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Old 05-18-2017, 06:34 AM   #1
LQ Newbie
Registered: May 2017
Posts: 5

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sending vlan tagged packets from ethernet port

Here is my scenario
Let's call it desktop
$ cat /etc/fedora-release
Fedora release 17 (Beefy Miracle)
$ uname -a
Linux CSG.localdomain 3.9.10-100.fc17.x86_64 #1 SMP Sun Jul 14 01:31:27 UTC 2013 x86_64 x86_64 x86_64 GNU/Linux
# ifconfig
lo: flags=73<UP,LOOPBACK,RUNNING> mtu 65536
inet netmask
inet6 ::1 prefixlen 128 scopeid 0x10<host>
loop txqueuelen 0 (Local Loopback)
RX packets 1893 bytes 167138 (163.2 KiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 1893 bytes 167138 (163.2 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0

p5p1: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet netmask broadcast
inet6 fe80::6e3b:e5ff:fe22:a919 prefixlen 64 scopeid 0x20<link>
ether 6c:3b:e5:22:a9:19 txqueuelen 1000 (Ethernet)
RX packets 474455038 bytes 718168282851 (668.8 GiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 28413363 bytes 1875851521 (1.7 GiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0

virbr0: flags=4099<UP,BROADCAST,MULTICAST> mtu 1500
inet netmask broadcast
ether 52:54:00:a5:a7:9a txqueuelen 0 (Ethernet)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
I want to send packets on ethernet port having vlan tag 1600.
At the other end is a switch having gateway and accepting vlan tagged packets.
I tried
# modprobe 8021q
# vconfig add p5p1 1600
Added VLAN with VID == 1600 to IF - : p5p1:-
# ifconfig p5p1.1600
# route -n
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface UG 0 0 0 p5p1 U 0 0 0 p5p1.1600 U 0 0 0 p5p1 U 0 0 0 virbr0
# ping -I p5p1.1600
PING ( from p5p1.1600: 56(84) bytes of data.
From icmp_seq=1 Destination Host Unreachable
From icmp_seq=2 Destination Host Unreachable
From icmp_seq=3 Destination Host Unreachable
From icmp_seq=4 Destination Host Unreachable
I connected ethernet cable (end fed to switch) to another laptop running wireshark and saw that there were arp broadcast packets 'who has ? tell' from mac 6c:3b:e5:22:a9:19
So , it seems that my desktop is not sending vlan tagged packets as the default gateway is associated with p5p1 instead of p5p1.1600.

BTW , I gave 192.x.x.x IP to p5p1 in hope that if destination ip is 172.16.x.x , that interface p5p1 won't be used.
Could be that p5p1.1600 is a sub-interface of p5p1 , so I also tried above with static IP to p5p1 , still no success in pinging .

How can I solve this ?
Please , let me know if any further details are required.

PS: If you have 2 linux PC's , one having wireshark then connect them together and verify that whether other is sending vlan tagged packets.That will be so useful to me.

Last edited by is2014; 05-18-2017 at 06:55 AM. Reason: comment at end for practical check
Old 05-23-2017, 10:04 AM   #2
LQ Newbie
Registered: May 2017
Posts: 5

Original Poster
Rep: Reputation: Disabled
to moderator ,
Can you move this thread to software forum .
Guess , i will find replies there.



network interface, packet, vlan

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