using 2nd network interface - won't try to TX anything

I'm trying to make use of a 2nd ethernet interface. The basic steps seem
to work OK. But nothing gets transmitted out the 2nd interface. Yet it
does see packets coming back the other way on that interface.

Here's what ifconfig shows:

================================================== ===========================
-bash-2.05b# ifconfig
ixp1 Link encap:Ethernet HWaddr 00:02:B3:02:02:02
inet addr:172.30.1.3 Bcast:172.30.1.255 Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:21049 errors:0 dropped:0 overruns:0 frame:0
TX packets:16493 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:256
RX bytes:17841196 (17.0 Mb) TX bytes:2523518 (2.4 Mb)

ixp2 Link encap:Ethernet HWaddr 00:02:B3:03:03:03
inet addr:172.30.2.3 Bcast:172.30.2.255 Mask:255.255.255.0
UP BROADCAST MULTICAST MTU:1500 Metric:1
RX packets:222 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:256
RX bytes:13320 (13.0 Kb) TX bytes:0 (0.0 b)

lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
UP LOOPBACK RUNNING MTU:16436 Metric:1
RX packets:8 errors:0 dropped:0 overruns:0 frame:0
TX packets:8 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:560 (560.0 b) TX bytes:560 (560.0 b)

-bash-2.05b#
================================================== ===========================

One thing I notice here that might be an issue is that the status RUNNING
is not included in ixp2. Could that be related to the problem? How would
I fix this if so?

TX bytes is 0 for ixp2 despite attempts to ping the other host on that LAN
segment. I'd think that if it were bad hardware, it would at least show
what it it tried to transmit. But there is 0 there as if it never tried
to send anything over ixp2 at all.

Here's what route shows:

================================================== ===========================
-bash-2.05b# route
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
172.30.1.0 * 255.255.255.0 U 0 0 0 ixp1
172.30.2.0 * 255.255.255.0 U 0 0 0 ixp2
169.254.0.0 * 255.255.0.0 U 0 0 0 lo
-bash-2.05b#
================================================== ===========================

The topology is that ixp1 is connected via a switch to eth1 on a PC, and
ixp2 is connected via a different switch to eth2 on the same PC. There are
not other hosts connected on these segments. There is no default gateway
as this test machine is not to be able to reach the internet.

Notice for ixp2 in the ifconfig output, there are some RX bytes tallied.
This goes up when I ping that IP address from the PC. During such ping
attempts, the PC attempts to get the MAC address, but is unsuccessful.
The tcpdump output from the PC looks like lots of:

================================================== ===========================
....
17:39:11.723759 arp who-has 172.30.2.3 tell 172.30.2.1
17:39:13.723775 arp who-has 172.30.2.3 tell 172.30.2.1
17:39:14.723782 arp who-has 172.30.2.3 tell 172.30.2.1
17:39:15.723790 arp who-has 172.30.2.3 tell 172.30.2.1
....
================================================== ===========================

So I suspect the RX bytes tally is for the ARP request broadcasts received.
The ARP table on the PC shows the ping target as incomplete. But the ARP
table on the machine under test does show the corresponding PC MAC address.
So it apparently sent an ARP request and got and answer, but did not count
it, or sent it via the other interface.

================================================== ===========================
-bash-2.05b# arp
Address HWtype HWaddress Flags Mask Iface
172.30.2.1 ether 00:50:FC:4A:C2:1C C ixp2
172.30.1.1 ether 00:07:40:8E:56:A4 C ixp1
-bash-2.05b# ping 172.30.2.1
PING 172.30.2.1 (172.30.2.1) 56(84) bytes of data.

--- 172.30.2.1 ping statistics ---
96 packets transmitted, 0 received, 100% packet loss, time 95007ms

-bash-2.05b# arp
Address HWtype HWaddress Flags Mask Iface
172.30.2.1 ether 00:50:FC:4A:C2:1C C ixp2
172.30.1.1 ether 00:07:40:8E:56:A4 C ixp1
-bash-2.05b#
================================================== ===========================

The PC doing the testing has the following:

