Subject: [OSPF] Clarification of DR & BDR Processing in OSPFV3

From: Thirumavalavan Periyannan <[email-masked]>
Date: Tue, 27 Dec 2011 17:16:21 +0530

Hi All,

I have a doubt in DR and BDR process in OSPFV3.

“   *AllDRouters*:

                     This multicast address has been assigned the value
FF02::6.

   *Both the Designated Router and Backup Designated Router must be*

*   prepared to receive packets* destined to this address.  Certain

   OSPF protocol packets are sent to this address during the

   flooding procedure.”

RFC says, DR & BDR must be *prepared* to receive packets destined to
FF02::6, Here is that *Prepared* means to say BDR needs

to process the packet with destination address FF02::6 (ALLDRouters)?

In CISCO routers, BDR is not processing the packet with destination address
“ALLDRouters”.

But the same BDR when it receives an update packet with destination address
as “ALLSPFRouters”, it is processing the packet.

So I want a clarification of the above lines in the standard.

Regards,

*Thirumavalavan *

Consultant

[image: Description: Description: Description: IP
Infustion]<http://www.ipinfusion.com/index.html>

---

From: Acee Lindem <[email-masked]>
Date: Tue, 27 Dec 2011 13:24:02 -0500

Hi Thirumalvalavan, 
See inline. 
On Dec 27, 2011, at 6:46 AM, Thirumavalavan Periyannan wrote:

> “   AllDRouters: 
>                      This multicast address has been assigned the value FF02::6.
>    Both the Designated Router and Backup Designated Router must be
>    prepared to receive packets destined to this address.  Certain
> RFC says, DR & BDR must be prepared to receive packets destined to FF02::6, Here is that Prepared means to say BDR needs

Yes. This is somewhat implementation and network interface type specific but it implies that the packet will be received and passed to the OSPFv3 instance's receive queue. 
For example, on ethernet this implies that packets sent the Multicast MAC 33:33:00:00:00:06. 

>  
> In CISCO routers, BDR is not processing the packet with destination address “ALLDRouters”.
> But the same BDR when it receives an update packet with destination address as “ALLSPFRouters”, it is processing the packet.

The receiving OSPFv3 router should process all packets addressed to FF02::6. I'd advise you turn on some debugs on the both the sending and receiving OSPFv3 routers to determine whether or not the packet is being rejected. 

Hope this helps,
Acee

> Thirumavalavan

---

From: Thirumavalavan Periyannan <[email-masked]>
Date: Thu, 29 Dec 2011 11:49:28 +0530

Hi Acee,

I used distribution list to drop the routing update packet (coming from DR)
only with this destination address “*ALLSPFRouters*” at Backup designated
router and

BDR received (without dropping) a routing update packet with destination
address *ALLDRouters*

And I checked the routing table; Expected route is not installed in routing
table that means BDR couldn’t process the update packet with destination
address as “*ALLDRouters*”

Regards,

*Thirumavalavan *

Consultant

*From:* Acee Lindem [mailto:[email-masked]]
*Sent:* Tuesday, December 27, 2011 11:54 PM
*To:* Thirumavalavan Periyannan
*Cc:* <[email-masked]>
*Subject:* Re: [OSPF] Clarification of DR & BDR Processing in OSPFV3

Hi Thirumalvalavan,

See inline.

Hi All,

“   *AllDRouters*:

   flooding procedure.”

Yes. This is somewhat implementation and network interface type specific
but it implies that the packet will be received and passed to the OSPFv3
instance's receive queue.

For example, on ethernet this implies that packets sent the Multicast MAC
33:33:00:00:00:06.

The receiving OSPFv3 router should process all packets addressed to
FF02::6. I'd advise you turn on some debugs on the both the sending and
receiving OSPFv3 routers to determine whether or not the packet is being
rejected.

Hope this helps,

Acee

Regards,

*Thirumavalavan*

Consultant

---

From: Tony Li <[email-masked]>
Date: Thu, 29 Dec 2011 01:43:45 -0800

This list is intended for discussing spec issues and is probably not the best place to debug the problem.  I suggest you contact the developer for the other implementation.  If you're unaware of who the developer is, then if you can tell us the OS and version that you're trying to work with, we may be able to direct you.

