[pim] About comments on draft-xu-pim-drpriority-auto-adjustment-01//re: pim wg mtg minutes Hiroshima

[Xu Xiaohu <xuxh at huawei.com>]

Hi Yiqun and all,

My response to Yiqun's comment is inline (sorry for missing your comment
during the WG session). 

BTW, according to the co-chairs' suggestions, we (the co-authors of this
draft) would like to solicit more comments on this draft.

 >Yiqun: A comment about changing back and forth on the RP
 >    priority.  You have to go back, otherwise if
 >    failures keep happening, everyone ends up at
 >    priority zero.  So we need to accept the disruption
 >    to the traffic when the link comes back up.  This
 >    should be addressed.

Your comment is very good. In fact, we had even thought about this case.
Allowing preemption is the easiest way. However, we still want to give the
operator another option in which traffic disruption can be avoided when the
failed upstream link on R1 (old DR) recovers (from down to up). The basic
idea is actually described in the draft (the following text is quoted from
the draft). I believe the PIM routers will not run into a corner of priority
zero. Correct?

**************************************************************************
   Once the failed upstream link on R1 recovers (from down to up), its
   DR priority can be either recovered or not according to the pre-
   configured preemption policy. For example, if preemption is not
   allowed, its DR priority will remain unchanged so as to avoid DR
   switchover. As a result, the transient multicast forwarding
   interruption due to multicast forwarding tree rebuilding will not
   occur. Once the current DR fails or its DR priority changes, the
   non-DR should start using its actual DR value to compete for a new
   round of DR election provided it has got route to the uplinks.
**************************************************************************

Best wishes,
Xiaohu


> -----邮件原件-----
> 发件人: pim-bounces at ietf.org [mailto:pim-bounces at ietf.org] 代表 Mike
> McBride (mmcbride)
> 发送时间: 2009年11月19日 5:14
> 收件人: pim at ietf.org
> 主题: [pim] pim wg mtg minutes Hiroshima
> 
> Have been posted:
> 
> http://www.ietf.org/proceedings/09nov/minutes/pim.txt
> 
> Thanks to David McWalter for taking the minutes. Please review and let
> us know if we missed something.
> 
> mike
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