Re: [dpdk-users] arp behaviour on dpdk

[Nishant Verma <vnish11@gmail.com>]

Missing Attachment..

On Tue, Aug 16, 2016 at 12:18 PM, Stephen Hemminger <
stephen@networkplumber.org> wrote:

> On Tue, 16 Aug 2016 12:10:50 +0530
> Raja Jayapal <raja.jayapal@tcs.com> wrote:
>
> > Hi Nishant,
> >
> > Please find attachment for the pcap file.
> >
> > Thanks,
> > Raja
> >
> > -----Nishant Verma <vnish11@gmail.com> wrote: -----
> > To: Raja Jayapal <raja.jayapal@tcs.com>
> > From: Nishant Verma <vnish11@gmail.com>
> > Date: 08/13/2016 02:42AM
> > Cc: "users@dpdk.org" <users@dpdk.org>, Nagaratna Patagar <
> nagaratna.patagar@tcs.com>
> > Subject: Re: [dpdk-users] arp behaviour on dpdk
> >
> > Hi Raja,
> >
> > What i understand is that Br1(linux machine) is getting ARP request but
> not sending ARP Response?
> > If this is the case, it means either packet is not liked by Br1 hence
> dropped or some how capture is not right.
> >
> > Can you share pcap file,  captured at Br1.
> >
> >
> >
> > On Thu, Aug 11, 2016 at 3:02 AM, Raja Jayapal <raja.jayapal@tcs.com>
> wrote:
> > Hi All,
> >
> >  I am running dpdk on KVM and would like to understand the arp behaviour
> on dpdk ports.
> >  The topology is as below.
> >
> >  br0(192.168.100.10)----> vnet0 -----> dpdk(NIC1-
> e1000)------->dpdk(NIC2-e1000)------>vnet1----->br1(192.168.100.20)
> >
> >  I am sending ARP packet from br0 using PackETH tool destined to br1.
> >  I have  edited the dpdk l2fwd code in such a way that , the destination
> is broadcast address(ffff).
> >  In br1 , i can see the arp resquest, but the host bridge is not
> responding for the arp request.
> >
> >  In br1:
> >  =====
> >  tcpdump: verbose output suppressed, use -v or -vv for full protocol
> decode
> >  listening on br1, link-type EN10MB (Ethernet), capture size 65535 bytes
> >  12:21:15.459667 ARP, Request who-has 192.168.100.20 (00:0a:e7:2c:44:2b
> (oui Unknown)) tell 192.168.100.10, length 46
> >  12:21:15.651610 ARP, Request who-has 192.168.100.20 (00:0a:e7:2c:44:2b
> (oui Unknown)) tell 192.168.100.10, length 46
> >  12:21:15.867692 ARP, Request who-has 192.168.100.20 (00:0a:e7:2c:44:2b
> (oui Unknown)) tell 192.168.100.10, length 46
> >
> >  In l2fwd application example also, the arp packets are getting received
> on the adjacent ports, but the arp reply has not been sent back from br1.
> >
> >  Could you please let me know how to make the host(br1) to reply the arp
> request.
>
> The host kernel has a number of checks to prevent ARP spoofing.
> Most likely your packet is invalid by one of these checks.
> Linux ARP does not keep many statistics, so that doesn't help.
>
> Look at the arp_ignore sysctl flag and read kernel source for
> net/ipv4/arp.c function
> arp_process to see what is going on. If you are completely stuck build a
> custom
> kernel and instrument kernel with printk's there.
>



-- 
Rgds,
Nishant