice(VoIP) ¼­ºñ½º¸¦ »ç¿ëÇÏ·Á ÇÕ´Ï´Ù. ±×¸®°í ÀÌ Voice ¼­ºñ½º´Â Internet ¼­ºñ½º¿¡ ºñÇØ QoS Ç°ÁúÀÌ ÁÁ¾Æ¾ß ÇϹǷΠInternet¿ë Default EPS Bearer¸¦ ÅëÇØ ¼­ºñ½º°¡ µÉ ¼ö ¾ø½À´Ï´Ù. µû¶ó¼­ ÀÌ °æ¿ì, On-demand·Î Voice¿ë Dedicated EPS Bearer°¡ »ý¼ºµÉ ¼ö ÀÖ½À´Ï´Ù.
  • Dedicated EPS Bearer´Â GBR·Î »ý¼ºµÉ ¼öµµ ÀÖ°í, Non-GBR·Î »ý¼ºµÉ ¼öµµ ÀÖ½À´Ï´Ù. À§ÀÇ ¿¹¿Í °°ÀÌ Voice¸¦ À§ÇÑ Dedicated EPS Bearer¶ó¸é GBR·Î »ý¼ºÀÌ µÇ¾î¾ß QoS Ç°ÁúÀ» º¸Àå ¹ÞÀ» ¼ö ÀÖÀ» °ÍÀÔ´Ï´Ù.



EPS Bearer´Â UE¿Í P-GW°£¿¡ »ý¼ºµÇ´Â Åͳηνá, ÀÌ ÅͳÎ(EPS Bearer)À» ÅëÇØ ´Ù¾çÇÑ Á¾·ùÀÇ Æ®·¡ÇÈ(5-tuple·Î ±¸ºÐµÇ´Â Æ®·¡ÇÈ)ÀÌ Áö³ª ´Ù´Ï°Ô µË´Ï´Ù. ÀÌ ´Ù¾çÇÑ Á¾·ùÀÇ Æ®·¡ÇÈÀ» IP flow¶ó°í ºÎ¸£°í, ÀÌ IP flow´Â ÆÐŶÀÇ 5-tuple (Source IP, Destination IP, Protocol ID, Source Port, Destination Port)·Î ±¸ºÐµË´Ï´Ù. ¿¹¸¦ µéÀÚ¸é, ¾î¶² UE°¡ ³×À̹ö¿¡ Á¢¼ÓÀ» ÇÑ´Ù¸é 5-tupleÀº ¾Æ·¡¿Í °°°Ô µÉ °ÍÀÌ°í ÀÌ Æ®·¡ÇÈÀÌ ÇϳªÀÇ IP flow·Î Á¤ÀÇ µÇ´Â °ÍÀÔ´Ï´Ù.

  • Source IP = UE IP ÁÖ¼Ò
  • Destination IP = ³×À̹ö ¼­¹ö IP ÁÖ¼Ò
  • Protocol ID = 6 (TCP¸¦ ÀǹÌÇÔ)
  • Source Port = Random number (Ephemeral port number)
  • Destination Port = 80 (WWWÀ» ÀǹÌÇÔ)



IP Flow¿Í SDF(Service Data Flow)



±×·¸´Ù¸é ÇϳªÀÇ UE°¡ »ç¿ëÇÏ´Â ÀÀ¿ë(¼­ºñ½º)¿¡ µû¶ó(¼Û¼ö½ÅÇÏ´Â Æ®·¡ÇÈ¿¡ µû¶ó), ¸Å¿ì ¸¹Àº °³¼öÀÇ IP flowµéÀÌ Á¸ÀçÇÏ°Ô µÉ °ÍÀä(³×À̹ö Á¢¼Ó, ´ÙÀ½ Á¢¼Ó, Ä«Åå, °ÔÀÓ, VoIP, YouTube µîµî). ÀÌ IP flowµéÀº P-GWÀÇ 5-tuple ±â¹ÝÀÇ classifier(ÀÏ¹Ý À¯¼± ÀåºñÀÇ ACLÀ̶ó°í º¸½Ã¸é µÊ)¿¡ ÀÇÇؼ­ SDF(Service Data Flow)·Î ¸ÅÇÎÀÌ µË´Ï´Ù. ÀÌ 5-tuple ±â¹ÝÀÇ classifier¸¦ LTE¿¡¼­´Â SDF TemplateÀ̶ó°í ºÎ¸¨´Ï´Ù. ÀÌ·¸°Ô ¿©·¯°³ÀÇ IP flowµéÀÌ °¢°¢ 5-tuple ±â¹ÝÀ¸·Î ºÐ·ùµÇ¾î SDF·Î ¸ÅÇÎÀÌ µÇ¸é, ÀÌÁ¦ P-GW´Â SDF º°·Î QoS¸¦ ó¸®ÇÏ°í(QoS ó¸® ¹æ¹ýÀº ´ÙÀ½ ½Ã°£¿¡...) ±× SDF°¡ EPS Bearer·Î ¸ÅÇÎÀÌ µÇ¾î UE±îÁö Àü´ÞµÇ°Ô µË´Ï´Ù.

P-GW¿¡¼­ SDFº°·Î QoS 󸮰¡ µÈ ÈÄ ESP Bearer·Î ¸ÅÇÎÀÌ µÇ¸é, P-GW¿¡¼­ UE±îÁö´Â SDF°¡ º¸ÀÌÁö ¾Ê°í EPS Bearer ´ÜÀ§·Î QoS 󸮰¡ µË´Ï´Ù.


 
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