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List: ms-ospf
Subject: Re: Receiving Self-Orignated Summary 3 LSAs
From: Acee Lindem <acee () REDBACK ! COM>
Date: 2004-10-27 9:41:29
Message-ID: 034b01c4bc09$22e29a20$0202a8c0 () aceeinspiron
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Hi Joseph,
It depends on whether the self-originated LSA is more recent. If is less
recent (as defined in section 13.1 of RFC 2328), it will be ignored. If it is
more recent, a new LSA with the correct cost and a larger sequence number
is originated. Note that the LSA interpreted as being equal due to fact that
the differing costs will result in different checksums.
Hope this helps,
Acee
----- Original Message -----
From: Joseph Placid
To: OSPF@PEACH.EASE.LSOFT.COM
Sent: Wednesday, October 27, 2004 3:47 AM
Subject: Re: Receiving Self-Orignated Summary 3 LSAs
Thanks Manish,
Qn 2) If R1 comes across a self-originated Summary LSA for the same Network in \
Area2 with a lower cost, what should it do?
>> Intra area route will always be preferred over Inter Area Route \
irrespective of cost.
Would R1:
1) Generate a new summary LSA into the Backbone with the lower cost?
2) Maxage this summary LSA (the one with the lower cost) and generate a new one \
into the backbone? 3) Simply regenerate the LSA with the right cost into the \
backbone? 4) Ignore the LSA with the lowercost and Do Nothing.
- Joseph Placid
-----Original Message-----
From: Mailing List [mailto:OSPF@PEACH.EASE.LSOFT.COM]On Behalf Of Manish Gupta
Sent: 27 October 2004 01:00 PM
To: OSPF@PEACH.EASE.LSOFT.COM
Subject: Re: Receiving Self-Orignated Summary 3 LSAs
Hi Joseph,
Please see inline.
-----Original Message-----
From: Mailing List [mailto:OSPF@peach.ease.lsoft.com]On Behalf Of Joseph Placid
Sent: Wednesday, 27 October 2004 12:31 PM
To: OSPF@peach.ease.lsoft.com
Subject: Receiving Self-Orignated Summary 3 LSAs
Hi All,
Consider this topology:
[Area 0] - - - - R1 - - - - [Area 2] - - - - R2 - - - - [Area 0]
When R1 receives a Network LSA from an internal router in Area 2, it summarises \
it into Area 0. This Summary LSA is seen by R2 since it has an interface in the \
backbone.
Qn 1) Will R2 import this Summary LSA into Area 2?
[Manish Gupta] R2 will not import this summary LSA in Area 2 since it has an \
INTRA Area route through Area 2 for summary network.
Qn 2) If R1 comes across a self-originated Summary LSA for the same Network in \
Area2 with a lower cost, what should it do?
Intra area route will always be preferred over Inter Area Route \
irrespective of cost.
Regards,
Joseph Placid
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<DIV><FONT face=Arial size=2>Hi Joseph, </FONT></DIV>
<DIV> </DIV>
<DIV><FONT face=Arial size=2>It depends on whether the self-originated LSA is
more recent. If is less</FONT></DIV>
<DIV><FONT face=Arial size=2>recent (as defined in section 13.1 of RFC 2328), it
will be ignored. If it is</FONT></DIV>
<DIV><FONT face=Arial size=2>more recent, a new LSA with the correct cost and a
larger sequence number </FONT></DIV>
<DIV><FONT face=Arial size=2>is originated. Note that </FONT><FONT face=Arial
size=2>the LSA interpreted as being equal due to fact that </FONT></DIV>
<DIV><FONT face=Arial size=2>the differing costs </FONT><FONT face=Arial
size=2>will result in different checksums.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Hope this helps,</FONT></DIV>
<DIV><FONT face=Arial size=2>Acee</FONT> </DIV>
<BLOCKQUOTE dir=ltr
style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #000000 \
2px solid; MARGIN-RIGHT: 0px"> <DIV style="FONT: 10pt arial">----- Original Message \
----- </DIV> <DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black"><B>From:</B>
<A title=joseph@ALUMNUX.COM href="mailto:joseph@ALUMNUX.COM">Joseph Placid</A>
</DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A title=OSPF@PEACH.EASE.LSOFT.COM
