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This chapter describes how to configure Gigabit Ethernet switching on the Catalyst enterprise LAN switches. The configuration tasks in this chapter apply to Gigabit Ethernet switching modules, fixed-configuration switches, and uplink ports on the supervisor engine.
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Note For complete syntax and usage information for the commands used in this chapter, refer to the Command Reference publication for your switch. |
This chapter consists of these sections:
These sections describe how Gigabit Ethernet works:
These sections describe how flow control works:
Flow control is a feature that Gigabit Ethernet ports use to inhibit the transmission of incoming packets. If a buffer on a Gigabit Ethernet port runs out of space, the port transmits a special packet that requests remote ports to delay sending packets for a period of time. This special packet is called a pause frame.
All Catalyst Gigabit Ethernet ports can receive and process pause frames from other devices. However, not all Catalyst Gigabit Ethernet ports can transmit pause frames to other devices.
Table 6-1 identifies the Catalyst Gigabit Ethernet switches, modules, and ports that can transmit pause frames to other devices.
Table 6-2 describes guidelines for using different configurations of the send and receive keywords with the set port flowcontrol command:
| Configuration | Description |
|---|---|
send on | Enables a local port to send pause frames to a remote port. Use send on when a remote port is set to receive on or receive desired. |
send off | Prevents a local port from sending pause frames to a remote port. Use send off when a remote port is set to receive off or receive desired. |
send desired | Indicates preference to send pause frames, but autonegotiates flow control. You can use send desired when a remote port is set to receive on, receive off, or receive desired. |
receive on | Enables a local port to process pause frames that a remote port sends. Use receive on when a remote port is set to send on or send desired. |
receive off | Prevents a local port from processing pause frames. Use receive off when a remote port is set to send off or send desired. |
receive desired | Indicates preference to process pause frames, but autonegotiates flow control. You can use receive desired when a remote port is set to send on, send off, or send desired. |
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Caution Unlike autonegotiation with 10/100 Fast Ethernet, Gigabit Ethernet port negotiation does not involve negotiating port speed. You cannot disable port negotiation on Gigabit Ethernet ports using the set port speed command. |
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Note Port negotiation is not supported on 1000BaseT Gigabit Ethernet ports. |
With Gigabit Ethernet ports, port negotiation is used to exchange flow-control parameters, remote fault information, and duplex information (even though Cisco Gigabit Ethernet ports only support full-duplex mode). With Gigabit Ethernet ports, you configure port negotiation using the set port negotiation command. Gigabit Ethernet port negotiation is enabled by default.
The ports on both ends of a Gigabit Ethernet link must have the same setting. The link will not come up if the ports at each end of the link are set inconsistently (port negotiation enabled on one port and disabled on the other). Table 6-3 shows the four possible port negotiation configurations for a Gigabit Ethernet link and the resulting link status for each configuration.
| Port Negotiation State | Link Status | ||
| Near End1 | Far End2 | Near End | Far End |
Off | Off | Up | Up |
On | On | Up | Up |
Off | On | Up | Down |
On | Off | Down | Up |
| 1Near End refers to the local Gigabit EtherChannel module port. 2Far End refers to the remote port at the other end of the Gigabit link. |
These sections describe how the Catalyst 4000 series oversubscribed Gigabit Ethernet modules work:
The Catalyst 4000 series gigabit ethernet modules provide a network-backbone connection for multiple servers or high-end workstations. The following modules are supported:
On all modules, each uplink module port has 1 Gbps dedicated bandwidth. These ports typically connect to the network backbone.
Table 6-4 lists the uplink module port IDs for each module
| Module | Port ID |
|---|---|
WS-X4412-2GB-T | 13 14 |
WS-X4416-2GB-TX | 17 18 |
WS-X4418-GB | 1 2 |
On all modules, the oversubscribed ports are segmented into groups of four ports each. Each group of four ports shares 1 Gbps of bandwidth. The average bandwidth that clients and servers need to connect to ports in the same group should not exceed 1 Gbps.
