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Central Services Topology

  • From: Chris Ullock <ullock@syndesis.com>
  • Date: Mon, 24 Sep 2001 16:58:39 -0400
  • Resent-Date: Mon, 24 Sep 2001 19:00:40 -0400
  • To: "'mpls-ops@mplsrc.com'" <mpls-ops@mplsrc.com>

The difference between a central services topology and a hub and spoke
topology is that with the latter spokes can communicate with one another
through the hub whereas with the former spokes can only communicate with the
hub.  

My understanding is that hub and spoke works by having 2 routing adjacencies
configured between the Hub CE and its PE, while the Central services
topology is much simpler in that the hub (central services) CE only requires
a single routing adjacency with its PE.

hub router	spoke router

hub vrf		vrf
import null	import hub
export hub	export spoke

spoke vrf	
import spoke
export null

central services router	client router

vrf			vrf
import client		import services
export services		import client

What I am wondering is whether this is too simplistic a view of central
services.  In a central services configuration, when routes are imported
into a VRF with RT1, and the VRF is set to export routes with RT2, is there
anything to prevent imported routes from being automatically advertised
(especially with Cisco IOS)?  


--
Chris Ullock
IP Product Planner
Syndesis
ullock@syndesis.com

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