IPv4 Management and Interfaces
IP interface addresses can be configured manually by the user, or automatically configured by a DHCP server. This section provides information for defining the device IP addresses, either manually or by making the device a DHCP client. This section covers the IPv4 management and interfaces.
IPv4 Interface
IPv4 interface addresses can be configured manually by the user, or automatically configured by a DHCP server. This section provides information for defining the device IPv4 addresses, either manually or by making the device a DHCP client. The IPv4 Interface page is used to configure IP addresses for device management. This IP address can be configured on a port, a LAG, VLAN, loopback interface or out-of-band interface. You can configure multiple IP addresses (interfaces) on the device. It then supports traffic routing between these various interfaces and also to remote networks. By default and typically, the routing functionality is performed by the hardware. If hardware resources are exhausted or there’s a routing table overflow in the hardware, IP routing is performed by the software.
Note |
The device software consumes one VLAN ID (VID) for every IP address configured on a port or LAG. The device takes the first VID that isn’t used starting from 4094. |
To configure the IPv4 addresses, follow these steps:
Procedure
Step 1 |
Click IP Configuration >IPv4 Management and Interfaces > IPv4 Interface. Enter the following fields:
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Step 2 |
Click Apply. The parameter is saved to the Running Configuration file. The following fields are displayed in the IPv4 Interface Table:
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Step 3 |
Click Add. |
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Step 4 |
Select the Interface: Select the port, LAG, VLAN or loopback as the interface associated with this IP configuration, and select an interface from the list. select an interface from the associated list. |
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Step 5 |
Select the IP Address Type: Select one of the following options:
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Step 6 |
Click Apply. The IPv4 address settings are written to the Running Configuration file.
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IPv4 Static Routes
This page enables configuring and viewing IPv4 static routes on the device. When routing traffic, the next hop is decided on according to the longest prefix match (LPM algorithm). A destination IPv4 address may match multiple routes in the IPv4 Static Route Table. The device uses the matched route with the highest subnet mask, that is, the longest prefix match. If more than one default gateway is defined with the same metric value, the lowest IPv4 address from among all the configured default gateways is used.
To define an IP static route, follow these steps:
Procedure
Step 1 |
Click IP Configuration > IPv4 Management and Interfaces > IPv4 Static Routes. The IPv4 Static Routes Table is displayed. The following fields are displayed for each entry:
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Step 2 |
Click Add. |
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Step 3 |
Enter values for the following fields:
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Step 4 |
Click Apply. The IP Static route is saved to the Running Configuration file. |
IPv4 Forwarding Table
To view the IPv4 Forwarding Table, follow these steps:
Procedure
Step 1 |
Click IP Configuration > IPv4 Management and Interfaces >IPv4 Forwarding Table. The IPv4 Forwarding Table is displayed. The following fields are displayed for each entry:
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Step 2 |
Click the Refresh icon to refresh the data. |
ARP
The device maintains an ARP (Address Resolution Protocol) table for all known devices that reside in the IP subnets directly connected to it. A directly connected IP subnet is the subnet to which an IPv4 interface of the device is connected. When the device is required to send/route a packet to a local device, it searches the ARP table to obtain the MAC address of the device. The ARP table contains both static and dynamic addresses. Static addresses are manually configured and don’t age out. The device creates dynamic addresses from the ARP packets it receives. Dynamic addresses age out after a configured time.
Note |
The mapping information is used for routing and to forward generated traffic. |
To define the ARP tables, complete the following steps:
Procedure
Step 1 |
Click IP Configuration > IPv4 Management and Interfaces > ARP. |
Step 2 |
Enter the parameters.
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Step 3 |
Click Apply. The ARP global settings are written to the Running Configuration file. The ARP table displays the following fields:
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Step 4 |
Click Add. |
Step 5 |
Enter the parameters:
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Step 6 |
Click Apply. The ARP entry is saved to the Running Configuration file. |
ARP Proxy
The Proxy ARP technique is used by the device on a given IP subnet to answer ARP queries for a network address that isn’t on that network.
Note |
The ARP proxy feature is only available when the device is in L3 mode. |
The ARP Proxy is aware of the destination of traffic, and offers another MAC address in reply. Serving as an ARP Proxy for another host effectively directs LAN traffic destination to the host. The captured traffic is then typically routed by the Proxy to the intended destination by using another interface, or by using a tunnel. The process in which an ARP-query-request for a different IP address, for proxy purposes, results in the node responding with its own MAC address is sometimes referred to as publishing.
