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Setting up Ethernet in FPGA

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bibo1978

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Re: Ethernet with FPGA

ok then run your board in promocious mode, i.e. don't drop wrong MAC addresses and put some of the undefined packets on the block RAM or on an extrenal RAM "which is better and will allow u to monitor more of this data".
afterwards you can read the data, this way you will need a PC to board controller mean of connection, rs232 can do this, u read out the data in the ram and analyze it,
An easier way is to put the data on the bram and use the BSCAN to read the BRAM using JTAG connection, this way you may monitor a small time traffic.
 

jdhar

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Ethernet with FPGA

I wish I could do this, however, I'm using an IP Core provided by Protel - I can only specify the MAC address. Aside from this however, I am connected to a switch - won't the switch - once it associates my MAC address with the port - not send out all packets that do'nt have my MAC or broadcast in the header? I thought that was the whole point of a switch, to intelligently route packets...
 

bibo1978

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Re: Ethernet with FPGA

switch doesn't route packets it works on L2 actaully so it doesn't look at the IP "in general some switches can do some routing L3- switches".
you can configure the switch port to pass all data to this port, also a switch will pass all broadcast frames and multicast frames to the port, I beleive there is a way that you define a port as a non-broadcast port but I donot know how if there is a way.
I don't know but may be you are running a spanning tree protocol 802.1q, 802.1p this protocol sends an spanning tree update every 2s i.e. you may configure your port as a client so that it will not pass this protocol update. you will need to read in the switch manual to know how this is done.
 

jdhar

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Ethernet with FPGA

I can see how switches don't look at IP's, but in an Ethernet packet, the destination MAC address is specified. So I thought switches kept a table of MAC addresses adn corresponding switch ports, and if detects a packet with a known MAC address, it forwards it to that port without disturbing the other ports. Only if it doesn't know the MAC address would it send it out to all ports, but when it learns of the MAC address of a corresponding port, it would no longer send useless packets to the port. Am I mistaken here? My switch is a simple linksys switch, so there is no configuration to it really. This switch is then connected to another 4-port router using an uplink port. I thought this was the main difference between a switch and a hub - a hub just passes all packets it receives to all ports, and doesn't read into the packet, but a switch actually learns about MAC addresses and their associated ports.

I also have a linux box on this network, maybe Ethereal on linux would be better?
 

bibo1978

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Re: Ethernet with FPGA

I agree on the MAC-table, this is what switch do it learns the addresses and look at MAC tables "can be a CAM in large switches", if address exist it just forwaird to adjacent CAM address "port number", otherwise it sends to all ports except the inbound port.
the MAC table address usually has a timeout, i.e. if no frames comes from the interface it will just remove the MAC address learnt from a previous transaction after timeout. you may configure a static MAC address on the switch the never timeout but I guess your switch has no console connection to be configured through, anyhow since you are using a trivial switch I guess may be it doesn't support spanning tree protocol "u have to check its manual",
so it seems so far that there is a broadcast frames over your network, so may be it comes from the router "routing protocols", you can configure the routers "both" not to send routing protocol updates to the ports connected to the switch , and configure the route "router-switch-router route" statically on both routers or use a less traffic routing protocol like link-state protocols
I guess may be this will decrease the braodcast traffic
 

    jdhar

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jdhar

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Ethernet with FPGA

Thx for your help again Bibo... I think one easy way to solve this is for me to monitor any packets transferred when I connect my laptop to the switch. This way, I can see if I received any weird packets from the router. If I do, I can go from there... if not, then I think this is definately a physical-layer problem.
 

prerna_saluja

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Re: nic in promocious mode

sir can u help me out with this, i had to do the similar project. I was using TEMAC core for this project, which i earlier i dint know i had to get the license for which is of 20,000$... can u help me out how you have done it.. its urgent
 

lucbra

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Re: nic in promocious mode

I think all answers are included in the thread.
If you aren't using Altium, then I can recommend the implementation based on OpenCores and the Nios processor. This implementation is well documented, and ready to rock and roll.

Regards;
 

jamesbowman

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Re: Ethernet with FPGA

Best bet is to make an ARP request packet. Construct an ARP WHO-HAS packet asking for the laptop's IP. The laptop will respond with its own ARP. After you have ARP running, ICMP (PING) is next.
 

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