[c-nsp] why vpls need some special line cards to support

[Phil Mayers]

On 09/01/12 17:02, Nick Hilliard wrote:
> On 09/01/2012 16:40, Phil Mayers wrote:
>> Many forwarding engines e.g. 6500 PFC3 cannot support this. Those platforms
>> require linecards with "extended" forwarding engines.
>
> it's not the forwarding engines that have the problem here - it's the line
> cards.  A PFC3B or later will support VPLS on SIP / ES/ES+ / OSM cards
> without any problems.  Or e-FlexWAN, if you are so inclined.

Sorry, I don't understand the distinction you're making. Perhaps we are 
using terminology differently?

As I understand it, a packet received on a LAN linecard will be 
forwarded by the local DFC or central PFC to the egress linecard, and 
the DFC3/PFC3 cannot simultaneously perform MAC lookup and label 
imposition. Hence, the limitation is the forwarding engine, no?

If the egress linecard is a WAN linecard, the WAN forwarding hardware 
will perform the MAC->egress LSP lookup. But it's not the PFC or DFC 
"supporting" it; it's the extra hardware on the WAN card.