Table Of Contents

Overview

Features

Performance Features

Management Options

Manageability Features

Availability Features

VLAN Features

Layer 2 Virtual Private Network (VPN) Services

Layer 3 VPN Services

Security Features

QoS Features

Layer 3 Features

Monitoring Features

Default Settings After Initial Switch Configuration

Network Configuration Examples

Multidwelling or Ethernet-to-the Subscriber Network

Layer 2 VPN Application

Layer 3 VPN Application

Where to Go Next

Overview

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This chapter provides this information about Catalyst 3750 Metro switch software:

•Features

•Default Settings After Initial Switch Configuration

•Network Configuration Examples

•Where to Go Next

Features

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Note Some features noted in this chapter are available only on the cryptographic (that is, supports encryption) versions of the switch software image. You must obtain authorization to use this feature and to download the cryptographic version of the software from Cisco.com. For more information, see the release notes for this release.

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Catalyst 3750 Metro switches have these features:

•Performance Features

•Management Options

•Manageability Features (includes a feature requiring the cryptographic version of the switch software image)

•Availability Features

•VLAN Features

•Layer 2 Virtual Private Network (VPN) Services

•Layer 3 VPN Services

•Security Features (includes a feature requiring the cryptographic version of the switch software image)

•QoS Features

•Layer 3 Features

•Monitoring Features

Performance Features

•Autosensing of port speed and autonegotiation of duplex mode on all switch ports for optimizing bandwidth

•Automatic-medium-dependent interface crossover (Auto-MDIX) capability on 10/100 Mbps interfaces and 10/100/1000 BASE-T/TX small form-factor pluggable (SFP) interfaces that enables the interface to automatically detect the required cable connection type (straight-through or crossover) and configure the connection appropriately

•Support for up to 1546 bytes for routed frames, up to 9000 bytes for frames that are bridged in hardware, and up to 2000 bytes for frames that are bridged by software

•IEEE 802.3x flow control on all ports (the switch does not send pause frames)

•EtherChannel for enhanced fault tolerance and for providing up to 2 Gbps (Gigabit EtherChannel) or 800 Mbps (Fast EtherChannel) full duplex of bandwidth between switches, routers, and servers

•Port Aggregation Protocol (PAgP) and Link Aggregation Control Protocol (LACP) for automatic creation of EtherChannel links

•Per-port storm control for preventing broadcast, multicast, and unicast storms

•Port blocking on forwarding unknown Layer 2 unknown unicast, multicast, and bridged broadcast traffic

•Cisco Group Management Protocol (CGMP) server support and Internet Group Management Protocol (IGMP) snooping for IGMP Versions 1, 2, and 3:

–(For CGMP devices) CGMP for limiting multicast traffic to specified end stations and reducing overall network traffic

–(For IGMP devices) IGMP snooping for efficiently forwarding multimedia and multicast traffic

•Multicast VLAN registration (MVR) to continuously send multicast streams in a multicast VLAN while isolating the streams from subscriber VLANs for bandwidth and security reasons

•IGMP filtering for controlling the set of multicast groups to which hosts on a switch port can belong

•IGMP throttling for configuring the action when the maximum number of entries is in the IGMP forwarding table

•IGMP report suppression for sending only one IGMP report per multicast router query to the multicast devices (supported only for IGMPv1 or IGMPv2 queries)

•Switch Database Management (SDM) templates for allocating system resources to maximize support for user-selected features

Management Options

•CLI—The Cisco IOS command-line interface (CLI) software is enhanced to support the Catalyst 3750 Metro switch features. You can access the CLI either by connecting your management station directly to the switch console port or by using Telnet from a remote management station. For more information about the CLI, see "Using the Command-Line Interface."

•CNS—Cisco Configuration Engine is network management software that acts as a configuration service for automating the deployment and management of network devices and services. You can automate initial configurations and configuration updates by generating switch-specific configuration changes, sending them to the switch, executing the configuration change, and logging the results.

For more information about CNS, see Chapter 5, "Configuring Cisco IOS CNS Agents."

•SNMP—Simple Network Management Protocol (SNMP) management applications such as CiscoWorks2000 LAN Management Suite (LMS) and HP OpenView. You can manage from an SNMP-compatible management station that is running platforms such as HP OpenView or SunNet Manager. The switch supports a comprehensive set of MIB extensions and four remote monitoring (RMON) groups. For more information about using SNMP, see Chapter 30, "Configuring SNMP."

Manageability Features

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Note The encrypted Secure Shell (SSH) feature listed in this section is available only on the cryptographic version of the switch software image.

