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This chapter provides configuration information and command-line interface (CLI) commands for the Catalyst 4912G switch. This chapter contains these sections:
The following sections describe specific configuration guidelines and command-line interface commands that you can use to configure the Gigabit ports.
The Gigabit Ethernet ports have the same default settings as the Ethernet and Fast Ethernet ports, except for the following:
The following sections describe the software configuration features on the Catalyst 4912G switch.
The following is an overview of the features supported on the Catalyst 4912G switch:
 | Caution Autonegotiation with Gigabit Ethernet is different than autonegotiation with Ethernet or Fast Ethernet. To avoid link configuration problems, you should read and understand the set port negotiation command description in the "set port negotiation" section and the set port flowcontrol command description in the "set port flowcontrol" section. |
These features are not supported on the Catalyst 4912G switch:
These commands are not supported on the Gigabit ports:
This section lists the Catalyst 4912G switch CLI commands, introduced in software release 4.1, that support 1000BaseX switching.
Ports can be characterized by their ability to generate and respond to flow-control frames (pause frames) as well as the pause behavior they require of their link partner.
Gigabit ports respond to received pause frames. Upon configuration, these ports advertise a pause capability. The ports at the two ends of the link negotiate a mutually acceptable flow-control configuration.
A pause frame is never generated by the Gigabit ports.
In all cases, pause frames received on the Gigabit ports are processed internally and are not switched through the system.
Enter the set port flowcontrol command to set the receive flow-control value for a particular port:
set port flowcontrol {receive | send} [mod_num/port_num] {off | on | desired}
The default for receive is off, the default for send is desired, and the user-selected values are off, on, or desired.
Perform one or more of these tasks to administer flow control:
| Task | Command |
|---|---|
Tell a local port to advertise that it will send flow-control frames1. | set port flowcontrol send mod_num/port_num on |
Tell a local port to advertise that it will send flow-control frames if the attached device elects to receive them. | set port flowcontrol send mod_num/port_num desired |
Tell a local port to advertise that it will never send flow-control frames. | set port flowcontrol send mod_num/port_num off |
Allow a local port to operate with an attached device that is required to send flow-control packets, or with an attached device that is not required to but may send flow-control packets. | set port flowcontrol receive mod_num/port_num on |
Same as task description for set port flowcontrol receive mod_num/port_num on. | set port flowcontrol receive mod_num/port_num desired |
Tell a local port to discard received flow-control frames without processing them. If negotiation is enabled, the local port advertises that it refuses to accept flow-control frames. If negotiation is enabled, this can cause the attached device not to send flow-control frames, or if the attached device is configured to send flow-control frames unconditionally, it can prevent the link from coming up. | set port flowcontrol receive mod_num/port_num off |
After entering this command, you see these displays:
Console> (enable) set port flowcontrol send 2/5 on Port 2/5 flow control send administration status set to on (port will send flowcontrol to far end) Console> (enable) Console> (enable) set port flowcontrol send 2/5 desired Port 2/5 flow control send administration status set to desired (port will send flowcontrol to far end if far end supports it) Console> (enable) Console> (enable) set port flowcontrol send 2/5 off Port 2/5 flow control send administration status set to off (port will not send flowcontrol to far end) Console> (enable) Console> (enable) set port flowcontrol receive 2/5 on Port 2/5 flow control receive administration status set to on (port will require far end to send flowcontrol) Console> (enable) Console> (enable) set port flowcontrol receive 2/5 desired Port 2/5 flow control receive administration status set to desired (port will allow far end to send flowcontrol if far end supports it) Console> (enable) Console> (enable) set port flowcontrol receive 2/5 off Port 2/5 flow control receive administration status set to off (port will not allow far end to send flowcontrol) Console> (enable)
To display the current flow-control status and statistics, perform this task:
| Task | Command |
|---|---|
Display the current flow-control status and statistics. | show port flowcontrol |
After entering this command, you see this display:
Console> (enable) show port flowcontrol
Port Send FlowControl Receive FlowControl RxPause TxPause Unsupported
admin oper admin oper opcodes
----- -------- -------- -------- -------- ------- ------- -----------
2/1 desired off off off 0 0 0
2/2 desired off off off 0 0 0
2/3 desired off off off 0 0 0
.
