Managing Physical Interface
CHAPTERS
2. Basic Parameters Configurations
3. Port Isolation Configurations
4. Loopback Detection Configuration
6. Appendix: Default Parameters
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This guide applies to: T1500G-8T v2 or above, T1500G-10PS v2 or above, T1500G-10MPS v2 or above, T1500-28PCT v3 or above, T1600G-18TS v2 or above, T1600G-28TS v3 or above, T1600G-28PS v3 or above, T1600G-52TS v3 or above, T1600G-52PS v3 or above, T1700X-16TS v3 or above, T1700G-28TQ v3 or above, T2500G-10TS v2 or above, T2600G-18TS v2 or above, T2600G-28TS v3 or above, T2600G-28MPS v3 or above, T2600G-28SQ v1 or above, T2600G-52TS v3 or above. |
1.1Overview
Interfaces are used to exchange data and interact with interfaces of other network devices. Interfaces are classified into physical interfaces and Layer 3 interfaces.
Physical interfaces are the ports on the switch panel. They forward packets based on MAC address table.
Layer 3 interfaces are used to forward IPv4 and IPv6 packets using static or dynamic routing protocols. You can use Layer 3 interfaces for IP routing and inter-VLAN routing.
This chapter introduces the configurations for physical interfaces.
1.2Supported Features
The switch supports the following features about physical interfaces:
Basic Parameters
You can configure port status, speed mode, duplex mode, flow control and other basic parameters for ports.
Port Isolation
You can use this feature to restrict a specific port to send packets to only the ports in the forwarding port list that you configure.
Loopback Detection
This function allows the switch to detect loops in the network. When a loop is detected on a port or VLAN, the switch will display an alert on the management interface and block the corresponding port or VLAN according to your configurations.
2Basic Parameters Configurations
2.1Using the GUI
Choose the menu L2 FEATURES > Switching > Port > Port Config to load the following page.
Figure 2-1 Configuring Basic Parameters
Follow these steps to configure basic parameters for the ports:
1)Configure the MTU size of jumbo frames for all the ports, then click Apply.
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Jumbo |
Configure the size of jumbo frames. By default, it is 1518 bytes. Generally, the MTU (Maximum Transmission Unit) size of a normal frame is 1518 bytes. If you want the switch supports to transmit frames of which the MTU size is greater than 1518 bytes, you can configure the MTU size manually here. |
2)Select one or more ports to configure the basic parameters. Then click Apply.
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UNIT/LAGS |
Click the UNIT number to configure physical ports. Click LAGS to configure LAGs. |
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Type |
Displays the port type. Copper indicates an Ethernet port, and Fiber indicates an SFP port. |
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Description |
(Optional) Enter a description for the port. |
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Status |
With this option enabled, the port forwards packets normally. Otherwise, the port cannot work. By default, it is enabled. |
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Speed |
Select the appropriate speed mode for the port. When Auto is selected, the port automatically negotiates speed mode with the neighbor device. The default setting is Auto. It is recommended to select Auto if both ends of the link support auto-negotiation. |
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Duplex |
Select the appropriate duplex mode for the port. There are three options: Half, Full and Auto. The default setting is Auto. Half: The port can send and receive packets, but only one-way at a time. Full: The port can send and receive packets simultaneously. Auto: The port automatically negotiates duplex mode with the peer device. |
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Flow Control |
With this option enabled, when a device gets overloaded it will send a PAUSE frame to notify the peer device to stop sending data for a specified period of time, thus avoiding the packet loss caused by congestion. By default, it is disabled. |
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Note: We recommend that you set the ports on both ends of a link as the same speed and duplex mode. |
2.2Using the CLI
Follow these steps to set basic parameters for the ports.
