Ethernet packet in L2 switch

HostA is connecting in L2 switch. When host A sent out a packet,is the packet broadcast to all hosts of the vlan? If no host of the L2 switch reply, then is it will forwarded to the Gateway?

Yes, if Switch don't have a mac address in its CAM then it will broadcast to all ports on a vlan including gateway.
Check this link,
http://www.cisco.com/en/US/tech/tk389/tk390/technologies_tech_note09186a00800a7af3.shtml#switchtechs
Please rate if that helps
Regards,
~JG

Similar Messages

Specialized ethernet packet type receipt?

Greetings,
I'm writing a specialized module which requires that I be able to tell the OS, "Give all ethernet packets of type X to me." In linux this is achieved with a little understanding of the sk_buff, packet_type structures and a call to dev_add_pack(struct packet_type *).
Since I can no longer get the Solaris source, can someone please enlighten me as to what I might do to accomplish this?
Cheers,
Sam
[email protected]

Sam,
The Sys V Unix way is to write a protocol handler that's written to talk to a DLPI provider (i.e. the network interface device driver). You specify the Ethernet type by putting it in the dl_sap field of a DL_BIND_REQ mesage.
While OS source can make these things quite a bit easier, DLPI is a published, open specification and has been for nearly two decades.
GCOM has implemented DLPI (and STREAMS) on Linux. You can read about DLPI and STREAMS from a Linux perspective at
http://www.gcom.com/home/linux/streams.html
You'll want to look at their ip_strms module to help you grok DLPI from a protocol handler perspective. You can find the source code at http://www.gcom.com/home/linux/lis/drvrs.html.
Regards,
Richard Masoner
http://www.masoner.net/

How to get ethernet packet directly from adaper in labview6.1

I want to get the ethernet packet directly from adaper directly. Which control or function should I use?

If you really need to work with raw ethernet frames, I think you'll want to turn to something outside of built-in LabVIEW functionality.
One approach would be to purchase or download dedicated packet-capture (aka packet sniffer, network monitor) software that provides a developer API (e.g. a DLL with various packet access/filtering/analysis functions), then access that API from LabVIEW (e.g. by using the Call Library Function Node).
Here's one such piece of software, called WinPCap:
http://winpcap.polito.it/
You didn't give many details about your application.
So, I'm going to get up on my soapbox for a moment and urge you to reconsider whether you really need to go this low-level. I'd suggest carefully defining your goal and making sure you can't a
chieve it with higher-level functions like TCP Read and TCP Write in LabVIEW.
Best Regards,
John Lum
National Instruments

How do I create, send and receive ethernet packets to UUT

I need to create and send ethernet packets to control and communicate with an RF board. I would also like to receive ethernet packets back which would be parsed and interpreted.

There you are!
I was wondering how this project was going.
As I said before, we need to know what protocol is being used.
Let me eaxplain. (Please refer to the diagrams and tutorial on pages 752-755 of 2002 NI catalog.)
802.3 is the spec for ethernet. It defines how packets will be transmitted on the wire.
Real Life analogy:
US Mail service.
It moves messages from one place to another. It defines that messages should be in an envelope. The Envelope must have a address so they know where it should be delivered to. You should also have a return address (but this is not enforced). Inside the envelope, you can put any kind of message you want as long as the person recieving it knows how to read it. The
reciever can look at the message and say "oh, this is english, I will read it in english".
Ethernet is similar. Ethernet (ignoring the electrical specs) defines a packet as consisting of
Source address (return address in US mail)
Destination address (delivery address)
Protocol (pretend there was a mark on the envelope that said this letter is in French).
Data (the letter itself)
Checksum (letter pages number as 1 of 4, 2 of 4, etc).
So what you have told me so far is that you want to send a letter!
You have been asking me how to comunicate with the other person but you have not told me what language they speak!
There are many different languages (i.e. protocol's) possible with 802.3.
Examples are
TCP/IP ( say this is English)
UDP (French)
etc....
LV has built in VI's to take a message and convert it to the protocol (lanuage) you want and send it on it's way.
So my question to you once more is;
What protocol are you using?
Ben
Ben Rayner
I am currently active on.. MainStream Preppers
Rayner's Ridge is under construction

