import re

regex=r"^host-vpp1out .*(?:\r?\n[^\S\r\n]*L3 .*)*"
test_str = ("VirtualFuncEthernet0/7/0.2001 (up):\n"
            "  L3 1.1.2.2/24 ip4 table-id 8 fib-idx 2\n"
            "  L3 2001:db8:0:1:1:1:2:2/112 ip6 table-id 8 fib-idx 1\n"
            "VirtualFuncEthernet0/9/0 (dn):\n"
            "host-vpp1out (up):\n"
            "  L3 1.1.1.1/24\n"
            "  L3 1.1.2.1/24\n"
            "  L3 2001:db8:0:1:1:1:1:1/112\n"
            "  L3 2001:db8:0:1:1:1:2:1/112\n"
            "local0 (dn):\n"
            "loop0 (up):\n"
            "  L3 1.1.1.1/32 ip4 table-id 7 fib-idx 1")

match = re.search(regex, test_str, re.MULTILINE)

if match:
    print(re.findall(r" L3 (\d[\d.:\/a-z]+)\/\d+", match.group()))