Table Of Contents

Configuring Interfaces and Circuits

Interface and Circuit Overview

Interface and Circuit Configuration Quick Start

Configuring Interfaces

Configuring an Interface

Entering a Description for the Interface

Configuring Interface Duplex and Speed

Setting Interface Maximum Idle Time

Showing Interface Duplex and Speed

Bridging an Interface to a VLAN

Configuring Spanning-Tree Bridging for the VLAN

Configuring Port Fast on an Interface

Enabling Port Fast

Enabling BPDU Guard

Showing Port Fast Information

Specifying VLAN Trunking to an Interface

Selecting a Default VLAN in a Trunk

Configuring Spanning-Tree Bridging for a Trunked Interface/VLAN Pair

Configuring the Low-Water Mark of Flow Control Blocks on an Interface

Smoothing Bursty Network Traffic on the CSS 11800 Gigabit Ethernet Module

Showing Bridge Configurations

Showing Trunking Configurations

Showing Interfaces

Showing Interface Statistics

Showing Ethernet Interface Errors

Shutting Down an Interface

Restarting the Interface

Shutting Down All Interfaces

Restarting All Interfaces

Configuring Circuits

Configuring Router-Discovery Lifetime

Configuring Router-Discovery Limited-Broadcast

Configuring Router-Discovery Max-Advertisement-Interval

Configuring Router-Discovery Min-Advertisement-Interval

Showing Circuits

Configuring a Circuit IP Interface

Configuring a Circuit IP Address

Configuring a Circuit-IP Broadcast Address

Configuring Circuit-IP Redirects

Configuring Circuit-IP Unreachables

Enabling Router-Discovery

Configuring Router-Discovery Preference

Enabling a Circuit IP

Disabling a Circuit IP

Showing IP Interfaces

Configuring RIP for an IP Interface

Configuring RIP Default-Route

Configuring RIP Receive

Configuring RIP Send

Configuring RIP Packet Logging

Showing RIP Configurations

Where to Go Next

Configuring Interfaces and Circuits

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This chapter describes how to configure the CSS interfaces and circuits, and bridge interfaces to VLANs. Information in this chapter applies to all CSS models, except where noted.

This chapter contains the following sections:

•Interface and Circuit Overview

•Configuring Interfaces

•Configuring Circuits

•Configuring a Circuit IP Interface

•Configuring RIP for an IP Interface

Interface and Circuit Overview

The CSS provides Ethernet interfaces (ports) that enable you to connect servers, PCs, routers, and other devices to the CSS.

Using the bridge command, you bridge (assign) the interfaces to a specific Virtual LAN (VLAN). Each VLAN circuit requires an IP address. Assigning an IP address to each VLAN circuit allows the CSS to route Ethernet interfaces from VLAN to VLAN.

Using the trunk command, you can assign multiple VLANs to a CSS Ethernet interface port (Fast Ethernet port or Gigabit Ethernet port). A trunk is a point-to-point link carrying the traffic of several VLANs, as illustrated in Figure 2-2. The advantage of a trunk is to save ports when creating a link between two devices implementing VLANs, typically two switches. A trunk bundles virtual links over one physical link. The unique physical link between the two CSSs is able to carry traffic for the specified VLANs.

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Note The trunk and vlan commands (and the associated software functionality) comply with the IEEE 802.1Q Standard for Local and Metropolitan Area Networks: Virtual Bridged Local Area Networks.

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The CSS forwards VLAN circuit traffic to the IP interface. The IP interface passes the traffic to the IP forwarding function where the CSS compares the destination of each packet to information contained in the routing table. Once the CSS resolves the packet addresses, it forwards the packet to the appropriate VLAN and destination port.

When trunking is enabled, the CSS automatically inserts a tag in every frame transmitted over the trunk link to identify the originating VLAN. When the VLAN-aware device receives the frame the device reviews the VLAN-tagged packet to identify the transmitting VLAN. If the VLAN is recognized, the frame is routed to the proper port and VLAN destination. If the frame is from a VLAN that is not assigned to the trunk port, the packet is ignored. By default, the CSS discards untagged packets.

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Note A VLAN-tagged frame is a frame that contains a 4-byte Tag Header immediately following the Source MAC address field in the frame. Each VLAN-tagged frame carries an explicit identification of the VLAN to which it belongs.

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Note that on an 802.1Q trunk, you may configure one VLAN (using the optional default-vlan command) to:

•Accept packets that arrive untagged on the interface

•Transmit untagged packets

By using this method, the CSS can determine which VLAN transmitted an untagged frame. This capability allows VLAN-aware devices and VLAN-unaware devices to transmit and receive information on the same cable.

Figure 2-1 illustrates the interfaces, circuits, and VLANs in a CSS and Figure 2-2 illustrates trunking between VLANs.

Figure 2-1 Content Services Switch Interfaces and Circuits

Figure 2-2 Interface Trunking Between VLANs

Interface and Circuit Configuration Quick Start

Table 2-1 provides a quick overview of the steps required to configure interfaces and circuits. Each step includes the CLI command required to complete the task. For a complete description of each feature and all the options associated with the CLI command, see the sections following Table 2-1.

Table 2-1 Interface and Circuit Configuration Quick Start 

Task and Command Example
1. Log into the CSS.
2. Enter configuration mode by typing config. # config (config)#
3. Enter the interface mode for the interface you wish to configure. This set of interface commands applies to the CSS 11501, CSS 11050, and CSS 11150. (config)# interface e1 (config-if[e1])# This set of interface commands applies to the CSS 11503, CSS 11506, and CSS 11800. (config)# interface 2/1 (config-if[2/1])#
4. Configure the interface duplex, speed, and flow control (default is auto-negotiate). (config-if[2/1])# phy auto-negotiate disable (config-if[2/1])# phy 1Gbits-FD-sym
5. Bridge the interface to a VLAN. All interfaces are assigned to VLAN1 by default. (config-if[2/1])# bridge vlan 2
6. Enable trunking for a CSS Gigabit Ethernet or Fast Ethernet port (optional). (config-if[2/1])# trunk (config-if[2/1])# vlan 2 Create VLAN<2>, [y/n]:y (config-if-vlan[2/1-2])# vlan 3 Create VLAN<3>, [y/n]:y (config-if-vlan[2/1-3])#
7. Configure circuits as required. Assign an IP address and subnet mask to each circuit. (config)# circuit VLAN1 (config-circuit[VLAN1])# ip address 10.3.6.1/24 (config-circuit-ip[VLAN1-10.3.6.1])# exit (config)# circuit VLAN3 (config-circuit[VLAN3])# ip address 10.3.7.1/24 (config-circuit-ip[VLAN3-10.3.7.1])# exit
8. Display the interface configuration (optional). (config-if[2/1])# show interface (config-if[2/1])# exit
9. Save your configuration changes (recommended). If you do not save the running configuration, all configuration changes are lost upon reboot. (config)# copy running-config startup-config

Configuring Interfaces

Interfaces are ports that enable you to connect devices to the CSS and connect the CSS to the Internet. The commands to configure interfaces on the CSS 11501, CSS 11050, and CSS 11150 differ slightly from the commands to configure interfaces on the CSS 11503, CSS 11506, and CSS 11800 because these models requires a slot/port designation. The CSS 11501, CSS 11050, and CSS 11150 do not use the slot/port designation.

