#!/usr/bin/perl
#
# $Copyright_v6PC$
#
# $Copyright$
#
# $TAHI: ct/nd/recvNaRFlag.seq,v 1.44 2004/04/02 02:28:23 akisada Exp $

########################################################################
BEGIN { $V6evalTool::TestVersion = '$Name:  $ '; }
 
use V6evalTool;
use nd;

ndOptions(@ARGV);

# The following generate debugging messages.
$nd::debug=$ndOpt_v|$ndOpt_vv;

# You can specifies debug options to a remote control program.
# If you want to know more detail, please see the following:
# - V6evalTool.pm: perldoc V6evalTool
# - V6evalRemote.pm: perldoc V6evalRemote
$nd::remote_debug="-o1" if $ndOpt_vv;

$IF=Link0;

$wait_echo=2;
$wait_ns=$nd::DELAY_FIRST_PROBE_TIME +
    ($nd::RETRANS_TIMER * $nd::MAX_SOLICIT) + 1;

$exit_rtn=$V6evalTool::exitPass;

#
#
#
#$type=$V6evalTool::NutDef{Type};
#if($type eq 'router') {
#    vLogHTML("This test is for the host only<BR>");
#    exit $V6evalTool::exitHostOnly;
#}

$type=$V6evalTool::NutDef{Type};
if($type ne 'host') {
#    vLogHTML(ndErrmsg("ERROR: $V6evalTool::NutDef{Type}: ".
#		      "Unknown target type<BR>"));
#    exit $V6evalTool::exitFail;
    vLogHTML("This test is for the host only<BR>");
    exit $V6evalTool::exitHostOnly;
}

#
#
#
$idx_ptn=0;
$idx_chg=1;
$idx_exp=2;
$idx_bin=3;
$idx_msg=4;

#
@def_unicast_na_tn2nut_rso=
    (
     unicast_na_tn2nut_rso,
     same,
     updated,
     $V6evalTool::exitFail,
     'unicast rso NA w/o TLL',
     );

#
@def_unicast_na_tn2nut_rsO=
    (
     unicast_na_tn2nut_rsO,
     same,
     updated,
     $V6evalTool::exitFail,
     'unicast rsO NA w/o TLL',
     );

#
@def_unicast_na_tn2nut_rSo=
    (
     unicast_na_tn2nut_rSo,
     same,
     updated,
     $V6evalTool::exitFail,
     'unicast rSo NA w/o TLL',
     );

#
@def_unicast_na_tn2nut_rSO=
    (
     unicast_na_tn2nut_rSO,
     same,
     updated,
     $V6evalTool::exitFail,
     'unicast rSO NA w/o TLL',
     );

#
@def_unicast_na_tn2nut_rso_tll=
    (
     unicast_na_tn2nut_rso_tll,
     same,
     updated,
     $V6evalTool::exitFail,
     'unicast rso NA w/ TLL',
     );

#
@def_unicast_na_tn2nut_rsO_tll=
    (
     unicast_na_tn2nut_rsO_tll,
     same,
     updated,
     $V6evalTool::exitFail,
     'unicast rsO NA w/ TLL',
     );

#
@def_unicast_na_tn2nut_rSo_tll=
    (
     unicast_na_tn2nut_rSo_tll,
     same,
     updated,
     $V6evalTool::exitFail,
     'unicast rSo NA w/ TLL',
     );

#
@def_unicast_na_tn2nut_rSO_tll=
    (
     unicast_na_tn2nut_rSO_tll,
     same,
     updated,
     $V6evalTool::exitFail,
     'unicast rSO NA w/ TLL',
     );