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Step 1 |
configure Enter global configuration mode. |
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Step 2 |
jumbo-size size Change the MTU (Maximum Transmission Unit) size to support jumbo frames. The default MTU size for frames received and sent on all ports is 1518 bytes. To transmit jumbo frames, you can manually configure MTU size of frames up to 9216 bytes. size: Configure the MTU size of jumbo frames. The value ranges from 1518 to 9216bytes. |
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Step 3 |
interface { fastEthernet port | range fastEthernet port-list | gigabitEthernet port | range gigabitEthernet port-list | ten-gigabitEthernet port | ten-range gigabitEthernet port-list | port-channel port-channel | range port-channel port-channel-list |} Enter interface configuration mode. |
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Step 4 |
Configure basic parameters for the port: description string Give a port description for identification. string: Content of a port description, ranging from 1 to 16 characters. shutdown no shutdown Use shutdown to disable the port, and use no shutdown to enable the port. When the status is enabled, the port can forward packets normally, otherwise it will discard the received packets. By default, all ports are enabled. speed { 10 | 100 | 1000 | 10000 | auto } Set the appropriate speed mode for the port. 10 | 100 | 1000 | 10000 | auto: Speed mode of the port. The options are subject to your actual product. The device connected to the port should be in the same speed and duplex mode with the port. When auto is selected, the speed mode will be determined by auto-negotiation. duplex { auto | full | half } Set the appropriate duplex mode for the port. auto | full | half: Duplex mode of the port. The device connected to the port should be in the same speed and duplex mode with the port. When auto is selected, the duplex mode will be determined by auto-negotiation. flow-control Enable the switch to synchronize the data transmission speed with the peer device, avoiding the packet loss caused by congestion. By default, it is disabled. |
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Step 5 |
show interface configuration [ fastEthernet port | gigabitEthernet port | | ten-gigabitEthernet port | port-channel port-channel-id ] Verify the configuration of the port or LAG. |
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Step 6 |
end Return to privileged EXEC mode. |
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Step 7 |
copy running-config startup-config Save the settings in the configuration file. |
The following example shows how to implement the basic configurations of port1/0/1, including setting a description for the port, configuring the jumbo frame, making the port automatically negotiate speed and duplex with the neighboring port, and enabling the flow-control:
Switch#configure
Switch#jumbo-size 9216
Switch(config)#interface gigabitEthernet 1/0/1
Switch(config-if)#no shutdown
Switch(config-if)#description router connection
Switch(config-if)#speed auto
Switch(config-if)#duplex auto
Switch(config-if)#flow-control
Switch(config-if)#show interface configuration gigabitEthernet 1/0/1
Port State Speed Duplex FlowCtrl Description
-------- ----- -------- ------ -------- -----------
Gi1/0/1 Enable Auto Auto Enable router connection
Switch(config-if)#show jumbo-size
Global jumbo size : 9216
Switch(config-if)#end
Switch#copy running-config startup-config
3Port Isolation Configurations
3.1Using the GUI
Port Isolation is used to limit the data transmitted by a port. The isolated port can only send packets to the ports specified in its forwarding Port list.
Choose the menu L2 FEATURES > Switching > Port > Port Isolation to load the following page.
Figure 3-1 Port Isolation List
The above page displays the port isolation list. Click 
to configure Port Isolation on the following page.
Figure 3-2 Port Isolation
Follow these steps to configure Port Isolation:
1)In the Port section, select one or multiple ports to be isolated.
2)In the Forwarding Port List section, select the forwarding ports or LAGs which the isolated ports can only communicate with. It is multi-optional.
3)Click Apply.