Configuring an interface requires you to:

•Configure an interface and enter into the interface mode

•Add a description of the interface (optional)

•Configure interface duplex and speed

•Set the maximum idle time for the interface

•Bridge the interface to a VLAN, or specify VLAN trunking to the interface

•Configuring Port Fast on an interface

•Configure the low water mark of flow control blocks (optional)

•Smooth bursty network traffic on the CSS 11800 Gigabit Ethernet Module (optional)

Configuring an Interface

To configure an interface, enter the interface command and a valid interface name. To use the interface command for a:

•CSS 11501, CSS 11050, or CSS 11150, enter the interface name in interface port format (for example, e1 for Ethernet interface port 1)

•CSS 11503, CSS 11506, or CSS 11800, enter the interface format in slot/port format (for example, 3/1 for Ethernet port 1 on the I/O module in slot 3)

To configure interface port 1 on a CSS 11501, CSS 11050, or CSS 11150, access interface mode for the port by entering:

(config)# interface e1

(config-if[e1])#

To configure interface 1 on a CSS 11503, CSS 11506, or CSS 11800, access interface mode for the I/O module in slot 2 by entering:

(config)# interface 2/1

(config-if[2/1])#

Note in both examples that the CSS changes from configuration mode to the specific interface mode.

Entering a Description for the Interface

To help you to identify the interface, use the description command to describe it. Enter a quoted text string from 1 to 255 characters in length including spaces.

For example:

(config-if[2/1])# description "Connects to server17"

To display an interface description, use the show running-config interface command. For example:

(config-if[2/1])# show running-config interface 2/1

!************************ INTERFACE ************************

interface 2/1

	description "Connects to server17"

	bridge vlan 2

To remove an interface description, enter:

(config-if[2/1])# no description

Configuring Interface Duplex and Speed

By default, the CSS Fast Ethernet interface and Gigabit Ethernet interface are configured to auto-negotiate, which enables the CSS ports to automatically detect the network line speed (Fast Ethernet only) and duplex of incoming signals, and to synchronize those parameters during data transfer. Auto-negotiation enables the CSS and the other devices on the link to achieve the maximum common level of operation.

When using Fast Ethernet ports with older equipment that cannot transmit the duplex and speed with its signals, you can manually configure the speed (10 Mbps, 100 Mbps) and duplex (half or full duplex) of the CSS port to match the transmitting equipment.

When using Gigabit Ethernet ports, if the link does not come up (perhaps due to traffic congestion), you may need to force the CSS and its link partner into a specific mode. The CSS allows you to manually select a full duplex and flow control (pause frame) mode. Flow control allows the CSS to control traffic during congestion by notifying the other port to stop transmitting until the congestion clears. When the other device receives the pause frame it temporarily stops transmitting data packets. When the CSS detects local congestion and becomes overwhelmed with data, the Gigabit Ethernet ports transmits a pause frame. Both the CSS Gigabit Ethernet and its link partner must be configured with the same pause method (asymmetric, symmetric, or both). By default, all Gigabit Ethernet ports are configured to full duplex mode with symmetric pause (pause frames transmitted and received by the CSS).

Use the phy command to configure the duplex, speed (Fast Ethernet ports only), and flow control (Gigabit Ethernet ports only) for the interface ports, as follows:

•phy auto-negotiate - For the 11000 series CSS only. Resets the Fast Ethernet and Gigabit Ethernet ports to automatically negotiate port speed and duplex of incoming signals.

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Note Pause mode during auto-negotiate is not supported for the Fast Ethernet ports.

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•phy auto-negotiate {enable | disable} - For the 11500 series CSS only. Disables the Gigabit Ethernet interface from automatically negotiating duplex of incoming signals. By default, auto-negotiation is enabled for all Gigabit Ethernet ports.

Gigabit Ethernet port auto-negotiation remains enabled when a pause mode command is specified in order for the Gigabit Ethernet interface ports to act upon the link partner's flow control capability. If it is necessary to disable auto-negotiation for the Gigabit Ethernet port when using a pause mode, enter the phy auto-negotiate disable command.

•phy 10Mbits-FD - Set the Fast Ethernet port to 10 Mbps and full-duplex.

•phy 10Mbits-HD - Set the Fast Ethernet port to 10 Mbps and half-duplex.

•phy 100Mbits-FD - Set the Fast Ethernet port to 100 Mbps and full-duplex.

•phy 100Mbits-HD - Set the Fast Ethernet port to 100 Mbps and half-duplex.

•phy 1Gbits-FD-asym - Set the Gigabit Ethernet port to full-duplex mode with asymmetric pause frames transmitted toward the link partner. Asymmetric is useful when you need the CSS to pause its link partner but not to respond to pause frames transmitted from its partner.

•phy 1Gbits-FD-no pause - Set the Gigabit Ethernet port to full-duplex mode with no pause frames transmitted or received.

•phy 1Gbits-FD-sym - Set the Gigabit Ethernet port to full-duplex mode with symmetric pause (pause frames transmitted and received by the CSS). Symmetric is useful for point-to-point links. By default, all Gigabit Ethernet ports are configured to full duplex mode with symmetric pause.

•phy 1Gbits-FD-sym-asym - Set the Gigabit Ethernet port to full-duplex mode with symmetric and asymmetric pause frames used with the local device.

For example, to configure Fast Ethernet interface 1 on the I/O module in slot 2 of the CSS 11503 to 100 Mbps and half-duplex, enter:

(config-if[2/1])# phy 100Mbits-HD

For example, to configure gigabit interface 1 on the SCM in slot 1 of the CSS 11503 to full-duplex mode with asymmetric pause, enter:

(config-if[1/1])# phy auto-negotiate disable

(config-if[1/1])# phy 1Gbits-FD-asym

Setting Interface Maximum Idle Time

Use the max-idle command as a troubleshooting tool to verify an interface's ability to receive traffic. If the interface does not receive traffic within the configured idle time, the CSS reinitializes it automatically.

Set the idle time to a value greater than the interval over which the interface is receiving traffic. For example, if the interface receives traffic every 90 seconds, set the idle time to a value greater than 90 seconds. If you set the idle time to less than 90 seconds, the CSS would continuously reinitialize the interface before the interface was able to receive traffic.

Enter the idle time from 15 to 65535 seconds. The default is 0, which disables the idle timer.

For example, to set the maximum idle time to 180 seconds for interface port 1 on a CSS 11503, the I/O module in slot 2, enter:

(config-if[2/1])# max-idle 180

To reset the idle time for an interface to its default value of 0, enter:

(config-if[2/1])# no max-idle

Showing Interface Duplex and Speed

To show duplex and speed values for all interfaces, enter the show phy command. For example:

(config)# show phy

To show duplex and speed value for a specific interface, enter the show phy command and the interface name. For a CSS 11501, CSS 11050, or CSS 11150, enter the interface name in interface port format (for example, e2). For a CSS 11503, CSS 11506, or CSS 11800, enter the interface format is slot/port (for example, 3/1).

