Re: [vpp-dev] Static ARP Flag Question

[John Lo (loj)]

Hi Jon,

This is not the right behavior.  I think it is caused by reuse of a static ARP 
entry in  the IP4 neighbor pool with static bit still set.  The code merely set 
the dynamic bit in the flags but left the static bit untouched (similarly for 
the static path) in arp.c function vnet_arp_set_ip4_over_ethernet_internal ():

  e->time_last_updated = vlib_time_now (vm);
  if (is_static)
    e->flags |= ETHERNET_ARP_IP4_ENTRY_FLAG_STATIC;
  else
    e->flags |= ETHERNET_ARP_IP4_ENTRY_FLAG_DYNAMIC;

I spotted another error in the function 
vnet_arp_flush_ip4_over_ethernet_internal()

     if (e->flags & ETHERNET_ARP_IP4_ENTRY_FLAG_STATIC)
        {
          e->flags &= ETHERNET_ARP_IP4_ENTRY_FLAG_DYNAMIC;
        }
      else if (e->flags & ETHERNET_ARP_IP4_ENTRY_FLAG_DYNAMIC)
        {
          arp_entry_free (eai, e);
        }

I believe the “if static” path should be:
          e->flags &= ~ETHERNET_ARP_IP4_ENTRY_FLAG_DYNAMIC;

Would you like to submit a patch to fix them?

Regards,
John

From: vpp-dev@lists.fd.io <vpp-dev@lists.fd.io> On Behalf Of Jon Loeliger
Sent: Wednesday, May 09, 2018 2:04 PM
To: vpp-dev <vpp-dev@lists.fd.io>
Subject: [vpp-dev] Static ARP Flag Question

VPP-ers,

Is this expected behavior for the Flags here?

Thanks,
jdl


vpp# set int ip address TenGigabitEthernet6/0/0 
10.10.20.1/24<http://10.10.20.1/24>
vpp# set interface state TenGigabitEthernet6/0/0 up
vpp# set ip arp TenGigabitEthernet6/0/0 10.10.20.100 08:00:27:41:a7:56 static

vpp# show ip arp
    Time           IP4       Flags      Ethernet              Interface
     53.7857  10.10.20.100     S    08:00:27:41:a7:56 TenGigabitEthernet6/0/0

vpp# set ip arp del TenGigabitEthernet6/0/0 10.10.20.100 08:00:27:41:a7:56 
static
vpp# show ip arp
vpp# set ip arp TenGigabitEthernet6/0/0 10.10.20.100 08:00:27:41:a7:56

vpp# show ip arp
    Time           IP4       Flags      Ethernet              Interface
     90.9054  10.10.20.100    SD    08:00:27:41:a7:56 TenGigabitEthernet6/0/0