#
#@def_multicast_na_tn2allnode_rso=
#    (
#     multicast_na_tn2allnode_rso,
#     same,
#     unchanged,
#     $V6evalTool::exitWarn,
#     'multicast rso NA w/o TLL (INVALID)',
#     );
#
#
#@def_multicast_na_tn2allnode_rsO=
#    (
#     multicast_na_tn2allnode_rsO,
#     same,
#     unchanged,
#     $V6evalTool::exitWarn,
#     'multicast rsO NA w/o TLL (INVALID)',
#     );
#
#
@def_multicast_na_tn2allnode_rSo=
    (
     multicast_na_tn2allnode_rSo,
     same,
     unchanged,
     $V6evalTool::exitFail,
     'multicast rSo NA w/o TLL (INVALID)',
     );

#
@def_multicast_na_tn2allnode_rSO=
    (
     multicast_na_tn2allnode_rSO,
     same,
     unchanged,
     $V6evalTool::exitFail,
     'multicast rSO NA w/o TLL (INVALID)',
     );

#
@def_multicast_na_tn2allnode_rso_tll=
    (
     multicast_na_tn2allnode_rso_tll,
     same,
     updated,
     $V6evalTool::exitFail,
     'multicast rso NA w/ TLL',
     );

#
@def_multicast_na_tn2allnode_rsO_tll=
    (
     multicast_na_tn2allnode_rsO_tll,
     same,
     updated,
     $V6evalTool::exitFail,
     'multicast rsO NA w/ TLL',
     );

#
@def_multicast_na_tn2allnode_rSo_tll=
    (
     multicast_na_tn2allnode_rSo_tll,
     same,
     unchanged,
     $V6evalTool::exitFail,
     'multicast rSo NA w/ TLL (INVALID)',
     );

#
@def_multicast_na_tn2allnode_rSO_tll=
    (
     multicast_na_tn2allnode_rSO_tll,
     same,
     unchanged,
     $V6evalTool::exitFail,
     'multicast rSO NA w/ TLL (INVALID)',
     );

#
@def_unicast_na_tn2nut_rso_tll2_diff=
    (
     unicast_na_tn2nut_rso_tll2,
     same,
     unchanged,
     $V6evalTool::exitFail,
     'unicast rso NA w/ TLL, diff. LLA',
     );

#
@def_unicast_na_tn2nut_rsO_tll_diff=
    (
     unicast_na_tn2nut_rsO_tll,
     diff,
     updated,
     $V6evalTool::exitFail,
     'unicast rsO NA w/ TLL, diff. LLA',
     );

#
@def_unicast_na_tn2nut_rSo_tll2_diff=
    (
     unicast_na_tn2nut_rSo_tll2,
     same,
     unchanged,
     $V6evalTool::exitFail,
     'unicast rSo NA w/ TLL, diff. LLA',
     );

#
@def_unicast_na_tn2nut_rSO_tll_diff=
    (
     unicast_na_tn2nut_rSO_tll,
     diff,
     updated,
     $V6evalTool::exitFail,
     'unicast rSO NA w/ TLL, diff. LLA',
     );

#
@def_multicast_na_tn2allnode_rso_tll2_diff=
    (
     multicast_na_tn2allnode_rso_tll2,
     same,
     unchanged,
     $V6evalTool::exitFail,
     'multicast rso NA w/ TLL, diff. LLA',
     );

#
@def_multicast_na_tn2allnode_rsO_tll_diff=
    (
     multicast_na_tn2allnode_rsO_tll,
     diff,
     updated,
     $V6evalTool::exitFail,
     'multicast rsO NA w/ TLL, diff. LLA',
     );

#
@def_multicast_na_tn2allnode_rSo_tll2_diff=
    (
     multicast_na_tn2allnode_rSo_tll2,
     same,
     unchanged,
     $V6evalTool::exitFail,
     'multicast rSo NA w/ TLL (INVALID), diff. LLA',
     );

#
@def_multicast_na_tn2allnode_rSO_tll2_diff=
    (
     multicast_na_tn2allnode_rSO_tll2,
     same,
     unchanged,
     $V6evalTool::exitFail,
     'multicast rSO NA w/ TLL (INVALID), diff. LLA',
     );