For example, to show the interface and duplex speed for interface port 1 on a CSS 11506, the I/O module in slot 2, enter:

(config)# show phy 2/1

Table 2-2 describes the fields in the show phy output.

Table 2-2 Field Descriptions for the show phy Command 

Field	Description
Name	The name of the physical interface.
Configured Speed	The configured speed for the Ethernet interface (port) in the CSS. Auto indicates that the speed is automatically negotiated.
Configured Duplex	The configured duplex for the Ethernet interface (port) in the CSS. Auto indicates that the duplex is automatically negotiated.
Actual Speed	The actual speed for the Ethernet interface (port) in the CSS.
Actual Duplex	The configure duplex for the Ethernet interface (port) in the CSS.
Link	The link status, up or down.
Rev	Revision number of the chip.
Partner Auto	Whether auto-negotiation is available on the link partner.

Bridging an Interface to a VLAN

To bridge an interface to a VLAN, use the bridge vlan command to specify a virtual local area network (VLAN) and associate it with the specified interface port. Enter an integer from 1 to 4094 as the VLAN identifier. The default is 1. All interfaces are assigned to VLAN1 by default.

The following list defines the maximum number of VLANs supported by the specific CSS models:

•CSS 11501 and CSS 11503 - A maximum of 256 VLANs

•CSS 11506 - A maximum of 512 VLANs

•CSS 11050 and CSS 11150 - A maximum of 16 VLANs

•CSS 11800 - A maximum of 128 VLANs

To configure e1 to VLAN2 on the CSS 11501, CSS 11050, or CSS 11150, enter:

(config-if[e1])# bridge vlan 2

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Note When you enter the bridge vlan command, enter the word vlan in lowercase letters and include a space before the VLAN number (for example, vlan 2).

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Note The CSS Gigabit Ethernet and Fast Ethernet interface ports support trunking to multiple VLANs through the trunk command. The trunk command would be used for the Ethernet interface instead of bridge vlan (and the other associated bridge CLI commands). See "Specifying VLAN Trunking to an Interface" for details.

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To restore the default VLAN1 on the CSS 11501, CSS 11050, or CSS 11150, enter:

(config-if[e7])# no bridge vlan

To display all interfaces and the VLANs to which they are configured, enter the show circuit command. See "Showing Circuits" in this chapter for information about the show circuits command.

In the show circuit display, VLANs appear as VLAN (uppercase, with no space before the VLAN number).

Configuring Spanning-Tree Bridging for the VLAN

This section describes how to configure spanning-tree bridging for the interfaces in a VLAN using the following bridge command options:

•bridge pathcost - Set the path cost for an interface

•bridge priority - Set the bridge spanning-tree priority

•bridge state - Set the bridge state to enable or disable for an interface

Configuring Spanning-Tree Bridge Pathcost

To set the spanning-tree path cost for an interface, use the bridge pathcost command. The cost is the contribution of the interface to the vast path cost towards spanning-tree root. Enter an integer from 1 to 65535. The default is dynamically configured based on the interface speed.

For example, to set a path cost of 9 for e7 on the CSS 11501, CSS 11050, or CSS 11150, enter:

(config-if[e7])# bridge pathcost 9

To restore the default path cost, enter:

(config-if[e7])# no bridge pathcost

Configuring Spanning-Tree Bridge Priority

To set the spanning-tree bridge priority for a port, use the bridge priority command. Enter an integer from 0 to 255. The default is 128.

For example, to set a bridge priority of 100 for e7 on the CSS 11501, CSS 11050, or CSS 11150, enter:

(config-if[e7])# bridge priority 100

To restore the default priority of 128, enter:

(config-if[e7])# no bridge priority

Configuring Spanning-Tree Bridge State

To set the spanning-tree bridge state to enable or disable for an interface, use the bridge state command. An interface is set to bridge state enable by default.

To enable the bridge state for e7 on the CSS 11501, CSS 11050, or CSS 11150, enter:

(config-if[e7])# bridge state enable

To disable the bridge state for e7, enter:

(config-if[e7])# bridge state disable

Configuring Port Fast on an Interface

The Port Fast feature immediately brings an 11500 series CSS interface (port) to the forwarding state from a blocking state, bypassing the listening and learning states. You can use Port Fast on ports connected to a single workstation or server to allow those devices to immediately connect to the network, rather than waiting for the spanning tree to converge.

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Note Ports connected to a single workstation or server should not receive bridge protocol data units (BPDUs).

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Caution Because the purpose of Port Fast is to minimize the time ports must wait for spanning-tree to converge, it is effective only when used on ports connected to end stations. If you enable Port Fast on a port connecting to another switch, you risk creating a spanning-tree loop. Consider using the BDPU guard feature to avoid this.

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The following sections provide information on:

•Enabling Port Fast

•Enabling BPDU Guard

•Showing Port Fast Information

Enabling Port Fast

A port with the Port Fast feature enabled is moved directly to the spanning-tree forwarding state without waiting for the standard forward-time delay.

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Caution Use Port Fast only when connecting a single end station to a CSS interface. Enabling this feature on a port connected to a switch or hub could prevent spanning tree from detecting and disabling loops in your network, which could cause broadcast storms and address-learning problems.

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To enable Port Fast on a non-trunked port, use the interface mode bridge port-fast enable command. You cannot configure Port Fast on a trunked port. By default, Port Fast is disabled on the port.

(config-if[2/1])# bridge port-fast enable

To disable the Port Fast feature, use the interface mode bridge port-fast disable command.

(config-if[2/1])# bridge port-fast disable

Enabling BPDU Guard

Use the BPDU guard to prevent a Port Fast port on the CSS from participating in the spanning tree. When you globally enable BPDU guard on the Port Fast ports, spanning tree shuts down the ports that receive BPDUs. For information to enable Port Fast on an interface port, see "Configuring Port Fast on an Interface".

In a valid configuration, the enabled Port Fast ports do not receive BPDUs. Receiving a BPDU on a Port Fast-enabled port signals an invalid configuration, such as the connection of an unauthorized device, and the BPDU guard feature puts the port in the disabled state. The BPDU guard feature provides a secure response to invalid configurations because you must manually put the port back in service.

To globally enable the BPDU guard on the CSS, use the global configuration bridge bdpu-guard enabled command:

#(config) bridge bpdu-guard enabled

To disable BPDU guard, use the global configuration bridge bdpu-guard disabled command:

#(config) bridge bpdu-guard disabled

Showing Port Fast Information

To display whether Port Fast is enabled or disabled on all interfaces, use the show bridge port-fast command. This command is available in all modes. This command also displays whether the BPDU guard feature is enabled or disabled on the CSS and the state of the interfaces.

