ARP resolution fails when MSG_DONTROUTE flag is set

[p***@wipro.com]

Hi,

Environment:
NetBSD 1.6.1 NetBSD 1.6.1 (GENERIC) #1: Thu Jun 14 04:52:29 PDT 2007

root@:/usr/src/sys/arch/i386/compile/GENERIC i386


I have the following two routes installed on kernel routing table of my
NetBSD
machine, for the same destination:

1. A directly connected route, with outgoing interface as Inf1
2. A host specific ?/32? route via an alternate path with outgoing
interface as
Inf2.

In this scenario, if a packet is sent to the destination, the packets
egresses
from Inf2.(longest prefix match)
If a packet is sent on interface Inf1 setting the MSG_DONTROUTE flag (to
bypass
the routing table), arp resolution is failing and I am getting the
following

/netbsd: arpresolve: can't allocate llinfo on fxp2 for

23.23.23.23


This problem exists only when we have a directly connected route and a
'/32'
route (via an alternate path) to the same destination. ARP resolution
fails for
the directly connected interface, an the packet gets dropped.
+--------+ 21.21.21.22 21.21.21.21 +----------+
| PC1 |-----------------------------------------| PC2 |
+--------+ +----------+
\ 23.23.23.24 25.25.25.26 /
\ /
\ /
\ /
\ /
\ /
\ /
\ /
\ /
\ /
\ /
\ /
\ /
\ /
\ /
\ /
\ /
\ /
\ /
\ /
\ /
\ /
\ /
\ /
23.23.23.23 \ / 25.25.25.25
+----------+
| PC3 |
+----------+

On PC1
======
bash-3.2# route show
Routing tables

Internet:
Destination Gateway Flags
10.11.0.0 link#1 U
10.11.1.59 00:10:18:82:09:66 UH
10.11.6.150 00:19:d1:5e:62:46 UH
10.11.8.204 00:10:18:82:02:f7 UH
21.21.21.0 link#2 U
21.21.21.21 link#2 UH
21.21.21.22 00:02:b3:28:52:61 UH
23.23.23.0 link#3 U
23.23.23.23 21.21.21.21 UG
localhost 127.0.0.1 UH

bash-3.2# traceroute 23.23.23.23
traceroute to 23.23.23.23 (23.23.23.23), 30 hops max, 40 byte packets
1 21.21.21.21 (21.21.21.21) 0.243 ms 0.120 ms 0.113 ms
2 23.23.23.23 (23.23.23.23) 0.332 ms 0.206 ms 0.233 ms


On PC2
======
bash-3.2# route show
Routing tables

Internet:
Destination Gateway Flags
default 100.0.2.3 UG
1.0.0.1 1.0.0.1 UH
1.0.0.1 link#5 U
10.11.0.0 link#1 U
10.11.6.150 00:19:d1:5e:62:46 UH
21.21.21.0 link#2 U
21.21.21.22 link#2 UH
23.23.23.0 21.21.21.22 UG
23.23.23.23 25.25.25.25 UG
25.25.25.0 link#4 U
25.25.25.25 link#4 UH
100.0.2.0 link#3 U
loopback link#5 U
localhost 127.0.0.1 UH


On PC3
======
bash-3.2# route show
Routing tables

Internet:
Destination Gateway Flags
10.11.0.0 link#1 U
10.11.6.11 00:02:a5:84:95:62 UH
10.11.6.150 00:19:d1:5e:62:46 UH
21.21.21.0 25.25.25.26 UG
23.23.23.0 link#2 U
25.25.25.0 link#3 U
25.25.25.26 link#3 UH
loopback link#5 U
localhost 127.0.0.1 UH


ping 23.23.23.23 is successful from PC1.
ping -r 23.23.23.23 is unsuccessful from PC1.

(ping -r is used to bypass the routing table and send the packet through

interface 23.23.23.24).

tail -f /var/log/messages (on PC1)
==================================
arpresolve: can't allocate llinfo on fxp2 for 23.23.23.23
arplookup: unable to enter address for
***@01:01:46:5c:17:17:17:18:17:17:17:17:08:00:7d:45 on null
(host is
not on local network)
arpresolve: can't allocate llinfo on fxp2 for 23.23.23.23
arplookup: unable to enter address for
***@01:01:46:5a:17:17:17:18:17:17:17:17:08:00:7c:44 on null
(host is
not on local network)
arpresolve: can't allocate llinfo on fxp2 for 23.23.23.23
arplookup: unable to enter address for
***@01:01:46:58:17:17:17:18:17:17:17:17:08:00:7b:43 on null
(host is
not on local network)

Please give me some way to bypass the routing table and send the packets
directly on an interface.