#
#
#
@defs=
    (
     \@def_unicast_na_tn2nut_rso,
     \@def_unicast_na_tn2nut_rsO,
     \@def_unicast_na_tn2nut_rSo,
     \@def_unicast_na_tn2nut_rSO,
     \@def_unicast_na_tn2nut_rso_tll,
     \@def_unicast_na_tn2nut_rsO_tll,
     \@def_unicast_na_tn2nut_rSo_tll,
     \@def_unicast_na_tn2nut_rSO_tll,
#     \@def_multicast_na_tn2allnode_rso,
#     \@def_multicast_na_tn2allnode_rsO,
     \@def_multicast_na_tn2allnode_rSo,
     \@def_multicast_na_tn2allnode_rSO,
     \@def_multicast_na_tn2allnode_rso_tll,
     \@def_multicast_na_tn2allnode_rsO_tll,
     \@def_multicast_na_tn2allnode_rSo_tll,
     \@def_multicast_na_tn2allnode_rSO_tll,
     \@def_unicast_na_tn2nut_rso_tll2_diff,
     \@def_unicast_na_tn2nut_rsO_tll_diff,
     \@def_unicast_na_tn2nut_rSo_tll2_diff,
     \@def_unicast_na_tn2nut_rSO_tll_diff,
     \@def_multicast_na_tn2allnode_rso_tll2_diff,
     \@def_multicast_na_tn2allnode_rsO_tll_diff,
     \@def_multicast_na_tn2allnode_rSo_tll2_diff,
     \@def_multicast_na_tn2allnode_rSO_tll2_diff,
     );

#
#
#
vCapture($IF);

#
#
#
$idx=0;
foreach(@defs) {
    my($ptn)=@$_[$idx_ptn];
    my($chg)=@$_[$idx_chg];
    my($exp)=@$_[$idx_exp];
    my($bin)=@$_[$idx_bin];
    my($msg)=@$_[$idx_msg];

    my($s)=check($ptn, $chg, $exp, $msg);
    if($s eq $exp) {
	$result{$idx}=$V6evalTool::exitPass;
	vLogHTML("<A NAME=\"T$idx\">OK</A><BR>");
    } else {
	$exit_rtn=$bin if $exit_rtn != $V6evalTool::exitFail;
	$result{$idx}=$bin;
	vLogHTML("<A NAME=\"T$idx\">".ndErrmsg("NG")."</A><BR>");
    }
    $title{$idx}="<TD>$msg</TD><TD>exp:$exp</TD><TD>result:$s</TD>";
    $idx++;

    readout($IF, $wait_ns);
}
$idx--;

#
#
#
vLogHTML("<HR><FONT SIZE=\"+1\">Termination</FONT><BR>");
clear();

#
#
#
@col=('PTN', 'EXP', 'RESULT');
ndPrintSummaryHTML("*** Test Summary: NA vs. IsRouter flag ***", @col,
                   %title, %result, $idx);

#
#
#
vLogHTML("*** EOT ***<BR>");
exit $exit_rtn;

#
#
#
sub readout {
	my($if, $tout) = @_;
	vRecv($if, $tout, 0, 0);
}

#
#
#
sub check($$$$)
{
    my($ptn, $chg, $exp, $msg)=@_;

    #
    #
    #
    vLogHTML("<FONT SIZE=\"+2\">*** $msg ***</FONT><BR>");
    $title{$idx}="$msg";

    #
    #
    #
    vLogHTML("<HR><FONT SIZE=\"+1\">Initialization</FONT><BR>");

#	goto error if nd2NoNce($IF) != 0;

    if($chg eq same) {
	goto error if init() != 0;
    } else {
	goto error if initZ() != 0;
    }

    #
    #
    #
    vLogHTML("<HR><FONT SIZE=\"+1\">Test</FONT><BR>");
    vLogHTML("Send $msg<BR>");
    vSend($IF, $ptn);

#    %ret=off_link_ping();

    $pktdesc{nd_echo_request_from_offlink}=
	"Send an echo-request from off-link src";
    %ret=vSend($IF, nd_echo_request_from_offlink);