.
Console> (enable)
The output field descriptions are described in Table 6-1.
| Field | Description |
|---|---|
Port | Module and port number. |
Send-Flowcontrol- | Flow-control administrative state. Possible settings: on indicates the local port sends flow control to the far end; off indicates the local port does not send flow control to the far end; desired indicates the local end sends flow control to the far end if the far end supports it. |
Send-Flowcontrol- | Flow-control operation. Possible indications: disagree indicates the two ports could not agree on a link protocol. |
Receive-Flowcntl- | Flow-control administrative state. Possible settings: on indicates the local port requires the far end to send flow control; off indicates the local port does not allow the far end to send flow control; desired indicates the local end allows the far end to send flow control. |
Receive-Flowcntl- | Flow-control operation. Possible indications: disagree indicates the two ports could not agree on a link protocol. |
RxPause | Count of pause frames received. |
TxPause | Count of pause frames transmitted. |
Unsupported opcodes | Count of pause frames with unsupported opcodes. These frames have a valid destination address (01:80:c2:00:00:01) and a valid Ethernet type (0x8808) but an invalid opcode. Pause frames with an opcode of 1 (Xoff) are recognized; all others are unsupported. All frames received at this multicast address are discarded by the bridge. |
| Caution Autonegotiation with Gigabit Ethernet is different than autonegotiation with Ethernet or Fast Ethernet. To avoid link configuration problems, you should read and understand this section and the "set port flowcontrol" section. |
Unlike 10/100 ports, autonegotiation with Gigabit Ethernet does not involve negotiating port speed. You cannot disable autonegotiation by setting the port speed and duplex state. In Gigabit Ethernet, the link negotiation protocol is used to exchange flow-control behavior, remote fault information, and duplex information (even though the Catalyst 4912G Gigabit ports only support full-duplex operation). In Gigabit Ethernet, the only way to control whether the link negotiation protocol runs is with the set port negotiation command.
Table 6-2 shows the four possible autonegotiation configurations for a link and the resulting link status for each configuration.
| Autonegotiation State | Link Status | ||
|---|---|---|---|
| Near End1 | Far End2 | Near End | Far End |
Off | Off | Up | Up |
Off | On | Up | Down |
On | Off | Down | Up |
On | On | Up | Up |
| 1Near end refers to the switch's front panel port. 2Far end refers to the remote port at the other end of the Gigabit link. |
Both ends of the link must have the same setting. The link will not come up if the two ends of the link are set inconsistently (for example, link negotiation enabled on one end and disabled on the other).
The default is link negotiation protocol enabled. To enable or disable the link negotiation protocol on the specified port, perform this task:
| Task | Command |
|---|---|
Enable or disable link negotiation protocol. | set port negotiation mod_num/port_num {enable | disable} |
After entering this command, you see this display:
Console> (enable) set port negotiation 2/5 disable Port 2/5 negotiation disabled. Console> (enable)
The default is link negotiation protocol enabled. To display the link negotiation protocol setting for the specified port, perform this task:
| Task | Command |
|---|---|
Display the link negotiation protocol setting. | show port negotiation [mod_num/port_num] |
After entering this command, you see this display:
Console> (enable) show port negotiation 2/5 Port Link Negotiation ------- -------------------- 2/5 disabled Console> (enable)
Configuring Gigabit ports is similar to configuring Ethernet or Fast Ethernet ports. This section describes the commands that support the Gigabit ports on the Catalyst 4912G switch.
The following show port commands have been modified to include Gigabit port information:
configerr---Configuration error. The near-end port configuration is incompatible with the capabilities being advertised by the far-end port. Ensure that flow control and duplex settings on both ends of the link are compatible.
remcfgerr---Remote configuration error. The far-end port advertises that it cannot interoperate with the near-end port based on the near-end port's previous advertisement. Ensure that flow control and duplex settings on both ends of the link are compatible.
remdisable---Remote disable. The far-end port was disabled by the user.
remfault---Remote fault. The far-end port thinks there is a hardware problem with the link. Possible causes are a faulty GBIC, cable, or connector.
errdisable---Error disable. Upon insertion or reset, all ports show errdisable while power-on self-test (POST) diagnostics are running (this behavior is normal). If the errdisable status does not clear, it might indicate a hardware or software fault.
