RE: Reminder of posting of draft-ietf-vrrp-ipv4-timers-01.txt

Sonum,
	Thank you for your comments on the draft. I have included my response to your comments in-line.

Bob Hott

-----Original Message-----
From: Mathur Sonum-CSM109 [mailto:[email protected]]
Sent: Tuesday, January 24, 2006 19:44
To: Hott, Robert W CIV B35-Branch; [email protected]
Subject: RE: [VRRP] Reminder of posting of
draft-ietf-vrrp-ipv4-timers-01.txt



Few comments on the draft

      If the VR_Mode = 1, then:
        o  Send an ADVERTISEMENT
        o  Set the Adver_Timer to Advertisement_Interval
       else:
        o  Send a FAST ADVERTISEMENT
        o  Set the Adver_2_Timer to Advertisement_Interval
 
For initialization, when VR_Mode = 1, then why are Fast Advts. not sent.
VR_Mode = 1 indicates that both types of VRRP implementations are
present. Then, to satisfy the backup routers with newer implementation,
Fast Advts. are needed. If not, they will declare Master Down and will
try to become Master causing more than one Masters to be active.
 
<Bob Hott> This is a good observation. You caught an error in the draft. The "VR_Mode" in the IF statement, above and on page 8 in the draft, should have been "VR_Type"! During initialization, the VRRP router, when it is the Master, should send out the type of advertisement that it is configured to send. Thank you for catching this error.



 -  If the Adver_2_Timer fires, then:
       If the VR_Mode is 1
       or
       if the VR_Type is 2, then:
        o  Send a FAST ADVERTISEMENT
        o  Reset the Adver_2_Timer to VR_Adver_Interval
 
When Adver_2_Timer fires, and VR_Type configured on the local router is
2, then local router should send a Fast Advt. Why do we need a check for
VR_Mode == 1 at all ? In my opinion, the only check for sending Fast
Advt should be VR_Type == 2. Please clarify.
 
<Bob Hott> For the above comment, this test is on pages 12 and 13 of the draft. I believe that we should have both tests following the firing of the Adver_2_Timer. It is possible that the VRRP router, although running this new implementation, would be configured to run as an older version (possibly to use authentication). Thus it should check to see if the VR_Mode is 1 (heterogeneous).


I would like to suggest removal of parameter 'VR_Mode'.  If there is a
situation of new implementation inter operating with older one, we can
live with ignore and log. Although 'VR_Mode' takes care of this issue,
but implementation would be relatively simpler if we don't consider the
heterogeneous environment. This is just my opinion, if this topic is
still open for discussion.

<Bob Hott> If you are in an environment in which a new implementation is interoperating with an older implementation, if the new implementation only logs and ignores the older implementation, then you run the risk of having two masters. If the new implementation is supposed to be the Master, it must force the older implementation to transition to a backup state. The older implementation will ignore the new FAST ADVERTISEMENTS, thus it will want to transition to Master, unless it sees an ADVERTISEMENT from the new implementation Master. For this reason, I don't think you want to ONLY ignore and log.

--
Sonum 


________________________________

	From: [email protected] [mailto:[email protected]] On
Behalf Of Hott, Robert W CIV B35-Branch
	Sent: Thursday, January 19, 2006 6:56 AM
	To: [email protected]
	Subject: [VRRP] Reminder of posting of
draft-ietf-vrrp-ipv4-timers-01.txt
	
	

	All, 
	        This is just a reminder that the draft for providing
sub-second timers for VRRP for IPv4 was posted. I would appreciate any
comments that you might have on this draft.

	Abstract: The router survivability capability provided by the
Virtual Router Redundancy Protocol for IPv4 (VRRPv4) satisfies the
requirements for many LAN environments. There are, however, LAN
environments that have sub-second failover requirements and thus a need
for finer granularity of the VRRP timers. This draft proposes extensions
to VRRPv4 [RFC 3768] for specifying sub-second Advertisement Intervals.
A new message type is introduced which permits the timer granularity for
the Advertisement Interval to be specified. In addition, a new field is
introduced permitting the specification of the number of missed
ADVERTISEMENTs before a Virtual Router Master is declared down. 

	Bob Hott 

	Robert (Bob) W. Hott 
	NSWC-DD 
	Code B35, Bldg. 1500A/122A 
	17320 Dahlgren Road 
	Dahlgren, VA 22448-5100 
	540-653-1497 (W) 
	540-653-8673 (FAX) 
	[email protected] (E-mail) 

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