[c-nsp] Where to use the ES20 over the 6704/8

[Justin Shore]

We've talked about this before I want to inquire about it again.  When 
would one use the ES20 over the 6704/8?  My understanding is that the ES 
line is a more dense substitute for advanced SPA ports.  These advanced 
features are useful for customer-facing interfaces.  Would that be a 
fair assessment?

I'm running MPLS across my existing 7600 core.  I'm adding 3 7609 
chassis as a distribution layer.  10G is needed to support our FTTx 
roll-out among other things.  I'm looking at 6704/8s for chassis to 
chassis connections and ES20s (soon to be ES40s) for customer-facing 
GigE or 10G interfaces if we plan on using MPLS capabilities for those 
customers.  We're running MPLS across our core now and will extend it to 
encompass the distribution layer as well.  We'll be carrying mcast 
across the network for IPTV, though I'm not sure if we'll be utilizing 
mvpn at this time.  MPLS-TE w/ FRR & BFD will be implemented as well. 
IS-IS is the IGP.  We have to run the SR train for CALEA support.

Does any of that make one lean towards the ES series over the 67xx 
series blades in either the backbone connections or the customer-facing 
connections?  The price difference is the biggest con at this point 
unless there's a technical reason to choose one over the other.

Thanks
  Justin