5

Current Network

I have the following network situation:

Internet
    |  
81.x.x.x (WAN)
Modem / DSL Router 1  
192.168.1.1 (LAN)  
    |  
    +-----------------------------+
    |                             |
192.168.1.2 (WAN)           192.168.1.100
Router 2                    PC 1
192.168.2.1 (LAN)
    |
    +-----------------------------+
    |                             |
192.168.2.100               192.168.2.101
PC 2                        Printer

My problem is, that computers in subnet 192.168.1.0/24 (PC 1) can't reach destinations behind Router 2 (so in the subnet 192.168.2.0/24), in my case eg the printer. The other direction works without problems:

  1. Pinging from PC 2 to PC 1 works
  2. Pinging from PC 1 to PC 2 fails
  3. Pinging from PC 1 to 192.168.1.2 (Router 2 WAN) works
  4. Pinging from PC 1 to 192.168.2.1 (Router 2 LAN) fails

Routing problem

So I thought this might be a routing problem. Trying tracert from PC 1 (192.168.1.100) to Router 2 (192.168.2.1) resulted in the following:

C:\Users\Alexander>tracert 192.168.2.1
Routenverfolgung zu 192.168.2.1 über maximal 30 Hops

  1     1 ms     1 ms     1 ms  192.168.1.1
  2     8 ms     8 ms     8 ms  d91-130-241-1.cust.tele2.at [91.130.241.1]
  3     *        *        *     Zeitüberschreitung der Anforderung.
  ...

This means the DSL Router routes the request to the internet, which is not what I want. So I entered the following static route on the DSL router (192.168.1.1)

Destination   Subnet Mask     Gateway       Interface
192.168.2.0   255.255.255.0   192.168.1.2   br0

I had the following interfaces to choose from.

  • Data_0_0_35_1/ppp_0_0_35_1
  • VoIP_0_0_40_1/ppp_0_0_40_1
  • EFM_0_0_32.31/nas_0_0_32.31
  • EFM_0_0_32.32/nas_0_0_32.32
  • EFM_0_0_32.33/nas_0_0_32.33
  • EFM_0_0_32.34/nas_0_0_32.34
  • LAN/br0

The arp table in the device info of the DSL router showed the following:

IP address      Flags       HW Address          Device
192.168.1.100   Complete    2C:41:38:8F:C7:3B   br0
192.168.1.101   Complete    BC:F5:AC:FF:7A:92   br0
192.168.1.102   Complete    C8:F7:33:E9:0B:C9   br0
192.168.1.2     Complete    F4:EC:38:9D:72:BD   br0

So I think interface br0 (bridge0) is correct. However the help text for the routing table said "Enter the destination network address, subnet mask, gateway AND/OR available WAN interface then click "Save/Apply" to add the entry to the routing table." As this should be not WAN interface in my point of view I tried both, but that had no differences in the result:

Again trying tracert from PC 1 (192.168.1.100) to Router 2 (192.168.2.1) resulted in the following:

C:\Users\Alexander>tracert 192.168.2.1
Routenverfolgung zu 192.168.2.1 über maximal 30 Hops

  1     1 ms     1 ms     1 ms  192.168.1.1
  2     *        *        *     Zeitüberschreitung der Anforderung.
  ...

And now

something changed but I don't know how to proceed. Additionally I disabled the SPI Firewall (Stateful Packet Inspection) an Router 2, but that did not change anything.

Has somebody a clue what I might forgot?