    $pktdesc{nd_echo_reply_to_offlink}=
	'Got an echo-reply that forwarded to TN';
    $pktdesc{nd_multicast_ns_nut2xsolnode}=
	'Got multicast NS to resolve the global address';
    %ret=vRecv($IF, $wait_echo, $ret{sentTime1}, 0,
	       nd_echo_reply_to_offlink,
	       nd_multicast_ns_nut2xsolnode,
	       );
    if($ret{status} == 0) {
	if($ret{recvFrame} eq nd_echo_reply_to_offlink) {
	    $s="unchanged";
	    $s2="$s (IsRouter: 1)";
	} else {
	    $s="updated";
	    $s2="$s (IsRouter: 1==>0)";
	}
    } else {
	vLogHTML("Never got an echo-reply that forwarded to TN<BR>");
	$s="updated";
	$s2="$s (IsRouter=0)";
    }

    if($s eq $exp) {
	vLogHTML("IsRouter flag was $s2<BR>");
    } else {
	vLogHTML(ndErrmsg("IsRouter flag was $s2<BR>"));
    }
    return($s);

  error:
    return("ERROR");
}

#
#
#
sub init()
{
#    return 1 if ndClearPrefix() != 0;
#    return 1 if ndClearDefr() != 0;
    return 1 if nd2ReachableByRa($IF) != 0;
    vClear($IF);
}

sub initZ()
{
#    return 1 if ndClearPrefix() != 0;
#    return 1 if ndClearDefr() != 0;
    return 1 if nd2ReachableByRaZ($IF) != 0;
    vClear($IF);
}

#
#
#
sub clear()
{
    $pktdesc{nd_unsol_ra_clrrtr}="Clear the Default Router List";
    vSend($IF, nd_unsol_ra_clrrtr);
}

########################################################################
__END__

=head1 NAME

recvNaRFlag - Verifying that a IsRouter flag is modified by a NA

=head1 TARGET

Host only

=head1 SYNOPSIS

 recvNaRFlag .seq [-tooloption ...] -p recvNaRFlag.def

=head1 INITIALIZATION

=begin html
<OL>
  <LI>Set the state of neighbor cache entry to REACHABLE
      whose IsRouter flag is true. 
  <LI>Cache either <A HREF="#Cache_a_LLA_of_TN">TN's LLA</A> or
      <A HREF="#Cache_a_bogus_LLA">a bogus LLA</A>
</OL>

=end html

=head2 Cache a LLA of TN

=begin html
<PRE>
  TN                 NUT
  ----------------------
<BR>
  State: No neighbor cache entry (for TN)
<BR>
  ==== unsolicited RA ===>
       src=TN's link-local
       dst=all-node
       M=0, O=0
       RouterLifetime=600
       ReachableTime=0
       RetransTimer=0
       Prefix Option:
           L=1, A=1
	   ValidLifetime=2592000
	   PreferredLifetime=604800
           Prefix=3ffe:501:ffff:100::/64
<BR>
  <=== Ns for DAD ====
       src=unspecified
       dst=solicited-node[NUT's global]
       target=NUT's global
<BR>
  State: INCOMPLETE (for TN)
<BR>
  <=== multicast NS ====
       src=NUT's link-local or global
       dst=solicited-node[TN's link-local]
       target=TN's link-local
       w/ SLLA
       timeout=RETRANS_TIMER * MAX_MULTICAST_SOLICIT
<BR>
  ==== solicited NA ===>
       src=TN's link-local
       dst=NUT's link-local
       R=1, S=1, O=1
       target=TN's link-local
       <B>TLLA=TN's LLA</B>
<BR>
  State: REACHABLE (for TN)
</PRE>