Timestamping ethernet packets

Without going to a 1588 solution, what is the recommended method for timestamping incoming Ethernet packets on a PXIe chassis with labView RT?
The packets of interest would be arriving at no faster than a few hundred Hz, but I need a timestamp accuracy <500us. Running a task at 2kHz seems like overkill and something which could negatively impact the other high throughput tasks I have (Video and DAQmx acquisition).
Thanks!
XL600

The sender is not synchronized with my PXI system in any way (And I have no means to change that) so attempting to use sender embedded timestamps isn't an option. All I really want to do is ensure my internal analog sampling timestamps and the Ethernet packet timestamps are aligned since I am comparing Ethernet data directly with various video, force, and position sensors connected to my PXI chassis.
The real world time isn't even important as long as timestamps within my PXI chassis are all aligned and <500us of error exists between the receipt of the Ethernet frame and the timestamping of that frame.
I did experiment with the following:
Send a UDP packet to the loopback address (And capture a RT High resolution timestamp when send) in one loop
Receive it in another loop using blocking receives and timestamp that
I saw a fairly consistent 17us difference between the send and receive timestamps. Given that loopback is memory to memory, that doesn't surprise me. The point though is that there doesn't seem to be very much delta between the UDP receive and the ability to capture a timestamp using the high resolution timer. If that small of a delay exists when I am receiving real ethernet packets, I don't have any problem at all. My trouble, of course, has been that I have no way to signal my PXI chassis when the packet is actually transmitted from the source to verify if the PXI chassis is able to capture the receive timestamp reliably with that small of a window.

How to specify which Ethernet port on a Mac Pro to send an Ethernet packet

Hi,
I am doing some development on a Mac Pro. The Mac Pro has two Ethernet ports on the rear: Ethernet 1 and Ethernet 2.
I want to specify which of these ports I send a UDP Ethernet packet from.
In my code I currently create a socket and send data through this. This works fine, but the data (packet) always seems to come out of Ethernet port 1 on the rear of the Mac Pro.
So, how / where do I set in my code which port (Ethernet 1 or Ethernet 2) on the back of the Mac Pro to send my packet out of?
Cheers!
SkinnyC

It's ok, found this
http://lists.apple.com/archives/macnetworkprog/2008/Feb/msg00070.html

Raw Ethernet Packet

Dear sir,
We are trying to establish communication between FPGA board and PC. Here FPGA transmits the data which is in raw Ethernet frame format. Now PC should receive the same data without filtering like
DD DD DD DD SS SS SS SS TP <data> where “DD” is the Destination Address, ”SS” is the Source Address and “TP” is the type of Protocol.
Kindly let me know the implementation procedure for the above mentioned issue in LabVIEW.
Thanks & Regards,
S Nagaraju

Use a FIFO to transmit the bytes of data of the packet to the PC and then decode them. For efficiency I think you can combine the bytes into U32s and unpack them on the PC side (I think FIFOs transmit 32-bytes of data even if you select a smaller data type). You may want to add some sort of header to the message so you can find the start/end of each received packet on the PC side.

Ethernet packet drops

I'm losing close to 50% of my packets when hard wired. No issues with AirPort, and no packet loss when any other system plugs into any of the switches. It is an issue regardless of the switch being plugged into.

Check this thread regarding 802.1Q:
http://discussions.apple.com/thread.jspa?threadID=378673
PowerBook G4 17" 1.33 GHz 2GB/80GB Mac OS X (10.4.5)

Broken ethernet connection using cabletron switches

I have a problem with PC connected to our
in house net.
I am using a Athlon 1100 With ASUS A7V-Board
as a server.
When i am downloading patches form a Netra X1
Domino-server there is a good chance to break
the ethernet connection. The ethernet card
just disconnects form the network.
This happens with a 3Com 905 B and a
Intel EtherExpress 10/100 (S?)
The 3Com can be reactivated by
ifconfig elxl0 down unplumb
ifconfig elxl0 plumb `cat /etc/hostname.elxl0` up
With the Intel Card
ifconfig iprb0 down unplumb blocks!!!
Since the same thing has happend a single time
with my "Workstation" (166 MMX, Intel 10/100) i
suspect the switch.
has anyone made experiences like this ?
P.S.: You need load for the crash min 2-3 MB/s

