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This chapter describes the procedures for configuring the Fast Ethernet ports on the supervisor engine module, the Fast Ethernet switching module, and the Ethernet switching module using the command-line interface (CLI). This chapter also contains information on features, such as Spanning-Tree Protocol (STP), and CLI Ethernet connectivity. Switch configuration examples are included.
Ethernet and Fast Ethernet switching modules share features such as
For additional information on all commands discussed in this chapter, refer to the Catalyst 5000 Series Command Reference publication.
The features you can customize have default values that will most likely suit your environment and need not be changed. The default values of these features are set as follows:
To customize the Ethernet ports, complete the tasks in the following sections.
To assign a name to each port, use the following procedure in privileged mode:
After entering the set port name command, you see this display:
Console> (enable) set port name 1/1 Router Connection Port 1/1 name set. Console> (enable) set port name 1/2 Server 1 Port 1/2 name set.
To verify that you set the port name correctly, enter the show port mod_num/port_num command. After entering this command, you see this display:
Console> (enable) show port Port Name Status Vlan Level Duplex Speed Type ---- -------------------- -------- -------- ------ ------ ----- ------- 1/1 Router Connection ready 2 high half 100 100BaseTX 1/2 Server 1 ready 1 high half 100 100BaseTX 2/1 ready 10 normal half 10 10BaseT 2/2 disabled 10 normal half 10 10BaseT 2/3 connect 10 normal half 10 10BaseT 2/4 connect 10 normal half 10 10BaseT . . . 2/23 0 0 0 0 0 0 2/24 0 0 0 0 0 0 Port Align-Err FCS-Err Xmit-Err Rcv-Err ---- ---------- ---------- ---------- ---------- 1/1 0 0 0 0 1/2 1 0 0 0 2/1 0 0 0 0 2/2 0 0 0 0 2/3 0 0 0 0 2/4 30 0 0 0 2/5 0 0 0 0 2/6 0 0 0 0 2/7 0 0 0 0 2/8 0 0 0 0 2/9 0 0 0 0 2/10 0 0 0 0 2/11 0 0 0 0 2/12 0 0 0 0 Port Single-Col Multi-Coll Late-Coll Excess-Col Carri-Sens Giants ---- ---------- ---------- ---------- ---------- ---------- ---------- 1/1 0 0 0 0 0 0 1/2 680 418 0 1 0 - 2/1 756 99 0 0 0 0 2/2 0 0 0 0 0 0 2/3 0 0 0 0 0 0 2/4 409 403 0 11 0 1256 2/5 0 0 0 0 0 0 2/6 0 0 0 0 0 0 2/7 0 0 0 0 0 0 2/8 0 0 0 0 0 0 2/9 0 0 0 0 0 0 2/10 0 0 0 0 0 0 2/11 0 0 0 0 0 0 2/12 0 0 0 0 0 0 Last-Time-Cleared -------------------------- Thu Jun 8 1995, 07:58:06 Console> (enable)
Configure the priority level of each port. When ports request simultaneous access to the switching bus, the Catalyst 5000 series switch uses the port priority level to determine the access order of ports to the switching bus.
To set the priority level, perform this task in privileged mode:
| Task | Command |
|---|---|
| Configure the priority level for each port. | set port level mod_num/port_num normal | high |
After entering the set port level command, you see this display:
Console> (enable) set port level 1/1 high Port 1/1 level set to high. Console> (enable) set port level 1/2 high Port 1/2 level set to high.
To verify that the port priority level is correct, enter the show port mod_num/port_num command. After entering this command, you see a display similar to the verification example in the section "Setting the Port Name."
Configure the port speed for 10/100BaseTX ports on the 10/100-Mbps Fast Ethernet Switching module if desired.