Table 2-3 describes the fields in the show bridge port-fast output.

Table 2-3 Field Description for the show bridge port-fast Command

Field	Description
BPDU guard is state on this switch.	The state of the BPDU guard feature on the CSS, ENABLED or DISABLED.
Name	The number of the module slot and interface.
IfIndex	The interface index number.
Type	The type of interface. •fe indicates a Fast Ethernet interface. •ge indicates a Gigabit Ethernet interface.
Oper	The operational state of the interface, Up or Down.
Admin	The administration state, Enable or Down.
PortFast State	Whether Port Fast is enabled or disabled on the interface.

Specifying VLAN Trunking to an Interface

To activate VLAN trunking for a CSS interface, use the trunk command and specify all VLANs that are to include the specified port as part of the VLAN. The trunk command also converts the link into a trunk link. To specify the number of each VLAN that is to be associated with the Gigabit Ethernet or Fast Ethernet port, use the vlan command. Enter an integer from 1 to 4094 as the VLAN identifier.

The following list defines the maximum number of VLANs supported by the specific CSS models:

•CSS 11501 and CSS 11503 - A maximum of 256 VLANs

•CSS 11506 - A maximum of 512 VLANs

•CSS 11050 and CSS 11150 - A maximum of 16 VLANs

•CSS 11800 - A maximum of 128 VLANs

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Note The CSS software has a dependency when using the trunk command. For trunking to be enabled, all VLAN bridging commands for any active VLAN must first be disabled for the Gigabit Ethernet or Fast Ethernet interface by using the no bridge vlan, no bridge priority, no bridge state, and no bridge pathcost commands. If you do not disable VLAN bridging on an interface, the CSS software instructs you to do so.

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To configure Gigabit Ethernet port 1 in slot 1 for use in VLAN2, VLAN3, and VLAN9, enter:

(config-if[1/1])# trunk

(config-if[1/1])# vlan 2

Create VLAN<2>, [y/n]:y

(config-if-vlan[1/1-2])# vlan 3

Create VLAN<3>, [y/n]:y

(config-if-vlan[1/1-3])# vlan 9

Create VLAN<9>, [y/n]:y

(config-if-vlan[1/1-9])#

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Note When you enter the trunk command, enter the word vlan in lowercase letters and include a space before the VLAN number (for example, vlan 2).

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Every time you enter a vlan command for a new VLAN, the software automatically prompts you to create the specified VLAN (where y instructs the software to create the VLAN and n cancels the VLAN creation).

To disable trunking on the specified interface and associated VLANs, enter:

(config-trunkif[2/3])# no trunk

The no trunk command turns off all trunking, removes all specified vlan commands associated with the interface, and deletes this information from the running configuration. The interface is returned to VLAN1 by default.

To display all interfaces and the VLANs to which they are configured, enter the show circuit command. See Table 2-10 for information about the show circuits command.

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Note In the show circuit display, VLANs appear as VLAN (uppercase, with no space before the VLAN number). For an interface that has trunking enabled, a "-n" (where n is the associated VLAN number) is appended to the prefix. In this example, 1/4-1 indicates slot 1, port 4, VLAN1.

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Selecting a Default VLAN in a Trunk

To define a default VLAN that has the capability to accept packets that arrive untagged on the interface, include the default-vlan command as part of the trunk/VLAN definition. The command also specifies that the packets transmitted from this VLAN will be untagged. The default VLAN must be explicitly set if you want untagged packets to be processed by the CSS. Otherwise these packets will be discarded.

The default-vlan command can only be specified for a single VLAN. If you attempt to use this command for another VLAN, the software instructs you to disable the current default VLAN (using the no default-vlan command).

For example:

(config-if[1/1])# trunk

(config-if[1/1])# vlan 2

Create VLAN<2>, [y/n]:y

(config-if-vlan[1/1-2])# vlan 3

Create VLAN<3>, [y/n]:y

(config-if-vlan[1/1-3])# default-vlan

To remove the default VLAN selection, enter:

(config-if-vlan[1/1-3])# no default-vlan

Configuring Spanning-Tree Bridging for a Trunked Interface/VLAN Pair

This section describes how to configure spanning-tree bridging for the interfaces in a VLAN using the following bridge command options:

•bridge pathcost - Set the path cost for a given interface/VLAN pair

•bridge priority - Set the bridge spanning-tree priority for a given interface/VLAN pair

•bridge state - Set the bridge state to enable or disable for a given interface/VLAN pair

When connecting a Cisco Catalyst switch to a CSS using an 802.1Q trunk and the spanning-tree protocol, be aware that Cisco switches run a spanning-tree instance per VLAN. When you configure an 802.1Q trunk on an Ethernet interface for the Catalyst switch, the Bridge Protocol Data Units (BPDUs) are tagged with the corresponding VLAN ID and the destination MAC address is changed from the standard 01-80-C2-00-00-00 to the proprietary 01-00-0c-cc-cc-cd. This modification allows Cisco switches operating in a non-Cisco (a mix of other vendors) 802.1Q trunk environment to maintain spanning-tree states for all VLANs.

Though the CSS maintains a spanning-tree instance per VLAN as well, it continues to use the standard 01-80-C2-00-00-00 destination MAC address for all BPDUs (tagged or untagged). When you connect a Cisco Catalyst switch to a CSS over an 802.1Q trunk, the result is that neither switch will recognize the other's BPDUs, and both will assume root status. If a spanning-tree loop is detected, the Catalyst switch goes into blocking mode on one of its looped ports.

Configuring Bridge Pathcost for a Trunked Interface/VLAN Pair

To set the spanning-tree port path cost for a given interface/VLAN pair, use the bridge pathcost command. The cost is the contribution of the given interface/VLAN pair to the vast path cost towards spanning-tree root. Enter an integer from 1 to 65535. The default is dynamically configured based on the link speed.

To set a path cost of 2 for slot 1, port 1, VLAN3, enter:

(config-if-vlan[1/1-3])# bridge pathcost 2

To restore the default path cost, enter:

(config-if-vlan[1/1-3])# no bridge pathcost

Configuring Bridge Priority for a Trunked Interface/VLAN Pair

To set the spanning-tree bridge priority for a given interface/VLAN pair, use the bridge priority command. Enter an integer from 0 to 255. The default is 128.

To set a bridge priority of 100 for slot 1, port 1, VLAN3, enter:

(config-if-vlan[1/1-3])# bridge priority 100

To restore the default priority of 128, enter:

(config-if-vlan[1/1-3])# no bridge priority

Configuring Bridge State for a Trunked Interface/VLAN Pair

To set the bridge state to enable or disable for a given interface/VLAN pair, use the bridge state command. An interface is set to bridge state enable by default.

To enable the bridge state for slot 1, port 1,VLAN3, enter:

(config-if-vlan[1/1-3])# bridge state enable

To disable the bridge state for slot 1, port 1, located in VLAN3, enter:

(config-if-vlan[1/1-3])# bridge state disable

Configuring the Low-Water Mark of Flow Control Blocks on an Interface

Use the fcb-lowwater command to configure the low-water mark of flow control blocks (FCBs) on the interface. The low-water mark is the percentage of the total number of FCBs available. If the number of FCBs available on a port goes below the low-water mark, then aggressive flow recovery occurs.

