-
Catalyst 2950 and Catalyst 2955 Switch Software Configuration Guide, 12.1(19)EA1
-
Index
-
Preface
-
Overview
-
Using the Command-Line Interface
-
Configuring Catalyst 2955 Switch Alarms
-
Getting Started with CMS
-
Assigning the Switch IP Address and Default Gateway
-
Configuring IE2100 CNS Agents
-
Clustering Switches
-
Administering the Switch
-
Configuring Switch-Based Authentication
-
Configuring 802.1X Port-Based Authentication
-
Configuring Interface Characteristics
-
Configuring SmartPort Macros
-
Configuring LRE
-
Configuring STP
-
Configuring MSTP
-
Configuring Optional Spanning-Tree Features
-
Configuring VLANs
-
Configuring VTP
-
Configuring Voice VLAN
-
Configuring DHCP Features
-
Configuring IGMP Snooping and MVR
-
Configuring Port-Based Traffic Control
-
Configuring UDLD
-
Configuring CDP
-
Configuring SPAN and RSPAN
-
Configuring RMON
-
Configuring System Message Logging
-
Configuring SNMP
-
Configuring Network Security with ACLs
-
Configuring QoS
-
Configuring EtherChannels
-
Troubleshooting
-
Supported MIBs
-
Working with the IOS File System, Configuration Files, and Software Images
-
Table Of Contents
Ports on the Catalyst 2950 LRE Switches
Environmental Guidelines for LRE Links
Guidelines for Using LRE Profiles
Guidelines for Configuring Cisco 575 LRE CPEs and 576 LRE 997 CPEs
Guidelines for Configuring Cisco 585 LRE CPEs
Assigning a Global Profile to All LRE Ports
Assigning a Profile to a Specific LRE Port
Assigning a Global Sequence to All LRE Ports
Assigning a Sequence to a Specific LRE Port
Using Rate Selection to Automatically Assign Profiles
Link Qualification and SNR Margins
Configuring LRE Link Persistence
Configuring Upstream Power Back-Off
Configuring for an LRE Upgrade
Global Configuration of LRE Upgrades
Controller Configuration of LRE Upgrades
Configuring LRE
This chapter describes how to configure the Long-Reach Ethernet (LRE) features on your
Catalyst 2950 LRE switch. This chapter consists of these sections:•
Upgrading LRE Switch Firmware
Note
For information about which Cisco LRE customer premises equipment (CPE) devices are supported by the LRE switches, see Table 1-2.
Understanding LRE Features
These sections describe LRE features:
•
Ports on the Catalyst 2950 LRE Switches
The Catalyst 2950 LRE switches use LRE technology to transfer data, voice, and video traffic over categorized and noncategorized unshielded twisted-pair cable (Category 1, 2, and 3 structured and unstructured cable such as existing telephone lines).
Connecting a switch LRE port to a remote Ethernet device (such as a PC) requires two types of connections:
•
•
The actual line speed in either direction between an LRE switch port and a remote Ethernet device depends on the LRE link speed and the CPE Ethernet link speed. For example, if a PC Ethernet port is configured to 100 Mbps and the LRE port is configured with an upstream link speed of 5.69 Mbps, the actual upload rate provided to the PC user is 5.69 Mbps, not 100 Mbps.
For LRE troubleshooting information, see the "Diagnosing LRE Connection Problems" section. For more information about the LRE commands, refer to the command reference for this release.
LRE Links and LRE Profiles
The LRE link settings define the connection between the LRE switch port and the CPE RJ-11 wall port. The LRE link provides symmetric and asymmetric bandwidth for data, voice, and video traffic. Symmetric transmission occurs when the downstream and upstream bandwidths are the same. Asymmetric transmission occurs when the downstream and the upstream bandwidths differ. Downstream transmission refers to the traffic going from the LRE switch to the CPE device. Upstream transmission refers to the traffic going from the CPE device to the LRE switch.
The switch controls upstream and downstream rates on the LRE link by using configurations called profiles. Depending on the profile, the upstream and downstream bands on an LRE link can range from approximately 1 to 18.750 Mbps.
This section discusses these topics:
LRE Profiles
When the LRE switch establishes a link with the CPE device, the switch downloads its profile settings to the CPE device so that the switch and CPE device operate with the same configuration.