Table 6-5 shows how the oversubscribed ports are grouped for module WS-4412-2GB-TX
1 2 3 4 |
5 6 7 8 |
9 10 11 12 | Uplink Ports 13 14 |
Table 6-6 shows how the oversubscribed ports are grouped for module WS-4416-2GB-TX.
1 2 3 4 |
5 6 7 8 |
9 10 11 12 |
13 14 15 16 | Uplink Ports 17 18 |
Table 6-7 shows how the oversubscribed ports are grouped for module WS-4418-2GB.
Uplink Ports 1 2 | 3 5 7 9 4 6 8 10 | 11 13 15 17 12 14 16 18 |
The oversubscribed Gigabit ports are designed for end-station connections. Cisco does not recommend connecting these ports to switches or routers.
Each group of four oversubscribed ports has a buffer for incoming frames to allow connected devices to transmit traffic simultaneously. Because the inbound buffer is small, the default (and recommended) flow-control configuration for the oversubscribed ports is receive desired and transmit on.
You can bundle multiple oversubscribed ports into a Gigabit EtherChannel link to connect to channel-capable servers. By bundling multiple oversubscribed ports in the same port group, you might increase the total available bandwidth as compared to using a single link. However, it does provide redundancy with quick failover for links to servers and hosts that support the Port Aggregation Protocol (PAgP).
Figure 6-1 shows an example of how the 18-port server switching module (WS-X4418-GB) can connect multiple network servers and high-end workstations to the Gigabit Ethernet network backbone. These configurations are shown:
Table 6-8 shows the Gigabit Ethernet default configuration.
| Feature | Default Value |
|---|---|
Port enable state | All ports are enabled |
Port name | None |
Port priority | Normal |
Duplex mode | Full duplex |
Flow control |
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Port negotiation | Enabled |
Spanning-Tree Protocol | Enabled for VLAN 1 |
Native VLAN | VLAN 1 |
Spanning-tree port cost | 4 |
Gigabit EtherChannel | Disabled on all Gigabit Ethernet ports (auto mode) |
These sections describe how to configure Gigabit Ethernet switching ports on the Catalyst enterprise LAN switches:
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Note For information on configuring Gigabit EtherChannel, refer to "Configuring Fast EtherChannel and Gigabit EtherChannel." |
You can assign names to the ports on Gigabit Ethernet modules to facilitate switch administration.
To assign a name to a port, perform this task in privileged mode:
| Task | Command | |
|---|---|---|
Step 1 | Assign a name to a port. | set port name mod_num/port_num [name_string] |
Step 2 | Verify that the port name is configured. | show port [mod_num[/port_num]] |
This example shows how to set the name for ports 2/1 and 2/2 and how to verify that the port names are configured correctly:
Console> (enable) set port name 2/1 Backbone Connection Port 2/1 name set. Console> (enable) set port name 2/2 Wiring Closet Port 2/2 name set. Console> (enable) show port 2 Port Name Status Vlan Level Duplex Speed Type ----- ------------------ ---------- ---------- ------ ------ ----- ------------ 2/1 Backbone Connectio connected trunk normal full 1000 1000BaseSX 2/2 Wiring Closet notconnect 1 normal full 1000 1000BaseSX <...output truncated...> Last-Time-Cleared -------------------------- Tue Dec 22 1998, 13:42:04 Console> (enable)
You can configure the priority level for each port. When two ports simultaneously request access to the switching bus, the switch uses the priority level to determine the order in which the ports
get access.
