Re: Strange ARP problem

Normando Marcolongo <[email protected]>
Newsgroups gmane.linux.drivers.vlan
Message-ID <[email protected]> 
Justin Cormack wrote:

>
>
> I think you have to do it while the interface is down.

Yeah I did but the problem persists. The fact is that Cisco too has the 
same MAC across multiple VLAN:

# arp -an
? (172.19.1.1) at 00:07:B3:1A:AC:0A [ether] on eth0
? (172.22.1.1) at 00:07:B3:1A:AC:0A [ether] on eth0.201

There you can see the linux machine catching the client broadcasts on 
the eth0.201:

09:48:39.392575 IP 172.22.1.5.137 > 172.22.1.255.137: NBT UDP 
PACKET(137): REGISTRATION; REQUEST; BROADCAST
09:48:40.128021 IP 172.22.1.5.137 > 172.22.1.255.137: NBT UDP 
PACKET(137): REGISTRATION; REQUEST; BROADCAST
09:48:40.688972 00:03:fe:ac:09:58 > 01:00:0c:cc:cc:cd sap aa ui/C len=39
09:48:40.877931 IP 172.22.1.5.137 > 172.22.1.255.137: NBT UDP 
PACKET(137): REGISTRATION; REQUEST; BROADCAST
09:48:41.627924 IP 172.22.1.5.137 > 172.22.1.255.137: NBT UDP 
PACKET(137): REGISTRATION; REQUEST; BROADCAST
09:48:42.378053 IP 172.22.1.5.137 > 172.22.1.255.137: NBT UDP 
PACKET(137): REGISTRATION; REQUEST; BROADCAST
09:48:42.688993 00:03:fe:ac:09:58 > 01:00:0c:cc:cc:cd sap aa ui/C len=39
09:48:43.127830 IP 172.22.1.5.137 > 172.22.1.255.137: NBT UDP 
PACKET(137): REGISTRATION; REQUEST; BROADCAST
09:48:43.877744 IP 172.22.1.5.137 > 172.22.1.255.137: NBT UDP 
PACKET(137): REGISTRATION; REQUEST; BROADCAST

and there you can see the client (.5) asking the MAC address of the 
server (.2) that replies. The reply is _not_ arriving on the client cable.

09:49:10.034136 arp who-has 172.22.1.2 tell 172.22.1.5
09:49:10.034159 arp reply 172.22.1.2 is-at 06:0b:db:a9:0f:d1

Note the mac address that is the correct one:

# ifconfig
eth0      Link encap:Ethernet  HWaddr 00:0B:DB:A9:0F:D1
          inet addr:172.19.1.11  Bcast:172.19.1.255  Mask:255.255.255.0
          inet6 addr: fe80::20b:dbff:fea9:fd1/64 Scope:Link
          UP BROADCAST RUNNING PROMISC MULTICAST  MTU:1500  Metric:1
          RX packets:299499 errors:0 dropped:0 overruns:0 frame:0
          TX packets:161893 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:22443458 (21.4 MiB)  TX bytes:220560315 (210.3 MiB)
          Base address:0xece0 Memory:fe8e0000-fe900000

eth0.201  Link encap:Ethernet  HWaddr 06:0B:DB:A9:0F:D1
          inet addr:172.22.1.2  Bcast:172.22.1.255  Mask:255.255.255.0
          inet6 addr: fe80::40b:dbff:fea9:fd1/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:78326 errors:0 dropped:0 overruns:0 frame:0
          TX packets:25 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:3923165 (3.7 MiB)  TX bytes:1610 (1.5 KiB)

I'm going to give up... Please if anyone has a suggestion is very welcome.