Adding route on PC client

I added the route to the client PC, but that did not change anything. (Ping from PC 1 to 192.168.1.2 works, to 192.168.2.1 fails)

ipconfig

PS C:\WINDOWS\system32> ipconfig
Windows-IP-Konfiguration
Drahtlos-LAN-Adapter WiFi:

   Verbindungsspezifisches DNS-Suffix: Home
   Verbindungslokale IPv6-Adresse  . : fe80::d0d5:82f1:5058:9099%7
   IPv4-Adresse  . . . . . . . . . . : 192.168.1.101
   Subnetzmaske  . . . . . . . . . . : 255.255.255.0
   Standardgateway . . . . . . . . . : 192.168.1.1

route print

PS C:\WINDOWS\system32> route print
===========================================================================
Schnittstellenliste
  6...18 67 b0 2b 07 48 ......Realtek PCIe GBE Family Controller
  9...c8 f7 33 e9 0b ca ......Microsoft Wi-Fi Direct Virtual Adapter
 11...ca f7 33 e9 0b c9 ......Microsoft Hosted Network Virtual Adapter
  7...c8 f7 33 e9 0b c9 ......Intel(R) Centrino(R) Advanced-N 6235
 10...c8 f7 33 e9 0b cd ......Bluetooth Device (Personal Area Network)
  1...........................Software Loopback Interface 1
  4...00 00 00 00 00 00 00 e0 Microsoft ISATAP Adapter
  5...00 00 00 00 00 00 00 e0 Teredo Tunneling Pseudo-Interface
===========================================================================

IPv4-Routentabelle
===========================================================================
Aktive Routen:
     Netzwerkziel    Netzwerkmaske          Gateway    Schnittstelle Metrik
          0.0.0.0          0.0.0.0      192.168.1.1    192.168.1.101     25
        127.0.0.0        255.0.0.0   Auf Verbindung         127.0.0.1    306
        127.0.0.1  255.255.255.255   Auf Verbindung         127.0.0.1    306
  127.255.255.255  255.255.255.255   Auf Verbindung         127.0.0.1    306
      192.168.1.0    255.255.255.0   Auf Verbindung     192.168.1.101    281
    192.168.1.101  255.255.255.255   Auf Verbindung     192.168.1.101    281
    192.168.1.255  255.255.255.255   Auf Verbindung     192.168.1.101    281
        224.0.0.0        240.0.0.0   Auf Verbindung         127.0.0.1    306
        224.0.0.0        240.0.0.0   Auf Verbindung     192.168.1.101    281
  255.255.255.255  255.255.255.255   Auf Verbindung         127.0.0.1    306
  255.255.255.255  255.255.255.255   Auf Verbindung     192.168.1.101    281
===========================================================================
Ständige Routen:
  Keine

IPv6-Routentabelle
===========================================================================
Aktive Routen:
 If Metrik Netzwerkziel             Gateway
  5    306 ::/0                     Auf Verbindung
  1    306 ::1/128                  Auf Verbindung
  5    306 2001::/32                Auf Verbindung
  5    306 2001:0:5ef5:79fd:471:3998:ae42:9bf1/128
                                    Auf Verbindung
  7    281 fe80::/64                Auf Verbindung
  5    306 fe80::/64                Auf Verbindung
  5    306 fe80::471:3998:ae42:9bf1/128
                                    Auf Verbindung
  7    281 fe80::d0d5:82f1:5058:9099/128
                                    Auf Verbindung
  1    306 ff00::/8                 Auf Verbindung
  5    306 ff00::/8                 Auf Verbindung
  7    281 ff00::/8                 Auf Verbindung
===========================================================================
Ständige Routen:
  Keine

route add

PS C:\WINDOWS\system32> route -p add 192.168.2.0 mask 255.255.255.0 192.168.1.2
 OK!

route print

PS C:\WINDOWS\system32> route print
===========================================================================
Schnittstellenliste
  6...18 67 b0 2b 07 48 ......Realtek PCIe GBE Family Controller
  9...c8 f7 33 e9 0b ca ......Microsoft Wi-Fi Direct Virtual Adapter
 11...ca f7 33 e9 0b c9 ......Microsoft Hosted Network Virtual Adapter
  7...c8 f7 33 e9 0b c9 ......Intel(R) Centrino(R) Advanced-N 6235
 10...c8 f7 33 e9 0b cd ......Bluetooth Device (Personal Area Network)
  1...........................Software Loopback Interface 1
  4...00 00 00 00 00 00 00 e0 Microsoft ISATAP Adapter
  5...00 00 00 00 00 00 00 e0 Teredo Tunneling Pseudo-Interface
===========================================================================