The syntax for this interface mode command is:

fcb-lowwater percentage

Enter the percentage as the total number of available FCBs. Enter a number from 1 to 100. The default is 25%.

To set the percentage of available FCBs to 40 percent:

(config-if[1/1-3])# fcb-lowwater 40

To reset the percentage of available FCBs to its default of 25, enter:

(config-if[1/1-3])# no fcb-lowwater

Smoothing Bursty Network Traffic on the CSS 11800 Gigabit Ethernet Module

Use the gem-traffic-bursty global configuration mode command when it becomes necessary to smooth bursty traffic for applications sensitive to packet loss. This command is only supported in the CSS 11800 for Gigabit Ethernet Modules (GEMs).

Traffic burstiness is the occurrence of extreme amounts of traffic for a short period of time (when traffic bursts over a rate of 16 Gbps for short intervals). During extremely heavy traffic loads, when a single GEM port has greater than one gigabit per second of incoming network traffic, substantial packet loss can occur. This condition can easily occur when a group of servers attached to multiple ports send traffic simultaneously to a single client uplink port.

If the traffic load at the client uplink port is at a rate close to a gigabit per second with occasional bursts of greater than one gigabit per second, you can use the gem-traffic-bursty command to reduce overall packet loss. This command can greatly reduce packet loss for applications sensitive to this condition, for example, video and audio streaming applications.

If the traffic load at the client uplink port remains at a constant rate greater than one gigabit per second, you may need to perform a network reconfiguration, for example, configure an additional client uplink port. You should not use the gem-traffic-bursty command to solve the problem.

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Note When you enter the gem-traffic-bursty command it applies to all GEM modules in the CSS 11800 chassis (installed prior to and after you enter the command).

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To smooth bursty traffic on the GEMs in a CSS 11800, enter:

(config)# gem-traffic-bursty

To reset the default traffic handling behavior on the GEM, enter:

(config)# no gem-traffic-bursty

Showing Bridge Configurations

The CSS enables you to show bridging information for a specific VLAN in the CSS. To display this information, use the show bridge command.

The syntax for this interface mode command is:

show bridge [forwarding|status] {vlan_number}

The options and variables are:

•forwarding - Displays the bridge forwarding table including the VLAN number, the MAC addresses, and port numbers.

•status - Displays the bridge spanning-tree status including the Spanning Tree Protocol (STP) state, designated root, bridge ID, and root maximum age, hello time and forward delay, and port information including state, VLAN, root and port cost, and designated root and port number.

•vlan_number - Displays the forwarding table or spanning tree status for the specified VLAN number. To see a list of VLAN numbers, enter show bridge [forwarding|status] ?

Table 2-4 describes the fields in the show bridge forwarding output.

Table 2-4 Field Descriptions for the show bridge forwarding Command

Field	Description
VLAN	The bridge interface virtual LAN number
MAC Address	The MAC address for the entries
Port Number	The port number for the bridge forwarding table

To display bridge status information, use the show bridge status command.

---

Note To display bridge forwarding or bridge status for a specific VLAN in the CSS, enter the show bridge forwarding or the show bridge status command with the VLAN number. Entering the show bridge command with a VLAN number returns a list of available VLANs.

---

Table 2-5 describes the fields in the show bridge status output.

Table 2-5 Field Descriptions for the show bridge status
Command 

Field	Description
STP State	The state of the spanning-tree protocol, enabled or disabled.
Root Max Age	The timeout period in seconds of the host for timing out root information.
Root Hello Time	The interval in seconds that the root broadcasts its hello message to other CSSs.
Root Fwd Delay	The delay time in seconds that the root uses for forward delay.
Designated Root	The bridge ID for the designated root.
Bridge ID	The bridge ID of this bridge.
Port	The port ID.
State	The state of the port. The possible states are: •Block - The blocking state. A port enters the blocking state after CSS initialization. The port does not participate in frame forwarding. •Listen - The listening state. This state is the first transitional state a port enters after the blocking state. The port enters this state when STP determines that the port should participate in frame forwarding. •Learn - The learning state. The port enters the learning state from the listening state. The port in the learning state prepares to participate in frame forwarding. •Forward - The forwarding state. The port enters the forwarding state from the learning state. A port in the forwarding state forwards frames. •Disabled - The disabled state. A port in the disabled state does not participate in frame forwarding or STP. A port in the disabled state is non operational.
Designated Bridge	The bridge ID for the designated bridge.
Designated Root	The bridge ID for the designated root.
Root Cost	The cost of the root.
Port Cost	The cost of the port.
Desg Port	Designated port.

Showing Trunking Configurations

The CSS enables you to show VLAN trunk status information for Gigabit Ethernet and Fast Ethernet ports. To display this information, use the show trunk command.

Table 2-6 describes the fields in the show trunk output.

Table 2-6 Field Description for the show trunk Command

Field	Description
Port	The CSS port
VLAN	The VLAN on the port
Default VLAN	The configured default VLAN on the port (if there is no configured default VLAN, "None" appears in this field)

Showing Interfaces

To display a list of valid interfaces for the CSS, use the show interface command. For example:

(config)# show interface

To display information for a specific interface, enter the show interface command and the interface name. For a CSS 11501, CSS 11050, or CSS 11150, enter the interface name in interface port format (for example, e2). For a CSS 11503, CSS 11506, or CSS 11800, enter the interface format is slot/port (for example, 3/1).

For example, to show interface information for port 1 on a CSS 11503, the I/O module in slot 2, enter:

(config)# show interface 2/1

Table 2-7 describes the fields in the show interface output.

Table 2-7 Field Descriptions for the show interface Command

Field	Description
Name	The name of the interface.
ifIndex	The ifIndex for the interface.
Type	The type of interface. The possible types include: •fe - Fast Ethernet interface •ge - Gigabit Ethernet interface •console - Console interface
Oper	Operational state, up or down.
Admin	Administration state, up or down.
Last Change	The date of the last state change.

Showing Interface Statistics

To display the extended 64-bit MIB-II statistics for a specific interface or all interfaces in the CSS, use the show mibii command. The Enterprise ap64Stats MIB defines these statistics. To display the RFC1213 32-bit statistics, include the -32 suffix.

---

Note The Gigabit Ethernet module port statistics are an aggregation of all ports on the module.

---

To display extended MIB-II statistics for a specific interface in the CSS, enter the show mibii command with the interface name. To see a list of interfaces in the CSS, enter show mibii ?.

Table 2-8 describes the fields in the show mibii output.

