Subject: FW: ce range in l2 mpls vpns

From: Juha Heinanen <[email-masked]>
Date: Thu, 23 Nov 2000 15:40:19 +0200 (EET)

eduard metz writes:

 > 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.

this too can and has been automated at least in case of atm. you simply
have one-to-one mapping between subinterface numbers and vpi numbers and
then when the ce learns a new label, it knows which subinterface it
belongs to based on its vpi component.

the same can be done with native mpls by using label stacking: the outer
label selects the vpn and the inner label determines a site within that
vpn.  it doesn't matter if a "vnp" has many sites or if it is just a
point to point link.

-- juha

---

From: eduard metz <[email-masked]>
Date: 23 Nov 00 14:29:50 MET

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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