RE: About loop avoidance when using BGP best external

Hi Xiaohu,

Your draft indeed requires no protocol change.
OTOH, the Bashandy draft covers the active-active case
where either link to the CE can fail and be backed up by the other.

--
Jakob Heitz.

> -----Original Message-----
> From: l2vpn-bounces@ietf.org [mailto:l2vpn-bounces@ietf.org] 
> On Behalf Of Xu Xiaohu
> Sent: Thursday, April 07, 2011 9:20 PM
> To: raszuk@cisco.com
> Cc: l2vpn@ietf.org
> Subject: About loop avoidance when using BGP best external
> 
> -----Original Message-----
> > From: idr-bounces@ietf.org [mailto:idr-bounces@ietf.org] On 
> Behalf Of 
> > Robert Raszuk
> > Sent: Sunday, April 03, 2011 2:26 AM
> > To: Jakob Heitz
> > Cc: idr
> > Subject: Re: [Idr] draft-bashandy-idr-bgp-repair-label-01: 
> when does 
> > PE revert back to standard label?
> > 
> > Hi Jakob,
> > 
> > > I think the draft needs to state that a received native 
> IP packet is 
> > > NEVER sent using the repair label. Specifically, if the 
> IP path to 
> > > the CE is broken, a packet received as a native IP packet 
> shoul be 
> > > sent to the PE next hop using the regular label, not the repair 
> > > label. The repair label should only be used for packets received 
> > > from MPLS.
> > 
> > The draft already states this:
> > 
> >     In a BGP free core, where traffic is tunneled between 
> edge routers
> >     and edge routers assign labels to prefixes, BGP 
> speakers advertise
> >     reachability information about prefixes and associate a 
> local label
> >     with each prefix such as L3VPN [9], 6PE [10], and Softwire [8].
> > 
> > But thinking further I do not see perhaps anything wrong on 
> attaching 
> > this attribute to unicast IPv4 and IPv6 AFIs where ASBRs 
> and network 
> > between them are MPLS enabled.
> > 
> > In fact if we would explicitly permit this in 
> > draft-bashandy-idr-bgp-repair-label it will automatically 
> address the 
> > problem as described in draft-xu-idr-best-external-loop-avoidance.
> 
> Hi Robert,
> 
> Sorry that I just notice this email mentioning my draft
> (draft-xu-idr-best-external-loop-avoidance).
> 
> IMO, the repair-label draft 
> (draft-bashandy-idr-bgp-repair-label) and my
> draft have many differences as listed below (here I just 
> refer the L3VPN CE
> multi-homing scenario):
> 
> 1. Different target scenarios:
> The repair-label draft targets the scenario where the best 
> route for the
> local CE site on each multi-homing PE router is pointed to 
> the CE router,
> while my draft targets the scenario of best external.  
> 
> 2. Different achievements:
> The repair-label draft only solves the problem of transient 
> loop in case the
> CE router is down (anyway, the CE destination is unreachable 
> at this time).
> While my draft not only solves the transient loop problem, 
> but also speeds
> up the convergence in case the best external route is still 
> available. 
> 
> 3. Different approaches:
> The repair-label draft requires some changes to the BGP 
> protocol while my
> draft doesn’t require any change to the BGP protocol.
> 　　
> Best wishes,
> Xiaohu
> 　　
> > Thx,
> > R.
> > 
> > 
> > _______________________________________________
> > Idr mailing list
> > Idr@ietf.org
> > https://www.ietf.org/mailman/listinfo/idr
> 
> 
> 