The LRE switches are shipped with system-defined profiles. You can configure a profile on a global or per-port basis. By default, all LRE ports on the Catalyst 2950ST-8 LRE and 2950ST-24 LRE switches are enabled with the LRE-10 profile, and all LRE ports on the Catalyst 2950ST-24 LRE 997 switches are enabled with the LRE-6 profile. These default profile allows the upstream and downstream effective data rate on the LRE link to be 10 Mbps and 6.0 Mbps, respectively.
Table 13-1 and Table 13-2 contain the full list of LRE profiles, as well as their downstream and upstream rates (in Mbps and their theoretical upstream and downstream signal-to-noise [SNR] rates in decibels [dB]).
Note
Note
Your data rates will always be less than the gross data rate listed in tables. A small percentage of the link rate is used by the Catalyst 2950 LRE switch for supervisory functions with the CPE device connected remotely.
In general, profiles are named for the data rate that you expect to achieve and not the gross data rate as given in the table. All system-defined profiles have the prefix LRE, followed by the downstream user data rate and then the upstream user data rate. If the profile is symmetric, only one data rate is given. The two profiles defined to comply with public frequency usage plans 998 and 997 (LRE-998-15-4 and LRE-997-10-4) are exceptions to this. These two uniquely named profiles also work in any private deployment.
•
When you assign a different profile to a switch LRE port, the port immediately resets and uses the newly assigned profile.
•
All other profiles have the interleave feature enabled and the LL feature disabled. The interleave feature provides maximum protection against small interruptions on the LRE link but delays data transmission.
For information on configuring the interleaving delay on the LRE ports, see the "Configuring LRE Interleave" section.
•
LRE Sequences
The LRE switches are shipped with predefined sequences. Sequences are sets of profiles and are used with the rate selection feature. The rate selection feature enables the switch to automatically select profiles. You can also define your own sets of sequences by using the command-line interface (CLI) commands or Cluster Management Suite (CMS). For more information, see the "Using Rate Selection to Automatically Assign Profiles" section.
Table 13-3 and Table 13-4 list the predefined sequences for rate selection contained in the software. When executing rate selection, the switch uses a sequence to choose an appropriate profile for a given LRE interface.
Beginning with the first profile in a sequence, the switch attempts to apply each profile within that sequence to the LRE interface. The switch continues these attempts until it converges (convergence time refers to the time required for the switch to settle on an appropriate profile for the LRE interface). The link is DOWN until a link is established by one of the profiles in the sequence, after which, it is UP.
For additional information on rate selection, see the "Using Rate Selection to Automatically Assign Profiles" section.
CPE Ethernet Links
The CPE Ethernet link settings define the connection between the CPE Ethernet port and a remote Ethernet device, such as a PC.
Note
Keep these considerations in mind when you have CPE devices connected to the LRE ports:
•
•
•
•
•
CPE toggle cannot be disabled on a Cisco 575 LRE or Cisco 576 LRE 997 CPE link but can be disabled on a Cisco 585 LRE CPE. For more information, see the "Configuring CPE Toggle" section.
Use the show controllers ethernet-controller privileged EXEC command to display the internal switch statistics, the statistics collected by the LRE switch interface, and the statistics collected by the LRE CPE interface. For information about this command, refer to the command reference for this release.
LRE Link Monitor
When the link monitor feature is enabled, an LRE switch tracks undesirable or interesting conditions on a link and takes system-defined actions after certain thresholds are reached. The link monitor can track these conditions:
•
•
•
•
•
•
The link parameters need to be monitored both for the upstream and downstream directions.
You can use the information that you get from the link monitor to log events, set traps, change to a lower rate profile, and disable the automatic power back-off feature.
LRE Message Logging Process
The Catalyst 2950 LRE switch software monitors switch conditions on a per-port basis and sends the debugging messages to an LRE message logging process that is different than the system message logging process described in "Configuring System Message Logging."
These options are available in the LRE logging process:
•
•
•
•
You can use the logging lre interface configuration command to specify the mode in which to log LRE events. To display the events on the LRE interfaces, use the show controllers lre log privileged EXEC command. For more information about these commands, refer to the command reference for this release.
