(usagi-users 03413) Re: Source address for neighbor solicitations

[Noriaki TAKAMIYA <takamiya@xxxxxxxxxxxxx>]

Hi,

>> Wed, 22 Jun 2005 10:41:27 +0200
>> [Subject: (usagi-users 03412) Source address for neighbor solicitations]
>> Ignacy Gawedzki <ig@xxxxxx> wrote...

=> I know that routers MUST have a link-local address on each interface, but

  As you know, RFC 3513 says...
--------------------------------------------------
2.8 A Node's Required Addresses

   A host is required to recognize the following addresses as
   identifying itself:

      o  Its required Link-Local Address for each interface.

   A router is required to recognize all addresses that a host is
   required to recognize, plus the following addresses as identifying
   itself:
--------------------------------------------------

=> in case a router doesn't, shouldn't it use any global address available to
=> send the NS instead of just silently failing?

  The following will help this:

  In RFC2461:
--------------------------------------------------
4.3.  Neighbor Solicitation Message Format
:
   IP Fields:

      Source Address
                     Either an address assigned to the interface from
                     which this message is sent or (if Duplicate Address
                     Detection is in progress [ADDRCONF]) the
                     unspecified address.
:
7.2.2.  Sending Neighbor Solicitations
:
   If the source address of the packet prompting the solicitation is the
   same as one of the addresses assigned to the outgoing interface, that
   address SHOULD be placed in the IP Source Address of the outgoing
   solicitation.  Otherwise, any one of the addresses assigned to the
   interface should be used.  Using the prompting packet's source
   address when possible insures that the recipient of the Neighbor
   Solicitation installs in its Neighbor Cache the IP address that is
   highly likely to be used in subsequent return traffic belonging to
   the prompting packet's "connection".
--------------------------------------------------
Noriaki Takamiya