To set the port priority level, perform this task in privileged mode:
| Task | Command | |
|---|---|---|
Step 1 | Configure the priority level for a port. | set port level mod_num/port_num {normal | high} |
Step 2 | Verify that the port priority level is configured correctly. | show port [mod_num[/port_num]] |
This example shows how to set the port priority level to high for port 2/1 and verify that the port priority is configured correctly:
Console> (enable) set port level 2/1 high Port 2/1 level set to high. Console> (enable) show port 2/1 Port Name Status Vlan Level Duplex Speed Type ----- ------------------ ---------- ---------- ------ ------ ----- ------------ 2/1 Backbone Connectio connected trunk high full 1000 1000BaseSX <...output truncated...> Last-Time-Cleared -------------------------- Tue Dec 22 1998, 13:42:04 Console> (enable)
To configure flow control on a Gigabit Ethernet port, perform this task in privileged mode:
| Task | Command | |
|---|---|---|
Step 1 | Set the flow-control parameters on a Gigabit Ethernet port. | set port flowcontrol {receive | send} mod_num/port_num {off | on | desired} |
Step 2 | Verify the flow-control configuration. | show port flowcontrol |
This example shows how to turn transmit and receive flow control on and how to verify the flow-control configuration:
Console> (enable) set port flowcontrol send 2/1 on
Port 2/1 flow control send administration status set to on
(port will send flowcontrol to far end)
Console> (enable) set port flowcontrol receive 2/1 on
Port 2/1 flow control receive administration status set to on
(port will require far end to send flowcontrol)
Console> (enable) show port flowcontrol 2/1
Port Send FlowControl Receive FlowControl RxPause TxPause Unsupported
admin oper admin oper opcodes
----- -------- -------- -------- -------- ------- ------- -----------
2/1 on on on on 0 0 0
Console> (enable)
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Note You cannot configure port negotiation on 1000BaseT Gigabit Ethernet ports in this release. |
To enable port negotiation on a 1000BaseX Gigabit Ethernet port, perform this task in privileged mode:
| Task | Command | |
|---|---|---|
Step 1 | Enable Gigabit Ethernet port negotiation. | set port negotiation mod_num/port_num enable |
Step 2 | Verify the port negotiation configuration. | show port negotiation [mod_num/port_num] |
This example shows how to enable port negotiation and verify the configuration:
Console> (enable) set port negotiation 2/1 enable Port 2/1 negotiation enabled Console> (enable) show port negotiation 2/1 Port Link Negotiation ----- ---------------- 2/1 enabled Console> (enable)
To disable port negotiation on a 1000BaseX Gigabit Ethernet port, perform this task in privileged mode:
| Task | Command | |
|---|---|---|
Step 1 | Disable Gigabit Ethernet port negotiation. | set port negotiation mod_num/port_num disable |
Step 2 | Verify the port negotiation configuration. | show port negotiation [mod_num/port_num] |
This example shows how to disable port negotiation and verify the configuration:
Console> (enable) set port negotiation 2/1 disable Port 2/1 negotiation disabled Console> (enable) show port negotiation 2/1 Port Link Negotiation ----- ---------------- 2/1 disabled Console> (enable)
For information on changing the default port enable state, see Chapter 5, "Configuring Ethernet and Fast Ethernet Switching".
For information on configuring a timeout period for ports in errdisable state, see Chapter 5, "Configuring Ethernet and Fast Ethernet Switching"
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Note For more detailed information on checking connectivity, see "Checking Port Status and Connectivity." |
Use the ping and traceroute commands to test connectivity out Gigabit Ethernet ports.
To check connectivity out a port, perform this task in privileged mode:
| Task | Command | |
|---|---|---|
Step 1 | Ping a remote host that is located out the port you want to test. | ping [-s] host [packet_size] [packet_count] |
Step 2 | Trace the hop-by-hop route of packets from the switch to a remote host located out the port you want to test. | traceroute host |
Step 3 | If the host is unresponsive, check the IP address and default gateway configured on the switch. | show interface |
This example shows how to ping a remote host and how to trace the hop-by-hop path of packets through the network using traceroute:
Console> (enable) ping somehost somehost is alive Console> (enable) traceroute somehost traceroute to somehost.company.com (10.1.2.3), 30 hops max, 40 byte packets 1 engineering-1.company.com (173.31.192.206) 2 ms 1 ms 1 ms 2 engineering-2.company.com (173.31.196.204) 2 ms 3 ms 2 ms 3 gateway_a.company.com (173.16.1.201) 6 ms 3 ms 3 ms 4 somehost.company.com (10.1.2.3) 3 ms * 2 ms Console> (enable
Posted: Mon May 1 12:29:31 PDT 2000
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