Replacement System Discs can be obtained from Apple's Customer Support - US (800) 767-2775 for a nominal fee. You'll need to have the model and serial number of your Mac available.
If you're not in the US, you may need to go through the regional Apple Store that serves your location to find the contact number - http://store.apple.com/Catalog/US/Images/intlstoreroutingpage.html

Does Airport Express support multiple ethernet connections via a switch?

If I use the following configuration, with the Airport Express extending my network, will it handle multiple devices connected via a switch?
Modem---Airport Extreme- - -802.11n- - -Airport Express---Switch---multiple devices (eg. network printer and iMac).
Or do I need to use a second Airport Extreme instead?

It works for me—even when the AirPort Express device is configured to extend the wireless network created by the AirPort Extreme router.

How do I get packets not processed switch in 3750?

I have 3750s running IOS 12.2(40)SE as a L3 switch using EIGRP. I have two vlans with IP addresses assigned and everything is working great, except I notice that most of the traffic is processor switched. In the 3750 how do you get traffic to not be process switched?
VoIP-MDF-SW3750-54-15#sh int stats
Interface Vlan1 is disabled
Vlan54
Switching path Pkts In Chars In Pkts Out Chars Out
Processor 632366 105372316 1038956 109093254
Route cache 460 28952 0 0
Total 632826 105401268 1038956 109093254
Vlan910
Switching path Pkts In Chars In Pkts Out Chars Out
Processor 445714 66703846 324654 25300982
Route cache 0 0 0 0
Total 445714 66703846 324654 25300982
FastEthernet1/0/1
Switching path Pkts In Chars In Pkts Out Chars Out
Processor 0 0 1568606 124838684
Route cache 0 0 0 0
Total 0 0 1568606 124838684
FastEthernet1/0/2
Switching path Pkts In Chars In Pkts Out Chars Out
Processor 0 0 1568586 124868792
Route cache 0 0 0 0
Total 0 0 1568586 124868792
FastEthernet1/0/3
Switching path Pkts In Chars In Pkts Out Chars Out
Processor 0 0 885767 75733684
Route cache 0 0 0 0
Total 0 0 885767 75733684
VoIP-MDF-SW3750-54-15#sh ip int vlan 54
Vlan54 is up, line protocol is up
Internet address is 164.xx.xx.xx/25
Broadcast address is 255.255.255.255
Address determined by non-volatile memory
MTU is 1500 bytes
Helper address is 164.xx.xx.xx
Directed broadcast forwarding is disabled
Multicast reserved groups joined: 224.0.0.1 224.0.0.2 224.0.0.22 224.0.0.13
224.0.0.10
Outgoing access list is not set
Inbound access list is not set
Proxy ARP is enabled
Local Proxy ARP is disabled
Security level is default
Split horizon is enabled
ICMP redirects are always sent
ICMP unreachables are always sent
ICMP mask replies are never sent
IP fast switching is enabled
IP CEF switching is enabled
IP CEF switching turbo vector
IP Null turbo vector
IP multicast fast switching is enabled
IP multicast distributed fast switching is disabled
IP route-cache flags are Fast, CEF

http://www.cisco.com/en/US/products/sw/iosswrel/ps5187/products_command_reference_chapter09186a008017cf2a.html#wp1110844
However, I recommend against it. It will cause high CPU usage.

