Hi, ----Original Message---- From: Mohammad M Molla [mailto:merajul_i@xxxxxxxxx] Sent: Saturday, November 17, 2007 1:07 AM To: Rajat Jain; kernelnewbies@xxxxxxxxxxxx Subject: RE: Ethernet Driver: Transmitted Packets not received by receiver > Actually, I wrote the driver for an embedded OS which still does not > have any network stack. I actually ported the linux driver. Uh, you mean it doesn't even have a TCP/IP yet? Ok, that'll make things difficult. > > Since there is no network stack, there is no higher layer to > communicate CRC info. I manually create an ARP request packet for > testing purpose and send it a particular remote machine to see > whether it is working or not. > > About tcpdump, as far I know tcpdump will get packets if the card > does not drop it. If the card drops packet due to CRC error or > something that packet should not go to tcpdump, right? But you can configure the remote NIC in promiscuous mode, no? > I don't have > tcpdump on remote machine. But since I am not getting any ARP reply > for my ARP request and I am also not getting any transmission error, > I am suspecting CRC might be the problem. But is there any way to > verify? As I said that the first step is to verify (using tcpdump / ethereal / other network sniffers) whether your packet IS getting transmitted on the wire or not. The mere fact that you don't get any transmission error and do get a transmission complete interrupt, may not be the best criteria to conclude transmission is succefully done on wire. Thanks, Rajat > > Thanks, > Meraj > > Rajat Jain <Rajat.Jain@xxxxxxxxxxxx> wrote: > > Hi, > >> The way I tested it - >> >> 1. I pinged from a remote machine. My driver received an ARP request. >> I filled up the response and sent it back. When transmission is done >> I got "Transmit interrupt" (no error). But on the remote machine, >> typing 'arp -a' I get an entry for my driver's machine with all >> written in MAC address field. >> >> 2. I also tested the other way. I sent a custom built arp packet to >> the remote machine. After completion of transmittion I got "Transmit >> interrupt" (again no error). But I don't receive any ARP reply and >> there is no entry in receiver's arp table for this either. > > > I think the best way to test is to use tcpdump at the remote machine. > Try something like "tcpdump -XX ether host 00:0f:30:00:0b:08" and it > will give you all packets with the given mac address. Provide MAC > address of card for which you are developing the driver. > > 1) Ping from your machine to remote machine (This would send an ARP > request to remote) 2) You should see something like this on remote > machine (on tcpdump): > > 17:23:55.491398 arp who-has 172.18.80.141 tell 172.18.80.8 > 0x0000: ffff ffff ffff 000f 3000 0b08 0806 0001 ........0....... > 0x0010: 0800 0604 0001 000f 3000 0b08 ac12 5008 ........0.....P. > 0x0020: 0000 0000 0000 ac12 508d 0000 0000 0000 ........P....... > 0x0030: 0000 0000 0000 0000 0000 0000 ............ > > 3) Then the remote machine will send an ARP reply: > > 17:23:55.493258 arp reply 172.18.80.141 is-at 00:0b:cd:26:ff:00 > 0x0000: 000f 3000 0b08 000b cd26 ff00 0806 0001 ..0......&...... > 0x0010: 0800 0604 0002 000b cd26 ff00 ac12 508d .........&....P. > 0x0020: 000f 3000 0b08 ac12 5008 ..0.....P. > > So if you don't see step 2, that means your network card ain't > sending anything on wire! > >> >> I am not calculating CRC in software and assuming the NIC card will >> calculate CRC. Is it possible that the CRC value is wrong or the NIC >> card actually does not calculate CRC on this card (the card is bcm >> 4713 on Cisco Lynksys router) and I have to calculate it in software? > > Most of the cards are capable of generating CRC, hence that should be > okay. However, have you communicated this to higher layer while > registering the interface) ? > > Thanks, > > Rajat > > > > > > Be a better pen pal. Text or chat with friends inside Yahoo! Mail. > See how. -- To unsubscribe from this list: send an email with "unsubscribe kernelnewbies" to ecartis@xxxxxxxxxxxx Please read the FAQ at http://kernelnewbies.org/FAQ
