On the routing switches, IP addresses are associated with individual VLANs. By default, there is a single VLAN (Default_VLAN) on the routing switch. In that configuration, a single IP address serves as the management access address for the entire device. If routing is enabled on the routing switch, the IP address on the single VLAN also acts as the routing interface.

Each IP address on a routing switch must be in a different subnet. You can have only one VLAN interface in a given subnet. For example, you can configure IP addresses 192.168.1.1/24 and 192.168.2.1/24 on the same routing switch, but you cannot configure 192.168.1.1/24 and 192.168.1.2/24 on the same routing switch.

You can configure multiple IP addresses on the same VLAN.

The number of IP addresses you can configure on an individual VLAN interface is 32.

You can use any of the IP addresses you configure on the routing switch for Telnet, Web management, or SNMP access, as well as for routing.

	NOTE: All HP devices support configuration and display of IP address in classical subnet format (example: 192.168.1.1 255.255.255.0) and Classless Interdomain Routing (CIDR) format (example: 192.168.1.1/24.) You can use either format when configuring IP address information. IP addresses are displayed in classical subnet format only.

The switch supports the RIP IP route exchange protocol.

This protocol provides routes to the IP route table and is disabled by default. For configuration information, see Configuring RIP parameters.

IP global parameters for routing switches lists the IP global parameters and the page where you can find more information about each parameter.

IP global parameters for routing switches

Parameter	Description	Default	See page
Address Resolution Protocol (ARP)	A standard IP mechanism that routers use to learn the MAC address of a device on the network. The router sends the IP address of a device in the ARP request and receives the device's MAC address in an ARP reply.	Enabled	Configuring ARP parameters
ARP age	The amount of time the device keeps a MAC address learned through ARP in the device's ARP cache. The device resets the timer to zero each time the ARP entry is refreshed and removes the entry if the timer reaches the ARP age. (Can be set using the menu interface to be as long as 1440 minutes. Go to Menu > Switch Configuration > IP Config.) See ARP age timer.	Five minutes	N/A
Time to Live (TTL)	The maximum number of routers (hops) through which a packet can pass before being discarded. Each router decreases a packet's TTL by 1 before forwarding the packet. If decreasing the TTL causes the TTL to be 0, the router drops the packet instead of forwarding it.	64 hops	See the chapter "Configuring IP Addressing" in the Management and Configuration Guide.
Directed broadcast forwarding	A directed broadcast is a packet containing all ones (or in some cases, all zeros) in the host portion of the destination IP address. When a router forwards such a broadcast, it sends a copy of the packet out each of its enabled IP interfaces. NOTE: You also can enable or disable this parameter on an individual interface basis. See IP interface parameters — routing switches.	Disabled	Enabling forwarding of directed broadcasts
ICMP Router Discovery Protocol (IRDP)	An IP protocol that a router can use to advertise the IP addresses of its router interfaces to directly attached hosts. You can enable or disable the protocol at the Global CLI Config level. You also can enable or disable IRDP and configure the following protocol parameters on an individual VLAN interface basis at the VLAN Interface CLI Config level. Forwarding method (broadcast or multicast) Hold time Maximum advertisement interval Minimum advertisement interval Router preference level	Disabled	Configuring IRDP Enabling IRDP globally
Static route	An IP route you place in the IP route table.	No entries	Static route types
Default network route	The router uses the default network route if the IP route table does not contain a route to the destination. Enter an explicit default route (0.0.0.0 0.0.0.0 or 0.0.0.0/0) as a static route in the IP route table.	None configured	Configuring the default route

The ARP age is the amount of time the switch keeps a MAC address learned through ARP in the ARP cache. The switch resets the timer to zero each time the ARP entry is refreshed and removes the entry if the timer reaches the ARP age. For more information on ARP, see IP tables and caches.

You can increase the ARP age timeout maximum to 24 hours or more with this command:

Syntax:

HP Switch(config)# ip arp-age 1000

To view the value of ARP age timer, enter the show ip command. The Arp Age time value is shown in bold in The show ip command displaying ARP age.

HP Switch(config)# show ip

 Internet (IP) Service

  IP Routing : Disabled

  Default Gateway : 15.255.120.1
  Default TTL     : 64
  

Arp Age         : 1000
  Domain Suffix   :
  DNS server      :

  VLAN                 | IP Config  IP Address     Subnet Mask      Proxy ARP
  -------------------- + ---------- --------------- --------------- ---------
  DEFAULT_VLAN         | Manual     15.255.111.13  255.255.248.0    No

You can also view the value of the ARP age timer in the configuration file. The ip arp-age 1000 value is shown in bold in The ip arp-age value in the running config file.

HP Switch(config)# show running-config

Running configuration:

; J9627A Configuration Editor; Created on release #XX.15.XX
; Ver #01:01:00

hostname "Switch"
savepower led
mirror-port 7
stack commander "TEST_STACK"
stack member 1 mac-address 0024A8D13A40


ip arp-age 100
vlan 1
   name "DEFAULT_VLAN"
   untagged 1-28
   ip address dhcp-bootp
   exit
vlan 222
   name "VLAN222"
   no ip address
   exit
snmp-server community "public" unrestricted
snmp-server host 16.181.51.82 community "public"

You can set or display the arp-age value using the menu interface (Menu > Switch Configuration > IP Config).

===========================- TELNET - MANAGER MODE ======================
                  Switch Configuration - Internet (IP) Service

  IP Routing : Disabled

  Default Gateway : 15.255.120.1
  Default TTL     : 64
  

Arp Age         : 1000

  IP Config [Manual] : Manual

  IP Address  : 15.255.111.11
  Subnet Mask : 255.255.248.0

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IP interface parameters — routing switches lists the interface-level IP parameters for routing switches.