To set the port speed for a port, perform this task in privileged mode:
| Task | Command |
|---|---|
| Set the port speed of a port. | set port speed mod num/port num [10 | 100 | auto] |
After entering the set port speed mod num/port num [10 | 100 | auto] command, you see the following display:
Console> (enable) set port speed Usage: set port speed <mod_num/port_num> <10|100|auto> Console> (enable) set port speed 2/1 auto Port 2/1 speed set to auto-sensing mode. Console> (enable) set port speed 2/2 10 Port 2/2 speed set to 10 Mbps. Console> (enable) set port speed 2/3 100 Port 2/3 speed set to 100 Mbps.
To verify that you set the port speed correctly, enter the show port mod_num/port_num command. After entering this command, you see a display similar to the verification example in the section "Setting the Port Name."
Set the transmission type to full or half duplex for the ports that will be used.
To set the transmission type of a port, perform this task in privileged mode:
| Task | Command |
|---|---|
| Set the transmission type of a port. | set port duplex mod num/port num full | half |
After entering the set port duplex command, you see this display:
Console> (enable) set port duplex 2/1 half Port 2/1 set to half-duplex. Console> (enable) set port duplex 2/2 half Port 2/2 set to half-duplex.
To verify that you set the transmission type correctly, enter the show port mod_num/port_num command. After entering this command, you see a display similar to the verification example in the section "Setting the Port Name."
Use the ping command to test the connection between an Ethernet or Fast Ethernet module in the Catalyst 5000 series switch and a host residing anywhere in your network. The ping command pings a host once per second until a normal response is received by the sending module. The host must be connected to a port with an address on the same IP network. Otherwise, you must configure a static route entry to reach the host network. To stop pinging, enter Ctrl-C.
To check connectivity using the ping command, perform these steps:
| Task | Command |
|---|---|
| Step 1 Send an echo request from the Catalyst 5000 series switch to the host. | ping host |
| Step 2 If the host is unresponsive, check the configuration for the IP address of the Catalyst 5000 series switch and default IP route. | show interface
show ip route |
After entering the ping command, you see the following display:
Console> (enable) ping 171.69.192.3 171.69.192.3 is aliveSample results of using the ping command are as follows:
You can configure the specialized features in this section on your Ethernet and Fast Ethernet modules.
The Catalyst 5000 series switch uses Spanning-Tree Protocol on all Ethernet and Fast Ethernet port- based VLANs. When creating fault-tolerant internetworks, a loop-free path must exist between all nodes in a network. A spanning-tree algorithm is used to calculate the best loop-free path throughout a Catalyst 5000 series switched network. Spanning-tree packets are sent and received by switches in the network at regular intervals.
The packets are not forwarded by the switches participating in the spanning tree, but are instead used by the switches to identify the loop-free path. The IEEE 802.1D bridge protocol called STP performs this function for Catalyst 5000 series switches. The default configuration has all spanning trees enabled.
Use this procedure to configure STP:
| Task | Command |
|---|---|
| Enable STP. | set spantree enable [vlan] |
After enabling STP, you see this screen:
Console> (enable) set spantree enable 1 VLAN1 bridge spanning tree enabled Console< (enable)To disable Spanning-Tree Protocol, use the set spantree disable command. To set the bridge forward delay for a VLAN, use the set spantree fwddelay delay [vlan] command. For more information on STP commands, refer to the Catalyst 5000 Series Command Reference publication.
To display all spanning-tree information, enter the show spantree command.
Console> show spantree ?
