HP OpenVMS Systems

ask the wizard
Content starts here

IP Subnet Routing?

» close window

The Question is:

I can connection with Alpha from PC (Windows) with telnet from various
 IP-adress. When I try connect to Alpha with FTP It possible from my subnet
 IP-address  and inpossible from another subnet. ( for example: my Ip-adress is and another IP-addres
s is  and Alpha Ip-address is ?) What can I do?

The Answer is :

  It appears that your local IP infrastructure and your local IP router(s)
  are incorrectly configured, or that there is a firewall or router or
  other similar construct effectively blocking access.
  Use of ping and traceroute and other tools would be in order, of course.
  10.* addresses are internal (private) addresses of course, and may or
  may not pass through your internal network routers and gateways, and
  there is a router or gateway between your subnets.
  Per RFC 1918:
   "The Internet Assigned Numbers Authority (IANA) has reserved the
   following three blocks of the IP address space for private internets:        -  (10/8 prefix)      -  (172.16/12 prefix)     - (192.168/16 prefix)"
   "Because private addresses have no global meaning, routing information
   about private networks shall not be propagated on inter-enterprise
   links, and packets with private source or destination addresses
   should not be forwarded across such links. Routers in networks not
   using private address space, especially those of Internet service
   providers, are expected to be configured to reject (filter out)
   routing information about private networks. If such a router receives
   such information the rejection shall not be treated as a routing
   protocol error."
  For addition details on the internal class A 10.*.*.* network address
  range, please see RFC 1918.
  Your OpenVMS version and the likely TCP/IP Services versions are both
  old and an upgrade to more current (and supported) versions is strongly

answer written or last revised on ( 18-JUN-2003 )

» close window