Re: [Bier] DR election ...

[Toerless Eckert <[e-mail]>]

https://en.wikipedia.org/wiki/MC-LAG ???

Thats an L2 technology, PIM would neither know nor care.

If you're talking about eg: dual-PE or in general dual PIM routers
connecting to the same LAN, PIM DR/DF priority can follow VRRP/HSRP
priority to leverage their fast failover draft-zhou-pim-vrrp-03.

There is no load-splitting in this approach though, so only one
router is DR/DF. If you want load-balancing, you may want
draft-ietf-pim-drlb (currently expired, already had last call).


Toerless

On Tue, Nov 10, 2015 at 02:52:49PM +0000, Jeffrey (Zhaohui) Zhang wrote:
> [ + PIM ]
> 
> Weiguo,
> 
> In the MC-LAG case, put aside BIER, how does it work today with PIM?
> 
> Jeffrey
> 
> From: Haoweiguo [mailto:[e-mail]]
> Sent: Tuesday, November 10, 2015 7:19 AM
> To: Jeffrey (Zhaohui) Zhang <[e-mail]>; Robert Raszuk <[e-mail]>; IJsbrand Wijnands <[e-mail]>
> Cc: [e-mail]
> Subject: RE: [Bier] DR election ...
> 
> 
> Hi Jeffrey,
> 
> There are two multi-homing scenarios, one is multi-homed network, another one is multi-homed device. For multi-homed network, the network is a LAN, DR/DF mechanism can be used to select one router as master and other routers as slave, only the master router can forward traffic to the LAN network, IGMP/MLD extension can be used for the DR/DF election, this is the focus of draft-wijnands-bier-mld-lan-election-00. However, if a multicast source or receiver is directly accessed to two multicast routers through MC-LAG, flow-based loadbalancing can be achieved for uplink direction traffic. In this case, IGMP/MLD can't be used for DR/DF election for the MC-LAG. I think the new DR/DF election mechanism should also cover the MC-LAG multi-homed scenario.
> 
> My two cents.
> 
> Thanks,
> 
> weiguo
> 
> ________________________________
> From: Jeffrey (Zhaohui) Zhang [[e-mail]]
> Sent: Monday, November 09, 2015 23:08
> To: Haoweiguo; Robert Raszuk; IJsbrand Wijnands
> Cc: [e-mail]<mailto:[e-mail]>
> Subject: RE: [Bier] DR election ...
> Not exactly sure about the details of active-active or active-standby scenarios and their relationship to BIER, but here is my understanding:
> 
> - BIER architecture has three layers: multicast overlay, bier forwarding, and routing underlay. It is really the multicast overlay's job to handle the multi-homing - be it PIM, IGMP/MLD, or BGP, or any other things.
> - While Ice's DR election draft was triggered from using IGMP/MLD to replace PIM for multicast overlay signaling in a BIER domain and the draft has some BIER keywords in it, it is really independent of BIER. The draft is still applicable if BIER had never happened.
> 
> Jeffrey
> 
> From: BIER [mailto:[e-mail]] On Behalf Of Haoweiguo
> Sent: Thursday, November 05, 2015 7:39 PM
> To: Robert Raszuk <[e-mail]<mailto:[e-mail]>>; IJsbrand Wijnands <[e-mail]<mailto:[e-mail]>>
> Cc: [e-mail]<mailto:[e-mail]>
> Subject: Re: [Bier] DR election ...
> 
> 
> I agree with Robert's comments. I think BIER also should cover active-active and active-standby access scenarios.
> 
> Thanks,
> 
> weiguo
> 
> ________________________________
> From: BIER [[e-mail]] on behalf of Robert Raszuk [[e-mail]]
> Sent: Friday, November 06, 2015 8:36
> To: IJsbrand Wijnands
> Cc: [e-mail]<mailto:[e-mail]>
> Subject: [Bier] DR election ...
> 
> Ice,
> 
> As we duscussed offline there are practically two major types of multihomed deployments in production networks:
> 
> 1. True multihoming ... each edge router connect to CEs over different subnet
> 
> 2. Active/standby .. there is multiaccess lan but VRRP is used so hosts can have single default out.
> 
> Now moreover beteen BIER domain and multicast senders and receivers there will pretty much always CEs. I am worried that most BIER slides skip those.
> 
> Cheers,
> R.

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-- 
---
Toerless Eckert, [e-mail]