Ping doesnt work with Multiple NIC Cards on FC16 Linux

gagansach · #1 2nd August 2012, 08:29 AM

Hi,

I have a machine with Fedora Linux FC16 installed and it has 2 D-Link NIC cards. The two ethernet interfaces are named as em1 and p2p1. I am able to ping on one of the ethernet interface which is em1 but not able to ping on the other interface which is p2p1. All the packets are getting lost on the p2p1 interface. Please help and suggest as to how this problem can be fixed.

[root@localhost test]# uname -a
Linux localhost.localdomain 3.1.0-7.fc16.i686.PAE #1 SMP Tue Nov 1 20:53:45 UTC 2011 i686 i686 i386 GNU/Linux
[root@localhost test]#

em1 Link encap:Ethernet HWaddr 00:0D:56:5B:32:6D
inet addr:192.168.1.25 Bcast:192.168.1.255 Mask:255.255.255.0
inet6 addr: fe80::20d:56ff:fe5b:326d/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:15869 errors:0 dropped:0 overruns:0 frame:0
TX packets:7764 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:6272538 (5.9 MiB) TX bytes:1324238 (1.2 MiB)
Interrupt:17

lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:16436 Metric:1
RX packets:33 errors:0 dropped:0 overruns:0 frame:0
TX packets:33 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:3467 (3.3 KiB) TX bytes:3467 (3.3 KiB)

p2p1 Link encap:Ethernet HWaddr 00:1C:F0:94:A5:AC
inet addr:10.10.70.25 Bcast:10.10.70.255 Mask:255.255.255.0
inet6 addr: Scope:Link
UP BROADCAST MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:0 (0.0 b) TX bytes:0 (0.0 b)
Interrupt:17 Base address:0x8e00

Regards,
Gagan

stevea · #2 2nd August 2012, 09:09 AM

I just suggested some ideas for posting questions, so lets give it a try.
http://forums.fedoraforum.org/showthread.php?t=282819

Please post the exact (cut & paste) ping and fail conditions.

Please post the output of,
ip link
ip addr
ip route
cat /etc/resolv.conf

The only useful things your post shows is that both interfaces are UP and assigned IPs. em1 has passed some data and p2p1 interface has passed zero bytes;
RX bytes:0 (0.0 b) TX bytes:0 (0.0 b)
So your pings were never routed out p2p1.

Without seeing the route table and the ping commands (esp the IP resolution of the ping target) we can't understand which interface SHOULD see traffic.

droidhacker · #3 2nd August 2012, 04:02 PM

So what I'm going to have to guess at, is that one of those interfaces is your default route, probably em1 since it is the one with the data traffic. The second interface is on a network address of 10.10.70.0/24. What would typically happen, is that an additional route would be configured such that traffic to THAT network (and only that network) would be routed through that interface.

As above has mentioned, in order to diagnose this, we need to see your routing table and know what address you're trying to "ping" that isn't going through that second interface.

provide the output of the "route" command, and the ip address of the machine you're trying to ping. A full description of your network would also help, i.e., why are you using two separate networks?

gagansach · #4 3rd August 2012, 06:48 AM

Hi,

Please find the output below for the following commands. Please suggest as to how to fix this issue.

[root@localhost test]# ping 192.168.1.10
PING 192.168.1.10 (192.168.1.10) 56(84) bytes of data.
64 bytes from 192.168.1.10: icmp_req=1 ttl=64 time=0.177 ms
64 bytes from 192.168.1.10: icmp_req=2 ttl=64 time=0.141 ms
--- 192.168.1.10 ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 1000ms
rtt min/avg/max/mdev = 0.141/0.159/0.177/0.018 ms
[root@localhost test]#

[root@localhost test]# ping 10.10.70.10
PING 10.10.70.10 (10.10.70.10) 56(84) bytes of data.
From 10.10.70.25 icmp_seq=2 Destination Host Unreachable
From 10.10.70.25 icmp_seq=3 Destination Host Unreachable
From 10.10.70.25 icmp_seq=4 Destination Host Unreachable
--- 10.10.70.10 ping statistics ---
5 packets transmitted, 0 received, +3 errors, 100% packet loss, time 4001ms
pipe 3

[root@localhost test]# ip route
default via 192.168.1.1 dev em1 proto static
10.10.70.0/24 dev p2p1 proto kernel scope link src 10.10.70.25
192.168.1.0/24 dev em1 proto kernel scope link src 192.168.1.25 metric 1
192.168.122.0/24 dev virbr0 proto kernel scope link src 192.168.122.1

[root@localhost test]# ip link
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue state UNKNOWN
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
2: p2p1: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast state DOWN qlen 1000
link/ether 00:1c:f0:94:a5:ac brd ff:ff:ff:ff:ff:ff
3: p3p1: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast state DOWN qlen 1000
link/ether 00:1b:11:c2:24:bc brd ff:ff:ff:ff:ff:ff
4: em1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
link/ether 00:0d:56:5b:32:6d brd ff:ff:ff:ff:ff:ff
5: virbr0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN
link/ether 52:54:00:d2:4b:4e brd ff:ff:ff:ff:ff:ff
6: virbr0-nic: <BROADCAST,MULTICAST> mtu 1500 qdisc noop master virbr0 state DOWN qlen 500
link/ether 52:54:00:d2:4b:4e brd ff:ff:ff:ff:ff:ff

