[c-nsp] Map IP Precedence to 802.1p on output of router sub-Fast

[Everton da Silva Marques]

I need to address this 802.1p issue for the following
platforms:

- Cisco 7507 RSP4/VIP/dCEF 12.0(27)S4
- Cisco 7609 SUP7203B 12.2(18)SXE4

Context is, we have multiple 802.1q sub-interfaces on
FastEthernet interfaces, like this:

interface FastEthernet1/1/0.100
 encapsulation dot1Q 100
 ip address 200.a.b.c 255.255.255.240
end
interface FastEthernet1/1/0.101
 encapsulation dot1Q 101
 ip address 200.x.y.z 255.255.255.248
end

On the 7609, the sub-interfaces are more like
GigabitEthernet2/26.102, but the overall scenario is
identical.

For every output packet leaving the device on those
sub-interfaces, how do we map the IP Precedence bits into
802.1p priority bits?

Packets already arrive at the 7500/7600 devices with the
correct IP Precedence bits marked. We only need to copy the
IP Precedence bits into the 802.1p priority.

Please advise.