Cisco Catalyst 4948 User Manual

50 Cisco LAN Switching Configuration Handbook
3. (Optional) Restrict access to NTP using authentication.
a. Enable NTP authentication:
(global) ntp authenticate
b. Define an authentication key:
(global) ntp authentication-key key-number md5 value
An MD5 authentication key numbered key-number is created. The key is given
a text-string value of up to eight clear-text characters. After the configuration
has been written to NVRAM, the key value displays in its encrypted form.
c. Apply one or more key numbers to NTP:
(global) ntp trusted-key key-number
Remote NTP peers must authenticate themselves using the authentication key num-
bered key-number. You can use this command multiple times to apply all desired
keys to NTP.
Example
This example shows a switch that is configured for the U.S. eastern time zone and day-
light savings time. The time is manually set.
Switch(config)# clock timezone EST –5
Switch(config)# clock summer-time EST recurring 1 sunday april 2:00
last sunday october 2:00
Switch(config)# end
Switch# clock set 15:30:00 August 11 1990
Switch# copy running-config startup-config
In the configuration that follows, NTP is enabled, and NTP is configured for authentication:
Switch(config)# ntp authenticate
Switch(config)# ntp authentication-key 1 md5 sourceA
Switch(config)# ntp authentication-key 2 md5 sourceB
Switch(config)# ntp trusted-key 1
Switch(config)# ntp trusted-key 2
Switch(config)# ntp peer 172.17.76.247 key 1
Switch(config)# ntp peer 172.31.31.1 key 2
One key, source1key, authenticates a peer at 172.17.76.247, whereas another key,
source2key, authenticates a peer at 172.31.31.1.

Cisco Catalyst 4948 Specifications

General

Switching Capacity	136 Gbps
Forwarding Rate	102 Mpps
Rack Units	1U
MAC Address Table Size	32, 000 entries
Authentication Method	RADIUS, TACACS+
RAM	256 MB
Flash Memory	64 MB
Power Device	Internal power supply
Voltage Required	100-240 VAC
Weight	16.5 lbs
Operating Humidity	10% to 85% non-condensing
Ports	48 x 10/100/1000
Power Supply	Internal
Layer Support	Layer 3
Jumbo Frame Support	Yes (up to 9216 bytes)
Routing Protocol	RIP, OSPF, EIGRP, BGP
Remote Management Protocol	SNMP, Telnet, SSH
Features	VLAN support, QoS
Compliant Standards	IEEE 802.3, IEEE 802.3u, IEEE 802.3ab, IEEE 802.1Q, IEEE 802.1p
Operating Temperature	32 °F to 104 °F (0 °C to 40 °C)

Summary

CLI Usage

Cisco Internetwork Operating System (IOS) Software

Describes the use of Cisco IOS Software for switching configuration, including user interface modes, commands, and help.

Supervisor Engine Configuration

IP Addressing and Services

Passwords and Password Recovery

Covers setting passwords and recovering lost or unknown passwords for switches.

Redundant Supervisors

Layer 2 Interface Configuration

Ethernet

EtherChannel

Covers configuration steps to bundle several switch ports into a single logical link.

Layer 3 Interface Configuration

Layer 3 Switching

Describes the process of Layer 3 switching and the elements needed for Layer 3 processing.

Layer 3 Ethernet Interfaces

Layer 3 EtherChannels

Covers configuring multiple interfaces into a single logical channel for Layer 3 processing.

Routing Tables

VLANs and Trunking

VLAN Configuration

Describes configuring, creating, and configuring VLANs on a switch.

VLAN Port Assignments

Trunking

Covers extending VLANs beyond switch boundaries using tagging mechanisms.

VLAN Trunking Protocol

Spanning Tree Protocol (STP)

STP Operation

Explains the spanning-tree algorithm, processes, and decisions made by a switch.

STP Configuration

Presents basic steps for configuring the Spanning Tree Protocol (STP).

STP Convergence Tuning

Configuring High Availability Features

Route Processor Redundancy (RPR/RPR+): Supervisor Redundancy

Discusses steps for configuring redundancy and failover for Catalyst 6500 with redundant supervisors.

Non-Stop Forwarding/Supervisor Switchover (NSF/SSO) with Supervisor Redundancy

Covers configuring and tuning non-stop forwarding and supervisor switchover.

Router Redundancy with HSRP

Discusses configuration steps for Layer 3 switches to share a common IP address for gateway redundancy.

Fast Software Upgrade (FSU) and Enhanced Fast Software Upgrade (eFSU)

Multicast

Multicast Addressing

IGMP Snooping

Explains configuring switches to constrain multicast traffic by listening to IGMP messages.

Server Load Balancing (SLB)

SLB

Covers configuration steps for load balancing traffic to one or more server farms.

SLB Firewall Load Balancing

Discusses steps to load balance traffic to one or more firewall farms.

SLB Probes

Controlling Traffic and Switch Access

Broadcast Suppression

Protocol Filtering

Explains configuring ports to prevent forwarding of flood packets of a particular protocol.

Port Security

Provides information to configure ports for use only by specified clients based on MAC addresses.

VLAN Access Control Lists

Describes controlling traffic through Layer 2 switches using access control lists applied to a VLAN.

Switch Authentication

802.1X Port Authentication

Quality of Service

QoS Theory

Discusses various operations and mechanisms that constitute quality of service (QoS).

QoS Configuration

Explains steps to configure and monitor QoS on a Catalyst switch.

Voice

Voice Ports

Voice QoS

Presents guidelines and suggestions for end-to-end quality of service (QoS) in a campus network.