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•Cisco IE2100 Series CNS embedded agents for automating switch management, configuration storage, and delivery

•DHCP for automating configuration of switch information (such as IP address, default gateway, hostname, and Domain Name System [DNS] and TFTP server names)

•DHCP relay agent information (option 82) for subscriber identification and IP address management

•DHCP server for automatic assignment of IP addresses and other DHCP options to IP hosts

•Directed unicast requests to a DNS server for identifying a switch through its IP address and its corresponding hostname and to a TFTP server for administering software upgrades from a TFTP server

•Support for downloading a software image by using a web browser (HTTP).

•Address Resolution Protocol (ARP) for identifying a switch through its IP address and its corresponding MAC address

•Unicast MAC address filtering to drop packets with specific source or destination MAC addresses

•Configurable MAC address scaling that allows disabling MAC address learning on a VLAN to limit the size of the MAC address table

•Cisco Discovery Protocol (CDP) Versions 1 and 2 for network topology discovery and mapping between the switch and other Cisco devices on the network

•Network Time Protocol (NTP) for providing a consistent timestamp to all switches from an external source

•Cisco IOS File System (IFS) for providing a single interface to all file systems that the switch uses

•In-band management access for up to 16 simultaneous Telnet connections for multiple CLI-based sessions over the network

•In-band management access for up to five simultaneous, encrypted SSH connections for multiple CLI-based sessions over the network (requires the cryptographic version of the switch software image)

•In-band management access through SNMP Versions 1 and 2, and 3 get and set requests

•Out-of-band management access through the switch console port to a directly attached terminal or to a remote terminal through a serial connection or a modem

•Support for metro Ethernet operation, administration, and maintenance (OAM) IEEE 802.1ag Connectivity Fault Management (CFM) and Ethernet Line Management Interface (E-LMI)

Availability Features

•HSRP for command switch and Layer 3 router redundancy

•UniDirectional Link Detection (UDLD) and aggressive UDLD for detecting and disabling unidirectional links on fiber-optic interfaces caused by incorrect fiber-optic wiring or port faults

•IEEE 802.1D Spanning Tree Protocol (STP) for redundant backbone connections and loop-free networks. STP has these features:

–Up to 128 spanning-tree instances supported

–Per-VLAN spanning-tree plus (PVST+) for balancing load across VLANs

–Rapid PVST+ for balancing load across VLANs and providing rapid convergence of spanning-tree instances

–UplinkFast and BackboneFast for fast convergence after a spanning-tree topology change and for achieving load balancing between redundant uplinks, including Gigabit uplinks

•IEEE 802.1s Multiple Spanning Tree Protocol (MSTP) for grouping VLANs into a spanning-tree instance and for providing multiple forwarding paths for data traffic and load balancing and rapid per-VLAN Spanning-Tree plus (rapid-PVST+) based on the IEEE 802.1w Rapid Spanning Tree Protocol (RSTP) for rapid convergence of the spanning tree by immediately transitioning root and designated ports to the forwarding state

•Optional spanning-tree features available in PVST+, rapid-PVST+, and MSTP mode:

–Port Fast for eliminating the forwarding delay by enabling a port to immediately transition from the blocking state to the forwarding state

–BPDU guard for shutting down Port Fast-enabled ports that receive bridge protocol data units (BPDUs)

–BPDU filtering for preventing a Port Fast-enabled port from sending or receiving BPDUs

–Root guard for preventing switches outside the network core from becoming the spanning-tree root

–Loop guard for preventing alternate or root ports from becoming designated ports because of a failure that leads to a unidirectional link

•Equal-cost routing for link-level and switch-level redundancy

•Flex Link Layer 2 interfaces to back up one another as an alternative to STP for basic link redundancy

•Link-state tracking to mirror the state of the ports that carry upstream traffic from connected hosts, servers, and other downstream devices. This feature allows the failover of the downstream traffic to an operational link on another Cisco Ethernet switch.

VLAN Features

•Support for up to 1005 VLANs for assigning users to VLANs associated with appropriate network resources, traffic patterns, and bandwidth

•Support for VLAN IDs in the full 1 to 4094 range as allowed by the IEEE 802.1Q standard

•VLAN Query Protocol (VQP) for dynamic VLAN membership

•Inter-Switch Link (ISL) and IEEE 802.1Q trunking encapsulation on all ports for network moves, adds, and changes; management and control of broadcast and multicast traffic; and network security by establishing VLAN groups for high-security users and network resources

•Dynamic Trunking Protocol (DTP) for negotiating trunking on a link between two devices and for negotiating the type of trunking encapsulation (802.1Q or ISL) to be used

•VLAN Trunking Protocol (VTP) and VTP pruning for reducing network traffic by restricting flooded traffic to links destined for stations receiving the traffic

•Voice VLAN for creating subnets for voice traffic from Cisco IP Phones

•VLAN 1 minimization for reducing the risk of spanning-tree loops or storms by allowing VLAN 1 to be disabled on any individual VLAN trunk link. With this feature enabled, no user traffic is sent or received on the trunk, but the switch CPU continues to send and receive control protocol frames.