3.2Using the CLI
Follow these steps to configure Port Isolation:
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Step 1 |
configure Enter global configuration mode. |
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Step 2 |
interface { fastEthernet port | range fastEthernet port-list | gigabitEthernet port | range gigabitEthernet port-list | ten-gigabitEthernet port | ten-range gigabitEthernet port-list | port-channel port-channel | range port-channel port-channel-list |} Specify the port to be isolated and enter interface configuration mode. |
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Step 3 |
port isolation { [fa-forward-list fa-forward-list] [gi-forward-list gi-forward-list] [te-forward-list te-forward-list] [ po-forward-list po-forward-list ] } Add ports or LAGs to the forwarding port list of the isolated port. It is multi-optional. fa-forward-list / gi-forward-list / te-forward-list: Specify the forwarding Ethernet ports. po-forward-list: Specify the forwarding LAGs. |
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Step 4 |
show port isolation interface { fastEthernet port | gigabitEthernet port | ten-gigabitEthernet port | port-channel port-channel } Verify the Port Isolation configuration of the specified port. |
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Step 5 |
end Return to privileged EXEC mode. |
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Step 6 |
copy running-config startup-config Save the settings in the configuration file. |
The following example shows how to add ports 1/0/1-3 and LAG 4 to the forwarding list of port 1/0/5:
Switch#configure
Switch(config)#interface gigabitEthernet 1/0/5
Switch(config-if)#port isolation gi-forward-list 1/0/1-3 po-forward-list 4
Switch(config-if)#show port isolation interface gigabitEthernet 1/0/5
Port LAG Forward-List
---- --- -----------------------
Gi1/0/5 N/A Gi1/0/1-3,Po4
Switch(config-if)#end
Switch#copy running-config startup-config
4Loopback Detection Configuration
4.1Using the GUI
To avoid broadcast storm, we recommend that you enable storm control before loopback detection is enabled. To get detailed introductions about storm control, refer to Configuring QoS_T1500&T1500G&T1600G (for T1500G-10PS v2, T1500G-8T v2, T1500G-10MPS v2, T1500-28PCT v3, T1600G-18TS v2, T1600G-28TS v3, T1600G-28PS v3, T1600G-52TS v4, T1600G-52PS v4) series switches; refer to Configuring QoS_T2600G&T1600G-52TS v3&T1600G_52PS v3 (for T1600G-52TS v3, T1600G-52PS v3, T2600G-28TS v3, T2600G-52ST v3, T2600G-28MPS v3, T2600G-28SQ v1).
Choose the menu L2 FEATURES > Switching > Port > Loopback Detection to load the following page.
Figure 4-1 Configuring Loopback Detection
Follow these steps to configure loopback detection:
1)In the Loopback Detection section, enable loopback detection and configure the global parameters. Then click Apply.
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Loopback Detection Status |
Enable loopback detection globally. |
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Detection Interval |
Set the interval of sending loopback detection packets in seconds. The valid value ranges from 1 to 1000 and the default value is 30. |
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Auto-recovery Time |
Set the recovery time globally. The blocked port in Auto Recovery mode will automatically be recovered to normal status after the Auto-recovery Time expires. The value ranges from 2 to 100,000 in seconds, and the default value is 90. |
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Web Refresh Status |
With this option enabled, the switch will refresh the web timely. By default, it is disabled. |
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Web Refresh Interval |
If you enabled web refresh status, set the refresh interval in seconds between 3 and 100. The default value is 6. |
2)In the Port Config section, select one or more ports to configure the loopback detection parameters. Then click Apply.
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Status |
Enable loopback detection for the port. |
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Operation Mode |
Select the operation mode when a loopback is detected on the port: Alert: The Loop Status will display whether there is a loop detected on the corresponding port. It is the default setting. Port Based: In addition to displaying alerts, the switch will block the port on which the loop is detected. VLAN-Based: If a loop is detected in a VLAN on that port, in addition to displaying alerts, the switch will block that VLAN. The traffic of the other VLANs can still be normally forwarded by the port. |
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Recovery Mode |
If you select Port Based or VLAN-Based as the operation mode, you also need to configure the recovery mode for the blocked port: Auto: The blocked port will automatically be recovered to normal status after the automatic recovery time expires. It is the default setting. Manual: You need to manually release the blocked port. Click Recovery to release the selected port. |
3)(Optional) View the loopback detection information.