Bonding two ethernet cards to two switches

We have a corporate secure network setup relying on VLANs. And a requirement to connect all VLANs over a bond (team of network cards) that are connected to two separate switches for fail-over security. This, (two switches) makes the usage of Link Aggregation (IEEE 802.3ad) impossible. So, I set the mode of the bond to static using ifconfig (bondmode static) and get a link and a DHCP adress from the native lan.
We configure our servers using a management lan and have this lan set as default gateway (at the top in Network/System Prefs). I create the bond using networksetup -createBond xxx en1 en2. Then set this bond to static and now have a DHCP adress.
Then I add two VLANs, on top of the bond. One of these VLANs is to become the Default Gateway as our clients will get OD info and other goodies form this server. Al is well, the VLANs recive a DHCP address and I configure these with the static IP addresses.
Now the problem arises. As i change the order of the networks, using networksetup -ordernetworkservices and put the correct VLAN as default Gateway the network connection fails. If I reset to dhcp the VLAN does not receive a DHCP address.
If I create the bond using just one network card everything works as expected. If I add a network card to the bond and rerun it fails.
Any ideas?
IEEE 802.3ad is of on the switches, maybee turn it on just to see if it changes anything?
Switch is a cisco with IEEE 802.3ad support but turned of.

I've found bonding to be reliable when set via the
GUI, but I've yet to find a stable command line
method.
Note that any ifconfig commands would be transient,
and lost at the next reboot. In any case your syntax
is incorrect. It should be:
ifconfig bond0 bonddev
en1
in other words, add device en1 to the existing bonded
interface bond0. You're passing in a physical
interface as the first parameter instead of the
virtual bonded interface.
The networksetup command should work, and should be
persistent. It's not clear why it isn't working.
If you have ARD or a monitor on this box I'd just go
ahead and do it via the GUI. Maybe not the answer you
wanted, but it works for me.
If I don't have an existing bond0, do I simply use same line above but with en0 to create it.
For example: ifconfig bond0 bonddev en0
And is there anything else that would require tweaking after the bond is setup.
G4 Xserver Mac OS X (10.4.4)

After initial backup with ethernet cable, how to switch to wireless backups

Initial full backup from MBP to TC via ethernet using TM worked (took 7hrs to do 150GB).
Now, how do I tell TM to do the incremental backups wirelessly?
My TC is connected to my DSL modem and working wirelessly for that, but when I try to click on TM in menu bar and say "back up now" it asks for my user name and password but says "invalid" when I put in my laptop's admin user and PW.
ACK--now what?
thanks!

DuQuoi,,
You may have realized it later but... It was not your own Username and Password it was asking for but the name of your Time Capsule and its' password that it needed to resume backups wirelessly. I know...the dialog box says 'your username and password', but it is incorrect.
Glad it's working for you now.

3750 Metro ethernet switch

Folks,
I have 6500's at the core and want to use the 3750 at the PE. My question is the following:
1) 3750 would do Q-IN-Q.
2) Once the packet reaches the 6500(sup 720) running MPLS. What happens to the frame. Do i use xconnect to transfer the frame to the appropriate PE?
Just confussed about how does the PE use the Q-IN-Q information to direct it to the appropriate PE?
Sample config would be highly appreciated.
Thanks

