[alcatel-nsp] Why do Network Ingress ports share a buffer pool

[Bryan]

Hello,

I am reading about Alcatel QoS in the book "Advanced QoS for
Multi-Service IP/MPLS Networks" and have a question about buffer pool
reservation. On page 146 it says network ingress ports can all share
the same pool to take advantage of the statistical multiplexing gain.
The reason is because all traffic has already been rate limited on
access ingress so chance of one flow consuming the entire buffer is
low.

But, if this is true, then don't the access egress and network egress
have the same statistical multiplexing gains to realize? After all,
anything coming in on a network ingress port is leaving through an
egress port (network or access).

Thanks,

Bryan