•Private VLANs to address VLAN scalability problems, to provide a more controlled IP address allocation, and to allow Layer 2 ports to be isolated from other ports on the switch

•VLAN mapping on enhanced-services (ES) ports to translate customer VLANs to service-provider VLANs for transporting packets across the service-provider network without affecting the customer VLAN IDs

•Custom ethertype to enable the user to change the ethertype value on a port to any value to direct the tagged and untagged traffic to different VLANs (ES ports only)

Layer 2 Virtual Private Network (VPN) Services

•802.1Q tunneling so that customers with users at remote sites across a service-provider network can keep VLANs segregated from other customers, and Layer 2 protocol tunneling on trunk, access, or tunnel ports to ensure that the customer's network has complete STP, CDP, and VTP information about all users

•Layer 2 point-to-point tunneling to facilitate the automatic creation of EtherChannels

•Layer 2 protocol tunneling bypass feature to provide interoperability with third-party vendors

•Intelligent 802.1Q tunneling QoS, the ability to copy the inner cost-of-service (CoS) value to the outer CoS value for 802.1Q tunneling

•Support for Ethernet over multiprotocol layer switching (EoMPLS) tunneling mechanism for transporting Ethernet frames over a service-provider MPLS network

•Support for hierarchical-virtual private LAN service (H-VPLS) using IEEE 802.1Q tunneling or Ethernet over multiprotocol label switching (EoMPLS)

Layer 3 VPN Services

•Support for MPLS VPNs provides the capability to deploy and administer scalable Layer 3 VPN services to business customers. Each VPN is associated with one or more VPN routing/forwarding (VRF) instances that include routing and forwarding tables and rules that define the VPN membership. (MPLS VPNs are supported only on ES ports.)

•Multiple VPN multi-VRF instances in customer edge (CE) devices to allow service providers to support multiple VPNs and to overlap IP addresses between VPNs.

Security Features

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Note The Kerberos feature listed in this section is available only on the cryptographic version of the switch software image.

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•Password-protected access (read-only and read-write access) to management interfaces for protection against unauthorized configuration changes

•Multilevel security for a choice of security level, notification, and resulting actions

•Static MAC addressing for ensuring security

•Protected port option for restricting the forwarding of traffic to designated ports on the same switch

•Port security option for limiting and identifying MAC addresses of the stations allowed to access the port

•Port security aging to set the aging time for secure addresses on a port

•BPDU guard for shutting down a Port Fast-configured port when an invalid configuration occurs

•Standard and extended IP access control lists (ACLs) for defining security policies in both directions on routed interfaces (router ACLs) and VLANs and inbound on Layer 2 interfaces (port ACLs)

•Extended MAC access control lists for defining security policies in the inbound direction on Layer 2 interfaces

•VLAN ACLs (VLAN maps) for providing intra-VLAN security by filtering traffic based on information in the MAC, IP, and TCP/User Datagram Protocol (UDP) headers

•Source and destination MAC-based ACLs for filtering non-IP traffic

•IEEE 802.1x port-based authentication to prevent unauthorized devices (clients) from gaining access to the network

–802.1x with VLAN assignment for restricting 802.1x-authenticated users to a specified VLAN

–802.1x with port security for controlling access to 802.1x ports

–802.1x with voice VLAN to permit an IP phone access to the voice VLAN regardless of the authorized or unauthorized state of the port

–802.1x with guest VLAN to provide limited services to non-802.1x-compliant users

–802.1x accounting to track network usage.

•TACACS+, a proprietary feature for managing network security through a TACACS server

•RADIUS for verifying the identity of, granting access to, and tracking the actions of remote users through authentication, authorization, and accounting (AAA) services

•Kerberos security system to authenticate requests for network resources by using a trusted third party (requires the cryptographic [that is, supports encryption] version of the switch software image)

•Password recovery disable capability to protect access to switches at customer sites

•DHCP snooping to filter untrusted DHCP messages between untrusted hosts and DHCP servers

•IP source guard to restrict traffic on nonrouted interfaces by filtering traffic based on the DHCP snooping database and IP source bindings

•Dynamic ARP inspection to prevent malicious attacks on the switch by not relaying invalid ARP requests and responses to other ports in the same VLAN

•Secure Socket Layer Version 3.0 support for the HTTP 1.1 server authentication, encryption, and message integrity, and HTTP client authentication to allow secure HTTP communications (requires a cryptographic version of the switch image)