If the syslog export feature is enabled, the switch sends the information to the LRE message logging process and to the system message logging process. For information about configuring this feature, see the "Configuring Syslog Export" section.
Configuring LRE Ports
These sections describe configuration guidelines and how to assign a profile to all or to individual LRE ports. These sections contain more information about LRE links, ports, and profiles:
•
•
•
•
•
•
•
•
•
•
•
•
•
Default LRE Configuration
This is the default LRE configuration:
•
•
•
•
•
•
•
•
•
•
•
Environmental Guidelines for LRE Links
The guidelines for your LRE environment are based on these factors:
•
Each terminated bridge tap in a room can further reduce LRE link distances by 300 feet (91 meters). The quality of the cable, the size of the cable bundles, and cross talk within the bundle also can affect overall reach.
•
If your site is a single building (or is a connected set of buildings), consult a qualified electrician to ensure that the wiring conforms to the appropriate regulations for indoor circuits.
If your site has separate buildings, you must determine how the buildings are cabled to each other. Where the wiring between the LRE switch and CPE device leaves the building (or the armored conduits certified for inside wiring standards), it must be protected against lightning and shorts to high-voltage power. This protection might be provided by fuses or overvoltage protectors that comply with local regulations for outside wiring protection. Consult an expert in local telecommunications regulations for the details of this protection.
•
–
–
–
–
–
–
•
The greatest impact on LRE performance is from the frequency response of the cable at the higher frequencies. LRE signals are more susceptible to interference at higher frequencies. The LRE upstream signal operates at the high end of the frequency spectrum. Cables have higher attenuation at higher frequencies and also interfere with other pairs in the bundle at higher frequencies. This interference or cross talk can significantly impact the signal quality.
Guidelines for Using LRE Profiles
When assigning a profile to a switch LRE port, keep these considerations in mind:
•
To maintain the quality of the LRE connection, use the asymmetric port profiles. These profiles use a low upstream rate but provide a high downstream rate.
Note
•
•
Use the show controllers lre status link privileged EXEC command to display the LRE link statistics and profile information on the LRE ports. For information about this command, refer to the switch command reference.
CPE Ethernet Link Guidelines
Follow these guidelines when configuring CPE Ethernet links:
•
•
Guidelines for Configuring Cisco 575 LRE CPEs and 576 LRE 997 CPEs
You can configure the CPE Ethernet port to operate at 10 or 100 Mbps and at half- or full-duplex mode, depending on the capability of the remote Ethernet device. Autonegotiation for port speed and duplex mode is supported.
The default speed for the CPE Ethernet port is auto. The default duplex mode is half duplex with back pressure.
When the default speed is set to 10 or 100 Mbps with half duplex, the values set are the same. Table 13-5 shows the speed and duplex settings on the CPE Ethernet port and the switch Ethernet port.
Note
100 Mbps with half duplex except for the profile LRE-10 (on the Catalyst 2950ST-8 LRE and 2950ST-24 LRE switches), which is set to 10 Mbps with full duplex.
Table 13-5 Speed and Duplex Settings
10
Full
10
Half
10
Half
10
Half
100
Full
100
Half
100
Half
100
Half
The speeds on the LRE links and CPE Ethernet links do not need to match. However, to prevent the possible loss of data when the LRE link is slower than the CPE Ethernet link, make sure that the CPE Ethernet port is set to half-duplex mode. Use duplex autonegotiation only if the remote device supports 802.1X full-duplex flow control. The PC user should notice no significant difference in performance between 100-Mbps half duplex and 100-Mbps full duplex. Use the cpe duplex and cpe speed interface configuration commands, respectively, to configure the duplex and speed settings on the Cisco 575 LRE CPE or the 576 LRE 997 CPE Ethernet port.
You cannot disable CPE toggle on a link from a Cisco 575 LRE or Cisco 576 LRE CPE to a remote device (such as a PC).
Guidelines for Configuring Cisco 585 LRE CPEs
You can configure the Cisco 585 LRE CPE Ethernet port speed and duplex mode from the CLI, depending on the capability of the remote Ethernet device. Autonegotiation for CPE port speed and duplex mode is supported. Use the cpe duplex and cpe speed interface configuration commands, respectively, to configure the duplex and speed settings on a Cisco 585 LRE CPE Ethernet port.