=end html

=head2 Cache a bogus LLA

=begin html
<PRE>
  TN                 NUT
  ----------------------
<BR>
  State: No neighbor cache entry (for TN)
<BR>
  ==== unsolicited RA ===>
       src=TN's link-local
       dst=all-node
       M=0, O=0
       RouterLifetime=600
       ReachableTime=0
       RetransTimer=0
       Prefix Option:
           L=1, A=1
	   ValidLifetime=2592000
	   PreferredLifetime=604800
           Prefix=3ffe:501:ffff:100::/64
<BR>
  <=== Ns for DAD ====
       src=unspecified
       dst=solicited-node[NUT's global]
       target=NUT's global
<BR>
  State: INCOMPLETE (for TN)
<BR>
  <=== multicast NS ====
       src=NUT's link-local or global
       dst=solicited-node[TN's link-local]
       target=TN's link-local
       w/ SLLA
       timeout=RETRANS_TIMER * MAX_MULTICAST_SOLICIT
<BR>
  ==== solicited NA ===>
       src=TN's link-local
       dst=NUT's link-local
       R=1, S=1, O=1
       target=TN's link-local
       <B>TLLA=a bogus LLA</B>
<BR>
  State: REACHABLE (for TN)
</PRE>

=end html

=head1 TEST PROCEDURE

B<recvNaRFlag> verifies that a IsRouter flag is modified by a NA.
in REACHABLE state when receiving an NA.

=begin html
<PRE>
  TN                 NUT
  ----------------------
<BR>
  State: REACHABLE (for TN)
<BR>
  ==== <A HREF="#JDG1">NA</A> ===>
       src=TN's link-local
       dst=the NUT's link-local or all-node
       R=0, S=0/1, O=0/1
       Target=TN's link-local
       w/ or w/o TLL
<BR>
  ==== echo-request ===>
       src=off-link global, but LLA is TN's one
       dst=NUT's global
<BR>
  <=== <A HREF="#JDG2">Judgment #2</A>: echo-reply ====
       src=NUT's global
       dst=off-link global, but LLA is TN's one
</PRE>

=end html

=head1 JUDGMENT

=begin html
<A NAME="JDG1"></A>
<PRE>
  1. Modification of the IsRouter flag depend upon both
     its neighbor cache state and a NS.
<HR>
  =========+================================+=================
  Current  |NA received by NUT              |IsRouter flag
  State    +---------------+-+--+-+---------+-------+---------
           |Destination    |r| s|o|TLLA     |Current|New
  =========+===============+=+==+=+=========+=======+=========
  REACHABLE Unicast         0  0 0 none      1       <A HREF="#CHG">0</A>
           +---------------+-+--+-+---------+-------+---------
            Unicast         0  0 1 none      1       <A HREF="#CHG">0</A>
           +---------------+-+--+-+---------+-------+---------
            Unicast         0  1 0 none      1       <A HREF="#CHG">0</A>
           +---------------+-+--+-+---------+-------+---------
            Unicast         0  1 1 none      1       <A HREF="#CHG">0</A>
           +===============+=+==+=+=========+=======+=========
            Unicast         0  0 0 same      1       <A HREF="#CHG">0</A>
           +---------------+-+--+-+---------+-------+---------
            Unicast         0  0 1 same      1       <A HREF="#CHG">0</A>
           +---------------+-+--+-+---------+-------+---------
            Unicast         0  1 0 same      1       <A HREF="#CHG">0</A>
           +---------------+-+--+-+---------+-------+---------
            Unicast         0  1 1 same      1       <A HREF="#CHG">0</A>
           +===============+=+==+=+=========+=======+=========
            Unicast         0  0 0 different 1       <A HREF="#UNCHG">unchanged</A>
           +---------------+-+--+-+---------+-------+---------
            Unicast         0  0 1 different 1       <A HREF="#CHG">0</A>
           +---------------+-+--+-+---------+-------+---------
            Unicast         0  1 0 different 1       <A HREF="#UNCHG">unchanged</A>
           +---------------+-+--+-+---------+-------+---------
            Unicast         0  1 1 different 1       <A HREF="#CHG">0</A>
           +===============+=+==+=+=========+=======+=========
            *Multicast      0  0 0 *none     1       <A HREF="#INVALID">unchanged</A>
                            <A HREF="#NOTE2">*invalid?</A>
           +---------------+-+--+-+---------+-------+---------
            *Multicast      0  0 1 *none     1       <A HREF="#INVALID">unchanged</A>
                            <A HREF="#NOTE2">*invalid?</A>
           +---------------+-+--+-+---------+-------+---------
            *Multicast      0 *1 0 *none     1       <A HREF="#INVALID">unchanged</A>
                            *invalid
           +---------------+-+--+-+---------+-------+---------
            *Multicast      0 *1 1 *none     1       <A HREF="#INVALID">unchanged</A>
                            invalid
           +===============+=+==+=+=========+=======+=========
            Multicast       0  0 0 same      1       <A HREF="#CHG">0</A>
           +---------------+-+--+-+---------+-------+---------
            Multicast       0  0 1 same      1       <A HREF="#CHG">0</A>
           +---------------+-+--+-+---------+-------+---------
            *Multicast      0 *1 0 same      1       <A HREF="#INVALID">unchanged</A>
                            *invalid
           +---------------+-+--+-+---------+-------+---------
            *Multicast      0 *1 1 same      1       <A HREF="#INVALID">unchanged</A>
                            *invalid
           +===============+=+==+=+=========+=======+=========
            Multicast       0  0 0 different 1       <A HREF="#UNCHG">unchanged</A>
           +---------------+-+--+-+---------+-------+---------
            Multicast       0  0 1 different 1       <A HREF="#CHG">0</A>
           +---------------+-+--+-+---------+-------+---------
            *Multicast      0 *1 0 different 1       <A HREF="#INVALID">unchanged</A>
                            *invalid
           +---------------+-+--+-+---------+-------+---------
            *Multicast      0 *1 1 different 1       <A HREF="#INVALID">unchanged</A>
                            *invalid
  =========+===============+=+==+=+=========+=======+=========
<A NAME="JDG2"></A>
  2. If a IsRouter flag is modified by rule, NUT will NOT throw
     an echo-reply to the default router (i.e. TN).
</PRE>

