user16451: My question is that where do I focus ? The outer nose or outer nose with upper lip 

user19138: The instruction is: sati-parimukkham, or parimukkham-sati.
This means: mind-around-mouth
It also means: mind-around-face
It also means: mind around the front
It also means: mind around the interface [between the personal and the external]
It also has been interpreted as meaning: mind the business at which you are about (that is minding).
This instruction is found in cases where a formula for meditation is being set forth, not exclusive to minding the in and out breaths.
There is no instruction that reads: 'focus where the breath is felt' or 'at the nose' or at any specific place. Try to focus on the point where the breath passes the nostrils you will quickly see that you cannot find that place. It moves around at light-speed!
That is why the instruction reads "around" (pari). The point is the focus, not the locus. This is also important as a preventive measure: our job here is not to maintain a state of concentration on any object. We are trying to develop concentration (or better, focus) as a skill with a tool to be used in understanding other things. You are not going to Nibbana with your mind focused on your nose!
Follow the instructions without trying to pick it apart and you will see the advantages of minding around the mouth as a starting point, minding the face as a matter of minding the sense-reactions, minding the front as minding the whole body, minding the interface as minding the inter-relations of the body and the external world, and minding your business as keeping you focused on the task. Round and round, up and down, back and forth. A spectrum.

user16297: A correct translation of agama passage EA 17.1 is "pervade the entire body" -- here is the excerpt from my translation at
http://lucid24.org/agama/ea/ea17/ea17-01/index.html

From the agama school, the dhayna samadhi sutra is an excellent representation of how most of the Agama schools understand breath meditation -- i.e. that awareness pervades the entire anatomical physical body) -- in radical contrast to Visuddhimagga's outlier (wrong) view that one should focus only at the nostrils and ignore the entire physical body. 
Excerpt from
http://lucid24.org/sted/16aps/index.html

409 CE Dhyāna Samādhi Sutra  
This is not from the EBT period, but is fully EBT compliant in describing step 3 of 16aps and capturing what is so peaceful, sublime, ambrosia, a brahma dwelling, and the Buddha’s preferred meditation of choice on his retreats.
  Dhyāna Samādhi Sutra (corresponds with Ānāpānā step 3, sabba kāya patisamvedi)
  Dhyāna Samādhi Sutra (chinese to english trans. By Dr. William Chu)  
T15n0614_p0275b25(08)║念諸息遍身。亦念息出入。
  “One is mindfully aware of various breaths suffusing the whole body, as one attends to the exhalation and inhalation of the breath.  
T15n0614_p0275b26(05)║悉觀身中諸出息入息。
  As one pervasively observes the various kinds of inhalation and exhalation inside the body,  
T15n0614_p0275b27(14)║覺知遍至身中乃至足指遍諸毛孔如水入沙。
  one becomes aware and comprehends what is happening throughout the body, up to and including one’s toes and pores—[awareness] pervades as if water seeps into sands.  
T15n0614_p0275b28(13)║息出覺知從足至髮遍諸毛孔亦如水入沙。譬如[夢-夕+棐]囊入出皆滿。
  In the same way, with [each] out-breath, awareness and understanding pervade—from the toes to the hairs, permeating all the pores—as if water seeps into sands. Just like a sack that is completely filled from its bottom to its opening,  
T15n0614_p0275b29(05)║口鼻風入出亦爾。觀身周遍見風行處。
  so too should one experience the body being saturated this way with [each] in-breath coming in from mouth [and/or] nose.  
T15n0614_p0275c01(07)║如藕根孔亦如魚網。復心非獨口鼻觀息入出。
  One should perceive that throughout the body, where ‘wind’ traverses, it is as if it traverses through the holes of a lotus root; it is as if it traverses through the eyes of a fish net.  
T15n0614_p0275c02(06)║一切毛孔及九孔中。亦見息入息出。
  Furthermore, one should not just perceive the breath as going in and out of one’s mouth [and/or] nose; one should also see that the breath comes in and out from all the pores and from the nine orifices of the body.  
T15n0614_p0275c03(09)║是故知息遍諸身
  For this reason, one should understand that the breath pervades throughout the body."