The default speed for the CPE Ethernet ports is auto. The default duplex mode is half duplex at 100 Mbps with back pressure.
You can enable or disable the CPE Ethernet ports on a per-port basis.
You can disable CPE toggle on a Cisco 585 LRE CPE.
The loopback interface configuration command is not supported on the LRE ports. External loopback on the LRE ports is also not supported. Connecting a CPE Ethernet port to another Ethernet port on the same CPE device can create a loop. If this happens, the switch stops sending to the CPE device and blocks Ethernet traffic coming from the CPE device.
Assigning a Global Profile to All LRE Ports
Global profiles are set on a switch-wide basis.
Port sequences, global sequences, and port profiles have priority over global profiles (see the "Precedence" section). If you assign a global profile to the switch, it cannot override any previously or subsequently set sequence port profile. For more information on sequence and profile precendence, see the "Guidelines for Using LRE Profiles" section.
Changes to the global profile settings are immediately put in effect, and the global mode automatically becomes the active mode.
Beginning in privileged EXEC mode, follow these steps to assign a global profile to the LRE ports:
Step 1
configure terminal
Enter global configuration mode.
Step 2
lre profile profile-name
Enter the global profile name. Select from the list in Table 13-1 or Table 13-2.
Step 3
end
Return to privileged EXEC mode.
Step 4
show controllers lre profile details
Verify the change.
Step 5
copy running-config startup-config
(Optional) Save your entries in the configuration file.
To return to the default global profile, use the no lre profile profile-name global configuration command.
To display the LRE link statistics and profile information on the LRE ports, use the show controllers lre privileged EXEC commands.
Assigning a Profile to a Specific LRE Port
You can set profiles on a per-port basis. You can assign the same profile or different profiles to the LRE ports on the switch. The default active profile on all LRE ports is LRE-10 on the Catalyst 2950ST-8 LRE and 2950ST-24 LRE switches and LRE-6 on the Catalyst 2950ST-24 LRE 997 switch.
The switch resets the ports with the updated profile settings when they are changed.
Beginning in privileged EXEC mode, follow these steps to assign a profile to a specific LRE port:
Step 1
configure terminal
Enter global configuration mode.
Step 2
interface interface-id
Enter interface configuration mode, and specify the LRE port to be configured.
Step 3
profile profile-name
Enter the port profile name (select from the list in Table 13-1 or Table 13-2).
Step 4
end
Return to privileged EXEC mode.
Step 5
show controllers lre profile details
Verify the change.
Step 6
copy running-config startup-config
(Optional) Save your entries in the configuration file.
To delete the profile from a sequence, use the no profile profile-name interface configuration command.
To display the LRE link statistics and profile information on the LRE ports, use the show controllers lre privileged EXEC command.
Assigning a Global Sequence to All LRE Ports
Global sequences are set on a switch-wide basis. If you assign a global sequence to the switch, it overrides any previously or subsequently set profiles. For more information on sequence and profile precendence, see the "Guidelines for Using LRE Profiles" section.
Changes to the global sequence settings are immediately put in effect, and the global mode automatically becomes the active mode.
Beginning in privileged EXEC mode, follow these steps to assign a global sequence to the LRE ports:
Step 1
configure terminal
Enter global configuration mode.
Step 2
lre rate selection sequence sequence-name
Enter the global sequence name. Select from the list in Table 13-3 and Table 13-4.
Step 3
end
Return to privileged EXEC mode.
Step 4
show controllers lre status sequence
Verify the change.
Step 5
copy running-config startup-config
(Optional) Save your entries in the configuration file.
To delete the assigned sequence, use the no lre rate selection sequence sequence-name global configuration command.
To display the LRE link statistics and sequence information on the LRE ports, use the show controllers lre status sequence details privileged EXEC command.
Assigning a Sequence to a Specific LRE Port
You can set sequences on a per-port basis. You can assign the same sequence or different sequences to the LRE ports on the switch. If you assign a sequence on a per-port basis, it overrides any previously or subsequently set profiles or global sequence.
The switch resets the ports with the updated sequence settings when they are changed.
Beginning in privileged EXEC mode, follow these steps to assign a sequence to a specific LRE port:
Step 1
configure terminal
Enter global configuration mode.
