From: Miroslav Kosut (miroslav.kosut@gmail.com)
Date: Thu Feb 26 2009 - 20:25:58 ARST
Hello experts,
this is what I realized while reading the OSPF's RFC:
Let's say every OSPF router creates the "tree" from the "graph" when
looking at the topology.
(note difference between graphs and trees - tree CAN'T contain loops)
When "node is a router" and "link is a network between routers", then:
If you had only point to point links, branch in the tree can be
divided to more only at nodes.
If you had multiaccess network such as ethernet, branch can also be
divided to more "at the network". So in this case a "fictitious" node
can be in the middle of multiaccess network.
.. and that's why Type 2 LSA exist - to describe this "fictitious"
node, also called DR.
Router LSAs describe it's connected networks, and
Network LSAs describe it's connected routers.
Hope it makes sense :-)
Regards,
Miro Kosut
On Feb 26, 2009, at 7:55 PM, Nadeem Ansari wrote:
> That is true but what is the use of this LSA for routing of a
> packet ? It is
> just to provide awareness about multi access segment
>
> On Thu, Feb 26, 2009 at 9:33 PM, Ronnie Angello <ronnie.angello@gmail.com
> >wrote:
>
>> These LSAs are generated by the DR to advertise connectivity to a
>> multiaccess network and connections to all of the routers that are
>> connected to the multiaccess network.
>>
>> For example, consider routers A and B connected via a point to point
>> Gigabit Ethernet link. Physically it's a point to point connection.
>> Logically, you have both routers A and B connected to the DR
>> "pseudonode." The router that's elected the DR will generate a
>> Type 2
>> LSA to advertise this pseudonode.
>>
>> On Thu, Feb 26, 2009 at 6:08 AM, Nadeem Ansari
>> <nadeem.ansari574@gmail.com> wrote:
>>> Hi Experts,
>>>
>>> I have an odd question related to OSPF Net Link States LSA-Type2,
>>> As it
>> has
>>> information about DR, Network Mask used on multiaccess network and
>> attached
>>> routers...
>>>
>>> What is the use and importance of this LSA in OSPF routine
>>> operation, As
>>> election and information about DR and BDR are distributed via OSPF
>>> Adj
>>> establishment
>>> Need your suggestion
>>>
>>> Regards
>>> Nadeem
>>>
>>>
>>> Blogs and organic groups at http://www.ccie.net
>>>
>>> _______________________________________________________________________
>>> Subscription information may be found at:
>>> http://www.groupstudy.com/list/CCIELab.html
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>
>>
>>
>> --
>> Ronald Angello
>> CCIE 17846
>> CCDP, CCIP, CCNP
>
>
> Blogs and organic groups at http://www.ccie.net
>
> _______________________________________________________________________
> Subscription information may be found at:
> http://www.groupstudy.com/list/CCIELab.html
Blogs and organic groups at http://www.ccie.net
This archive was generated by hypermail 2.1.4 : Sun Mar 01 2009 - 09:44:13 ARST