================================================== ===========================
root@tanith:/root 82# ifconfig
eth0 Link encap:Ethernet HWaddr 00:50:FC:B3:5F:26
inet addr:172.30.0.1 Bcast:172.30.0.255 Mask:255.255.255.0
inet6 addr: fe80::250:fcff:feb3:5f26/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:3623 errors:0 dropped:0 overruns:0 frame:0
TX packets:3603 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:224207 (218.9 KiB) TX bytes:1998944 (1.9 MiB)
Interrupt:201 Base address:0x6000

eth1 Link encap:Ethernet HWaddr 00:07:40:8E:56:A4
inet addr:172.30.1.1 Bcast:172.30.1.255 Mask:255.255.255.0
inet6 addr: fe80::207:40ff:fe8e:56a4/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:152725 errors:0 dropped:0 overruns:0 frame:0
TX packets:193340 errors:0 dropped:0 overruns:0 carrier:0
collisions:32254 txqueuelen:1000
RX bytes:19980287 (19.0 MiB) TX bytes:176632964 (168.4 MiB)
Interrupt:209 Base address:0x8000

eth2 Link encap:Ethernet HWaddr 00:50:FC:4A:C2:1C
inet addr:172.30.2.1 Bcast:172.30.2.255 Mask:255.255.255.0
inet6 addr: fe80::250:fcff:fe4a:c21c/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:28685 errors:0 dropped:0 overruns:0 frame:0
TX packets:29568 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:1728314 (1.6 MiB) TX bytes:16021972 (15.2 MiB)
Interrupt:217 Base address:0x4000

eth3 Link encap:Ethernet HWaddr 00:0D:61:4D:C9:3A
inet addr:192.168.2.27 Bcast:192.168.2.255 Mask:255.255.255.0
inet6 addr: fe80::20d:61ff:fe4d:c93a/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:8068633 errors:0 dropped:0 overruns:0 frame:0
TX packets:5464124 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:3225398207 (3.0 GiB) TX bytes:371598322 (354.3 MiB)
Interrupt:201 Base address:0xd000

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:224639 errors:0 dropped:0 overruns:0 frame:0
TX packets:224639 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:1748770581 (1.6 GiB) TX bytes:1748770581 (1.6 GiB)

root@tanith:/root 83# route
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
172.30.1.0 * 255.255.255.0 U 0 0 0 eth1
192.168.2.0 * 255.255.255.0 U 0 0 0 eth3
172.30.0.0 * 255.255.255.0 U 0 0 0 eth0
172.30.2.0 * 255.255.255.0 U 0 0 0 eth2
169.254.0.0 * 255.255.0.0 U 0 0 0 eth3
default 192.168.2.2 0.0.0.0 UG 0 0 0 eth3
root@tanith:/root 84# arp
Address HWtype HWaddress Flags Mask Iface
172.30.2.3 (incomplete) eth2
192.168.2.241 ether 00:0E:2E:53:3E:CA C eth3
192.168.2.23 ether 00:12:3F:2A4:86 C eth3
172.30.1.3 ether 00:02:B3:02:02:02 C eth1
192.168.2.2 ether 00:06:B1:34:AD:B0 C eth3
192.168.2.12 ether 00:14:22:7B:5D:38 C eth3
192.168.2.231 ether 00:01:02:9B:3C:A9 C eth3
================================================== ===========================

Interface eth3 on the PC is the connection to the office LAN using a different
private IP space.

Interface eth0 is currently not connected on the PC.

--
|---------------------------------------/----------------------------------|
| Phil Howard KA9WGN (ka9wgn.ham.org) / Do not send to the address below |
| first name lower case at ipal.net / spamtrap-2007-05-10-(E-Mail Removed) |
|------------------------------------/-------------------------------------|

On the first machine, it seems lack a record for default route. you
must add a default route to the interface what you want to use.

Your origin config:
================================================== ===========================
-bash-2.05b# route
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref
Use Iface
172.30.1.0 * 255.255.255.0 U 0 0
0 ixp1
172.30.2.0 * 255.255.255.0 U 0 0
0 ixp2
169.254.0.0 * 255.255.0.0 U 0 0
0 lo
-bash-2.05b#
================================================== ===========================

On 11 May 2007 07:15:05 -0700 linarin <(E-Mail Removed)> wrote:

| On the first machine, it seems lack a record for default route. you
| must add a default route to the interface what you want to use.
|
| Your origin config:
| ================================================== ===========================
| -bash-2.05b# route
| Kernel IP routing table
| Destination Gateway Genmask Flags Metric Ref
| Use Iface
| 172.30.1.0 * 255.255.255.0 U 0 0
| 0 ixp1
| 172.30.2.0 * 255.255.255.0 U 0 0
| 0 ixp2
| 169.254.0.0 * 255.255.0.0 U 0 0
| 0 lo
| -bash-2.05b#
| ================================================== ===========================

There is nowhere that machine needs to go to other than 172.30.1.0/24 and
172.30.2.0/24 and those are specifically already routed.

