NSA 2600 interfaces:
x0 - LAN IP x.x.10.223 x1 - WAN ISP #1 x2 - WAN ISP #2 x3 - WAN ISP #3 and x4 - LAN IP y.y.16.10
x0 - LAN IP x.x.10.223 x1 - WAN ISP #1 x2 - WAN ISP #2 x3 - WAN ISP #3 and x4 - LAN IP y.y.16.10
The main server we are seeing routing issues with is an IBM AS400 with multiple IPs configured through virtual interfaces on its NIC. The IP addresses are on the LAN segments and are as follows: x.x.10.4 x.x.10.6 y.y.16.22
x.x.10.4 x.x.10.6 y.y.16.22
This configuration was setup by a vendor for the AS400 and the y.y.16.0 subnet is for replication to be routed out of the x2 ISP #2x2 ISP #2
interface
Upon plugging in all the interfaces, the ARP table starts filling up with the devices on the LAN segments. y.y.16.22, x.x.10.4 y.y.16.22, x.x.10.4
and x.x.10.6x.x.10.6
do not show up. We have tried adding static ARP entries for them and the pings perform abnormally in that they will respond for a period of time then start dropping off one IP at a time.
Now if we leave the x4 (second LAN interface) unplugged then the x.x.10.4x.x.10.4
and x.x.10.6x.x.10.6
will appear in the ARP entries initially. We have run packet captures and find that ping requests from the Sonicwall NSA 2600 are 'generated' then 'consumed' but sometimes not forwarded.
EDIT # 3: Found out the AS400 is using what is called a Proxy ARP configuration. The physical NIC is used as a console for the system and also acts as a proxy for the virtual interfaces configured inside the AS400. The proxy responds to all ARP requests with the physical MAC address and then handles routing internally to the virtual interfaces. I've attached a drawing to clarify the setup HEREas follows.
Still no headway on what is causing this behavior.