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discrepancy between o/p for ospf and ospfv3

‎05-27-2020 10:01 AM

hi Experts,

 

I could not understand this behaviour, want to check with you as to why the ospf o/p’s for ospf and ospfv3 differ as below:

The ID field for OSPF shows the 32 bit router ID but not for ospfv3. I see this observation is in line with technical documentation, but want your help in understanding the reason?

 

Appreciate your help!

 

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2 REPLIES 2
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Routing

Re: discrepancy between o/p for ospf and ospfv3

‎05-27-2020 03:00 PM

Hi Nexon,

 

I got a couple of devices running OSPF3 and OSPF and got the same question as you, as my outputs points to the same:

 

root@router# run show ospf3 database
May 27 14:32:45

OSPF3 database, Area 0.0.0.0
Type        ID      Adv Rtr Seq        Age Cksum  Len
IntraArPfx *0.0.0.1 2.2.2.2 0x80000001 8   0xcfa8 44

OSPF3 Link-Local database, interface vlan.200 Area 0.0.0.0
Type ID Adv Rtr Seq Age Cksum Len
Link *0.0.0.1 2.2.2.2 0x80000001 8 0xaae7 56

 

{master:0}[edit]
root@router# run show ospf database
May 27 14:32:53

OSPF database, Area 0.0.0.0
Type    ID           Adv Rtr       Seq        Age   Opt  Cksum  Len
Router *2.2.2.2      2.2.2.2       0x80000002 16    0x22 0x2132 48
Router 10.10.10.2    10.10.10.2    0x80000100 17    0x22 0x1b46 48
Router 10.85.154.144 10.85.154.144 0x80000042 1903  0x22 0xbf4f 48
Router 10.85.154.150 10.85.154.150 0x80000041 17    0x22 0x7ada 36

 

On OSPF3, the ID is for the link ID rather than the Router ID. Here is the exact definition:

 

Link identifier included in the advertisement. An asterisk (*) preceding the identifier marks database entries that originated from the local routing device. - https://www.juniper.net/documentation/en_US/junos/topics/reference/command-summary/show-ospf3-databa...

 

While on OSPF(2) is the LSA identifier: LSA identifier included in the advertisement. An asterisk preceding the identifier marks database entries that originated from the local routing device. - https://www.juniper.net/documentation/en_US/junos/topics/reference/command-summary/show-ospf-databas...

 

Basically, it is something specific to OSPF3 to ID the links. For example, on the Hello Packets for OSPF(2) we have Router ID and other fields (section A.3.2 of RFC1583), while on OSPF3 the Hello Packet:

 

The Hello packet now contains no address information at all.
      Rather, it now includes an Interface ID that the originating
      router has assigned to uniquely identify (among its own
      interfaces) its interface to the link.  This Interface ID will be
      used as the network-LSA's Link State ID if the router becomes the
      Designated Router on the link. RFC5340

This would mean that this is expected behavior, as on OSPF2 you have the LSA ID, while on OSPF3 you have the Link ID.

 

If this solved your question, please mark my answer as the solution, and kudos are always appreciated! 

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Re: discrepancy between o/p for ospf and ospfv3

‎05-28-2020 01:16 AM

Hi Nexon,

 

You can still use the extensive option to see the router-id for the neighbour, in case that is needed : 

 

Router      0.0.0.1          10.255.4.85      0x80000003  1028  0xa697  40
  bits 0x2, Options 0x13
  Type PointToPoint (1), Metric 10
      Loc-If-Id 2, Nbr-If-Id 3, Nbr-Rtr-Id 10.255.4.93 <<<<<<<<

 

BR,

Vishal

 

PS: Please accept my response as solution if it answers you query, kudos are appreciated too!