In SN 54, the Anapana Samyutta, prior to this sutta in the first 9 suttas, the 16 steps of 16 APS have not been associated with the 4 tetrads of 4sp (satipatthana, right mindfulness). So the first thing to understand about this context is that the Buddha is trying to explain how the breath is related to each of the 4 tetrads. One might question, how is the breath related to the anatomical body (kāya)? So the Buddha explains that the breath is also a type of body. One might question, how is vedana (feeling) a breath? And the Buddha explains the breath is a certain type of feeling. One might question how is the breath related to the tetrad of citta-anupassana, and so on. So in saying that the breath is one type of body, the context here is trying to justify how the breath ties in to 4sp (satipatthana) practice in general, how it ties in to kāya anupassana (body contemplation). He’s not trying to redefine the default definition of body understood as physical.
The second thing to notice is that the Buddha is saying the breath is a type of kāya (body), is ONE type of body, among the already established understanding of body as being composed of 4 elements. He is not overriding the definition of kāya here, he is not saying breath is the only type of body, and he certainly didn’t say in this context breath is the whole body and the anatomical body should be discarded from meditative awareness.
The third thing to notice, even if we want to practice 16 APS taking the breath to be the only part of the physical body that we’re contemplating, ignoring the remaining 3 of the 4 elements, this body of breath has shape, dimension, occupying the same physical space as our anatomical body.

detailed comprehensive analysis on term 'pari mukha'
http://lucid24.org/tped/p/parimukha/book/index.html

16451: <p>My question is that where do I focus ? The outer nose or outer nose with upper lip </p>
 19138: <p>The instruction is: sati-parimukkham, or parimukkham-sati.<br />
This means: mind-around-mouth<br />
It also means: mind-around-face<br />
It also means: mind around the front<br />
It also means: mind around the interface [between the personal and the external]<br />
It also has been interpreted as meaning: mind the business at which you are about (that is minding).</p>

<p>This instruction is found in cases where a formula for meditation is being set forth, not exclusive to minding the in and out breaths.</p>

<p>There is no instruction that reads: 'focus where the breath is felt' or 'at the nose' or at any specific place. Try to focus on the point where the breath passes the nostrils you will quickly see that you cannot find that place. It moves around at light-speed!</p>

<p>That is why the instruction reads "around" (pari). The point is the focus, not the locus. This is also important as a preventive measure: our job here is not to maintain a state of concentration on any object. We are trying to develop concentration (or better, focus) as a skill with a tool to be used in understanding other things. You are not going to Nibbana with your mind focused on your nose!</p>

<p>Follow the instructions without trying to pick it apart and you will see the advantages of minding around the mouth as a starting point, minding the face as a matter of minding the sense-reactions, minding the front as minding the whole body, minding the interface as minding the inter-relations of the body and the external world, and minding your business as keeping you focused on the task. Round and round, up and down, back and forth. A spectrum.</p>
 16297: <p>A correct translation of agama passage EA 17.1 is "pervade the entire body" -- here is the excerpt from my translation at
<a href="http://lucid24.org/agama/ea/ea17/ea17-01/index.html" rel="nofollow noreferrer">http://lucid24.org/agama/ea/ea17/ea17-01/index.html</a></p>

<p><a href="https://i.stack.imgur.com/02Hyl.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/02Hyl.png" alt="enter image description here"></a></p>

<p>From the agama school, the dhayna samadhi sutra is an excellent representation of how most of the Agama schools understand breath meditation -- i.e. that awareness pervades the entire anatomical physical body) -- in radical contrast to Visuddhimagga's outlier (wrong) view that one should focus only at the nostrils and ignore the entire physical body. </p>

<p>Excerpt from
<a href="http://lucid24.org/sted/16aps/index.html" rel="nofollow noreferrer">http://lucid24.org/sted/16aps/index.html</a></p>

<blockquote>
  <p>409 CE Dhyāna Samādhi Sutra  </p>
  
  <p>This is not from the EBT period, but is fully EBT compliant in describing step 3 of 16aps and capturing what is so peaceful, sublime, ambrosia, a brahma dwelling, and the Buddha’s preferred meditation of choice on his retreats.<br>
  Dhyāna Samādhi Sutra (corresponds with Ānāpānā step 3, sabba kāya patisamvedi)
  Dhyāna Samādhi Sutra (chinese to english trans. By Dr. William Chu)  </p>
  