=end html

=head1 TERMINATION

  Send RA with RouterLifetime=0 to clear the Default Router List.

=head1 NOTE

=begin html
<PRE>
  1. The test does not invoke any remote command.<BR>
<A NAME="NOTE2"></A>
  2. An implementation may update Rflag of an NCE when receiving
     an multicast NA w/o TLL. The NA is not invalid as a receiver side,
     whereas it is invalid as a sender side (please see the following).
     In such case, this test judges "WARN" that never means the implementation
     is wrong. The test intends to inform such behavior.<BR>
<BLOCKQUOTE>Sender side:
<HR>
4.4.  Neighbor Advertisement Message Format<BR>
   Possible options:<BR>
      Target link-layer address
                     The link-layer address for the target, i.e., the
                     sender of the advertisement.  <B>This option MUST be
                     included on link layers that have addresses when
                     responding to multicast solicitations.</B>  When
                     responding to a unicast Neighbor Solicitation this
                     option SHOULD be included.
<HR>
Receiver side:
<HR>
7.1.2.  Validation of Neighbor Advertisements<BR>
   A node MUST silently discard any received Neighbor Advertisement
   messages that do not satisfy all of the following validity checks:<BR>
      - The IP Hop Limit field has a value of 255, i.e., the packet
        could not possibly have been forwarded by a router.<BR>
      - If the message includes an IP Authentication Header, the message
        authenticates correctly.<BR>
      - ICMP Checksum is valid.<BR>
      - ICMP Code is 0.<BR>
      - ICMP length (derived from the IP length) is 24 or more octets.<BR>
      - Target Address is not a multicast address.<BR>
      - If the IP Destination Address is a multicast address the
        Solicited flag is zero.<BR>
      - All included options have a length that is greater than zero.
<HR></BLOCKQUOTE></PRE>