IPv4-Routentabelle
===========================================================================
Aktive Routen:
     Netzwerkziel    Netzwerkmaske          Gateway    Schnittstelle Metrik
          0.0.0.0          0.0.0.0      192.168.1.1    192.168.1.101     25
        127.0.0.0        255.0.0.0   Auf Verbindung         127.0.0.1    306
        127.0.0.1  255.255.255.255   Auf Verbindung         127.0.0.1    306
  127.255.255.255  255.255.255.255   Auf Verbindung         127.0.0.1    306
      192.168.1.0    255.255.255.0   Auf Verbindung     192.168.1.101    281
    192.168.1.101  255.255.255.255   Auf Verbindung     192.168.1.101    281
    192.168.1.255  255.255.255.255   Auf Verbindung     192.168.1.101    281
      192.168.2.0    255.255.255.0      192.168.1.2    192.168.1.101     26
        224.0.0.0        240.0.0.0   Auf Verbindung         127.0.0.1    306
        224.0.0.0        240.0.0.0   Auf Verbindung     192.168.1.101    281
  255.255.255.255  255.255.255.255   Auf Verbindung         127.0.0.1    306
  255.255.255.255  255.255.255.255   Auf Verbindung     192.168.1.101    281
===========================================================================
Ständige Routen:
  Netzwerkadresse          Netzmaske  Gatewayadresse  Metrik
      192.168.2.0    255.255.255.0      192.168.1.2       1
===========================================================================

IPv6-Routentabelle
===========================================================================
Aktive Routen:
 If Metrik Netzwerkziel             Gateway
  5    306 ::/0                     Auf Verbindung
  1    306 ::1/128                  Auf Verbindung
  5    306 2001::/32                Auf Verbindung
  5    306 2001:0:5ef5:79fd:471:3998:ae42:9bf1/128
                                    Auf Verbindung
  7    281 fe80::/64                Auf Verbindung
  5    306 fe80::/64                Auf Verbindung
  5    306 fe80::471:3998:ae42:9bf1/128
                                    Auf Verbindung
  7    281 fe80::d0d5:82f1:5058:9099/128
                                    Auf Verbindung
  1    306 ff00::/8                 Auf Verbindung
  5    306 ff00::/8                 Auf Verbindung
  7    281 ff00::/8                 Auf Verbindung
===========================================================================
Ständige Routen:
  Keine

ping 192.168.1.2

PS C:\WINDOWS\system32> ping 192.168.1.2

Ping wird ausgeführt für 192.168.1.2 mit 32 Bytes Daten:
Antwort von 192.168.1.2: Bytes=32 Zeit=1ms TTL=64
Antwort von 192.168.1.2: Bytes=32 Zeit=7ms TTL=64
Antwort von 192.168.1.2: Bytes=32 Zeit=2ms TTL=64
Antwort von 192.168.1.2: Bytes=32 Zeit=2ms TTL=64

Ping-Statistik für 192.168.1.2:
    Pakete: Gesendet = 4, Empfangen = 4, Verloren = 0
    (0% Verlust),
Ca. Zeitangaben in Millisek.:
    Minimum = 1ms, Maximum = 7ms, Mittelwert = 3ms

ping 192.168.2.1

PS C:\WINDOWS\system32> ping 192.168.2.1

Ping wird ausgeführt für 192.168.2.1 mit 32 Bytes Daten:
Zeitüberschreitung der Anforderung.
Zeitüberschreitung der Anforderung.
Zeitüberschreitung der Anforderung.
Zeitüberschreitung der Anforderung.

Ping-Statistik für 192.168.2.1:
    Pakete: Gesendet = 4, Empfangen = 0, Verloren = 4
    (100% Verlust),

Route on 192.168.2.1

I was not able to add a route on 192.168.2.1. I tried to add 192.168.1.0 with 255.255.255.0 and Gateway 192.168.1.1 with the following error code

Error code: 4011
Destination Network address cannot be inside the subnet of WAN IP
address, please enter again.