Usage: show spantree [vlan]
show spantree <mod_num/port_num>
Console> (enable) show spantree 1 VLAN 1 Spanning tree enabled Designated Root 00-1f-00-40-0b-90-c9-00 Designated Root Priority 45 Designated Root Cost 0 Designated Root Port 1/0 Root Max Age 20 sec Hello Time 2 sec Forward Delay 20 sec Bridge ID MAC ADDR 00-40-0b-90-c9-00 Bridge ID Priority 45 Bridge Max Age 20 sec Hello Time 2 sec Forward Delay 20 sec Port Vlan Port-State Cost Priority Fast-Start -------- ---- ------------- ----- -------- ---------- 1/1 1 forwarding 10 32 disabled 2/3 1 not-connected 100 32 disabled 2/4 1 not-connected 100 32 disabled 2/5 1 not-connected 100 32 disabled 2/6 1 not-connected 100 32 disabled 2/7 1 not-connected 100 32 disabled 2/8 1 forwarding 100 32 disabled 2/9 1 not-connected 100 32 disabled 2/10 1 not-connected 100 32 disabled 2/11 1 not-connected 100 32 disabled 2/12 1 not-connected 100 32 disabled 2/13 1 Learning 100 32 disabled 2/14 1 not-connected 100 32 disabled 2/15 1 not-connected 100 32 disabled 2/16 1 not-connected 100 32 disabled 2/17 1 not-connected 100 32 disabled 2/18 1 not-connected 100 32 disabled 2/19 1 not-connected 100 32 disabled 2/20 1 not-connected 100 32 disabled 2/21 1 not-connected 100 32 disabled 2/22 1 not-connected 100 32 disabled 2/23 1 not-connected 100 32 disabled 2/24 1 not-connected 100 32 disabled 4/13-24 1 not-connected 100 32 disabled 4/25-36 1 not-connected 100 32 disabled 4/37-48 1 not-connected 100 32 disabled Console> (enable)
Use these commands to perform additional STP functions:
| Task | Command |
|---|---|
| Disable the spanning tree algorithm for a VLAN. | set spantree disable [vlan] |
| Set the bridge forward delay for a VLAN. | set spantree fwddelay delay [vlan] |
| Set the bridge hello time for a VLAN. | set spantree hello interval [vlan] |
| List the available set spantree commands. | set spantree help |
| Set the bridge maximum aging time for a VLAN. | set spantree maxage agingtime [vlan] |
| Set the bridge path cost for a port. | set spantree portcost mod_num/port_num cost |
| Allow a port that is connected to a single workstation or PC to start faster. | set spantree portfast mod_num/port_num {enable | disable} |
| Set the bridge priority for a port in spanning-tree algorithm. | set spantree portpri mod_num/port_num priority |
| Set the port priority for a subset of VLANs in the trunk port. | set spantree portvlanpri mod_num/port_num priority [vlans] |
| Set the bridge priority for a VLAN. | set spantree priority bridge_priority [vlan] |
You can design fault-tolerant connections using Ethernet only or Ethernet combined with other topologies. Figure 4-1 and Figure 4-2 show spanning tree operating on fault-tolerant Fast Ethernet topologies.
STP is a link management protocol that provides path redundancy while preventing undesirable loops in the network. For an Ethernet network to function properly, only one active path must exist between two stations.
Multiple active paths between stations cause loops in the network. Loops result in some switches seeing stations appear on both sides of the switch. This condition confuses the forwarding algorithm and allows forwarding of duplicate frames. If a loop exists in the network topology, the potential exists for duplication of messages.
To provide path redundancy, STP defines a tree that spans all switches in an extended network. STP forces certain redundant data paths into a standby (blocked) state. If one of the network segments in the spanning tree becomes unreachable, or if STP costs change, the spanning-tree algorithm reconfigures the spanning-tree topology and reestablishes the link by activating the standby path.
The STP operation is transparent to end stations, which are unaware whether they are connected to a single LAN segment or a switched LAN of multiple segments.
All switches in an extended LAN participating in STP gather information on other switches in the network through an exchange of data messages. These messages are defined by IEEE 802.1d as Bridge Protocol Data Units (BPDUs). This exchange of messages results in the following actions:
The STP root switch is the logical center of the spanning-tree topology in a switched network. All paths that are not needed to reach the root switch from anywhere in the switched network are placed in STP backup. The follow variables, set for the root switch, affect the entire spanning-tree performance:
Refer to Figure 4-3 as an example. These BPDUs contain information about the transmitting switch and its ports, including switch and port Media Access Control (MAC) addresses, switch priority, port priority, and port cost. This information is used by STP to elect the root switch and root port for the switched network, as well as the root port and designated port for each switched segment.