href="mailto:OSPF@PEACH.EASE.LSOFT.COM">OSPF@PEACH.EASE.LSOFT.COM</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Wednesday, October 27, 2004 3:47
AM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> Re: Receiving Self-Orignated
Summary 3 LSAs</DIV>
<DIV><BR></DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN
class=328273807-27102004>Thanks Manish,</SPAN></FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN
class=328273807-27102004></SPAN></FONT> </DIV>
<DIV><SPAN class=328273807-27102004>
<DIV><SPAN class=468422706-27102004><FONT face=Arial color=#0000ff size=2>Qn
2) If R1 comes across a self-originated Summary LSA for the same Network
in Area2 with a lower cost, what should it do?</FONT></SPAN></DIV>
<DIV><SPAN class=468422706-27102004><FONT face=Arial color=#0000ff
size=2><SPAN
class=020492507-27102004> <SPAN \
class=328273807-27102004>>> </SPAN>Intra area route will always be
preferred over Inter Area Route irrespective of
cost.</SPAN></FONT></SPAN></DIV>
<DIV><SPAN class=468422706-27102004></SPAN><FONT size=2><FONT face=Arial><FONT
color=#0000ff></FONT></FONT></FONT> </DIV>
<DIV><FONT size=2><FONT face=Arial><FONT color=#000000><SPAN
class=328273807-27102004>Would R1: </SPAN></FONT></FONT></FONT></DIV>
<DIV><FONT size=2><FONT face=Arial><FONT color=#000000><SPAN
class=328273807-27102004></SPAN></FONT></FONT></FONT> </DIV>
<DIV><FONT size=2><FONT face=Arial><FONT color=#000000><SPAN
class=328273807-27102004>1) Generate a new summary LSA
into the Backbone with the lower cost?</SPAN></FONT></FONT></FONT></DIV>
<DIV><FONT size=2><FONT face=Arial><FONT color=#000000><SPAN
class=328273807-27102004>2) Maxage this summary LSA
(the one with the lower cost) and generate a new one into the
backbone?</SPAN></FONT></FONT></FONT></DIV>
<DIV><FONT size=2><FONT face=Arial><FONT color=#000000><SPAN
class=328273807-27102004>3) Simply regenerate the LSA
with the right cost into the backbone?</SPAN></FONT></FONT></FONT></DIV>
<DIV><FONT size=2><FONT face=Arial><FONT color=#000000><SPAN
class=328273807-27102004>4) Ignore the LSA with the
lowercost and Do Nothing. </SPAN></FONT></FONT></FONT></DIV>
<DIV><FONT size=2><FONT color=#0000ff><FONT face=Arial><SPAN
class=328273807-27102004></SPAN></FONT></FONT></FONT> </DIV>
<DIV><FONT size=2><FONT color=#0000ff><FONT face=Arial><SPAN
class=328273807-27102004></SPAN></FONT></FONT></FONT> </DIV>
<DIV><FONT size=2><FONT color=#0000ff><FONT face=Arial><SPAN
class=328273807-27102004></SPAN></FONT></FONT></FONT> </DIV>
<DIV><FONT size=2><FONT color=#0000ff><FONT face=Arial><SPAN
class=328273807-27102004>- Joseph
Placid </SPAN></FONT></FONT></FONT></DIV>
<DIV><FONT size=2><FONT color=#0000ff><FONT face=Arial><SPAN
class=328273807-27102004></SPAN></FONT></FONT></FONT> </DIV>
<DIV><FONT size=2><FONT color=#0000ff><FONT face=Arial><SPAN
class=328273807-27102004></SPAN></FONT></FONT></FONT> </DIV>
<DIV><FONT size=2><FONT color=#0000ff><FONT face=Arial><SPAN
class=328273807-27102004></SPAN></FONT></FONT></FONT> </DIV>
<DIV><FONT size=2><FONT color=#0000ff><FONT face=Arial><SPAN
class=328273807-27102004></SPAN></FONT></FONT></FONT> </DIV>
<DIV><FONT size=2><FONT color=#0000ff><FONT face=Arial><SPAN
class=328273807-27102004></SPAN></FONT></FONT></FONT> </DIV>
<DIV><FONT size=2><FONT color=#0000ff><FONT face=Arial><SPAN
class=328273807-27102004> </SPAN></FONT></FONT></FONT></SPAN><FONT
face=Tahoma><FONT size=2>-----Original Message-----<BR><B>From:</B> Mailing
List [mailto:OSPF@PEACH.EASE.LSOFT.COM]<B>On Behalf Of </B>Manish
Gupta<BR><B>Sent:</B> 27 October 2004 01:00 PM<BR><B>To:</B>
OSPF@PEACH.EASE.LSOFT.COM<BR><B>Subject:</B> Re: Receiving Self-Orignated
Summary 3 LSAs<BR><BR></DIV></FONT></DIV>
<BLOCKQUOTE></FONT>
<DIV><SPAN class=020492507-27102004><FONT face=Arial color=#0000ff size=2>Hi
Joseph, </FONT></SPAN></DIV>
<DIV><SPAN class=020492507-27102004><FONT face=Arial color=#0000ff
size=2>Please see inline.</FONT></SPAN></DIV>