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Loop Status |
Displays whether a loop is detected on the port. |
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Block Status |
Displays whether the port is blocked. |
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Block VLAN |
Displays the blocked VLANs. |
4.2Using the CLI
Follow these steps to configure loopback detection:
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Step 1 |
configure Enter global configuration mode. |
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Step 2 |
loopback-detection Enable the loopback detection feature globally. By default, it is disabled. |
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Step 3 |
loopback-detection interval interval-time Set the interval of sending loopback detection packets which is used to detect the loops in the network. interval-time: The interval of sending loopback detection packets. The valid values are from 1 to 1000 seconds. By default, the value is 30 seconds. |
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Step 4 |
loopback-detection recovery-time recovery-time Set the auto-recovery time, after which the blocked port in Auto Recovery mode can automatically be recovered to normal status. recovery-time: Specify the detection interval, ranging from 2 to 100,000 seconds. The default value is 90. |
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Step 5 |
interface { fastEthernet port | range fastEthernet port-list | gigabitEthernet port | range gigabitEthernet port-list | ten-gigabitEthernet port | ten-range gigabitEthernet port-list | port-channel port-channel | range port-channel port-channel-list |} Enter interface configuration mode. |
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Step 6 |
loopback-detection Enable loopback detection for the port. By default, it is disabled. |
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Step 7 |
loopback-detection config process-mode { alert | port-based | vlan-based } recovery-mode { auto | manual } Set the process mode when a loopback is detected on the port. There are three modes: alert: The switch will only display alerts when a loopback is detected. It is the default setting. port-based: In addition to displaying alerts, the switch will block the port on which the loop is detected. vlan-based: In addition to displaying alerts, the switch will block the VLAN of the port in which the loop is detected. Set the recovery mode for the blocked port. There are two modes: auto: After the recovery time expires, the blocked port will automatically recover to normal status and restart to detect loops in the network. manual: The blocked port can only be released manually. You can use the command ‘loopback-detection recover’ to recover the blocked port to normal status. |
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Step 9 |
show loopback-detection global Verify the global configuration of Loopback Detection. |
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Step 10 |
show loopback-detection interface { fastEthernet port | gigabitEthernet port | ten-gigabitEthernet port | port-channel port-channel } Verify the Loopback Detection configuration of the specified port. |
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Step 11 |
end Return to privileged EXEC mode. |
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Step 12 |
copy running-config startup-config Save the settings in the configuration file. |
The following example shows how to enable loopback detection globally (keep the default parameters):
Switch#configure
Switch(config)#loopback-detection
Switch(config)#show loopback-detection global
Loopback detection global status : enable
Loopback detection interval : 30s
Loopback detection recovery time : 3 intervals
Switch(config-if)#end
Switch#copy running-config startup-config
The following example shows how to enable loopback detection of port 1/0/3 and set the process mode as alert and recovery mode as auto:
Switch#configure
Switch(config)#interface gigabitEthernet 1/0/3
Switch(config-if)#loopback-detection
Switch(config-if)#loopback-detection config process-mode alert recovery-mode auto
Switch(config-if)#show loopback-detection interface gigabitEthernet 1/0/3
Port Enable Process Mode Recovery Mode Loopback Block LAG
---- ------ ------------ ------------- -------- ----- ----
Gi1/0/3 enable alert auto N/A N/A N/A
Switch(config-if)#end
Switch#copy running-config startup-config
5.1Example for Port Isolation
5.1.1Network Requirements
As shown below, three hosts and a server are connected to the switch and all belong to VLAN 10. Without changing the VLAN configuration, Host A is not allowed to communicate with the other hosts except the server, even if the MAC address or IP address of Host A is changed.
Figure 5-1 Network Topology
5.1.2Configuration Scheme
You can configure port isolation to implement the requirement. Set port 1/0/4 as the only forwarding port for port 1/0/1, thus forbidding Host A to forward packets to the other hosts.
Since communications are bidirectional, if you want Host A and the server to communicate normally, you also need to add port 1/0/1 as the forwarding port for port 1/0/4.
Demonstrated with T2600G-28TS, the following sections provide configuration procedure in two ways: using the GUI and using the CLI.
5.1.3Using the GUI
1)Choose the menu L2 FEATURES > Switching > Port > Port Isolation to load the following page. It displays the port isolation list.
Figure 5-2 Port Isolation List
2)Click Edit on the above page to load the following page. Select port 1/0/1 as the port to be isolated, and select port 1/0/4 as the forwarding port. Click Apply.
Figure 5-3 Port Isolation Configuration
3)Select port 1/0/4 as the port to be isolated, and select port 1/0/1 as the forwarding port. Click Apply.
Figure 5-4 Port Isolation Configuration
4)Click 
to save the settings.