The stable active topology of a switched network is determined by the following:
The process of developing the initial spanning tree, and its eventual modification due to the change in location or failure of a switch or switch port, necessitates the regular exchange of BPDUs.
Each configuration BPDU contains the following minimal information:
The switch sends configuration BPDUs in order to communicate and compute the spanning-tree topology. A MAC frame conveying a BPDU sends the switch group address to the destination address field. All switches connected to the LAN on which the frame is transmitted receive the BPDU. BPDUs are not directly forwarded by the switch, but the information contained in the frame can be used to calculate a BPDU by the receiving switch, and in the event of a topology change, instigate the transmission of a BPDU.
The following results occur as a result of the BPDU exchange:
If all switches are enabled with default settings, the switch with the lowest MAC address in the network becomes the root switch. The network shown in Figure 4-4 assumes that Switch A has the lowest MAC address and is therefore the root switch. In some situations, however, due to traffic patterns, number of forwarding ports, or line types, Switch A might not be the ideal root switch. Changing the switch priority of the most desirable switch for the root to a higher priority (lower numerical number) forces an STP recalculation to form a new stable topology.
In addition, the path between source and destination stations in a switched network might not be the most ideal when the stable STP topology is based on default parameters. For instance, the connection of higher speed links to a higher-numbered port than the current root port can dictate making a root-port change. The point is to make the fastest link the root port.
Propagation delays occur in passing protocol information through a switched LAN. As a result, topology changes can take place at different times and different places in a switched network. For a switch port to transition directly from non-participation in the stable topology to the forwarding state can create temporary data loops. Ports must wait for new topology information to propagate through the switched LAN before starting to forward frames. They must also allow the frame lifetime to expire for frames that have been forwarded using the old topology.
Each port on a switch using STP exists in one of the following five states:
The port states, as shown in Figure 4-5, occur as follows:
You can modify each port state by using management software. When STP is enabled, every switch in the network goes through the blocking state and the transitory states of listening and learning at power up. If properly configured, the ports then stabilize to the forwarding or blocking state.
When the spanning-tree algorithm determines that a port should be placed in the forwarding state, the following occurs:
A port in the blocking state does not participate in frame forwarding. Refer to Figure 4-6. After initialization, a BPDU is sent to each port in the switch. A switch initially assumes itself to be the root until an exchange of BPDUs with other switches. This message exchange establishes which switch in the network is really the root. If only one switch resides in the network, no exchange of BPDUs occurs, and the forward delay timer expires. The ports move to the listening state. A switch always enters the blocking state following switch initialization.
A port in the blocking state performs as follows:
The listening state is the first transitional state a port enters following the blocking state, when STP determines that the port should participate in frame forwarding. Learning is disabled in this state. Figure 4-7 shows a port in the listening state.
A port in the listening state performs as follows:
A port in the learning state is preparing to participate in frame forwarding. This is the second transitory state through which a port moves in anticipation of frame forwarding. The port enters the learning state from the listening state through the operation of STP.
A port in the learning state performs as follows:
A port in the forwarding state forwards frames. Refer to Figure 4-8 for an example of a port in forwarding state. The forwarding state is entered from the learning state through the operation of STP.
A port in the forwarding state performs as follows:
 | Caution Use the immediate forwarding mode only on ports connected to individual workstations. To prevent illegal topologies, enable STP on ports connected to switches or other devices that forward messages. |
A port in the disabled state does not participate in frame forwarding or the operation of STP. Refer to Figure 4-9 for an example of a port in the disabled state. In this state a port is virtually nonoperational.
A disabled port does the following:
The Catalyst 5000 series switch allows you to group end stations with a common set of requirements into logical LAN segments called virtual LANs (VLANs). For example, several end stations in different physical locations attached to different switches can be grouped as a department, such as engineering or accounting. If the end stations are located in close proximity to one another, they can be grouped into a LAN segment. If any of the end stations are on a different LAN segment, typically located in different buildings or locations, they can be grouped together into a VLAN that has all the same attributes as a LAN.
For more information about configuring VLANs, refer to Chapter 7, "Configuring Virtual LANs."