Well.. its about product features .. you gotta compare products with your requirments at various layer of your network and to come out with justification of your requirments . Any ways below is snippet for you to have some justification between two products
===============================================
What is the difference between the Cisco Catalyst 3750 Metro Series and the Cisco Catalyst 3750 Series?
The Cisco Catalyst 3750 Metro Series is built for Metro Ethernet access in a customer location, enabling the delivery of more differentiated Metro Ethernet services. These switches feature bidirectional hierarchical QoS and Traffic Shaping; intelligent 802.1Q tunneling with class-of-service (CoS) mutation; VLAN translation; MPLS, EoMPLS, and Hierarchical Virtual Private LAN Service (H-VPLS) support; and redundant AC or DC power. They are ideal for service providers seeking to deliver profitable business services, such as Layer 2, Layer 3, and MPLS VPNs, in a variety of bandwidths and with different SLAs. With flexible software options, the Cisco Catalyst 3750 Metro Series offers a cost-effective path for meeting current and future service requirements from service providers.
The standard Cisco Catalyst 3750 Series is an innovative product line for midsize organizations and enterprise branch offices. Featuring Cisco Systems® StackWise technology, Cisco Catalyst 3750 Series products improve LAN operating efficiency by combining industry-leading ease of use and high resiliency for stackable switches.
What is the Metro Ethernet positioning of the Cisco Catalyst 3750 Metro Series, the Cisco Catalyst 3550 Series, and the Cisco Catalyst 2950 Series?
Cisco Catalyst 3750 Metro Series Switches
=========================================
Cisco Catalyst 3750 Metro Series switches are a new line of premier, customer-located switches that bring greater intelligence for Metro Ethernet access, enabling the delivery of more differentiated Metro Ethernet services. These fixed configuration switches feature bidirectional hierarchical QoS and Traffic Shaping; intelligent 802.1Q tunneling; VLAN translation; MPLS, EoMPLS, and H-VPLS support; and redundant AC or DC power. They are ideal for service providers seeking to deliver profitable business services, such as Layer 2, Layer 3, and MPLS VPNs, in a variety of bandwidths and with different SLAs. With flexible software options, the Cisco Catalyst 3750 Metro Series offers a cost-effective path for meeting current and future service requirements from service providers.
Cisco Catalyst 3550 Series Switches
==================================
With a range of Fast Ethernet, Gigabit Ethernet, DC power, and fiber configurations, the Cisco Catalyst 3550 Series is an intelligent metro access switch for service providers serving the enterprise and small and medium-sized business markets. Featuring 802.1Q tunneling, high-performance IP routing, and subsecond Spanning Tree Protocol convergence, this line of powerful, cost-effective, fixed-configuration switches enables Metro Ethernet services such as Transparent LAN services and business-class Internet access.
Cisco Catalyst 2950 Series Switches
===================================
Ideal for Metro Ethernet access in residential markets, the Cisco Catalyst 2950 Series is an affordable line of fixed-configuration Fast Ethernet and Gigabit Ethernet switches. Featuring advanced rate limiting, voice VLAN support, and multicast management, these switches enable residential Metro Ethernet services such as Internet access, voice over IP (VoIP), and broadcast video.
Hope it helps
Ps rate this post if it helps u ..
Thanks and Regards
Raj

Access Connections Ethernet Location Switching only saves one port at a time

Like many other people, I cannot get automatic location switching between two Ethernet networks to work properly.
I have two stored network locations; one for home and one for work. Both of these are set up as Best Available Network with both Ethernet and Wireless.
Under Tools - Location Switching, both networks are listed, and "Include Ethernet connections in automatic switching and prompt me to save Ethernet ports" is checked. However, in the details column, the current location has 1 saved port(s), and the other has 0 saved ports. The saved port is always the one most recently connected.
If I go to Edit Saved Ports, only one location is listed, with the correct IP address and MAC address for the router. If I connect at the other location, only that location is listed, again with the correct IP address and MAC address.
The router IP addresses are different (work is 192.168.0.1, and home is 192.168.1.254), and obviously the MAC addresses are different, so it should be possible for Access Connections to distinguish them. Unfortunately the only "editing" that is possible is to delete the saved port. I would be happy to add a saved port manually, but that is not an option. In addtion, despite the "...prompt me to save Ethernet ports" being checked, I have never received a prompt. Even if I delete the saved port, it resaves automatically next time without any prompt.
I have also tried setting up both locations as Ethernet only, but have exactly the same problem.
My T520 was supplied with Access Connections 5.85 preinstalled. I tried upgrading to 5.97 in the hope that it had been fixed in the meantime. Unfortunately it has not.
Access Connections is still marginally useful to me for automatic switching between Wireless and Ethernet, and for a simple manual switch of settings such as default printer, home page, and file sharing. However, it would be very useful for the home and work locations to be autodetected and switched.
From the number of unresolved questions on this board on the same topic, it appears that this is a long standing deficiency with Access Connections. Is there any chance of this being fixed?

I found from another bulletin board that ethernet location switching seemed to work OK with Access Connections 3.82, but stopped working with releases after that, and from my experience still does not work with 5.97
http://www.thinkpads.com/forum/viewtopic.php?f=18&t=38514
Two questions:
1. Does anyone know if Access Connections 3.82 works with Windows 7?
2. If so, where could I get a copy? The oldest version on the Lenovo website appears to be 5.50
I will refrain from commenting on the necessity of going back to such an old version to recover basic functionality for this utility......

Ethernet packet in L2 switch

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