Re: [dpdk-dev] [PATCH] testpmd: modify the mac of csum forwarding

["Qiu, Michael" <michael.qiu@intel.com>]

On 2015/8/7 13:37, Zhang, Helin wrote:
>
>> -----Original Message-----
>> From: Qiu, Michael
>> Sent: Friday, August 7, 2015 11:53 AM
>> To: Zhang, Helin; dev@dpdk.org
>> Subject: Re: [dpdk-dev] [PATCH] testpmd: modify the mac of csum forwarding
>>
>> On 2015/8/7 9:06, Zhang, Helin wrote:
>>>> -----Original Message-----
>>>> From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Michael Qiu
>>>> Sent: Thursday, August 6, 2015 8:29 PM
>>>> To: dev@dpdk.org
>>>> Subject: [dpdk-dev] [PATCH] testpmd: modify the mac of csum
>>>> forwarding
>>>>
>>>> For some ethnet-switch like intel RRC, all the packet forwarded out
>>>> by DPDK will be dropped in switch side, so the packet generator will never
>> receive the packet.
>>> Is it because of anti-sproof? E.g. When the hardware found that the
>>> dest mac is the port itself, then it will be dropped during TX.
>>> You need to tell the root cause, and why we need to modify like this.
>> Actually, it is not the hardware from PEP(PCI End Point) side, but the switch side.
>>
>> The TX is OK for DPDK and NIC, but in switch, it receives the packet and try to
>> forward it, but the dest mac is the same as the NIC which transmit this packet.
>> So switch will drop it as "Loopback Suppression Drop" in RRC. This should only
>> happen when switch forwarding packets using dest mac.
>>
>>
>>>> Signed-off-by: Michael Qiu <michael.qiu@intel.com>
>>>> ---
>>>>  app/test-pmd/csumonly.c | 4 ++++
>>>>  1 file changed, 4 insertions(+)
>>>>
>>>> diff --git a/app/test-pmd/csumonly.c b/app/test-pmd/csumonly.c index
>>>> 1bf3485..bf8af1d 100644
>>>> --- a/app/test-pmd/csumonly.c
>>>> +++ b/app/test-pmd/csumonly.c
>>>> @@ -550,6 +550,10 @@ pkt_burst_checksum_forward(struct fwd_stream
>> *fs)
>>>>  		 * and inner headers */
>>>>
>>>>  		eth_hdr = rte_pktmbuf_mtod(m, struct ether_hdr *);
>>>> +		ether_addr_copy(&peer_eth_addrs[fs->peer_addr],
>>>> +				&eth_hdr->d_addr);
>>>> +		ether_addr_copy(&ports[fs->tx_port].eth_addr,
>>>> +				&eth_hdr->s_addr);
>>> Is it really necessary? Why other NICs do not need this?
>> Because other NICs is connect directly to packet generator...., if we using switch
>> to connect the generator and the NICs, I think it will need this.
> There are 'iofwd' and 'mac' mode in testpmd, and mac forware will modify the dest
> mac before transmitting the packet. They are for different cases.
> Why not use mac forwarding mode for your testing, and just keep it as is?

Yes, I don't touch iofwd, I just modify the csum, when we test checksum
offload, especially for checksum insert in TX side.

Thanks,
Michael

> Regards,
> Helin
>
>> Thanks,
>> Michael
>>>>  		parse_ethernet(eth_hdr, &info);
>>>>  		l3_hdr = (char *)eth_hdr + info.l2_len;
>>>>
>>>> --
>>>> 1.9.3
>