The Catalyst 5000 series switch increases network throughput by supporting simultaneous, parallel conversations between Ethernet segments. Switched connections between Ethernet segments last only for the duration of the packet. New connections can be made between different segments for the next packet.
The Catalyst 5000 series switch solves congestion problems caused by high bandwidth devices and a large number of users by assigning each of the devices, for example, servers, to its own 10- or 100-Mbps segment. Because each Ethernet port on the Catalyst 5000 series switch represents a separate Ethernet segment, servers in a properly configured switched environment achieve full access to the bandwidth.
Because the major bottleneck in Ethernet networks is usually the effect of collisions on devices, an effective solution is full-duplex communication, an option for each port on the Catalyst 5000 series switch. Normally, Ethernet operates in half-duplex communication mode, which means that stations can either receive or transmit. With full-duplex technology, two communicating stations can transmit and receive at the same time. When packets can flow in both directions simultaneously, effective Ethernet bandwidth doubles from 10 Mbps to 20 Mbps for 10BaseT ports and to 200 Mbps for Fast Ethernet ports.
Each Ethernet port on the Catalyst 5000 series switch can be connected to a single workstation or server, or to a hub through which workstations or servers connect to the network.
Ports on a typical Ethernet hub are all connected to a common backplane within the hub, and the bandwidth of the network is shared by all devices attached to the hub. If two stations establish a session that uses a significant level of bandwidth, the network performance of all other stations attached to the hub is degraded.
To reduce degradation, the Catalyst 5000 series switch treats each port as an individual segment and, when stations on different ports need to communicate, switches frames from one port to the other at wire speed. The switching ensures that each session receives the full 10 Mbps of bandwidth.
In order to switch frames between ports efficiently, the Catalyst 5000 series switch maintains an address table in hardware. When a frame enters the Catalyst 5000 series switch, it associates the MAC address of the sending station with the port on which it was received.
The Catalyst 5000 series switch builds the address table by using the source address of the frames received. When the switch receives a frame for a destination address not yet listed in its address table, it floods the frame to all ports of the same VLAN except the port that received the frame. When the destination station replies, the switch adds its relevant source address and port ID to the address table. The Catalyst 5000 series switch then forwards subsequent frames to a single port without flooding to all ports.
The address table can store at least 16,000 address entries without having to flood any entries. The Catalyst 5000 series switch uses an aging mechanism, defined by a configurable aging timer, so that, if an address remains inactive for a specified number of seconds, it is removed from the address table.
A single Catalyst 5000 series switch configuration example is shown in Figure 4-10. For simplicity, this example shows all devices on each module as either full duplex or half duplex. However, each port on each module can be independently configured for either full- or half-duplex operation.
This example also shows a direct correlation between port speed and traffic priority, although the two parameters are completely independent.
