Thanks Peter,
Ole
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Ole Drews Jensen
Systems Network Manager
CCNA, MCSE, MCP+I
RWR Enterprises, Inc.
[EMAIL PROTECTED]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
http://www.OleDrews.com/CCNP
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NEED A JOB ???
http://www.oledrews.com/job
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-----Original Message-----
From: Peter Van Oene [mailto:[EMAIL PROTECTED]]
Sent: Tuesday, July 03, 2001 2:37 PM
To: [EMAIL PROTECTED]
Subject: RE: OSPF: Flooding LSU/LSA [7:10803]
This looks good. Keep in mind that the BDR does not transmit LSA's however,
unless the DR fails to do so.
*********** REPLY SEPARATOR ***********
On 7/3/2001 at 2:08 PM Ole Drews Jensen wrote:
>So it kind of boils down to this: If we look at only one network, routers
>send lsu/lsa to only the DR/BDR, and the DR/BDR then send to all OSPF
>routers.
>
>Example 1:
>
> Router A = DROTHER
> Router B = DROTHER
> Router C = DR
> Router D = DROTHER
> Router E = BDR
>
> 1) Router A sends LSU/LSA to C & E (224.0.0.6)
> 2) DR sends the LSU/LSA to A,B,C,D & E (224.0.0.5)
>
>If Router B is connected to another OSPF network on one of its other
>interfaces, the following will happen:
>
> 3) Router B sends LSU/LSA to the DR/BDR routers of that network
>(224.0.0.6)
> 4) The DR of that network sends the LSU/LSA to all OSPF routers on
>that network (224.0.0.5)
>
>Am I right, or would this be to simplify it too much, or am I completely
>off
>the track???
>
>Thanks,
>
>Ole
>
>~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> Ole Drews Jensen
> Systems Network Manager
> CCNA, MCSE, MCP+I
> RWR Enterprises, Inc.
> [EMAIL PROTECTED]
>~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> http://www.OleDrews.com/CCNP
>~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> NEED A JOB ???
> http://www.oledrews.com/job
>~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
>
>-----Original Message-----
>From: Peter Van Oene [mailto:[EMAIL PROTECTED]]
>Sent: Tuesday, July 03, 2001 1:57 PM
>To: Ole Drews Jensen; [EMAIL PROTECTED]
>Subject: Re: OSPF: Flooding LSU/LSA [7:10803]
>
>
>The standard procedure when receiving a valid LSA is to retransmit that LSA
>out a set of interfaces. However, section 13.3 of RFC 2328 describes a
>list
>of numerous caveats. One of those is that should you receive an LSA that
>in
>all probability was successfully received by other routers out a particular
>interface, there is no need to retransmit it. This applies particularly
>when you are not the DR or BDR and you receive an LSA from the DR. The
>standardized procedure is not to retransmit that LSA out the receiving
>interface. However, that LSA is retransmitted out of all other interfaces
>that do not conflict the with noted caveats in 13.3.
>
>As far as examples go, the DR sends to the rest of the broadcast segment as
>it is adjacent to all. Each of those routers in turn flood out whatever
>other transit interfaces they possess excluding the one where the LSA was
>received.
>
>Does that help?
>
>Pete
>
>
>*********** REPLY SEPARATOR ***********
>
>On 7/3/2001 at 9:42 AM Ole Drews Jensen wrote:
>
>>> I am currently reading the CiscoPress BSCN book, and I find myself a bit
>>> confused on the LSU/LSA procedures in OSPF.
>>>
>>> When many routers are connected on the same LAN segment, and are
>>therefore
>>> neighbors to eachother, a DR and a BDR will be elected.
>>>
>>> First they write that routers do not flood OSPF updates/advertisements
>to
>>> all the OSPF routers (224.0.0.5), but only to the DR OSPF routers
>>> (224.0.0.6). It is then the task of the DR(s) to flood whatever needs to
>>> be flooded to all the routers.
>>>
>>> However, a little later in the book, they tell me that when a router
>>> receives an update from a DR router, it will flood it to all routers.
>>>
>>> They also write that when a router receives an update, it will flood it
>>to
>>> all DR OSPF routers on other connected LAN segments.
>>>
>>> Can someone give me a simple explanation on who sends what to where?
>>>
>>> Thanks in advance,
>>>
>>> Ole
>>>
>>> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>> Ole Drews Jensen
>>> Systems Network Manager
>>> CCNA, MCSE, MCP+I
>>> RWR Enterprises, Inc.
>>> [EMAIL PROTECTED]
>>> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>> http://www.OleDrews.com/CCNP
>>> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>> NEED A JOB ???
>>> http://www.oledrews.com/job
>>> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
s
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