Table 2-8 Field Descriptions for the show mibii Command 

Field	Description
MAC	The interface address at the protocol layer immediately below the network layer in the protocol stack. For interfaces that do not have such an address (for example, a serial line), this object contains an octet string of zero length.
Administrative	The desired state of the interface (Enabled, Disabled, or Testing). The testing state indicates that no operational packets can be passed.
MTU	The size of the largest datagram that can be sent or received on the interface, specified in octets. For interfaces that are used for transmitting network datagrams, this is the size of the largest network datagram that can be sent on the interface.
In Octets	The total number of octets received on the interface, including framing characters.
In Unicast	The number of subnetwork-unicast packets delivered to a higher-layer protocol.
In Multicast	The number of non-unicast (for example, subnetwork-broadcast or subnetwork-multicast) packets delivered to a higher-layer protocol.
In Errors	The number of inbound packets that contained errors preventing them from being delivered to a higher-layer protocol.
In Discards	The number of inbound packets that were chosen to be discarded even though no errors had been detected to prevent their being delivered to a higher-layer protocol. One possible reason for discarding such a packet could be to free up buffer space.
In Unknown	The number of packets received over the interface that were discarded because of an unknown or unsupported protocol.
Last Change	The value of sysUpTime at the time the interface entered its current operational state. If the state has not changed since the time the CSS came up, the sysUptime is when the port was initialized.
Operational	The current operational state of the interface (Up, Down, or Testing). The Testing state indicates that no operational packets can be passed.
Speed	An estimate of the interface's current bandwidth in bits per second. For interfaces that do not vary in bandwidth or for those where no accurate estimation can be made, this object contains the nominal bandwidth.
Queue Len	The length of the output packet queue (in packets).
Out Octets	The total number of octets transmitted out of the interface, including framing characters.
Out Unicast	The total number of packets that higher-level protocols requested be transmitted to a subnetwork-unicast address, including those that were discarded or not sent.
Out Multicast	The total number of packets that higher-level protocols requested be transmitted to a non-unicast (for example, a subnetwork-broadcast or subnetwork-multicast) address, including those that were discarded or not sent.
Out Errors	The number of outbound packets that could not be transmitted because of errors.
Out Discards	The number of outbound packets that were chosen to be discarded even though no errors had been detected to prevent their being transmitted. One possible reason for discarding such a packet could be to free up buffer space.

To clear interface statistics, use the clear statistics command in SuperUser mode. For example:

# clear statistics

Showing Ethernet Interface Errors

To list the errors on an Ethernet interface, use the show ether-errors command and options. When required, enter the interface name as a case-sensitive unquoted text string. To see a list of interfaces, enter show ether-errors ?.

The command provides the following options:

•show ether-errors - Display the extended 64-bit statistics for errors on all Ethernet interfaces in the CSS. The Enterprise ap64Stats MIB defines these statistics.

•show ether-errors interface name - Display the extended 64-bit statistics for errors on a specific Ethernet interface in the CSS. The Enterprise ap64Stats MIB defines these statistics. Enter the interface name as a case-sensitive unquoted text string.

•show ether-errors zero - Display the Ethernet errors for all Ethernet interfaces in the CSS and reset the statistics to zero upon retrieval.

•show ether-errors zero interface name - Display the Ethernet errors for the specified Ethernet interface in the CSS and reset the statistics to zero upon retrieval. Enter the interface name as a case-sensitive unquoted text string.

•show ether-errors-32 - Display the RFC1398 32-bit statistics, include the -32 suffix.

•show ether-errors-32 interface name - Display the RFC1398 32-bit statistics, include the -32 suffix. Enter the interface name as a case-sensitive unquoted text string.

Table 2-9 describes the fields in the show ether-errors output.

Table 2-9 Field Descriptions for the show ether-errors Command 

Field	Description
Alignment	The number of frames with alignment errors (frames that do not end with a whole number of octets and have a bad CRC) received on the interface.
FCS	The number of frames received on the interface that are an integral number of octets in length but do not pass the FCS check.
Single Collision	The number of successfully transmitted frames on the interface for transmissions that were inhibited by exactly one collision.
Multiple Collisions	The number of successfully transmitted frames on the interface for transmissions that were inhibited by more than one collision.
SQE Test	The number of times that the SQE TEST ERROR message is generated.
Deferred Tx	The number of frames for which the first transmission attempt on the interface is delayed because the medium is busy. The count represented by an instance of this object does not include frames involved in collisions.
Internal RX Errors	The number of frames for which reception on the interface failed due to an internal MAC sublayer receive error.
Frame too Long	The number of frames received on the interface that exceeded the maximum permitted frame size.
Carrier Sense Errors	The number of times that the carrier sense condition was lost or never asserted when attempting to transmit a frame on the interface.
Internal Tx Errors	The number of frames for which transmission on the interface failed due to an internal MAC sublayer transmit error.
Excessive Collisions	The number of frames for which transmission on the interface failed due to excessive collisions.
Late Collisions	The number of times that a collision is detected on the interface later than 512 bit-times into the transmission of a packet.

Shutting Down an Interface

To shutdown an interface, use the admin-shutdown command in interface mode.

---

Caution Shutting down an interface terminates all connections to the interface.

---

To shut down interface e3 on the CSS 11501, CSS 11050, or CSS 11150, enter:

(config-if[e3]) admin-shutdown physical

Restarting the Interface

To restart the interface, enter the no admin-shutdown command. To restart interface e3 on the CSS 11501, CSS 11050, or CSS 11150, enter:

(config-if[e3])# no admin-shutdown physical

Shutting Down All Interfaces

To shut down all interfaces simultaneously, use the admin-shutdown command at the SuperUser prompt. This command provides a quick way to shut down all physical devices in the CSS except the Console and Management ports.

---

Caution Shutting down an interface terminates all connections to the interface.

---

To shut down all interfaces, enter:

# admin-shutdown

To shutdown one interface, use the admin-shutdown command in interface mode. See "Shutting Down an Interface" earlier in this chapter.

Restarting All Interfaces

To restart all interfaces, enter:

# no admin-shutdown

Configuring Circuits

A circuit on the CSS is a logical entity that maps IP interfaces to a logical port or group of logical ports (for example, a VLAN). Each VLAN circuit requires an IP address. Assigning an IP address to each VLAN circuit allows the CSS to route Ethernet interfaces from VLAN to VLAN.

To enter a specific circuit configuration mode, enter the circuit command and VLAN as shown in the following example:

(config)# circuit VLAN7

(config-circuit[VLAN7])#

---

Note When you use the circuit command, enter the word `VLAN' in uppercase letters and do not include a space between VLAN and the VLAN number (for example, VLAN7).

---

You can configure the following settings for a circuit:

•router-discovery lifetime - Configure router discovery lifetime

•router-discovery limited-broadcast - Transmit router discovery packets using 225.255.255.255

•router-discovery max-advertisement-interval - Configure router discovery maximum advertisement interval timer

•router-discovery min-advertisement-interval - Configure router discovery minimum advertisement interval timer

---

Note The CSS allows you to enable router discovery and define a router discovery preference for each interface. To enable router discovery and define a preference per interface, see "Enabling Router-Discovery" and "Configuring Router-Discovery Preference", respectively, later in this chapter.