<BLOCKQUOTE dir=ltr style="MARGIN-RIGHT: 0px">
<DIV class=OutlookMessageHeader dir=ltr align=left><FONT face=Tahoma
size=2>-----Original Message-----<BR><B>From:</B> Mailing List
[mailto:OSPF@peach.ease.lsoft.com]<B>On Behalf Of </B>Joseph
Placid<BR><B>Sent:</B> Wednesday, 27 October 2004 12:31 PM<BR><B>To:</B>
OSPF@peach.ease.lsoft.com<BR><B>Subject:</B> Receiving Self-Orignated
Summary 3 LSAs<BR><BR></FONT></DIV>
<DIV><FONT face=Arial size=2><SPAN class=468422706-27102004>Hi
All,</SPAN></FONT></DIV>
<DIV><FONT face=Arial size=2><SPAN
class=468422706-27102004></SPAN></FONT> </DIV>
<DIV><FONT face=Arial size=2><SPAN class=468422706-27102004>Consider this
topology:</SPAN></FONT><SPAN class=468422706-27102004><FONT size=2><FONT
face=Arial></FONT></FONT></SPAN></DIV>
<DIV><SPAN class=468422706-27102004><FONT size=2><FONT
face=Arial></FONT></FONT></SPAN> </DIV>
<DIV><FONT face=Arial color=#0000ff size=2></FONT> </DIV>
<DIV><SPAN class=468422706-27102004><FONT size=2><FONT face=Arial>[Area 0]
- - - - R1 - - - - [Area 2] - - - - R2 - - - - [Area
0]</FONT></FONT></SPAN></DIV>
<DIV><SPAN class=468422706-27102004><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=468422706-27102004><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=468422706-27102004><FONT face=Arial size=2>When R1
receives a Network LSA from an internal router in Area 2, it summarises it
into Area 0. This Summary LSA is seen by R2 since it has
an interface in the backbone.</FONT></SPAN></DIV>
<DIV><SPAN class=468422706-27102004><FONT face=Arial
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=468422706-27102004><FONT face=Arial size=2>Qn
1) Will R2 import this Summary LSA into Area
2?</FONT> <BR><SPAN class=020492507-27102004><FONT face=Arial
color=#0000ff size=2>[Manish Gupta] R2 will not import this summary
LSA in Area 2 since it has an INTRA Area route through Area 2 for summary
network.</FONT></SPAN></SPAN></DIV>
<DIV><SPAN class=468422706-27102004><SPAN
class=020492507-27102004></SPAN></SPAN> </DIV>
<DIV><SPAN class=468422706-27102004><FONT face=Arial size=2>Qn 2) If
R1 comes across a self-originated Summary LSA for the same Network in
Area2 with a lower cost, what should it do?</FONT></SPAN></DIV>
<DIV><SPAN class=468422706-27102004><FONT face=Arial color=#0000ff
size=2><SPAN
class=020492507-27102004>
Intra area route will always be preferred over Inter Area Route
irrespective of cost.</SPAN></FONT></SPAN></DIV>
<DIV><SPAN class=468422706-27102004><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=468422706-27102004><FONT face=Arial
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=468422706-27102004><FONT face=Arial
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=468422706-27102004><FONT face=Arial
size=2>Regards,</FONT></SPAN></DIV>
<DIV><SPAN class=468422706-27102004><FONT face=Arial size=2>Joseph
Placid</FONT></DIV></BLOCKQUOTE></SPAN><FONT
size=3><BR><BR>***************************************************************************<BR>This \
message is proprietary to Future Software Limited (FSL)<BR>and is intended
solely for the use of the individual to whom it<BR>is addressed. It may
contain privileged or confidential information<BR>and should not be
circulated or used for any purpose other than for<BR>what it is
intended.<BR><BR>If you have received this message in error, please notify
the<BR>originator immediately. If you are not the intended recipient,<BR>you
are notified that you are strictly prohibited from using,<BR>copying,
altering, or disclosing the contents of this message.<BR>FSL accepts no
responsibility for loss or damage arising from<BR>the use of the information
transmitted by this email including<BR>damage from
virus.<BR>***************************************************************************<BR></BLOCKQUOTE></BLOCKQUOTE></FONT></BODY></HTML>
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