--
|---------------------------------------/----------------------------------|
| Phil Howard KA9WGN (ka9wgn.ham.org) / Do not send to the address below |
| first name lower case at ipal.net / spamtrap-2007-05-11-(E-Mail Removed) |
|------------------------------------/-------------------------------------|

phil-news-(E-Mail Removed) wrote:
> I'm trying to make use of a 2nd ethernet interface. The basic steps seem
> to work OK. But nothing gets transmitted out the 2nd interface. Yet it
> does see packets coming back the other way on that interface.
>
> Here's what ifconfig shows:
>
> ================================================== ===========================
> -bash-2.05b# ifconfig
> ixp1 Link encap:Ethernet HWaddr 00:02:B3:02:02:02
> inet addr:172.30.1.3 Bcast:172.30.1.255 Mask:255.255.255.0
> UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
> RX packets:21049 errors:0 dropped:0 overruns:0 frame:0
> TX packets:16493 errors:0 dropped:0 overruns:0 carrier:0
> collisions:0 txqueuelen:256
> RX bytes:17841196 (17.0 Mb) TX bytes:2523518 (2.4 Mb)
>
> ixp2 Link encap:Ethernet HWaddr 00:02:B3:03:03:03
> inet addr:172.30.2.3 Bcast:172.30.2.255 Mask:255.255.255.0
> UP BROADCAST MULTICAST MTU:1500 Metric:1
> RX packets:222 errors:0 dropped:0 overruns:0 frame:0
> TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
> collisions:0 txqueuelen:256
> RX bytes:13320 (13.0 Kb) TX bytes:0 (0.0 b)
>
> lo Link encap:Local Loopback
> inet addr:127.0.0.1 Mask:255.0.0.0
> UP LOOPBACK RUNNING MTU:16436 Metric:1
> RX packets:8 errors:0 dropped:0 overruns:0 frame:0
> TX packets:8 errors:0 dropped:0 overruns:0 carrier:0
> collisions:0 txqueuelen:0
> RX bytes:560 (560.0 b) TX bytes:560 (560.0 b)
>
> -bash-2.05b#
> ================================================== ===========================
>
> One thing I notice here that might be an issue is that the status RUNNING
> is not included in ixp2. Could that be related to the problem? How would
> I fix this if so?

Try taking the interface down and bringing it back up again?

When I'm trying to debug this sort of thing, I find it really helps to
run multiple instances of tcpdump -n. Each instance captures from a
single interface at each end. (And limit pinging to 3 or 4 packets so
important stuff doesn't scroll away.) That way you can troubleshoot
things like hubs and switches that don't forward ARPs properly.

Oh, and it might help those of us in need of an afternoon siesta :-) to
label your machines A and B or something. I found the phrase "the
machine under test" a tad ambiguous.

On 10 May 2007, in the Usenet newsgroup comp.os.linux.networking, in article
<(E-Mail Removed)>, phil-news-(E-Mail Removed) wrote:

>I'm trying to make use of a 2nd ethernet interface. The basic steps
>seem to work OK. But nothing gets transmitted out the 2nd interface.

When you try, what (if any) error messages does your application give?

The real question is WTF Is this? "ixp1' shows up on google as a
very uncommon device name - one page which google says is at
http://www.nslu2-linux.org/wiki/FAQ/...tworkInterface says:

What is the ixp1 interface, and can it be used for anything useful?

The IXP420 has two network interfaces built in, ixp0 and ixp1. ixp0 is
wired to the ethernet socket on the back through the RealTek PHY chip.
ixp1 however is not connected to anything at all and the lines aren't
brought out anywhere on the PCB. This means that it is not possible to
use ixp1 at all.

I also find it interesting that your ifconfig output gives

>lo Link encap:Local Loopback
> inet addr:127.0.0.1 Mask:255.0.0.0

as expected, but the routing table says

>169.254.0.0 * 255.255.0.0 U 0 0 0 lo

Sorry, Phil, that don't compute.