If the Gigabit Ethernet module is online and one of its ports shows errdisable, try disabling and then enabling the port. If that fails, reset the Gigabit Ethernet module.
Refer to the Command Reference publication for complete command descriptions.
The show port broadcast command displays the statistics related to broadcast suppression on the backplane. The Catalyst 4912G switch does not support broadcast suppression. This command is disabled.
Enter the set span command to enable or disable SPAN and to set up the port and VLAN analyzer. The default configuration has port monitoring disabled, port 2/1 as the monitoring port (destination), VLAN 1 as the monitored VLAN (source), and both transmit and receive packets monitored. If the parameter rx, tx, or both is not specified, the default is both. The command syntax is as follows:
set span enable
set span disable
set span {src_mod/src_ports} {dest_mod/dest_port} [rx | tx | both]
set span {src_vlan} {dest_mod/dest_port} [both]
This example shows a successful enabling of SPAN for the monitoring of transmit traffic on port 2/3 through port 2/4:
Console> (enable) set span enable span enabled. Console> (enable) Console> (enable) set span 2/3 2/4 tx Enabled monitoring of ports 2/3 transmit traffic by ports 2/4. Console> (enable)
Enter the set trunk command to configure trunk ports and to add VLANs to the allowed VLAN list for existing trunks. The dot1q syntax specifies an IEEE 802.1Q trunk. The command syntax is as follows:
set trunk mod_num/port_num [on | off | desirable | auto | nonegotiate] [vlan_range] [isl | dot1q | dot10 | lane]
In the following example, port 5 is set as an 802.1Q trunk port:
Console> (enable) set trunk 2/5 nonegotiate dot1q Port(s) 2/5 trunk mode set to nonegotiate. Port(s) 2/5 trunk type set to dot1q. Console> (enable)
Enter the show counters command to show all counters for a port. For the Catalyst 4912G switch, the command has been modified to include counters for the following:
The following sections describe certain commands that have been modified for the Catalyst 4912G switch for use in the Privileged Command Mode.
The set boot and the clear boot set the BOOT environment variable that determines which images the Catalyst 4912G switch will load at startup. The default filename is the first valid file in the device.
set boot system flash device:[filename] [supervisor] clear boot system flash device:[filename] [supervisor] clear boot system [supervisor]
The supervisor is the only valid argument for these commands. You can enter several boot system commands to provide a fail-safe method for booting the switch. The system stores and executes the boot system commands in the order in which you enter them. You need to remember to clear old entries when building a new image with a different filename in order to use the new image. If you use the clear boot system without any argument, the complete BOOT environment variable is cleared. If you want to rearrange the booting order, clear them all first, and then redefine the list.
Console> (enable) set boot system flash slot2:cat4912G-sup.3-1-2.bin BOOT variable = slot2:cat4912G-sup.3-1-2.bin; Console> (enable) set boot system flash slot2:cat4912G-sup.3-1-1.bin BOOT variable = slot2:cat4912G-sup.3-1-2.bin;slot2:cat4912G-sup.3-1-1.bin;
The reset command is used to restart the system. This reset is a software-generated emulation of a hardware reset.
This example shows the command for resetting the system:
Usage: reset [system]
The set cam command is used to add entries to the content-addressable memory (CAM) table (host table) and to set the aging time for entries in the CAM table. The default for CAM aging is 300 seconds. Setting the value to 0 disables aging. Static and permanent entries set up by this command are not subject to aging; only dynamic entries are aged. Static (nonpermanent) entries remain in the Catalyst 4912G switch until the system is reset. Permanent entries are stored in the NVRAM on the Network Management Processor (NMP) and remain until they are removed by the clear cam or clear config command.
The usage of the command is as follows:
set cam agingtime <vlan> <agingtime> set cam <dynamic|static|permanent> <unicast_mac> <mod/port> [vlan] set cam <static|permanent> <multicast_mac> <mod/ports...> [vlan] (agingtime = 0,15..1000000 seconds, 0 to disable vlan = 1..1000 Ports of a multicast group must be of the same VLAN. Must specify vlan if port(s) are trunk ports.))