Step 1 Configure a name for the port by entering the set port name command. You see this display:
system1 (enable) set port name 1/1 Router Connection Port 1/1 name set. system1 (enable) set port name 1/2 Server 1 Port 1/2 name set. system1 (enable) set port name 2/1 Server 2 Port 2/1 name set. system1 (enable) set port name 2/2 Server 3 Port 2/2 name set. . . . system1 (enable) set port name 2/12 Server 13 Port 2/12 name set. system1 (enable) set port name 3/1 Hub 1 Port 3/1 name set. system1 (enable) set port name 3/1 Hub 2 Port 3/2 name set. system1 (enable) set port name 3/1 Hub 3 Port 3/3 name set. . . . system1 (enable) set port name 3/12 Nodename 12 Port 3/12 name set. system1 (enable) set port name 4/1 Switch 1 Port 4/1 name set. system1 (enable) set port name 4/2 Switch 2 Port 4/2 name set. system1 (enable) set port name 4/3 Switch 3 Port 4/3 name set. . . . system1 (enable) set port name 4/24 Switch 12 Port 4/24 name set. system1 (enable) set port name 5/1 Switch 13 Port 5/1 name set. system1 (enable) set port name 5/2 Switch 14 Port 5/2 name set. system1 (enable) set port name 5/3 Switch 15 Port 5/3 name set. . . . system1 (enable) set port name 5/24 Nodename 36 Port 5/24 name set
Step 2 Configure the priority level for the port by entering the set port level command. You see this display:
system1 (enable) set port level 1/1 high Port 1/1 level set to high. system1 (enable) set port level 1/2 high Port 1/2 level set to high. system1 (enable) set port level 2/1 high Port 2/1 level set to high. system1 (enable) set port level 2/2 high Port 2/2 level set to high. system1 (enable) set port level 2/3 high Port 2/3 level set to high. . . . system1 (enable) set port level 2/12 high Port 2/12 level set to high. system1 (enable) set port level 3/1 normal Port 3/1 level set to normal. system1 (enable) set port level 3/2 normal Port 3/2 level set to normal. system1 (enable) set port level 3/3 normal Port 3/3 level set to normal. . . . system1 (enable) set port level 3/12 normal Port 3/12 level set to normal. system1 (enable) set port level 4/1 normal Port 4/1 level set to normal. system1 (enable) set port level 4/2 normal Port 4/2 level set to normal. system1 (enable) set port level 4/3 normal Port 4/3 level set to normal. . . . system1 (enable) set port level 4/24 normal Port 4/24 level set to normal. system1 (enable) set port level 5/1 normal Port 5/1 level set to normal. system1 (enable) set port level 5/2 normal Port 5/2 level set to normal. system1 (enable) set port level 5/3 normal Port 5/3 level set to normal. . . . system1 (enable) set port level 5/24 normal Port 5/24 level set to normal.
Step 3 Configure a name for the port by entering the port speed command. You see this display:
Console> (enable) set port speed Usage: set port speed <mod_num/port_num> <10|100|auto> Console> (enable) set port speed 2/1 100 Port 2/1 speed set to 100 Mbps. Console> (enable) set port speed 2/2 100 Port 2/2 speed set to 100 Mbps. Console> (enable) set port speed 2/3 100 Port 2/3 speed set to 100 Mbps. Console> (enable) set port speed 2/4 100 Port 2/4 speed set to 100 Mbps. Console> (enable) set port speed 2/5 100 Port 2/5 speed set to 100 Mbps. . . . Console> (enable) set port speed 2/12 100 Port 2/12 speed set to 100 Mbps.
Step 4 Configure the transmission type of the port (half or full duplex) by entering the set port duplex command. You see this display:
system1 (enable) set port duplex 1/1 full Port 1/1 set to full-duplex. system1 (enable) set port duplex 1/2 full Port 1/2 set to full-duplex. system1 (enable) set port duplex 2/1 full Port 2/1 set to full-duplex. system1 (enable) set port duplex 2/2 full Port 2/2 set to full-duplex. system1 (enable) set port duplex 2/3 full Port 2/3 set to full-duplex. . . . system1 (enable) set port duplex 2/12 full Port 2/12 set to full-duplex. Port 3/1 set to half-duplex. system1 (enable) set port duplex 3/2 half Port 3/2 set to half-duplex. system1 (enable) set port duplex 3/3 half Port 3/3 set to half-duplex. . . . system1 (enable) set port duplex 3/12 half Port 3/12 set to half-duplex. system1 (enable) set port duplex 4/1 full Port 4/1 set to half-duplex. system1 (enable) set port duplex 4/2 full Port 4/2 set to half-duplex. system1 (enable) set port duplex 4/3 full Port 4/3 set to half-duplex. . . . system1 (enable) set port duplex 4/24 full Port 4/24 set to half-duplex. system1 (enable) set port duplex 5/1 half Port 5/1 set to half-duplex. system1 (enable) set port duplex 5/2 half Port 5/2 set to half-duplex. system1 (enable) set port duplex 5/3 half Port 5/3 set to half-duplex. . . . system1 (enable) set port duplex 5/24 half Port 5/24 set to half-duplex.
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