Eu encontrei uma solução para o meu problema. Eu simplesmente usei o OpenConnect em vez do próprio cliente da Cisco.
O OpenConnect ( link ) é um cliente de código aberto para o AnyConnect SSL VPN da Cisco, construído em torno de GnuTLS e OpenSSL. Funciona em BSD, Linux, Mac e Windows.
Para mim, resolveu o problema tanto no Linux (Ubuntu 14, usando o pacote network-manager-openconnect ) como no Windows (Win7 64bit, usando link / link ).
Abaixo estão as rotas antes e depois da conexão VPN com o OpenConnect. Compare-os com o caso AnyConnect, onde as rotas 172.16.0.0 foram removidas.
Agora tenho acesso aos recursos da VPN e à minha LAN local (no meu dispositivo de amostragem conectado à rede em 172.16.97.2).
Rotas antes da conexão OpenConnect:
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Interface List
20...00 ff 08 2c e8 75 ......TAP-Windows Adapter V9
15...52 54 00 c3 42 45 ......Red Hat VirtIO Ethernet Adapter #2
14...52 54 00 f4 a4 80 ......Red Hat VirtIO Ethernet Adapter
1...........................Software Loopback Interface 1
11...00 00 00 00 00 00 00 e0 Microsoft ISATAP Adapter
12...00 00 00 00 00 00 00 e0 Teredo Tunneling Pseudo-Interface
13...00 00 00 00 00 00 00 e0 Microsoft ISATAP Adapter #2
17...00 00 00 00 00 00 00 e0 Microsoft ISATAP Adapter #3
===========================================================================
IPv4 Route Table
===========================================================================
Active Routes:
Network Destination Netmask Gateway Interface Metric
0.0.0.0 0.0.0.0 10.191.244.1 10.191.244.11 261
10.191.244.0 255.255.255.0 On-link 10.191.244.11 261
10.191.244.11 255.255.255.255 On-link 10.191.244.11 261
10.191.244.255 255.255.255.255 On-link 10.191.244.11 261
127.0.0.0 255.0.0.0 On-link 127.0.0.1 306
127.0.0.1 255.255.255.255 On-link 127.0.0.1 306
127.255.255.255 255.255.255.255 On-link 127.0.0.1 306
172.16.0.0 255.255.0.0 On-link 172.16.97.1 261
172.16.97.1 255.255.255.255 On-link 172.16.97.1 261
172.16.255.255 255.255.255.255 On-link 172.16.97.1 261
224.0.0.0 240.0.0.0 On-link 127.0.0.1 306
224.0.0.0 240.0.0.0 On-link 10.191.244.11 261
224.0.0.0 240.0.0.0 On-link 172.16.97.1 261
255.255.255.255 255.255.255.255 On-link 127.0.0.1 306
255.255.255.255 255.255.255.255 On-link 10.191.244.11 261
255.255.255.255 255.255.255.255 On-link 172.16.97.1 261
===========================================================================
Persistent Routes:
Network Address Netmask Gateway Address Metric
0.0.0.0 0.0.0.0 192.168.220.1 1
0.0.0.0 0.0.0.0 10.191.244.1 Default
===========================================================================
Rotas após a conexão openconnect:
===========================================================================
Interface List
20...00 ff 08 2c e8 75 ......TAP-Windows Adapter V9
15...52 54 00 c3 42 45 ......Red Hat VirtIO Ethernet Adapter #2
14...52 54 00 f4 a4 80 ......Red Hat VirtIO Ethernet Adapter
1...........................Software Loopback Interface 1
11...00 00 00 00 00 00 00 e0 Microsoft ISATAP Adapter
12...00 00 00 00 00 00 00 e0 Teredo Tunneling Pseudo-Interface
13...00 00 00 00 00 00 00 e0 Microsoft ISATAP Adapter #2
17...00 00 00 00 00 00 00 e0 Microsoft ISATAP Adapter #3
===========================================================================
IPv4 Route Table
===========================================================================
Active Routes:
Network Destination Netmask Gateway Interface Metric
0.0.0.0 0.0.0.0 10.191.244.1 10.191.244.11 261
0.0.0.0 0.0.0.0 192.168.220.1 192.168.221.140 2
10.191.244.0 255.255.255.0 On-link 10.191.244.11 261
10.191.244.11 255.255.255.255 On-link 10.191.244.11 261
10.191.244.255 255.255.255.255 On-link 10.191.244.11 261
127.0.0.0 255.0.0.0 On-link 127.0.0.1 306
127.0.0.1 255.255.255.255 On-link 127.0.0.1 306
127.255.255.255 255.255.255.255 On-link 127.0.0.1 306
172.16.0.0 255.255.0.0 On-link 172.16.97.1 261
172.16.97.1 255.255.255.255 On-link 172.16.97.1 261
172.16.255.255 255.255.255.255 On-link 172.16.97.1 261
192.168.220.0 255.255.254.0 On-link 192.168.221.140 257
192.168.221.140 255.255.255.255 On-link 192.168.221.140 257
192.168.221.255 255.255.255.255 On-link 192.168.221.140 257
193.28.147.7 255.255.255.255 10.191.244.1 10.191.244.11 6
224.0.0.0 240.0.0.0 On-link 127.0.0.1 306
224.0.0.0 240.0.0.0 On-link 10.191.244.11 261
224.0.0.0 240.0.0.0 On-link 172.16.97.1 261
224.0.0.0 240.0.0.0 On-link 192.168.221.140 257
255.255.255.255 255.255.255.255 On-link 127.0.0.1 306
255.255.255.255 255.255.255.255 On-link 10.191.244.11 261
255.255.255.255 255.255.255.255 On-link 172.16.97.1 261
255.255.255.255 255.255.255.255 On-link 192.168.221.140 257
===========================================================================
Persistent Routes:
Network Address Netmask Gateway Address Metric
0.0.0.0 0.0.0.0 10.191.244.1 Default
0.0.0.0 0.0.0.0 192.168.220.1 1
===========================================================================