Subject: [rbridge] Control plane scalability

From: gibanez at it.uc3m.es (Guillermo Ibáñez)
Date: Thu, 12 May 2005 20:11:41 +0200

[rbridge] Control plane scalability

*
*Guillermo Ib??ez wrote:
Alex,
      I join this discussion a bit late..., but it looks still quite 
open and your main points look unanswered.
      I support the idea of  a "cloud of rbridges"  supporting a 
50.000-100.000  hosts  networks and 1000 VLANs.  I see this kind of 
"target" network for rbridges somewhere  in the middle between current 
enterprise networks and MANs. It makes little sense to design new 
devices for current network sizes.  One key difference of thowever is 
that there would be only one administrator/owner of the complete network 
and hosts.
      The topology  that I think might scale is to consider two levels: 
a core of rbridges strongly interconnected with multiple spanning trees, 
rooted (preferably, for optimum path) each tree at each edge rbridge. 
Every edge  rbridge acts also as the root of its own spanning tree 
network (second level) below. The path from host to host in this type of 
network may be optimum for traffic crossing the core (the dominant part 
of traffic in the current client-server model) if one of the edge 
bridges in the core path is the root.
      To progress on scalability discussion I would suggest first to 
agree on maximum network size to set a basis for scalability 
discussions. Once the size limit is set, it is easier to choose between 
multi-topology and multi-instance solutions.
*      *The contradiction and difficulty I see with handling VLANs is 
that VLANs may collide  a bit  with the selfconfiguration objective, 
unless VLAN assignment is fully automatic and VLAN to tree association 
is also automatic, as it is the case of VLAN tag (in the core) 
associated to MAC address of edge bridge, like in Global Open Ethernet 
[NEC, Iwata].
    
Guillermo
*
Alex Zinin* zinin at psg.com 
<mailto:rbridge%40postel.org?Subject=%5Brbridge%5D%20Control%20plane%20scalability&In-Reply-To=p06200714be4e9a4e4b59%40%5B10%5C.0%5C.0%5C.171%5D>
/Fri Mar 4 15:39:17 PST 2005/
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Margaret,

  Sounds like an interesting topic :)

-- 
Alex
http://www.psg.com/~zinin <http://www.psg.com/%7Ezinin>

Friday, March 4, 2005, 3:13:33 PM, Margaret Wasserman wrote:

>/ Hi Alex,
/
>>>/  Are you planning to build one massive device that would run all of the
/>>>/  bridging and routing for this 50,000 node network?
/>>/
/>>/Margaret, when building switched Ethernet networks today, folks don't build
/>>/different broadcast domains using separate sets of single-VLAN 
/>>/devices. Neither
/>>/they use a single massive device to connect all stations 50,000 as you suggest
/>>/above. They build VLANs using multi-VLAN switches connected by VLAN trunks.
/>>/Those VLANs are distributed location-wise, and switches in the core of the
/>>/network have visibility to most (if not all) VLANs through those trunks.
/
>/ Yes, I am somewhat aware of these deployments, but I don't understand why
/>/ this implies that the core switches would be rbridges and/or why they would be
/>/ part of most of the rbridge clouds.
/
>/ Maybe we can talk about this when we have a whiteboard handy?  I'm not
/>/ trying to score debating points here .  I think we're just thinking 
/>/ about this differently,
/>/ and I'd like to understand how you believe the topology will work as opposed
/>/ to how I think it will work.
/
>/ Margaret
/

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