Step 2
interface interface-id
Enter interface configuration mode, and enter the number of the LRE port to be configured.
Step 3
sequence sequence-name
Enter the port sequence name (select from the list in Table 13-3 or Table 13-4).
Step 4
end
Return to privileged EXEC mode.
Step 5
show controllers lre status sequence
Verify the change.
Step 6
copy running-config startup-config
(Optional) Save your entries in the configuration file.
To remove a sequence from a port, use the no sequence sequence-name interface configuration command.
To display the LRE link statistics and sequence information on the LRE ports, use the show controllers lre status sequence details privileged EXEC command.
Using Rate Selection to Automatically Assign Profiles
An LRE network requires a profile to be configured for each LRE port that is connected to a CPE device. The default is LRE-10 on the Catalyst 2950ST-8 LRE and 2950ST-24 LRE switches and LRE-6 on the Catalyst 2950ST-24 LRE 997 switch. You can use the rate selection feature to automatically choose a profile from a set of profiles that the switch port uses to establish an LRE link (a link between an LRE switch port and an attached CPE device).
Rate selection is enabled by default, but you must choose a sequence for rate selection to start (in other words, there is no default sequence defined). When rate selection is running, the switch chooses the profile for the LRE interface from a sequence, or predefined series of profiles, that are configured for that interface. The rate-selection algorithm begins with the first profile in the sequence and successively tries the next profiles (in descending order) until a link is established with the CPE device.
When rate selection is enabled, the LRE switch executes rate selection in these scenarios:
•
•
•
•
•
In any of these cases, rate selection obtains the optimal profile for your line conditions.
Note
The switch chooses the appropriate profile for an LRE interface when it executes rate selection. If line conditions of the LRE interface change, rate selection must be executed again.
Precedence
The rate selection feature can be applied at both the port level and at the switch level. Profiles and sequences have a system-defined priority level that work with rate selection to determine the rate for a port or the entire switch. Port sequences have the highest priority; that is, they take precedence over any other profile or sequence. The priority levels, from highest to lowest, are as shown:
1.
2.
3.
4.
See Table 13-1 and Table 13-2 for the list of profiles and Table 13-3 and Table 13-4 for the list of system-defined sequences. You can also use CLI commands or CMS to define your own sequences.
Note
Profile Locking
You can also use rate selection as an installation tool to lock in a particular profile. In this case, you execute rate selection only once at installation; afterwards, rate selection is never executed, even if one of the four listed events occur. You use the rate selection profile lock interface configuration command to lock the profile chosen by rate selection. You can also enter the clear lre rate section [lock] [interface-id] privileged EXEC command to rerun rate selection on the interfaces that have locked the profiles, as needed.
An advantage to profile locking is that the convergence time during bootup is faster if a profile is locked on an LRE port rather than having to go through a profile sequence.
Beginning in privileged EXEC mode, follow these steps to lock a profile in an LRE port that has rate selection enabled:
To unlock a port, use the no rate selection profile lock interface configuration command.
Link Qualification and SNR Margins
When rate selection is running, the SNR is used as an indicator of link quality. The switch does not provide any internal mechanism to ensure link quality. There can be different requirements for link quality, depending on the required bit-error rate and the noise level of the environment. A noisier environment would require a higher SNR to be able to provide a stable link. A lower bit-error rate would require a higher SNR. Typically a 6-dB margin provides an error rate of 10-21 bits.
To provide link stability, you should add a margin to the required SNR. You can configure your margins to an amount that is appropriate for the noise level of your environment. Increasing the margin requirement can cause the system to choose a lower profile, which would in turn translate to a lower rate but with a higher reach.
The switch does not guarantee any margins after a link is activated; margins are only guaranteed only when the link is established. When a link is activated, if the SNR requirements do not match the configured margin level, the link is not established.
Downstream means the remote end of the link, and upstream the local end. The link has to satisfy both the local and remote margin requirements. If either one is not met, the link is advertised as down. This command has no significance if rate selection is disabled on the interface.
Table 13-6 and Table 13-8 list the SNR requirements for downstream rates for different profiles. Table 13-7 and Table 13-9 list the SNR requirements for upstream rates for different profiles.