To enable ARP Proxy on all IP interfaces, complete the following steps:
Procedure
Step 1 |
Click IP Configuration> IPv4 Management and Interfaces >ARP Proxy. |
Step 2 |
Select ARP Proxy to enable the device to respond to ARP requests for remotely-located nodes with the device MAC address. |
Step 3 |
Click Apply. The ARP proxy is enabled, and the Running Configuration file is updated. |
UDP Relay/IP Helper
Switches don’t typically route IP Broadcast packets between IP subnets. However, this feature enables the device to relay specific UDP Broadcast packets, received from its IPv4 interfaces, to specific destination IP addresses.
To configure the relaying of UDP packets received from a specific IPv4 interface with a specific destination UDP port, add a UDP Relay:
Procedure
Step 1 |
Click IP Configuration > IPv4 Management and Interfaces > UDP Relay/IP Helper. |
Step 2 |
Click Add. |
Step 3 |
Select the Source IP Interface to where the device is to relay UDP Broadcast packets based on a configured UDP destination port. The interface must be one of the IPv4 interfaces configured on the device. |
Step 4 |
Enter the UDP Destination Port number for the packets that the device is to relay. Select a well-known port from the drop-down list, or click the port radio button to enter the number manually. |
Step 5 |
Enter the Destination IP Address that receives the UDP packet relays. If this field is 0.0.0.0, UDP packets are discarded. If this field is 255.255.255.255, UDP packets are flooded to all IP interfaces. |
Step 6 |
Click Apply. The UDP relay settings are written to the Running Configuration file. |
DHCP Relay
This section covers Dynamic Host Configuration Protocol (DHCP)Relay. A DHCP relay agent is any host that forwards DHCP packets between clients and servers. Relay agents are used to forward requests and replies between clients and servers when they are not on the same physical subnet. Relay agent forwarding is distinct from the normal forwarding of an IP router, where IP datagrams are switched between networks somewhat transparently. By contrast, relay agents receive DHCP messages and then generate a new DHCP message to send on another interface.
Properties
DHCP Relay transfers DHCP packets to the DHCP server. The device can transfer DHCP messages received from VLANs that do not have IP addresses. Whenever DHCP Relay is enabled on a VLAN without an IP address, Option 82 is inserted automatically.
TO set the DHCP Snooping/Relay properties, complete the followin steps:
Procedure
Step 1 |
Click IP Configuration > IPv4 Management and Interfaces > DHCP Relay > Properties. |
Step 2 |
Configure the following fields:
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Step 3 |
Click Apply. The settings are written to the Running Configuration file. |
Step 4 |
To define a DHCP server, click Add. The Add DHCP Server dialog appears, with the IP version indicated. |
Step 5 |
Enter the IP address of the DHCP server and click Apply. The settings are written to the Running Configuration file. |
Interface Settings
DHCP Relay can be enabled on any interface or VLAN. For DHCP relay to be functional, an IP address must be configured on the VLAN or interface.
DHCP Relay relays DHCP packets to the DHCP server. The device can relay DHCP messages received from VLANs that do not have IP addresses. Whenever DHCP Relay is enabled on a VLAN without an IP address, Option 82 is inserted automatically. This insertion is in the specific VLAN and does not influence the global administration state of Option 82 insertion.
DHCP snooping provides a security mechanism to prevent receiving false DHCP response packets and to log DHCP addresses. It does this by treating ports on the device as either trusted or untrusted. A trusted port is a port that is connected to a DHCP server and is allowed to assign DHCP addresses. DHCP messages received on trusted ports are allowed to pass through the device. An untrusted port is a port that is not allowed to assign DHCP addresses. By default, all ports are considered untrusted until you declare them trusted (in the Interface Settings page).
To enable DHCP Snooping/Relay on specific interfaces, follow these steps:
Procedure
Step 1 |
Click IP Configuration > IPv4 Management and Interfaces > DHCP Relay > Interface Settings. |
Step 2 |
To enable DHCP Relay on an interface, click ADD. |
Step 3 |
Select DHCP Relay to enable. |
Step 4 |
Click Apply. The settings are written to the Running Configuration file. |