Configuring Gigabit EtherChannel is very similar to configuring Fast EtherChannel on 100-Mbps ports.
Gigabit EtherChannel provides parallel bandwidth of up to 8 Gbps (4 Gbps full duplex) between Catalyst switches or hosts by grouping multiple Gigabit Ethernet interfaces into a single logical transmission path.
You can configure Gigabit Ethernet ports into Gigabit EtherChannel groups containing two or four segments, yielding 4- or 8-Gbps bandwidth (2- or 4-Gbps in each direction).
Inbound broadcast and multicast packets on one segment in a channel are blocked from returning on the other segment of the channel. Outbound broadcast and multicast packets are sent through only one channel segment.
If a segment within a channel fails, traffic previously carried over the failed link switches to the remaining segment within the channel. A trap is sent upon a failure identifying the switch, the channel, and the failed link.
Channels are configured using the standard CLI or Simple Network Management Protocol (SNMP).
Catalyst series software includes an enhancement to the EtherChannel feature called the Port Aggregation Protocol (PAgP). PAgP facilitates the automatic creation of EtherChannel links by sending packets between EtherChannel-capable ports. The protocol learns and informs the neighbors and their group capabilities dynamically. Once PAgP identifies correctly paired EtherChannel links, it groups the ports into a channel. The channel is then added to the spanning tree as a single bridge port.
PAgP includes four user-configurable channel modes: on, off, auto, and desirable. Each mode affects the way a port handles PAgP packets. By default, ports are in auto mode. Table 6-3 describes each mode.
| Mode | Description |
|---|---|
on | Forces the port to channel without negotiation. |
off | Prevents the port from channeling without negotiation. |
auto | Places a port into a passive negotiating state; the port responds to received PAgP packets but does not initiate PAgP packet negotiation. (Default) |
desirable | Places a port into an active negotiating state, in which the port initiates negotiations with other ports by sending PAgP packets. |
Both the auto and desirable modes allow ports to negotiate with connected ports to determine if they can form a channel, based on criteria such as port speed, trunking state, VLAN numbers, and so on.
Channel ports can be in different channel modes as long as the modes are compatible. For instance, a port in desirable mode can form a channel successfully with another port that is in desirable or auto mode. Similarly, a port in auto mode can form a channel with another port in desirable mode. However, a port in auto mode cannot form a channel with another port that is also in auto mode, since neither port will initiate the needed negotiations.
If improperly configured, some EtherChannel ports are disabled automatically to avoid network loops and other problems. Use the following guidelines to avoid configuration problems:
| Acceptable Channel Segments | ||||||
|---|---|---|---|---|---|---|
| 1 + 2 | 3 + 4 | 1 + 2 + 3 + 4 | 5 + 6 | 7 + 8 | 5 + 6+ 7+ 8 |
Enter the set port channel port_list {on | off | auto | desirable} command to configure EtherChannel.
To force a channel without negotiation, complete these steps:
| Task | Command |
|---|---|
Step 1 Make sure that the ports you want to channel are configured correctly. (See the "Gigabit EtherChannel Configuration Guidelines" section.) |
|
Step 2 Ensure a loop-free topology for all channeled VLANs. |
|
Step 3 Create a channel. | set port channel port_list on |
To set a channel port to auto, enter this command in privileged mode:
| Task | Command |
|---|---|
Set a channel port to auto. | set port channel port_list auto |
To set a channel port to desirable, enter this command in privileged mode:
| Task | Command |
|---|---|
Set a channel port to desirable. | set port channel port_list desirable |
To remove a channel, enter this command in privileged mode:
| Task | Command |
|---|---|
Remove a channel. | set port channel port_list off |
This example shows how to enable Gigabit EtherChannel on ports 2 through 6:
Console> (enable) set port channel 2/2-6 on Port(s) 2/2-6 channel mode set to on. Console> (enable)
To verify that the Gigabit EtherChannel is configured correctly, enter the show port channel [mod_num[port_num]] command.
Follow these guidelines when using the channel as a trunk:
Posted: Thu Apr 8 13:47:54 PDT 1999
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