[root@localhost test]# ip addr
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue state UNKNOWN
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: p2p1: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast state DOWN qlen 1000
link/ether 00:1c:f0:94:a5:ac brd ff:ff:ff:ff:ff:ff
inet 10.10.70.25/24 brd 10.10.70.255 scope global p2p1
3: p3p1: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast state DOWN qlen 1000
link/ether 00:1b:11:c2:24:bc brd ff:ff:ff:ff:ff:ff
4: em1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
link/ether 00:0d:56:5b:32:6d brd ff:ff:ff:ff:ff:ff
inet 192.168.1.25/24 brd 192.168.1.255 scope global em1
inet6 fe80::20d:56ff:fe5b:326d/64 scope link
valid_lft forever preferred_lft forever
5: virbr0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN
link/ether 52:54:00:d2:4b:4e brd ff:ff:ff:ff:ff:ff
inet 192.168.122.1/24 brd 192.168.122.255 scope global virbr0
6: virbr0-nic: <BROADCAST,MULTICAST> mtu 1500 qdisc noop master virbr0 state DOWN qlen 500
link/ether 52:54:00:d2:4b:4e brd ff:ff:ff:ff:ff:ff
[root@localhost test]#

---------- Post added at 11:18 AM ---------- Previous post was at 11:16 AM ----------

Hi,

Please find output for ifconfig command as well,

[root@localhost test]# ifconfig
em1 Link encap:Ethernet HWaddr 00:0D:56:5B:32:6D
inet addr:192.168.1.25 Bcast:192.168.1.255 Mask:255.255.255.0
inet6 addr: fe80::20d:56ff:fe5b:326d/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:23 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:0 (0.0 b) TX bytes:4636 (4.5 KiB)
Interrupt:17

lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:16436 Metric:1
RX packets:6 errors:0 dropped:0 overruns:0 frame:0
TX packets:6 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:340 (340.0 b) TX bytes:340 (340.0 b)

p2p1 Link encap:Ethernet HWaddr 00:1C:F0:94:A5:AC
inet addr:10.10.70.25 Bcast:10.10.70.255 Mask:255.255.255.0
UP BROADCAST MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:0 (0.0 b) TX bytes:0 (0.0 b)
Interrupt:17 Base address:0xe00

p3p1 Link encap:Ethernet HWaddr 00:1B:11

2:24:BC
UP BROADCAST MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:0 (0.0 b) TX bytes:0 (0.0 b)
Interrupt:18 Base address:0x4f00

virbr0 Link encap:Ethernet HWaddr 52:54:00

2:4B:4E
inet addr:192.168.122.1 Bcast:192.168.122.255 Mask:255.255.255.0
UP BROADCAST MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:0 (0.0 b) TX bytes:0 (0.0 b)

Regards,
Gagan

stevea · #5 3rd August 2012, 07:04 AM

Thanks for the info - it really helps.

Quote:

[root@localhost test]# ping 10.10.70.10
PING 10.10.70.10 (10.10.70.10) 56(84) bytes of data.
From 10.10.70.25 icmp_seq=2 Destination Host Unreachable
From 10.10.70.25 icmp_seq=3 Destination Host Unreachable
From 10.10.70.25 icmp_seq=4 Destination Host Unreachable
--- 10.10.70.10 ping statistics ---
5 packets transmitted, 0 received, +3 errors, 100% packet loss, time 4001ms
pipe 3

"Destination Host Unreachable" means that no device connected to the p2p1 LAN is responding to an ARP request to address 10.10.70.10.

Quote:

2: p2p1: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast state DOWN qlen 1000
link/ether 00:1c:f0:94:a5:ac brd ff:ff:ff:ff:ff:ff

NO-CARRIER means that the p2p is not connected to a live network.
Perhaps a bad cable or a bad switch/hub port. Examine the LEDs on the enet interface plug.

gagansach · #6 6th August 2012, 08:00 AM

Hi,

I have verified that there was no problem with the NIC Card and neither the cable as well. The ping started working when I connected the NIC Card to a HUB and then to the other machine's NIC Card.

Regards,
Gagan

jlpierce · #7 6th August 2012, 01:14 PM

Quote:

Originally Posted by gagansach

Hi,

I have verified that there was no problem with the NIC Card and neither the cable as well. The ping started working when I connected the NIC Card to a HUB and then to the other machine's NIC Card.

Regards,
Gagan

That tells me that you had the two NICs directly connected with a cable and no switch/hub in the middle! For future reference when you wish to connect to NICs directly you need a special ethernet cable known as a Crossover, in which the Transmit and Receive pins are reversed from one end to the other. A hub or switch does that crossover automatically by design.