  <p>T15n0614_p0275b25(08)║念諸息遍身。亦念息出入。<br>
  “One is mindfully aware of various breaths suffusing the whole body, as one attends to the exhalation and inhalation of the breath.  </p>
  
  <p>T15n0614_p0275b26(05)║悉觀身中諸出息入息。<br>
  As one pervasively observes the various kinds of inhalation and exhalation inside the body,  </p>
  
  <p>T15n0614_p0275b27(14)║覺知遍至身中乃至足指遍諸毛孔如水入沙。<br>
  one becomes aware and comprehends what is happening throughout the body, up to and including one’s toes and pores—[awareness] pervades as if water seeps into sands.  </p>
  
  <p>T15n0614_p0275b28(13)║息出覺知從足至髮遍諸毛孔亦如水入沙。譬如[夢-夕+棐]囊入出皆滿。<br>
  In the same way, with [each] out-breath, awareness and understanding pervade—from the toes to the hairs, permeating all the pores—as if water seeps into sands. Just like a sack that is completely filled from its bottom to its opening,  </p>
  
  <p>T15n0614_p0275b29(05)║口鼻風入出亦爾。觀身周遍見風行處。<br>
  so too should one experience the body being saturated this way with [each] in-breath coming in from mouth [and/or] nose.  </p>
  
  <p>T15n0614_p0275c01(07)║如藕根孔亦如魚網。復心非獨口鼻觀息入出。<br>
  One should perceive that throughout the body, where ‘wind’ traverses, it is as if it traverses through the holes of a lotus root; it is as if it traverses through the eyes of a fish net.  </p>
  
  <p>T15n0614_p0275c02(06)║一切毛孔及九孔中。亦見息入息出。<br>
  Furthermore, one should not just perceive the breath as going in and out of one’s mouth [and/or] nose; one should also see that the breath comes in and out from all the pores and from the nine orifices of the body.  </p>
  
  <p>T15n0614_p0275c03(09)║是故知息遍諸身<br>
  For this reason, one should understand that the breath pervades throughout the body."</p>
</blockquote>

<p><a href="https://i.stack.imgur.com/ST5Al.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/ST5Al.png" alt="enter image description here"></a></p>

<p>In SN 54, the Anapana Samyutta, prior to this sutta in the first 9 suttas, the 16 steps of 16 APS have not been associated with the 4 tetrads of 4sp (satipatthana, right mindfulness). So the first thing to understand about this context is that the Buddha is trying to explain how the breath is related to each of the 4 tetrads. One might question, how is the breath related to the anatomical body (kāya)? So the Buddha explains that the breath is also a type of body. One might question, how is vedana (feeling) a breath? And the Buddha explains the breath is a certain type of feeling. One might question how is the breath related to the tetrad of citta-anupassana, and so on. So in saying that the breath is one type of body, the context here is trying to justify how the breath ties in to 4sp (satipatthana) practice in general, how it ties in to kāya anupassana (body contemplation). He’s not trying to redefine the default definition of body understood as physical.
The second thing to notice is that the Buddha is saying the breath is a type of kāya (body), <strong><em>is ONE type of body</em></strong>, among the already established understanding of body as being composed of 4 elements. He is not overriding the definition of kāya here, <strong><em>he is not saying breath is the only type of body, and he certainly didn’t say in this context breath is the whole body and the anatomical body should be discarded from meditative awareness</em></strong>.
The third thing to notice, even if we want to practice 16 APS taking the breath to be the only part of the physical body that we’re contemplating, ignoring the remaining 3 of the 4 elements, this body of breath has shape, dimension, occupying the same physical space as our anatomical body.</p>

<p><a href="https://i.stack.imgur.com/o4yHP.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/o4yHP.png" alt="enter image description here"></a></p>

<p>detailed comprehensive analysis on term 'pari mukha'
<a href="http://lucid24.org/tped/p/parimukha/book/index.html" rel="nofollow noreferrer">http://lucid24.org/tped/p/parimukha/book/index.html</a></p>
