[chord] Some questions

[Hai Dao Le]

Thanks for your valuable answer. 
Still, I am confusing about the returned results from 'findroute'. E.g:

Searching for 64f971e0ece9b50ad136746c227682c4ebfc4525 from f2bc0103a87ff62a8102bd0987fbd15b61cd5f2b at 203.237.53.28:3333 (vnode 0)
0: 64f971e0ece9b50ad136746c227682c4ebfc4525 203.237.53.28 3333 21
1: 7c53972f5408f2cd5dbe8c4c124f8faa6d404994 203.237.53.28 3333 14
2: 7feaa3b37154799410aca7d309e4ca1e7e1dd250 203.237.53.28 3333 7
3: 9a1315b6b45a81bed9546c221cde7ff760c0d46e 203.237.53.28 3333 6
4: ab84d5bcca20453c31f124a11c92c81045cb1719 203.237.53.28 3333 5
5: b121eeb7622c578ecd0b4580af293c2c2c287011 203.237.53.28 3333 18
6: b137973c3b36fb1e3ca530c249783b56571a74bd 203.237.53.28 3333 12
7: b78726131dad1b4cac67b1e0b36df36ac2560b9d 203.237.53.28 3333 9
8: b7f1c46b7dd6841fb2fdffd6dc23448cffcebdc9 203.237.53.28 3333 25
9: c147c684c72aabb83f12e05d7e0bcdf3e2ebe8bb 203.237.53.28 3333 27
10: c5b2ac6ac52ca45fc7b40c1e825f8746ee5fd716 203.237.53.28 3333 3
11: c7d47220632440e0cf9eca9b0ebea905b223f245 203.237.53.28 3333 19
12: c9698d3f06bf3c0655e7df19a6fb551dd6e6f0e5 203.237.53.28 3333 20
13: cd3c7adfa12672090111269078a1b0afb9a3a531 203.237.53.28 3333 23
14: d9d8dff4947b1d9e213a55380a444210b0bd7422 203.237.53.28 3333 1
15: e1330498a2d140d2a53ddccc32a8ed5facfa8d4e 203.237.53.28 3333 11
16: 63352430303222afddddcb8830ba78e2c5e1c492 203.237.53.28 3333 28
17: 64f971e0ece9b50ad136746c227682c4ebfc4525 203.237.53.28 3333 21
 key 64f9 rsz 18 64f9 7c53 7fea 9a13 ab84 b121 b137 b787 b7f1 c147 c5b2 c7d4 c96 9 cd3c d9d8 e133 6335 64f9 done 56 msec

I guess this lookup was started from vnode 14 and ended at vnode 21. But my request was from vnode 0! Is the fact that the lookup request is started from a random node in the ring?

Is there any function that I can utilize to measure the pairwise latency between nodes?

Best regards,

Hai

-----Original Message-----
From:	Emil Sit [mailto:sit at MIT.EDU]
Sent:	Sat 11/4/2006 1:25 AM
To:	Hai Dao Le
Cc:	chord at amsterdam.lcs.mit.edu
Subject:	Re: [chord] Some questions
On Wed, 01 November 2006 at 00:08 (+0900), Hai Dao Le wrote:
> 1. How does 'findroute' work? I run this command in some nodes and get
> very similar results. 

findroute simply asks the node to do a lookup.

> 2. Do you think I can use these results for calculating the path length,
> or even the stretch?

findroute should give you the path length.  and from that, if you
have the pairwise latency matrix, you can calculate the stretch.

> 3. Where is the source code of lookup?

It's a little complicated and depends on which lookup
method you are using.  You could start by looking in
route_chord.C.  Ignore anything you see about upcalls
which are currently not used.

-- 
Emil Sit / MIT CSAIL PDOS / http://pdos.csail.mit.edu/chord/