The MPLS WG Archive

[Eric Rosen <erosen@cisco.com>]

David> I would argue that it should not shunt incompatible traffic into that
David> LSP.  Don't allow a non-IP LSP to tunnel through an IP-LSP. 

What would be the point of this? 

I  admit I've  never  quite understood  the  role of  the  L3PID in  RSVP-TE
signaling. 

In practice, the only situations in which PHP causes a packet's bottom label
to be  popped off are  situations in which  the payload is an  "ordinary" IP
packet.  If the  payload is a layer 2  frame encapsulated via draft-martini,
or a VPN packet encapsulated according to one of the L3VPN schemes, then PHP
will never result in the bottom label being popped off.

So in practice, PHP always results in either an IP packet or an MPLS packet,
and the  appropriate ethertype (IP or  MPLS) can then be  applied before the
packet is transmitted to its next hop.