Thanks,
Normando

>
> Justin
>
> On 24 May 2005, at 12:30, Normando Marcolongo wrote:
>
>> Justin Cormack wrote:
>>
>>
>>>
>>> I think that lots of equipment doesnt like you mixing tagged and   
>>> untagged traffic on the same network.
>>>
>>> If you have to it might help setting the Mac addresses on the two   
>>> interfaces to be different.
>>>
>>>
>> So how can I change the mac on the eth0.201 interface?
>>
>> # ifconfig eth0.201 hw ether 00:0B:DB:A9:1F:D1
>> SIOCSIFHWADDR: Device or resource busy
>>
>> Thanks!!!
>> Normando
>>
>>
>>>
>>> On 24 May 2005, at 11:32, Normando Marcolongo wrote:
>>>
>>>
>>>> Hi!
>>>>
>>>> Let me explain the simple architecture here. A linux machine  with  
>>>> kernel 2.6.11.7 (Debian Sarge) and e1000 driver. A Cisco  Catalyst  
>>>> 6509 configured with a trunk port this way:
>>>>
>>>> interface GigabitEthernet4/13
>>>>  switchport
>>>>  switchport trunk native vlan 100
>>>>  switchport trunk allowed vlan 100,201
>>>>  switchport mode trunk
>>>>
>>>> The linux machine has:
>>>>
>>>> # cat /proc/net/vlan/config
>>>> VLAN Dev name    | VLAN ID
>>>> Name-Type: VLAN_NAME_TYPE_RAW_PLUS_VID_NO_PAD
>>>> eth0.201       | 201  | eth0
>>>>
>>>> # ifconfig
>>>> eth0      Link encap:Ethernet  HWaddr 00:0B:DB:A9:0F:D1
>>>>           inet addr:172.19.1.11  Bcast:172.19.1.255  Mask:  
>>>> 255.255.255.0
>>>>           inet6 addr: fe80::20b:dbff:fea9:fd1/64 Scope:Link
>>>>           UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
>>>>           RX packets:49984 errors:0 dropped:0 overruns:0 frame:0
>>>>           TX packets:80330 errors:0 dropped:0 overruns:0 carrier:0
>>>>           collisions:0 txqueuelen:1000
>>>>           RX bytes:4335305 (4.1 MiB)  TX bytes:110105417 (105.0 MiB)
>>>>           Base address:0xece0 Memory:fe8e0000-fe900000
>>>>
>>>> eth0.201  Link encap:Ethernet  HWaddr 00:0B:DB:A9:0F:D1
>>>>           inet addr:172.22.1.2  Bcast:172.22.1.255  Mask: 
>>>> 255.255.255.0
>>>>           inet6 addr: fe80::20b:dbff:fea9:fd1/64 Scope:Link
>>>>           UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
>>>>           RX packets:255 errors:0 dropped:0 overruns:0 frame:0
>>>>           TX packets:361 errors:0 dropped:0 overruns:0 carrier:0
>>>>           collisions:0 txqueuelen:0
>>>>           RX bytes:22471 (21.9 KiB)  TX bytes:21547 (21.0 KiB)
>>>>
>>>> If I put a test client on the VLAN100 the linux machine can ping   
>>>> the 6509's VLAN100 interface and the test client.
>>>> Now, I can ping from the linux machine the VLAN201 interface of  
>>>> the  6509 and (obviuosly) vice versa.
>>>> If I put a test client on the VLAN201 the test client _cannot_   
>>>> resolve the MAC address of the linux machine while the linux   
>>>> machine has this resolved. If I do a tcpdump on the linux machine  
>>>> I  see:
>>>> on the eth0.201 the ARP request from the client _and_ the reply   
>>>> from the linux machine to the client (this will never reach the   
>>>> client for an unknown reason)
>>>> on the eth0 the same (I think I've understood that this is normal)
>>>> putting static ARPs on the server/client solves the problem.
>>>> Can you give me some directions? Need some other information?
>>>>
>>>> Thanks,
>>>> Normando
>>>> -- Normando Marcolongo | Micso s.r.l. via Tiburtina, 318 |  
>>>> I-65128  Pescara, Italy tel/fax (+39)08554105 | mob. (+39)3386296362
>>>> <normando.vcf>
>>>> _______________________________________________
>>>> Vlan mailing list
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>>>> http://www.lanforge.com/mailman/listinfo/vlan
>>>>
>>>>
>>>
>>> _______________________________________________
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>>>
>>>
>>>
>>
>>
>> -- 
>>  Normando Marcolongo | Micso s.r.l.
>>   via Tiburtina, 318 | I-65128 Pescara, Italy
>> tel/fax (+39)08554105 | mob. (+39)3386296362
>>
>>
>> <normando.vcf>
>> _______________________________________________
>> Vlan mailing list
>> [email protected]
>> http://www.lanforge.com/mailman/listinfo/vlan
>>
>
> _______________________________________________
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>
>
>


-- 
  Normando Marcolongo | Micso s.r.l.
   via Tiburtina, 318 | I-65128 Pescara, Italy
tel/fax (+39)08554105 | mob. (+39)3386296362

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