vyatta@vyatta:~$ show interfaces

Codes: S - State, L - Link, u - Up, D - Down, A - Admin Down

Interface IP Address S/L Description

--------- ---------- --- -----------

eth0 172.24.42.51/24 u/u

eth1 192.168.101.1/24 u/u

eth2 192.168.12.1/24 u/u

eth3 192.168.13.1/24 A/D

lo 127.0.0.1/8

::1/128

vyatta@vyatta:~$

Based on the output, what is the problem with eth3?