Folks,

 To answer the original question---the DR should not
 explicitly ack the LSA received from a non-DR router,
 as it will flood the LSA back to the interface to
 AllSPFRouters, so the router that sent the LSA will treat
 this update as an implied ack.

 As for Feng's point 2 below, the statement is not correct.
 You have to ack LSAs during the LSDB exchange process according
 to normal rules, there's no special case for the Exchange process.
 This question has been explained lately on the list, pls see
 the archives.

--
Alex Zinin
Monday, October 22, 2001, 3:01:41 PM, Xie, Feng wrote:
> Hi, Gurpreet:
>      I think there could be two cases in which no explict acknowledgments
> are needed:
>      1. The case described by section 13, 7(a);
>      2. In DB sync in which router A sends a request to router C. When
> router C responds to this request with some link state update, router A may
> send the next request or do nothing if there is no further request. Refer to
> RFC2328, p105. My understanding is that in this case, the next request or no
> request may serve as an implicit ack because if the update is not received
> by router A, it will resend its request again.
> Feng Xie
> -----Original Message-----
> From: Singh, Gurpreet [mailto:Gurpreet.SinghSPIRENTCOM.COM]
> Sent: Monday, October 22, 2001 5:48 PM
> To: OSPFDISCUSS.MICROSOFT.COM
> Subject: Re: Acknowledgement for Router LSA from DROther.
> Hi Xie
>       However,
>         acknowledgments can also be accomplished implicitly by sending
>         Link State Update packets (see step 7a of Section 13)."
> Does this mean that implied acknowledgement is done only in the case of 7a
> of section 13 ?
> Section 7a is valid only for LSAs for which the router has the same instance
> in the database as the received LSA.
> Gurpreet
> -----Original Message-----
> From: Xie, Feng [mailto:Feng.XieMARCONI.COM]
> Sent: Monday, October 22, 2001 5:36 PM
> To: OSPFDISCUSS.MICROSOFT.COM
> Subject: Re: Acknowledgement for Router LSA from DROther.
> Hi, Gurpreet:
>     According to RFC2328, p152,
>     "Each newly received LSA must be acknowledged.  This is usually
>         done by sending Link State Acknowledgment packets.  However,
>         acknowledgments can also be accomplished implicitly by sending
>         Link State Update packets (see step 7a of Section 13)."
>     Base on the above statement, my understanding is that A may not need to
> send an explicit link acknowledgment for every router lsa it receives from C
> if the router lsa is received during DB sync.
> Feng Xie
> -----Original Message-----
> From: Singh, Gurpreet [mailto:Gurpreet.SinghSPIRENTCOM.COM]
> Sent: Monday, October 22, 2001 5:27 PM
> To: OSPFDISCUSS.MICROSOFT.COM
> Subject: Acknowledgement for Router LSA from DROther.
> Hi
>     If there are three routers on the same sub-net A (DR) , B (Backup DR)
> and C (DR Other). Should A acknowledge a router LSA (which A does not have a
> copy in the database) received from C ?  i.e. should router LSA from a
> DROther be acknowledged by the DR (Designated Router)
> Thanks
> Gurpreet

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