---

Configuring Router-Discovery Lifetime

To configure the maximum age in seconds that hosts remember router advertisements, use the router-discovery lifetime command with an integer between 0 and 9000 seconds. The default is 3 x the max-advertisement-interval.

For example:

(config-circuit[VLAN7])# router-discovery lifetime 600

To reset the time to the default of 3 x the max-advertisement-interval, enter:

(config-circuit[VLAN7)# no router-discovery lifetime

Configuring Router-Discovery Limited-Broadcast

To transmit router discovery packets using the broadcast address 255.255.255.255, use the router-discovery limited-broadcast command. The default is 224.0.0.1. For example:

(config-circuit[VLAN7])# router-discovery limited-broadcast

To revert to the default of 224.0.0.1, enter:

(config-circuit[VLAN7)# no router-discovery limited-broadcast

Configuring Router-Discovery Max-Advertisement-Interval

To configure the router discovery maximum advertisement interval, use the router-discovery max-advertisement-interval command. The maximum value defines the interval between advertisements in seconds. Enter an integer from 4 to 1800. The default is 600 (10 minutes). For example:

(config-circuit[VLAN7])# router-discovery 
max-advertisement-interval 300

To restore the router discovery maximum advertisement interval to the default of 600, enter:

(config-circuit[VLAN7])# no router-discovery 
max-advertisement-interval

Configuring Router-Discovery Min-Advertisement-Interval

To configure router discovery minimum advertisement interval timers, use the router-discovery min-advertisement-interval command. The minimum value defines the minimum interval between advertisements in seconds. Enter an integer from 0 to 1800.

The default is 0.75 times the max-advertisement-interval. If this value is greater than 0, it must be less than the maximum value.

For example:

(config-circuit[VLAN7])# router-discovery 
min-advertisement-interval 100

To reset the minimum router advertisement interval to the default of 0.75 times the maximum advertisement value, enter:

(config-circuit[VLAN7])# no router-discovery 
min-advertisement-interval

Showing Circuits

To show circuit information, use the show circuits command. A circuit on the CSS is a logical entity that maps IP interfaces to a logical port or group of logical ports.

This command provides the following options:

•show circuits - Display all circuit information for circuits that are currently up

•show circuits all - Display all circuit information regardless of circuit state

•show circuit name circuit name - Display circuit information for a specific circuit regardless of state

To list all circuits and their interfaces in the Up state, enter:

# show circuits

To list all circuits and their interfaces regardless of their state, enter:

# show circuits all

To list an individual circuit, enter:

# show circuits name VLAN5

Table 2-10 describes the fields in the show circuits output.

Table 2-10 Field Descriptions for the show circuits Command 

Field	Description
Circuit Name	The circuit name. Note that in the show circuit output, VLANs appear as VLAN (uppercase, with no space before the VLAN number).
Circuit State	The state of the circuit. The possible states are: •active-ipEnabled •down-ipEnabled •active-ipDisabled •down-ipDisabled
IP Address	IP interface address.
Interface(s)	The interface associated with the circuit.
Operational Status	The operational status of the interface (up or down).

Configuring a Circuit IP Interface

A circuit on the CSS is a logical entity that maps IP interfaces to a logical port or group of logical ports (for example, a VLAN). Each VLAN circuit requires an IP address. Assigning an IP address to each VLAN circuit allows the CSS to route Ethernet interfaces from VLAN to VLAN.

To enter a specific circuit configuration mode, enter the circuit command and VLAN as shown in the following example:

(config)# circuit VLAN7

(config-circuit[VLAN7])#

---

Note When you use the circuit command, enter the word `VLAN' in uppercase letters and do not include a space between VLAN and the VLAN number (for example, VLAN7).

---

The following sections describe how to define a circuit IP address.

•Configuring a Circuit IP Address

•Configuring a Circuit-IP Broadcast Address

•Configuring Circuit-IP Redirects

•Configuring Circuit-IP Unreachables

•Enabling Router-Discovery

•Configuring Router-Discovery Preference

•Enabling a Circuit IP

•Disabling a Circuit IP

•Showing IP Interfaces

Configuring a Circuit IP Address

To assign an IP address to a circuit, use the ip address command from the specific circuit mode. Enter the IP address and a subnet mask in CIDR bitcount notation or a mask in dotted-decimal notation. The subnet mask range is 8 to 31.

To configure an IP address and subnet mask for VLAN7, enter:

(config-circuit[VLAN7])# ip address 173.3.6.58/8

When you specify an IP address, the mode changes to the specific circuit-ip-VLAN-IP address as shown:

(config-circuit-ip[VLAN7-173.3.6.58])#

To remove a local IP address from a circuit, enter the following command from the circuit mode:

(config-circuit[VLAN7])# no ip address

Configuring a Circuit-IP Broadcast Address

To change the broadcast address associated with a circuit, use the broadcast command. If you leave the broadcast address at zero, the all-ones host is used for numbered interfaces.

The default broadcast address is an all-ones host address (for example, IP address 173.3.6.58/24 has a broadcast address of 173.3.6.58/255). This command is available in IP configuration mode.

To change the broadcast address on circuit VLAN7, enter:

(config-circuit-ip[VLAN7-173.3.6.58])# broadcast 0.0.0.0

To reset the broadcast IP address to the default all-ones host address, enter:

(config-circuit[VLAN7-173.3.6.58])# no broadcast

Configuring Circuit-IP Redirects

To enable the transmission of Internet Control Message Protocol (ICMP) redirect messages, use the redirects command. The default state is enabled.

For example:

(config-circuit-ip[VLAN7-173.3.6.58])# redirects

To disable the transmission of ICMP redirect messages, enter:

(config-circuit-ip[VLAN7-173.3.6.58])# no redirects

Configuring Circuit-IP Unreachables

To enable the transmission of ICMP "destination unreachable" messages, use the unreachables command. The default state is enabled.

For example:

(config-circuit-ip[VLAN7-173.3.6.58])# unreachables

To disable the transmission of ICMP "destination unreachable" messages, enter:

(config-circuit-ip[VLAN7-173.3.6.58])# no unreachables

Enabling Router-Discovery

To enable router discovery for an interface, use the router-discovery command. When enabled, router discovery transmits packets with a multicast address of 244.0.0.1. To enable an interface to transmit packets with a multicast address of 255.255.255.255, use the router-discovery limited-broadcast command in circuit mode (see "Configuring Router-Discovery Limited-Broadcast", earlier in this chapter). Router discovery is disabled by default.

For example:

(config-circuit-ip[VLAN7-192.168.1.58])# router-discovery

To disable router discovery, enter:

(config-circuit-ip[VLAN7-192.168.1.58])# no router-discovery

Configuring Router-Discovery Preference

To configure the router discovery preference value, use the router-discovery preference command and a value to define the router preference value to advertise. The value is an integer from 0 (default) to 65535. If you use the default value, you do not need to use this command.

