How to ping a router behind two routers ?

  • Thread starter Thread starter Sam Mok
  • Start date Start date
S

Sam Mok

Dear Sir/ Miss,

Our company have 4 routers locate in 3 places !

Example :
Location one Router 10.144.9.1 (10.144.9.1~254) which connect to location
two router 10.16.15.1 (10.16.15.1~254)
And
Location two another router 10.16.15.11 (10.16.15.1~254) which connect to
location three router 192.168.0.1(192.168.0.1~254)

Can I ping 10.16.15.11 or 192.168.0.1 from 10.144.9.39 ?
If yes , please can you tell me how to set a fix route command in my
10.144.9.39 workstation ?

I had tried :
route add /p 10.16.15.0 mask 255.255.255.0 10.16.15.1 and
route add /p 10.192.168.0 mask 255.255.255.0 10.16.15.11

But failed ... I can only ping local and 10.16.15.1 to 10.16.15.254 , but
can ping 10.16.15.11 and 192.168.0.1~254 , why ?
Help ! Please !

Sam Mok
2004-06-17
 
: Our company have 4 routers locate in 3 places !
:
: Example :
: Location one Router 10.144.9.1 (10.144.9.1~254) which connect to location
: two router 10.16.15.1 (10.16.15.1~254)
: And
: Location two another router 10.16.15.11 (10.16.15.1~254) which connect to
: location three router 192.168.0.1(192.168.0.1~254)
:
: Can I ping 10.16.15.11 or 192.168.0.1 from 10.144.9.39 ?
: If yes , please can you tell me how to set a fix route command in my
: 10.144.9.39 workstation ?
:
: I had tried :
: route add /p 10.16.15.0 mask 255.255.255.0 10.16.15.1 and
: route add /p 10.192.168.0 mask 255.255.255.0 10.16.15.11
:
: But failed ... I can only ping local and 10.16.15.1 to 10.16.15.254 , but
: can ping 10.16.15.11 and 192.168.0.1~254 , why ?
: Help ! Please !

Perhaps ICMP echo requests are being denied?!

--
Roland Hall
/* This information is distributed in the hope that it will be useful, but
without any warranty; without even the implied warranty of merchantability
or fitness for a particular purpose. */
Online Support for IT Professionals -
http://support.microsoft.com/servicedesks/technet/default.asp?fr=0&sd=tech
How-to: Windows 2000 DNS:
http://support.microsoft.com/default.aspx?scid=kb;EN-US;308201
FAQ W2K/2K3 DNS:
http://support.microsoft.com/default.aspx?scid=kb;EN-US;291382
 
Dear Roland ,

Do you mean that I can't ping 192.168.0.1~254 from 10.144.9.1~254 in our
company's settings ?

Sam Mok
 
Dear Sir/ Miss,

Our company have 4 routers locate in 3 places !

Example :
Location one Router 10.144.9.1 (10.144.9.1~254) which connect to location
two router 10.16.15.1 (10.16.15.1~254)
And
Location two another router 10.16.15.11 (10.16.15.1~254) which connect to
location three router 192.168.0.1(192.168.0.1~254)

Can I ping 10.16.15.11 or 192.168.0.1 from 10.144.9.39 ?
If yes , please can you tell me how to set a fix route command in my
10.144.9.39 workstation ?

I had tried :
route add /p 10.16.15.0 mask 255.255.255.0 10.16.15.1 and
route add /p 10.192.168.0 mask 255.255.255.0 10.16.15.11

But failed ... I can only ping local and 10.16.15.1 to 10.16.15.254 , but
can ping 10.16.15.11 and 192.168.0.1~254 , why ?
Click to expand...

Do those machines have a route to return the ping to you?

Jeff
 
Dear Jeff ,

No , 10.16.15.11 and 192.168.0.1~254 don't return the ping to me if I ping
from 10.144.9.1~254 !
But it can be pinged by 10.16.15.1~254 , any suggestions ? Thanks very much
!

Sam Mok
 
: Dear Roland ,
:
: Do you mean that I can't ping 192.168.0.1~254 from 10.144.9.1~254 in our
: company's settings ?

No, I have no way of knowing that. I said if ICMP echo requests are being
denied, you'll never get a response. PING and TRACERT can be denied a
response if ICMP echo requests are disabled on the router.

If your WAN setup is:

net1 -[router]- net2 -[router]- net3

and you can ping from any host on net2 to net3 but not from net1 to net2 or
net3 then perhaps the router between net1 and net2 is blocking ICMP echo
requests.

--
Roland Hall
/* This information is distributed in the hope that it will be useful, but
without any warranty; without even the implied warranty of merchantability
or fitness for a particular purpose. */
Online Support for IT Professionals -
http://support.microsoft.com/servicedesks/technet/default.asp?fr=0&sd=tech
How-to: Windows 2000 DNS:
http://support.microsoft.com/default.aspx?scid=kb;EN-US;308201
FAQ W2K/2K3 DNS:
http://support.microsoft.com/default.aspx?scid=kb;EN-US;291382
 
: No , 10.16.15.11 and 192.168.0.1~254 don't return the ping to me if I
ping
: from 10.144.9.1~254 !
: But it can be pinged by 10.16.15.1~254 , any suggestions ? Thanks very
much

Sam...