=end html

=head1 REFERENCE

=begin html
RFC2461
<HR>
<PRE>
7.2.5.  Receipt of Neighbor Advertisements<BR>
   <A NAME="INVALID"><B>When a valid Neighbor Advertisement is received (either solicited or
   unsolicited), the Neighbor Cache is searched for the target's entry.</B></A>
   If no entry exists, the advertisement SHOULD be silently discarded.
   There is no need to create an entry if none exists, since the
   recipient has apparently not initiated any communication with the
   target.<BR>
   Once the appropriate Neighbor Cache entry has been located, the
   specific actions taken depend on the state of the Neighbor Cache
   entry, the flags in the advertisement and the actual link-layer
   address supplied.<BR>
     IF(State == INCOMPLETE) {
         If the target's Neighbor Cache entry is in the INCOMPLETE state when
         the advertisement is received, one of two things happens.  If the
         link layer has addresses and no Target Link-Layer address option is
         included, the receiving node should silently discard the received
         advertisement.  Otherwise, the receiving node performs the following
         steps:<BR>
         - It records the link-layer address in the Neighbor Cache entry.<BR>
         - If the advertisement's Solicited flag is set, the state of the
           entry is set to REACHABLE, otherwise it is set to STALE.<BR>
         - It sets the IsRouter flag in the cache entry based on the Router
           flag in the received advertisement.<BR>
         - It sends any packets queued for the neighbor awaiting address
           resolution.<BR>
         Note that the Override flag is ignored if the entry is in the
         INCOMPLETE state.
     } ELSIF(State != INCOMPLETE) {
         If the target's Neighbor Cache entry is in any state other than
         INCOMPLETE when the advertisement is received, processing becomes
         quite a bit more complex.<BR>
         IF(Override==0 && TLLA!=LLA) {
             If the Override flag is clear and the supplied link-layer
             address differs from that in the cache, then one of two
             actions takes place:<BR>
             <A NAME="UNCHG"><B>IF(REACHABLE) {
                 if the state of the entry is REACHABLE, set it to STALE,
                 but do not update the entry in any other way;
             }</A></B> ELSE {
                 otherwise, the received advertisement should be ignored
                 and must not update the cache.
             }
         } ELSIF(Override==1 ||
                 (Override==0 && TLLA==LLA) ||
                 TLLA==NULL) {
             If the Override flag is set, both the Override
             flag is clear and the supplied link-layer address is the same as that
             in the cache, or no Target Link-layer address option was supplied,
             the received advertisement must update the Neighbor Cache entry as
             follows:<BR>
             - The link-layer address in the Target Link-Layer Address option
               must be inserted in the cache (if one is supplied and is different
               than the already recorded address).<BR>
             - If the Solicited flag is set, the state of the entry must be set
               to REACHABLE.  If the Solicited flag is zero and the link-layer
               address was updated with a different address the state must be set
               to STALE.  Otherwise, the entry's state remains unchanged.<BR>
             An advertisement's Solicited flag should only be set if the
             advertisement is a response to a Neighbor Solicitation.  Because
             Neighbor Unreachability Detection Solicitations are sent to the
             cached link-layer address, receipt of a solicited advertisement
             indicates that the forward path is working.  Receipt of an
             unsolicited advertisement, however, suggests that a neighbor has
             urgent information to announce (e.g., a changed link-layer
             address).  If the urgent information indicates a change from what
             a node is currently using, the node should verify the reachability
             of the (new) path when it sends the next packet.  There is no need
             to update the state for unsolicited advertisements that do not
             change the contents of the cache.<BR>
             - <A NAME="CHG"><B>The IsRouter flag in the cache entry must be set based on the
               Router flag in the received advertisement.</A></B>  In those cases where
               the IsRouter flag changes from TRUE to FALSE as a result of this
               update, the node must remove that router from the Default Router
               List and update the Destination Cache entries for all destinations
               using that neighbor as a router as specified in Section 7.3.3.
               This is needed to detect when a node that is used as a router
               stops forwarding packets due to being configured as a host.
         }
     }
</PRE>

=end html

=head1 SEE ALSO

  perldoc V6evalTool
  perldoc V6evalRemote

=cut