topic Re: source ip in arp who-has request not valid in Switches, Hubs, and Modems

source ip in arp who-has request not valid

psa14 — Wed, 01 Jul 2009 08:07:38 GMT

Hi,

my switch is a procurve 2626.
When i want to ping a PC from lan 192.168.10.x to lan 192.168.22.x it works.
But when i want to ping a network equipement
from lan 192.168.10.x to lan 192.168.22.x it doesn't work (Such as switchs, wifi equipement ...).

I have 2 VLANs (vlan 1 and vlan 2)
On the vlan 1, i have 4 subnets :
192.168.1.x, gw 192.168.1.33
192.168.10.x, gw 192.168.10.253
192.168.22.x, gw 192.168.22.254
192.168.21.x, gw 192.168.21.254

Routing is enable

The procurve switch has 4 IPs addresses :
192.168.1.33, 192.168.10.253, 192.168.22.254,
192.168.21.254

I sniff the subnet 192.168.22.x and see that
the arp request looks like :
procurve-mac-> broadcast who-has 192.168.22.33 ? tell 192.168.1.33

I think the problem is from the source in the request. Why the procurve uses 192.168.1.33 as source and not 192.168.22.254 ? Is there a parameter on the switch to modify ?

Thanks

Pascal

Re: source ip in arp who-has request not valid

Pieter 't Hart — Thu, 02 Jul 2009 08:04:50 GMT

this is because the order that adresses are assigned
it will use the primary adress for arp requests, not separate secondary adresses for each matching subnet.

from 2600-2800-4100-6108-MgmtConfigGde:
The switch assigns the first IP address manually configured on a VLAN as the primary IP address. The switch then assigns any subsequent IP addresses (for other subnets) manually configured on the VLAN as secondary
addresses.

Re: source ip in arp who-has request not valid

psa14 — Thu, 02 Jul 2009 11:07:05 GMT

Hi Peter,
thanks for you response,

i fact, i want this switch acts as rounting between 4 physical networks.
I want to route packets from and to the 4 networks in the vlan 1.
1.x<->10.x
1.x<->22.x
1.x<->21.x
10.x<->22.x
21.x<->22.x
10.x<->21.x

The vlan2 exists on the 4 networks, but there are one subnet.

I have made a test ping between subnet 10.x
and subnet 22.x. It works only for pc
equipement and not for other network equipement.

Is it possible with the procurve ?

Thanks

Re: source ip in arp who-has request not valid

Pieter 't Hart — Thu, 02 Jul 2009 11:33:20 GMT

Just beacause it's not separate (sub)interfaces, but secondary adresses on a single interface , I think the 2626 may not route between primary/secondary and between secondary/secondary adresses.

what output does "show ip route" produce?.

Re: source ip in arp who-has request not valid

Eric Plikuhn — Thu, 15 Jul 2010 22:35:12 GMT

I see the same on a number of my Procurve switches:

Switch configuration:
vlan 1
name "Local"
untagged 1-18
ip address 1.2.3.4 255.255.255.0
ip address 10.118.254.254 255.255.0.0

Packet dump:
Who has 10.118.0.47? Tell 1.2.3.4

Unfortunately some equipment will not respond to the ARP request since the address is out of the subnet.

Have you found a solution for this?