However the device lists the following routes:

ID  Destination   Network         Subnet Mask   Gateway Interface
1   192.168.2.0   255.255.255.0   0.0.0.0       LAN & WLAN
2   192.168.1.0   255.255.255.0   0.0.0.0       WAN
3   239.0.0.0     255.0.0.0       0.0.0.0       LAN & WLAN
4   0.0.0.0       0.0.0.0         192.168.1.1   WAN
  • What's the model of your router2 ? Maybe, the router2 has an configuration which enable NAT from the "LAN" interface to the "WAN" inerface, it can explain why the ping from PC1 to PC2 fails and PC2 to PC1 success. – Sorcha Oct 2 '15 at 11:49
  • Perhaps your DSL router does not send IP redirects? – Ron Trunk Oct 2 '15 at 13:13
  • @RonTrunk: I did not see a setting like that and don't know what I would have to change. – Alexander Taubenkorb Oct 3 '15 at 10:18
  • How are you testing for connectivity? By using ping? How about use something else like rdp? Also the 2.1 router has your 1 manually added route : 0/0 192.168.1.1 and 1.0 directly connected to it. How about try add the route to 1.0 with 1.2 interface as outgoing manually there too. – allwynmasc Nov 3 '15 at 8:43
  • Well i agree with the NAT problem why don't you use a switch instead of router 2 ? that may fix your problem if the problem is the NAT or u can just disable NAT from router 2 or even u may fix the problem by port forwarding and if they are only 2 computers you can just connect them to router 1 if its possible just try different things i hope u can fix this ! – user20544 Nov 9 '15 at 15:24
2

first of all your topology seams to be as following enter image description here

following your description enter image description here

pc2 could reach PC1 cause the pc2 GW (which is R2) can reach PC1 (cause it is directly connected to the both network).

so same way let us ask a very importent question . what is the PC1 GW and do PC1 GW know about subnet 192.168.2.X or not ?????????

if PC1 GW is the modem so you must add static route on the modem tell it if you want to reach 192.168.2.X you should go to 192.168.1.2 . otherwise you need to set the GW of PC1 to be 192.168.1.2

  • 1
    Thank you for your answer! The topology is almost correct. There are a few changes: 1) modem and top switch are one single device. 2) Same goes for R2 and the switch below. But I think that does not make a difference. The gateway of PC 1 is the dsl router (192.168.1.1) on which I added the static route to the 192.168.2.0/24 network (see secion routing problem). In my understanding this should be sufficient, but it obviously isn't. – Alexander Taubenkorb Oct 3 '15 at 10:26
1

Agree with the Sorcha's comment: if Router 2 does NAT, this will prevent pinging from PC 1 to 192.168.2.x, because NAT works as a firewall as a side effect. Your statement "Pinging from PC 2 to PC 1 works" confirms that this is the case (that is, NAT) because after Router 2 translates ICMP message's source IP 192.168.2.100 to 192.168.1.2, PC 1 replies to 192.168.1.2, which then gets translated back to 192.168.2.100, so ping works. Next, 192.168.1.x hosts should know a route to the 192.168.2.0 segment. This can be accomplished in several ways. If Router 1 supports static routes, configure it there and leave PC 1 and others configured with Router 1 as their default gateway. When Router 1 receives a packet from PC 1 destined to PC 2 it send the packet back through the same interface on which it has received it and possibly sends an ICMP redirect message to PC 1. Windows hosts are able to understand this (https://support.microsoft.com/en-us/kb/195686) and start sending traffic directly through Router 2. Another way to configure the route to the 192.168.2.0 segment is to do this manually on each of the 192.168.1.x hosts by using the following Windows command: route -p add 192.168.2.0 mask 255.255.255.0 192.168.1.2.

So there are, probaly, two issues: NAT on Router 2 and no route to the 192.168.2.0 segment.

  • Thanks. I tried your suggestion, but without any luck (see my edited original post). – Alexander Taubenkorb Nov 25 '15 at 17:36

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.