Also, the MAC addresses in the ifconfig output:

>ixp1 Link encap:Ethernet HWaddr 00:02:B3:02:02:02

>ixp2 Link encap:Ethernet HWaddr 00:02:B3:03:03:03

[compton ~]$ etherwhois 00:02:B3
00-02-B3 (hex) Intel Corporation
0002B3 (base 16) Intel Corporation
M/S: JF3-420
2111 N.E. 25th Ave.
Hillsboro OR 97124
UNITED STATES
[compton ~]$

but those last six chars are stretching probability as serial numbers
from someone like Intel.

>The topology is that ixp1 is connected via a switch to eth1 on a PC, and
>ixp2 is connected via a different switch to eth2 on the same PC. There are
>not other hosts connected on these segments. There is no default gateway
>as this test machine is not to be able to reach the internet.

On that PC - does a packet sniffer show anything coming from this "ixp2"
interface?

Old guy

On 11 May 2007, in the Usenet newsgroup comp.os.linux.networking, in article
<(E-Mail Removed) .com>, linarin wrote:

>On the first machine, it seems lack a record for default route. you
>must add a default route to the interface what you want to use.

I guess you missed the line where Phil wrote:

There is no default gateway as this test machine is not to be able
to reach the internet.

A default route is ONLY needed to reach places not described by other
entries in the routing table.

>Your origin config:
>================================================= ===========================
>-bash-2.05b# route
>Kernel IP routing table
>Destination Gateway Genmask Flags Metric Ref Use Iface
>172.30.1.0 * 255.255.255.0 U 0 0 0 ixp1
>172.30.2.0 * 255.255.255.0 U 0 0 0 ixp2
>169.254.0.0 * 255.255.0.0 U 0 0 0 lo
>-bash-2.05b#
>================================================= ===========================

The table says that he has 172.30.1.0/24 _directly_ reachable on ixp1, and
172.30.2.0/24 _directly_ reachable on ixp1. "directly" means that no
gateway is involved. However I do find it interesting that the loopback
is using LinkLocal addresses instead of 127.0.0.0/8.

Old guy

Moe Trin wrote:
> On 10 May 2007, in the Usenet newsgroup comp.os.linux.networking, in article
> <(E-Mail Removed)>, phil-news-(E-Mail Removed) wrote:
....
> I also find it interesting that your ifconfig output gives
>> lo Link encap:Local Loopback
>> inet addr:127.0.0.1 Mask:255.0.0.0
> as expected, but the routing table says
>> 169.254.0.0 * 255.255.0.0 U 0 0 0 lo
> Sorry, Phil, that don't compute.

Fedora seems hang 169.254.0.0 on a random interface.

> ixp1 however is not connected to anything at all and the lines
> aren't brought out anywhere on the PCB.
> On that PC - does a packet sniffer show anything coming from this "ixp2"
> interface?

Wasn't this the interface that was not running?

phil-news-(E-Mail Removed) wrote:

X bytes:17841196 (17.0 Mb) TX bytes:2523518 (2.4 Mb)
>
>ixp2 Link encap:Ethernet HWaddr 00:02:B3:03:03:03
> inet addr:172.30.2.3 Bcast:172.30.2.255 Mask:255.255.255.0
> UP BROADCAST MULTICAST MTU:1500 Metric:1

>One thing I notice here that might be an issue is that the status RUNNING
>is not included in ixp2. Could that be related to the problem? How would
>I fix this if so?

I think that's exactly your problem. What could cause it? Could be
several things. Hardware issues can cause this. Is Linux properly
detecting the card? Is it configuring it properly? Driver issue?
Anything in syslog? Boot messages? I'd start there. Doesn't look like
a routing issue. Your setup otherwise looks OK, but for whatever
reason, that network card/driver isn't initializing properly.

On Fri, 11 May 2007 19:24:07 -0500 Moe Trin <(E-Mail Removed)> wrote:
| On 11 May 2007, in the Usenet newsgroup comp.os.linux.networking, in article
| <(E-Mail Removed) .com>, linarin wrote:
|
|>On the first machine, it seems lack a record for default route. you
|>must add a default route to the interface what you want to use.
|
| I guess you missed the line where Phil wrote:
|
| There is no default gateway as this test machine is not to be able
| to reach the internet.
|
| A default route is ONLY needed to reach places not described by other
| entries in the routing table.
|
|>Your origin config:
|>================================================ ============================
|>-bash-2.05b# route
|>Kernel IP routing table
|>Destination Gateway Genmask Flags Metric Ref Use Iface
|>172.30.1.0 * 255.255.255.0 U 0 0 0 ixp1
|>172.30.2.0 * 255.255.255.0 U 0 0 0 ixp2
|>169.254.0.0 * 255.255.0.0 U 0 0 0 lo
|>-bash-2.05b#
|>================================================ ============================
|
| The table says that he has 172.30.1.0/24 _directly_ reachable on ixp1, and
| 172.30.2.0/24 _directly_ reachable on ixp1. "directly" means that no
| gateway is involved. However I do find it interesting that the loopback
| is using LinkLocal addresses instead of 127.0.0.0/8.