Please do not print this email unless it is absolutely necessary.

The information contained in this electronic message and any attachments to this message are intended for the exclusive use of the addressee(s) and may contain proprietary, confidential or privileged information. If you are not the intended recipient, you should not disseminate, distribute or copy this e-mail. Please notify the sender immediately and destroy all copies of this message and any attachments.

WARNING: Computer viruses can be transmitted via email. The recipient should check this email and any attachments for the presence of viruses. The company accepts no liability for any damage caused by any virus transmitted by this email.

www.wipro.com

--
Posted automagically by a mail2news gateway at muc.de e.V.
Please direct questions, flames, donations, etc. to news-***@muc.de

[Bernd Ernesti]

Post by p***@wipro.com
Hi,
NetBSD 1.6.1 NetBSD 1.6.1 (GENERIC) #1: Thu Jun 14 04:52:29 PDT 2007

Sorry, but 1.6.1 is simply too old and unsupported for years, so people
won't put any work into debbuging problems in it.

Please try a 4.0 system.

Bernd


--
Posted automagically by a mail2news gateway at muc.de e.V.
Please direct questions, flames, donations, etc. to news-***@muc.de

[p***@wipro.com]

Hi Brend,

I have actually tried this scenario even on NetBSD 4.0 but the problem
exists. Could you please have a look at it once?

Thanks for your interest.

Puneet.

-----Original Message-----
From: Bernd Ernesti [mailto:***@lists.veego.de]
Sent: Monday, September 22, 2008 11:56 AM
To: tech-***@NetBSD.org
Cc: Puneet Mehta (WT01 - Telecom Equipment)
Subject: Re: ARP resolution fails when MSG_DONTROUTE flag is set

Post by p***@wipro.com
Hi,
NetBSD 1.6.1 NetBSD 1.6.1 (GENERIC) #1: Thu Jun 14 04:52:29 PDT 2007

Sorry, but 1.6.1 is simply too old and unsupported for years, so people
won't put any work into debbuging problems in it.

Please try a 4.0 system.

Bernd


Please do not print this email unless it is absolutely necessary.

The information contained in this electronic message and any attachments to this message are intended for the exclusive use of the addressee(s) and may contain proprietary, confidential or privileged information. If you are not the intended recipient, you should not disseminate, distribute or copy this e-mail. Please notify the sender immediately and destroy all copies of this message and any attachments.

WARNING: Computer viruses can be transmitted via email. The recipient should check this email and any attachments for the presence of viruses. The company accepts no liability for any damage caused by any virus transmitted by this email.

www.wipro.com

--
Posted automagically by a mail2news gateway at muc.de e.V.
Please direct questions, flames, donations, etc. to news-***@muc.de

[Bernd Ernesti]

Post by p***@wipro.com
Hi Brend,

Whoever that is.

Post by p***@wipro.com
I have actually tried this scenario even on NetBSD 4.0 but the problem
exists.

You should have mentioned that from the beginning.

Post by p***@wipro.com
Could you please have a look at it once?

No time.

Bernd


--
Posted automagically by a mail2news gateway at muc.de e.V.
Please direct questions, flames, donations, etc. to news-***@muc.de

[David Young]

Post by p***@wipro.com
Hi,
NetBSD 1.6.1 NetBSD 1.6.1 (GENERIC) #1: Thu Jun 14 04:52:29 PDT 2007
I have the following two routes installed on kernel routing table of my
NetBSD
1. A directly connected route, with outgoing interface as Inf1
2. A host specific ?/32? route via an alternate path with outgoing
interface as
Inf2.
In this scenario, if a packet is sent to the destination, the packets
egresses
from Inf2.(longest prefix match)
If a packet is sent on interface Inf1 setting the MSG_DONTROUTE flag (to
bypass
the routing table), arp resolution is failing and I am getting the
following

Puneet,

Please file a report on this issue in the NetBSD problem report tracker.
You can use send-pr for that .

Dave