Zhao-Yang Dong <zhaoyang@NORTEL.COM> Thu, 14 April 2005 23:42 UTC

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Date: Thu, 14 Apr 2005 19:31:47 -0400
Reply-To: Mailing List <OSPF@PEACH.EASE.LSOFT.COM>
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From: Zhao-Yang Dong <zhaoyang@NORTEL.COM>
To: OSPF@PEACH.EASE.LSOFT.COM
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In an OSPF link state database, each LSA is supposed to have a unique Link
State ID (LSID). Sometimes this is not true, especially in multiple vendor
devices environment. 

 

When originating summary and/or AS-external LSAs, how to assign unique LSID
for a network number who has multiple (different length of) masks is
described in RFC 2328 appendix E. However, I did not see any discussion in
RFC 2328 nor this archive how to handle/process summary and/or AS-external
LSAs received from other routers with the same LSID but different length of
masks. 

 

According RFC 2328, a LSA is identified by LS type, LSID and advertising
router. To determine which LSA of two LSA instances is newer, LS sequence
number, checksum and age are compared. Network mask does not seem play any
role while processing the received LSAs. 

 

My question is, for example, if I received a LSA with LSID=A.B.C.D and 24
bits mask and installed in my database, and later I received the same LSA
(i.e. same LS type, LSID and advertising router) but with 28 bits mask. If
the second LSA has the larger sequence number, should I replace my database
copy with the second LSA?

 

Thanks,

Zhaoyang

Zhao-Yang Dong
Dave Katz
Tom Petch
OSPF LSID with vary length masks Acee Lindem
Re: LSIDs with vary length masks Acee Lindem
Re: OSPF LSID with vary length masks Acee Lindem
Re: OSPF LSID with vary length masks Acee Lindem
Re: OSPF LSID with vary length masks Acee Lindem
Re: Overlapping Routes Dave Katz