It's running Fedora Core 2 and for some reason the network scripts do set
that up. I don't know why, but I don't see why that would impact what I
am doing. I guess someone developing FC way back then didn't understand
what "link local" really meant.

--
|---------------------------------------/----------------------------------|
| Phil Howard KA9WGN (ka9wgn.ham.org) / Do not send to the address below |
| first name lower case at ipal.net / spamtrap-2007-05-12-(E-Mail Removed) |
|------------------------------------/-------------------------------------|

On Fri, 11 May 2007 14:09:00 -0400 Allen McIntosh <(E-Mail Removed)> wrote:
| phil-news-(E-Mail Removed) wrote:
|> I'm trying to make use of a 2nd ethernet interface. The basic steps seem
|> to work OK. But nothing gets transmitted out the 2nd interface. Yet it
|> does see packets coming back the other way on that interface.
|>
|> Here's what ifconfig shows:
|>
|> ================================================== ===========================
|> -bash-2.05b# ifconfig
|> ixp1 Link encap:Ethernet HWaddr 00:02:B3:02:02:02
|> inet addr:172.30.1.3 Bcast:172.30.1.255 Mask:255.255.255.0
|> UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
|> RX packets:21049 errors:0 dropped:0 overruns:0 frame:0
|> TX packets:16493 errors:0 dropped:0 overruns:0 carrier:0
|> collisions:0 txqueuelen:256
|> RX bytes:17841196 (17.0 Mb) TX bytes:2523518 (2.4 Mb)
|>
|> ixp2 Link encap:Ethernet HWaddr 00:02:B3:03:03:03
|> inet addr:172.30.2.3 Bcast:172.30.2.255 Mask:255.255.255.0
|> UP BROADCAST MULTICAST MTU:1500 Metric:1
|> RX packets:222 errors:0 dropped:0 overruns:0 frame:0
|> TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
|> collisions:0 txqueuelen:256
|> RX bytes:13320 (13.0 Kb) TX bytes:0 (0.0 b)
|>
|> lo Link encap:Local Loopback
|> inet addr:127.0.0.1 Mask:255.0.0.0
|> UP LOOPBACK RUNNING MTU:16436 Metric:1
|> RX packets:8 errors:0 dropped:0 overruns:0 frame:0
|> TX packets:8 errors:0 dropped:0 overruns:0 carrier:0
|> collisions:0 txqueuelen:0
|> RX bytes:560 (560.0 b) TX bytes:560 (560.0 b)
|>
|> -bash-2.05b#
|> ================================================== ===========================
|>
|> One thing I notice here that might be an issue is that the status RUNNING
|> is not included in ixp2. Could that be related to the problem? How would
|> I fix this if so?
|
| Try taking the interface down and bringing it back up again?

I've done that many times in many combinations. No change.


| When I'm trying to debug this sort of thing, I find it really helps to
| run multiple instances of tcpdump -n. Each instance captures from a
| single interface at each end. (And limit pinging to 3 or 4 packets so
| important stuff doesn't scroll away.) That way you can troubleshoot
| things like hubs and switches that don't forward ARPs properly.
|
| Oh, and it might help those of us in need of an afternoon siesta :-) to
| label your machines A and B or something. I found the phrase "the
| machine under test" a tad ambiguous.

Is "machine A" and "machine PC" good enough. I actually have two of the
machines being tested (both identical, both have the same issue), so I
may end up also having to refer to "machine B".

I need to get some crossover cables and see if by some remote chance the
switches between these machines is playing a part.

--
|---------------------------------------/----------------------------------|
| Phil Howard KA9WGN (ka9wgn.ham.org) / Do not send to the address below |
| first name lower case at ipal.net / spamtrap-2007-05-12-(E-Mail Removed) |
|------------------------------------/-------------------------------------|