Tony

On Dec 28, 2011, at 10:19 PM, Thirumavalavan Periyannan wrote:

> Hi Acee,
>  
> I used distribution list to drop the routing update packet (coming from DR) only with this destination address “ALLSPFRouters” at Backup designated router and
> BDR received (without dropping) a routing update packet with destination address ALLDRouters
>  
> And I checked the routing table; Expected route is not installed in routing table that means BDR couldn’t process the update packet with destination address as “ALLDRouters”
>  
> Regards,
> Thirumavalavan
> Consultant
>  
> From: Acee Lindem [mailto:[email-masked]] 
> Sent: Tuesday, December 27, 2011 11:54 PM
> To: Thirumavalavan Periyannan
> Cc: <[email-masked]>
> Subject: Re: [OSPF] Clarification of DR & BDR Processing in OSPFV3
>  
> Hi Thirumalvalavan, 
> See inline. 
> _______________________________________________
> OSPF mailing list
> [email-masked]
> https://www.ietf.org/mailman/listinfo/ospf

---

From: Thirumavalavan Periyannan <[email-masked]>
Date: Thu, 29 Dec 2011 15:16:54 +0530

Ok Thanks Tony.

 I will come back to you with detailed information.

Regards,
Thirumavalavan
Consultant

-----Original Message-----
From: Tony Li [mailto:[email-masked]]
Sent: Thursday, December 29, 2011 3:14 PM
To: Thirumavalavan Periyannan
Cc: Acee Lindem; [email-masked]
Subject: Re: [OSPF] Clarification of DR & BDR Processing in OSPFV3

This list is intended for discussing spec issues and is probably not the
best place to debug the problem.  I suggest you contact the developer for
the other implementation.  If you're unaware of who the developer is, then
if you can tell us the OS and version that you're trying to work with, we
may be able to direct you.

Tony

On Dec 28, 2011, at 10:19 PM, Thirumavalavan Periyannan wrote:

> Hi Acee,
>
> I used distribution list to drop the routing update packet (coming
> from DR) only with this destination address "ALLSPFRouters" at Backup
> designated router and BDR received (without dropping) a routing update
> packet with destination address ALLDRouters
>
> And I checked the routing table; Expected route is not installed in
routing table that means BDR couldn't process the update packet with
destination address as "ALLDRouters"
> "   AllDRouters:
FF02::6.
>    flooding procedure."
> RFC says, DR & BDR must be prepared to receive packets destined to
> FF02::6, Here is that Prepared means to say BDR needs to process the
packet with destination address FF02::6 (ALLDRouters)?
> In CISCO routers, BDR is not processing the packet with destination
address "ALLDRouters".
> But the same BDR when it receives an update packet with destination
address as "ALLSPFRouters", it is processing the packet.

---

From: Acee Lindem <[email-masked]>
Date: Thu, 29 Dec 2011 04:52:42 -0500

I was just about to say the same. The distribution-list is a proprietary extension that is not part of the standard OSPF protocol. 
Thanks,
Acee

---

From: Thirumavalavan Periyannan <[email-masked]>
Date: Thu, 29 Dec 2011 16:28:59 +0530

Distribution-list is just a method which I used to
simulate the issue for BDR to receive only the update packet with
destination address ALLDRouters
and BDR was not able to process it.

It looks like as an implementation issue.

Regards,
Thirumavalavan
Consultant

-----Original Message-----
From: Acee Lindem [mailto:[email-masked]]
Sent: Thursday, December 29, 2011 3:23 PM
To: Tony Li
Cc: Thirumavalavan Periyannan; [email-masked]
Subject: Re: [OSPF] Clarification of DR & BDR Processing in OSPFV3

I was just about to say the same. The distribution-list is a proprietary
extension that is not part of the standard OSPF protocol.
Thanks,
Acee

>> I used distribution list to drop the routing update packet (coming from
DR) only with this destination address "ALLSPFRouters" at Backup
designated router and
FF02::6.
>> RFC says, DR & BDR must be prepared to receive packets destined to
FF02::6, Here is that Prepared means to say BDR needs
>> Yes. This is somewhat implementation and network interface type
specific but it implies that the packet will be received and passed to the
OSPFv3 instance's receive queue.
address "ALLDRouters".