You're trying to add a route to your host which won't make any difference on
the router. Routers know their neighbors and that's all they need to know.
Anything they don't know goes out their DFG which means, set known routes
[neighbors] statically and default via a DFG to unknowns.

What Jeff is asking you is if you set a route in one direction, you have to
then set a route back from the other end to this network or you'll never get
a response.

If you have:

Internet/ISP -[router]- net1 -[router]- net2

The first router would need to know that net2 can be reached via the DFG on
the 2nd router. If you don't tell it this, it will try to go out the DFG to
the Internet and it will never get a successful response. On the 2nd
router, you only need to set a DFG because there is only one route for net2.
That provides a route back to net1 so you can get responses. Network
communications for unicast packets requires a round trip. But, if the
router has a configuration setting to allow traffic but block ICMP messages,
then PING and TRACERT will never return a valid response.

If you have:

Internet/ISP -[router]- net1 -[router]- net2 -[router]- net3

Then the first router needs to know that to get to net2 and net3 packets
need to route via the DFG on router2.
The second router needs to know that net3 is reached via the gateway on the
third router and everything else goes out the DFG, which is router 2. You
could set a static route to net1 but there is no need since it will route
the same direction anyway. The first router is the most important here
because it needs to have static routes set for any private networks. You
could also have another network that directly attaches to net1 so router 1
would need a static route to this network via that gateway and net4 would
only need a DFG unless it leads to another network on the other end, which
would add more static routes to net1 and net4, etc.


--
Roland Hall
/* This information is distributed in the hope that it will be useful, but
without any warranty; without even the implied warranty of merchantability
or fitness for a particular purpose. */
Online Support for IT Professionals -
http://support.microsoft.com/servicedesks/technet/default.asp?fr=0&sd=tech
How-to: Windows 2000 DNS:
http://support.microsoft.com/default.aspx?scid=kb;EN-US;308201
FAQ W2K/2K3 DNS:
http://support.microsoft.com/default.aspx?scid=kb;EN-US;291382
 
Dear Roland ,

Thanks for your informations so much , although I can't fully understand !

Sam Mok


Roland Hall said:
: No , 10.16.15.11 and 192.168.0.1~254 don't return the ping to me if I
ping
: from 10.144.9.1~254 !
: But it can be pinged by 10.16.15.1~254 , any suggestions ? Thanks very
much

Sam...

You're trying to add a route to your host which won't make any difference on
the router. Routers know their neighbors and that's all they need to know.
Anything they don't know goes out their DFG which means, set known routes
[neighbors] statically and default via a DFG to unknowns.

What Jeff is asking you is if you set a route in one direction, you have to
then set a route back from the other end to this network or you'll never get
a response.

If you have:

Internet/ISP -[router]- net1 -[router]- net2

The first router would need to know that net2 can be reached via the DFG on
the 2nd router. If you don't tell it this, it will try to go out the DFG to
the Internet and it will never get a successful response. On the 2nd
router, you only need to set a DFG because there is only one route for net2.
That provides a route back to net1 so you can get responses. Network
communications for unicast packets requires a round trip. But, if the
router has a configuration setting to allow traffic but block ICMP messages,
then PING and TRACERT will never return a valid response.

If you have:

Internet/ISP -[router]- net1 -[router]- net2 -[router]- net3

Then the first router needs to know that to get to net2 and net3 packets
need to route via the DFG on router2.
The second router needs to know that net3 is reached via the gateway on the
third router and everything else goes out the DFG, which is router 2. You
could set a static route to net1 but there is no need since it will route
the same direction anyway. The first router is the most important here
because it needs to have static routes set for any private networks. You
could also have another network that directly attaches to net1 so router 1
would need a static route to this network via that gateway and net4 would
only need a DFG unless it leads to another network on the other end, which
would add more static routes to net1 and net4, etc.


--
Roland Hall
/* This information is distributed in the hope that it will be useful, but
without any warranty; without even the implied warranty of merchantability
or fitness for a particular purpose. */
Online Support for IT Professionals -
http://support.microsoft.com/servicedesks/technet/default.asp?fr=0&sd=tech
How-to: Windows 2000 DNS:
http://support.microsoft.com/default.aspx?scid=kb;EN-US;308201
FAQ W2K/2K3 DNS:
http://support.microsoft.com/default.aspx?scid=kb;EN-US;291382
Click to expand...
 
in message : Thanks for your informations so much , although I can't fully understand !

Sorry. It's hard to explain here sometimes. We need a whiteboard or Visio
includes.

The summary of what I was saying is if you have one subnet, you need only a
DFG. If you have additional private networks where the first network feeds
the second and the second feeds the third, etc., then your first router [
that connects you to your ISP] needs to know how to get to all of those
private networks with static routing and each subsequent router needs a
route to each additional network. THEN, the additional routers you have
added each need to know how to get to any other private network and where to
default to if the target is unknown. That's what the "route back" was
referring to.

--
Roland Hall
/* This information is distributed in the hope that it will be useful, but
without any warranty; without even the implied warranty of merchantability
or fitness for a particular purpose. */
Online Support for IT Professionals -
http://support.microsoft.com/servicedesks/technet/default.asp?fr=0&sd=tech
How-to: Windows 2000 DNS:
http://support.microsoft.com/default.aspx?scid=kb;EN-US;308201
FAQ W2K/2K3 DNS:
http://support.microsoft.com/default.aspx?scid=kb;EN-US;291382
 
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