Changeset 11066 for dotorg/trunk/html/beps/bep_0022.rst

Timestamp:

05/13/2008 04:48:48 PM (8 months ago)

Author:

dave

Message:

change to use reverse DNS followed by DNS query for the SRV record at the host's domain name.

Files:

• dotorg/trunk/html/beps/bep_0022.rst (modified) (4 diffs)

dotorg/trunk/html/beps/bep_0022.rst

@@ -18 +18 @@
 the client, it frees upstream capacity in the user's access network
 benefiting the user and those that share the access network.  When
-peers transfer to or from an ISP cache, the ISP experiences less
-transit traffic.
+subsequent peers transfer from their ISP's cache, the ISP experiences
+less transit traffic.
 
 
@@ -25 +25 @@
 =======================
 
-To find the caches for its ISP, a BitTorrent client running on an ipv4
-host performs a DNS lookup for the SRV resource record at
+To find the caches for its ISP, a BitTorrent client performs a reverse
+DNS lookup on its host's IP address and then obtains the SRV resource
+record associated with the host's domain name.  For example, a host with
+IPv4 address w.x.y.z obtains the PTR record at
 
-  _bittorrent._tcp.w.x.y.z.in-addr.arpa
+::
+  z.y.x.w.in-addr.arpa
 
-where w.x.y.z is replaced with the IPv4 address z.y.x.w of the
-BitTorrent client's host.  The target field in the SRV resource record
-contains the domain name of the cache and the port specifies the
-location on that cache where the BitTorrent implementation listens.
+Assume the returned PTR record contains example.com.  The client then
+looks up the SRV record at
 
-The SRV resource record type is described in `RFC 2782`_.  The
-w.x.y.z.in-addr.arpa portion of the domain name is the same name host
-z.y.x.w would use for host address to host name translation as
-described in `RFC 1034`_.
+:: 
+  _bittorrent._tcp.example.com
 
-If the host implements IPv6 then replace w.x.y.z.in-addr.arpa
-according to the convention specified in `RFC 3596`_.
+The target field in the SRV resource record contains the domain name
+of the cache and the port specifies the location on that cache where
+the BitTorrent implementation listens.
+
+The SRV resource record type is described in `RFC 2782`_.  Reverse DNS
+lookups are described in `RFC 1034`_.
 
 
@@ -52 +55 @@
 ranges defined by IANA, i.e., 10.*.*.*, 172.*.*.*, or 192.*.*.*.  When
 communicating with hosts outside the private network, the NAT
-translates the private IP to an IP address routed by the ISP.  When a
-host sends packets across the public Internet, the packets' source IP
-address is the host's *public IP address*.
+translates the private IP to an IP address that is globally routable.
+This globally routable address is the host's *public IP address*.
 
 When finding a cache, the BitTorrent client must use its host's public
 IP address.  A BitTorrent client can obtain its host's public IP by
 either querying the tracker and looking at the value to the returned
-*external ip* key [#BEP-0024] or from other peers using the *Extension
-Protocol* proposed in [#BEP-0010].  uTorrent and BitTorrent mainline
-implement both methods for determining one's external IP.  libtorrent
-implements the *Extension Protocol*.
+*external ip* key [#BEP-0024] or from other peers using the *yourip*
+extension defined for the *Extension Protocol* proposed in [#BEP-0010].
 
 
@@ -72 +72 @@
    November 1987. http://tools.ietf.org/html/rfc1034
 
-
 .. _`RFC 2782`: A DNS RR for specifying the location of services (DNS
    SRV). Gulbrandsen, Vixie, Esibov. February 2000. 
    http://tools.ietf.org/html/rfc2782
-
-.. _`RFC 3596`: DNS Extensions to Support IP Version 6, Thomson, Huitema, Ksinant, Souissi. 
-   October 2003. http://www.ietf.org/rfc/rfc3596.txt
 
 .. [#BEP-10] BEP_0010.  Extension Protocol. Norberg, Strigeus, Hazel