The MPLS WG Archive

[eduard metz <e.t.metz@usa.net>]

hello juha,

you're probably right that no "coordination" between pe and ce is needed
(other than ilmi/lmi as you described below) when the network between the ce's
can be treated as a single subnet. in this case the configuration effort is
really low (which is great). however, there are many situations in which this
is not the case. for example: when the network is treated as a collection of
point-to-point links (with individual /30s), or when the network is native l2
...

in these cases some alignment / coordination between pe and ce configuration
is required. you need to know which circuit is connected to which site to end
up with a correct, and working configuration.

cheers, eduard

(using alternative email)

Metz, E.T. writes:

>> When CE and PE configuration are
>> not aligned on this point, the CE may expect to connect to one site on 
>> a particular circuit, while the PE actually connects it to another one.


> in fr or atm world, the ce learns via lmi or ilmi about new or deleted
> labels.  then it sends an inarp message along the vc and learns who is
> behind that vc and starts to exchange ospf messages with it.  the vc
> topology doesn't need to be full mesh and still all the vpn members can
> share a common ip subnet.



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