Re: [VRRP] Proposal for Maintenance Event for VRRP [RFC-5798]

sreenatha <sreenatha.setty@ibtechnology.com> Fri, 22 February 2013 04:26 UTC

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Date: Fri, 22 Feb 2013 09:55:35 +0530
From: sreenatha <sreenatha.setty@ibtechnology.com>
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To: "Anurag Kothari (ankothar)" <ankothar@cisco.com>
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Subject: Re: [VRRP] Proposal for Maintenance Event for VRRP [RFC-5798]
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Hi Anurag,
    Your proposal is:

- If a Maintenance event is received, then:

+ Cancel the Adver_Timer

+ Send an ADVERTISEMENT with Priority = 0

-endif // maintenance recv


     And you mentioned that router need to send regular ADVERTISEMENT message till it receives the ADVERTISEMENT message from the backup router.

"2. How much time Master router should wait to receive ADVERTISEMENT message from any backup router?

[Anurag] Master doesn't have to wait. After receiving the maintenance event it will send regular ADVERTISEMENT with Priority = 0 till some other router send back an ADVERTISEMENT message at which point it will transition to Backup."

If Advert_Timer is cancelled, how regular ADVERTISEMENT messages are sent?

So i am suggesting slight changes in the Proposal:

- If a Maintenance event is received, then:

+ Change the router priority to 0

+ Send an ADVERTISEMENT with Priority = 0

+ Reset the Adver_Timer

  -endif // maintenance recv

This will ensure that:
1. ADVERTISEMENT message with priority 0 is sent  immediately on receiving Maintenance event.
2. Master router will send regular Advertisement message till it receives the ADVERTISEMENT message from any backup routers.

Thanks,
Sreenatha Setty




On 02/21/2013 10:12 PM, Anurag Kothari (ankothar) wrote:
> Hi Sreenatha
>
> This ideas is based on the way the priority is defined in Section 5.2.4. and 6.1. of RFC-5798.
>
> "
>     The priority value zero (0) has special meaning, indicating that the
>     current Master has stopped participating in VRRP.  This is used to
>     trigger Backup routers to quickly transition to Master without having
>     to wait for the current Master to time out.
> "
>
> "
>     Priority              <snip>  The value of 0 (zero) is
>                                 reserved for the Master router to
>                                 indicate it is releasing responsibility
>                                 for the virtual router.  The range 1-254
>                                 (decimal) is available for VRRP routers
>                                 backing up the virtual router. <snip>
> "
>
> Please see my responses inline [Anurag]:
>
> Thanks
> -Anurag
>
> -----Original Message-----
> From: vrrp-bounces@ietf.org [mailto:vrrp-bounces@ietf.org] On Behalf Of sreenatha
> Sent: Thursday, February 21, 2013 11:03 AM
> To: vrrp@ietf.org
> Subject: Re: [VRRP] Proposal for Maintenance Event for VRRP [RFC-5798]
>
> Hi Anurag,
>       Proposed idea is good. I have some queries on this proposal:
>
> 1. On receiving new maintenance_event, priority of the router is not changed, right? So if back-up router has less priority, even if Master receives the ADVERTISEMENT from the backup router, Master will discard.
> So how the Master router state is going to change?
>
> [Anurag] On receiving the maintenance event the priority of router (or VRID) will change to 0.
>
> 2. How much time Master router should wait to receive ADVERTISEMENT message from any backup router?
>
> [Anurag] Master doesn't have to wait. After receiving the maintenance event it will send regular ADVERTISEMENT with Priority = 0 till some other router send back an ADVERTISEMENT message at which point it will transition to Backup.
>
> 3. Standard VRRP MIB(RFC-2787) does not allow user to configure '0' for VRRP Priority. So you are proposing to change this value also?
>
> [Anurag] Yes. Priority 0 will have to be made a user configurable value to indicate the intention of a router to relinquish Master Status.
>
> Thanks,
> Sreenatha Setty
>
> On 02/21/2013 01:30 AM, vrrp-request@ietf.org wrote:
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>> Today's Topics:
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>>      1. Proposal for Maintenance Event for VRRP [RFC-5798]
>>         (Anurag Kothari (ankothar))
>>
>>
>> ----------------------------------------------------------------------
>>
>> Message: 1
>> Date: Tue, 19 Feb 2013 22:08:41 +0000
>> From: "Anurag Kothari (ankothar)"<ankothar@cisco.com>;
>> To:"vrrp@ietf.org"  <vrrp@ietf.org>;
>> Subject: [VRRP] Proposal for Maintenance Event for VRRP [RFC-5798]
>> Message-ID:
>> 	<A2BB90B33FFDF740876C5AAE307D83DB1C290327@xmb-rcd-x05.cisco.com>;
>> Content-Type: text/plain; charset="us-ascii"
>>
>> Hi
>>
>> I want to propose a new Maintenance Event (modification of Shutdown Event) for VRRP (RFC-5798] which would allow to gracefully failover the VRRP Master to Redundant (Backup Router).
>>
>> Problem Statement:
>> VRRP preemption is not configured on the redundant / backup router.
>> How to initiate VRRP Traffic to failover to the redundant / backup
>> router gracefully without modifying the configuration on the redundant
>> / backup router (i.e. adding preemption)
>>
>> Proposed Solution:
>> Addition to Section 6.4.3 of RFC-5798:
>>
>> - If a Maintenance event is received, then:
>>
>> + Cancel the Adver_Timer
>>
>> + Send an ADVERTISEMENT with Priority = 0
>>
>> -endif // maintenance recv
>>
>> Unlike Shutdown event the router will not "Transition to the {Initialize} state" and continue to be Master and forward traffic  till the backup router sends an ADVERTISEMENT (triggered by receiving an ADVERTISEMENT with Priority = 0) and becomes master.
>> Here are couple of examples of how a maintenance event may be
>> triggered
>>
>>
>> 1)      By some user command e.g. "maintenance-mode" in the vrrp configuration.
>>
>> 2)      By setting the priority = 0 for a particular VRID.
>>
>> Thanks
>> -Anurag
>>
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