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Re: [dna] #9: Detailed description of ND packets
There is an issue in Section 4.5.1. This section should also describe the
link layer addresses in the NS packet, to make clear that the NS is
sent to the previously cached link layer address of the router (NOT to
a multicast address).
" The probing node SHOULD NOT include a Source link-layer address
option if it has not performed duplicate address detection [RFC4862],
for the source address of the NS, on the newly attached link."
In DNAv4 (RFC 4436), the goal was not only to detect network attachment, but
also to establish bi-directional reachability. By not including the Source
link-layer address, Simple DNA does not achieve this goal.
Assuming that the NS is sent to a unicast MAC address of the target router,
it will not
be received unless the host is attached to the router from which it had
previously
obtained an address. Assuming that the host had previously done duplicate
address
detection and that the address is still presumed operable (e.g. this wasn't
done so
long ago as to be useless), then there is no risk of neighbor cache
pollution.
Either the NS packet vanishes into space, or it is received by the router to
which
it was addressed, with little risk of neighbor cache pollution.
Given this, it would seem to me that in any situation in which an NS probe
would be
recommended, the Source link-layer address should be included. Where
duplicate
address detection was never performed, or where it is no longer valid, there
is
no address to confirm, so that doing simple DNAv6 doesn't make sense.
-----Original Message-----
From: dna-bounces@ietf.org [mailto:dna-bounces@ietf.org] On Behalf Of dna
issue tracker
Sent: Sunday, November 02, 2008 6:10 PM
To: suresh.krishnan@ericsson.com
Cc: dna@ietf.org
Subject: Re: [dna] #9: Detailed description of ND packets
#9: Detailed description of ND packets
------------------------------------------+---------------------------------
Reporter: suresh.krishnan@ericsson.com | Owner: Suresh Krishnan
Type: defect | Status: closed
Priority: major | Milestone:
Component: simple | Version:
Severity: Active WG Document | Resolution: fixed
Keywords: |
------------------------------------------+---------------------------------
Changes (by suresh.krishnan@ericsson.com):
* status: new => closed
* resolution: => fixed
Comment:
4.5. Contents of the Neighbor Discovery messages
4.5.1. Neighbor Solicitation messages
This section describes the contents of the neighbor solicitation
probe messages sent during the probing procedure.
Source Address: A link-local address assigned to the
probing host.
Destination Address: The link-local address of the router being
probed as learnt from the SDAT.
Hop Limit: 255
ND Options:
Target Address: The link-local address of the router being
probed as learnt from the SDAT.
The probing node SHOULD NOT include a Source link-layer address
option if it has not performed duplicate address detection [RFC4862],
for the source address of the NS, on the newly attached link.
4.5.2. Router Solicitation messages
This section describes the contents of the router solicitation probe
message sent during the probing procedure.
Source Address: A link-local address assigned to the
probing host.
Destination Address: The all-routers multicast address.
Hop Limit: 255
The probing node SHOULD NOT include a Source link-layer address
option if it has not performed duplicate address detection [RFC4862],
for the source address of the NS, on the newly attached link.
--
Ticket URL: <http://svn.tools.ietf.org/wg/dna/trac/ticket/9#comment:1>
dna <http://tools.ietf.org/dna/>
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