For example:

(config-circuit-ip[VLAN7-192.168.1.58])# router-discovery 
preference 100

To restore the router discovery preference value to the default of 0, enter:

(config-circuit-ip[VLAN7-192.168.1.58])# no router-discovery 
preference

Enabling a Circuit IP

To enable the IP interface on a circuit, use the enable command. The default is enable.

For example:

(config-circuit-ip[VLAN7-173.3.6.58])# enable

Disabling a Circuit IP

To disable the IP interfaces on a circuit, enter:

(config-circuit-ip[VLAN7-173.3.6.58])# no enable

Showing IP Interfaces

Use the show ip interfaces command to display configured IP interfaces on the CSS. The display includes the circuit state, IP address, broadcast address, Internet Control Message Protocol (ICMP) settings, and Router Discovery Program (RDP) settings.

Table 2-11 describes the fields in the show ip interfaces output.

Table 2-11 Field Descriptions for the show ip interfaces Command 

Field	Description
Circuit Name	The name of the circuit associated with the IP interface.
State	The state of the IP interface. The possible states are: •active (1) - The interface is up •disabled - The interface is disabled •noCircuit - The interface is waiting for an underlying circuit
IP Address	The IP address assigned to the circuit.
Network Mask	The network mask of the circuit.
Broadcast Address	The broadcast IP address associated with the IP interface. If left at zero, the all-ones host is used for numbered interfaces. 255.255.255.255 is always used for unnumbered interfaces.
Redundancy	Indicates whether the redundancy protocol is running on the interface. The default state is disable.
ICMP Redirect	Whether the transmission of Internet Control Message Protocol (ICMP) redirect messages is enabled or disabled. The default state is Enabled.
ICMP Unreachable	Whether the transmission of ICMP "destination unreachable" messages is enabled or disabled. The default state is enabled.
RIP	Whether RIP is enabled or disabled.

Configuring RIP for an IP Interface

The CSS enables you to configure Routing Information Protocol (RIP) attributes on each IP interface. To configure RIP parameters and run RIP on an IP interface, use the following routing commands within the specific circuit IP mode. The default mode is to send RIP version 2 (v2) and receive either RIP or RIP2.

The timers used by RIP in the CSS include the following default values. These RIP timer values are not user-configurable in the CSS.

•Transmit (TX) time that is random between 15 and 45 seconds to avoid router synchronization problems

•Route expiration time of 180 seconds (if the CSS loses the link to the next hop router the route is immediately removed)

•Hold down time (the amount of time the CSS transmits with an infinite metric) of 120 seconds

You can configure the following routing options for each IP interface:

•rip - Start RIP on the IP interface

•rip default-route - Advertise a default route on this interface

•rip receive - Specify the RIP version that the IP interface receives

•rip send - Specify the RIP version that the IP interface sends

•rip log - Enables the logging of received or transmitted RIP packets

To start running RIP on an IP interface, enter:

(config-circuit-ip[VLAN7-192.168.1.58)# rip

To stop running the RIP on the interface, enter:

(config-circuit-ip[VLAN7-192.168.1.58])# no rip

Configuring RIP Default-Route

To advertise a default route on an IP interface with a specific metric, use the
rip default-route command.

You can also specify an optional metric in the command line. The CSS uses this metric when advertising a route. Enter a number from 1 to 15. The default is 1.

For example:

(config-circuit-ip[VLAN7-192.168.1.58])# rip

default-route 9

Configuring RIP Receive

To specify the RIP version that the interface receives, use the rip receive command. The rip receive options are:

•rip receive both - Receive both RIP version 1 and RIP version 2 (default)

•rip receive none - Receive no RIP packets

•rip receive v1 - Receive RIP version 1 packets only

•rip receive v2 - Receive RIP version 2 packets only

For example:

(config-circuit-ip[VLAN7-192.168.1.58])# rip receive both

Configuring RIP Send

To specify the RIP version that the interface sends, use the rip send command. The rip send options are:

•rip send none - Send no RIP packets

•rip send v1 - Send RIP version 1 packets only

•rip send v2 - Send RIP version 2 packets only (default)

For example:

(config-circuit-ip[VLAN7-192.168.1.58])# rip send v1

Configuring RIP Packet Logging

To enable the CSS to log received or transmitted RIP packets on the interface, use the rip log command. Use the no form of this command to disable logging (default setting). The rip log options are:

•rip log rx - CSS logs RIP packets received on the interface

•rip log tx - CSS logs RIP packets transmitted on the interface

For example:

(config-circuit-ip[VLAN7-192.168.1.58])# rip log rx

Showing RIP Configurations

To show a RIP configuration for one IP address or all IP addresses configured in the CSS, use the show rip command. The command provides the following options:

•show rip - Displays RIP configurations for all interfaces (including the logging of RIP packets)

•show rip ip_address - Displays a single RIP interface entry

•show rip globals - Displays RIP global statistics

•show rip statistics - Displays RIP interface statistics for all interfaces

•show rip statistics ip_address - Displays RIP interface statistics for a specific interface

Table 2-12 describes the fields in the show rip output.

Table 2-12 Field Descriptions for the show rip Command 

Field	Description
IP Address	The advertised RIP interface address.
State	The operational state of the RIP interface.
RIP Send	The RIP version that the interface sends. The possible values are: •none - Do not send RIP packets •RIPv1 - Send RIP version 1 packets only •RIPv2 - Send RIP version 2 packets only (default)
RIP Recv	The RIP version that the interface receives. The possible values are: •both - Receiving both version 1 and version 2 (default) •none - Receiving no RIP packets •Ripv1 - Receiving RIP version 1 packets only •Ripv2 - Receiving RIP version 2 packets only
Default Metric	The default metric used when advertising the RIP interface.
Tx Log	The setting for the logging of RIP packet transmissions (enabled or disabled). The default setting is disabled.
Rx Log	The setting for the logging of RIP packet received (enabled or disabled). The default setting is disabled.

To display global RIP statistics, enter:

# show rip globals

Table 2-13 describes the fields in the show rip globals output.

Table 2-13 Field Descriptions for the show rip globals Command

Field	Description
RIP Route Changes	The global number of route changes made to the IP route database by RIP
RIP Query Responses	The global number of query responses sent to RIP query from other systems

To display the RIP interface statistics for all RIP interface entries, enter:

# show rip statistics

Table 2-14 describes the fields in the show rip statistics output.

Table 2-14 Field Descriptions for the show rip statistics Command

Field	Description
System Route Changes	The global number of route changes made to the IP route database by RIP
System Global Query Responses	The global number of query responses sent to RIP query from other systems
IP Address	The RIP interface IP address
Triggered Updates Sent	The number of triggered RIP updates sent by the interface
Bad Packets Received	The number of bad RIP response packets received by the interface
Bad Routes Received	The number of bad routes in valid RIP packets received by the interface

Where to Go Next

Chapter 3, Configuring CSS Network Protocols, describes how to configure the CSS DNS, ARP, RIP, IP, routing, spanning-tree bridging, SSH, and opportunistic Layer 3 forwarding.