[nsp] 6500's and MPLS

[sthaug at nethelp.no]

> Steinar, can You please elaborate ?
> 
> > scarce resource), or you can use normal Ethernet ports towards the CEs
> > and connect a normal GigE port (doing switchport VLAN trunk) to a GE-WAN
> > port (doing 802.1q on GE-WAN subinterfaces, each subinterface in a VRF).
> 
> Connect GigE port to GE-WAN ports on the same box ??? I don't get it.

The whole point here is to be able to use the "normal" Ethernet ports on
the box for aggregation, since they are considerably less expensive than
the GE-WAN ports. Thus if you need to aggregate traffic from 8 switches
(for example), and the sum of the traffic is less than 1 Gbps, you can
connect these switches with VLAN trunks to your regular GigE ports. That
makes traffic from these switches available (as VLANs) inside the 7600.
Now if you want to MPLS terminate these VLANs (putting each VLAN in its
own VRF), you need to get the traffic to the GE-WAN port and create
subinterfaces, each subinterface in its own VRF, on the GE-WAN port.
This can be done by running a connection (802.1q VLAN trunk) from one
regular GigE port to a GE-WAN port.

You can obviously buy two GE-WAN cards, and connect your other 8 switches
directly to the ports on the GE-WAN cards. However, this is a considerably
more expensive solution.

> > The back to back GE ports trick is documented by Cisco
> 
> Do You have URL by the chance ?

I can't find a URL that describes the customer (PE-CE) side right now. 
There is documentation on how to do this on the PE-P side at

http://www.cisco.com/univercd/cc/td/doc/product/core/cis7600/cfgnotes/optical/121e/mpls.htm#1032132

Specifically,

"MPLS Provider (P) functionality is not supported on Ethernet
interfaces that also support Layer 2 switching. The only way to
support P functionality on these interfaces is to create a trunk from
a Gigabit Ethernet interface on, for example, a WS-6516-GBIC module to
an interface on the OSM-4GE-WAN module that is configured to allow P
switching. The interface on the WS-6516-GBIC module should be placed
in trunking mode, and appropriate subinterfaces should be created on
the OSM-4GE-WAN module interface.".

Steinar Haug, Nethelp consulting, sthaug at nethelp.no