5.1.4Using the CLI
Switch#configure
Switch(config)#interface gigabitEthernet 1/0/1
Switch(config-if)#port isolation gi-forward-list 1/0/4
Switch(config-if)#exit
Switch(config)#interface gigabitEthernet 1/0/4
Switch(config-if)#port isolation gi-forward-list 1/0/1
Switch(config-if)#end
Switch#copy running-config startup-config
Verify the Configuration
Switch#show port isolation interface
Port LAG Forward-List
---- --- ------------
Gi1/0/1 N/A Gi1/0/4
Gi1/0/2 N/A Gi1/0/1-28,Po1-14
Gi1/0/3 N/A Gi1/0/1-28,Po1-14
Gi1/0/4 N/A Gi1/0/1
...
5.2Example for Loopback Detection
5.2.1Network Requirements
As shown below, Switch A is a convergence-layer switch connecting to several access-layer switches. Loops can be easily caused in case of misoperation on the access-layer switches. If there is a loop on an access-layer switch, broadcast storms will occur on Switch A or even in the entire network, creating excessive traffic and degrading the network performance.
To reduce the impacts of broadcast storms, users need to detect loops in the network via Switch A and timely block the port on which a loop is detected.
Figure 5-5 Network Topology
5.2.2Configuration Scheme
Enable loopback detection on ports 1/0/1-3 and configure SNMP to receive the trap notifications. For detailed instructions about SNMP, refer to Configuring SNMP & RMON. Here we introduce how to configure loopback detection and monitor the detection result on the management interface of the switch.
Demonstrated with T2600G-28TS, the following sections provide configuration procedure in two ways: using the GUI and using the CLI.
5.2.3Using the GUI
1)Choose the menu L2 FEATURES > Switching > Port > Loopback Detection to load the configuration page.
2)In the Loopback Detection section, enable loopback detection and web refresh globally. Keep the other parameters as default values and click Apply.
Figure 5-6 Global Configuration
3)In the Port Config section, enable ports 1/0/1-3, select the operation mode as Port -Based so that the port will be blocked when a loop is detected, and keep the recovery mode as Auto so that the port will automatically be recovered to normal status after the auto-recovery time. Click Apply.
Figure 5-7 Port Configuration
4)Monitor the detection result on the above page. The Loop status and Block status are displayed on the right side of ports.
5.2.4Using the CLI
1)Enable loopback detection globally and configure the detection interval and recovery time.
Switch#configure
Switch(config)#loopback-detection
Switch(config)#loopback-detection interval 30
Switch(config)#loopback-detection recovery-time 3
2)Enable loopback detection on ports 1/0/1-3 and set the process mode and recovery mode.
Switch(config)#interface range gigabitEthernet 1/0/1-3
Switch(config-if-range)#loopback-detection
Switch(config-if-range)#loopback-detection config process-mode port-based recovery-mode auto
Switch(config-if-range)#end
Switch#copy running-config startup-config
Verify the Configuration
Verify the global configuration:
Switch#show loopback-detection global
Loopback detection global status : enable
Loopback detection interval: 30 s
Loopback detection recovery time : 90 s
Verify the loopback detection configuration on ports:
Switch#show loopback-detection interface
Port Enable Process Mode Recovery Mode Loopback Block LAG
---- -------- ----------------- ------------ ------------ -- ---- -----
Gi1/0/1 enable port-based auto N/A N/A N/A
Gi1/0/2 enable port-based auto N/A N/A N/A
Gi1/0/3 enable port-based auto N/A N/A N/A
Default settings of ports are listed in th following tables.
Table 6-1Default Parameters for Switching
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Parameter |
Default Setting |
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Port Config |
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Jumbo |
1518 bytes |
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Type |
Copper (For RJ45 Ports) Fiber (For SFP Ports) |
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Status |
Enabled |
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Speed |
Auto (For RJ45 Ports) 1000M (For SFP Ports) |
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Duplex |
Auto (For RJ45 Ports) Full (For SFP Ports) |
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Flow Control |
Disabled |
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Loopback Detection |
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Loopback Detection Status |
Disabled |
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Detection Interval |
30 seconds |
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Auto-recovery Time |
90 seconds |
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Web Refresh Status |
Disabled |
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Web Refresh Interval |
6 seconds |
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Port Status |
Disable |
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Operation mode |
Alert |
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Recovery mode |
Auto |