QoS Features

•Standard QoS to classify, police, mark, queue, and schedule incoming traffic on a standard port or on an ES port, as well as queue and schedule outgoing traffic on a standard port

Classification

–IP type-of-service/Differentiated Services Code Point (IP ToS/DSCP) and 802.1p CoS marking priorities on a per-port basis for protecting the performance of mission-critical applications

–IP ToS/DSCP and 802.1p CoS marking based on flow-based packet classification (classification based on information in the MAC, IP, and TCP/UDP headers) for high-performance quality of service at the network edge, allowing for differentiated service levels for different types of network traffic and for prioritizing mission-critical traffic in the network

–Trusted port states (CoS, DSCP, and IP precedence) within a QoS domain and with a port bordering another QoS domain

–Trusted boundary for detecting the presence of a Cisco IP phone, trusting the CoS value received, and ensuring port security

–DSCP transparency to prevent the switch from rewriting the DSCP field in the user IP packet when QoS is enabled

Policing and out-of-profile marking

–Traffic-policing policies on the switch port for managing how much of the port bandwidth should be allocated to a specific traffic flow (single-rate traffic policing)

–Aggregate policing for policing traffic flows in aggregate to restrict specific applications or traffic flows to metered, predefined rates

–Out-of-profile markdown for packets that exceed bandwidth utilization limits (drop policy actions are passing through the packet without modification, marking down the assigned DSCP in the packet, or dropping the packet)

Ingress queueing and scheduling

–Two configurable ingress queues for user traffic (one queue can be the priority queue)

–Weighted tail drop (WTD) as the congestion-avoidance mechanism for managing the queue lengths and providing drop precedences for different traffic classifications

–Shaped round robin (SRR) as the scheduling service for determining the rate at which packets are dequeued to the internal ring (sharing is the only supported mode on ingress queues)

Egress queues and scheduling

–Four egress queues per port

–An egress priority queue on a standard port. Shaped round robin (SRR) services the priority queue until it is empty before servicing the other three queues.

–WTD as the congestion-avoidance mechanism for managing the queue lengths and providing drop precedences for different traffic classifications

–SRR as the scheduling service for determining the rate at which packets are dequeued to the egress interface (shaping or sharing is supported on egress queues). Shaped egress queues are guaranteed but limited to using a share of port bandwidth. Shared egress queues are also guaranteed a configured share of bandwidth, but can use more than the guarantee if other queues become empty and do not use their share of the bandwidth.

•Hierarchical QoS on ES ports to classify, police, mark, queue, and schedule incoming or outgoing traffic

Classification

–Three QoS configuration levels in the hierarchy: class, VLAN, and physical interface

–Classification based on the CoS value, the DSCP value, the IP precedence value, the MPLS experimental (EXP) bits, or the VLAN

Policing and out-of-profile marking

–Two-rate traffic policing based on the committed information rate (CIR) and the peak information rate (PIR)

–Out-of-profile markdown for packets that exceed bandwidth utilization limits (policy actions are to send packets that conform without modification, to mark down the priority of packets that exceed, and to drop packets that violate)

Egress queueing and scheduling

–Each packet assigned to an egress queue based on the traffic class and VLAN

–Weighted Random Early Detection (WRED) as the congestion-avoidance mechanism

–Class-based weighted fair queueing (CBWFQ) as a queue scheduling management feature to provide guaranteed bandwidth to particular traffic classes, such as voice, that are delay sensitive, while still fairly serving all other traffic in the network

–Low-latency queueing (LLQ) as a scheduling congestion-management feature to provide strict-priority queueing for a traffic class and to enable delay-sensitive data, such as voice, to be sent before packets in other queues are sent

–Traffic shaping to decrease the burstiness of Internet traffic

•Automatic QoS (auto-QoS) to simplify the deployment of existing QoS features by classifying traffic and configuring egress queues

Layer 3 Features

•HSRP for Layer 3 router redundancy

•IP routing protocols for load balancing and for constructing scalable, routed backbones:

–RIP Versions 1 and 2

–OSPF

–Enhanced Interior Gateway Routing Protocol GRP (EIGRP)

–Border Gateway Protocol (BGP) Version 4

–International Organization for Standardization (ISO) Connectionless Network Service (CLNS). The switch supports ISO Interior Gateway Routing Protocol (IGRP) and Intermediate System-to-Intermediate System (IS-IS) routing

•IP routing between VLANs (inter-VLAN routing) for full Layer 3 routing between two or more VLANs, allowing each VLAN to maintain its own autonomous data-link domain

•Policy-based routing (PBR) for configuring defined policies for traffic flows

•Multiple VPN routing/forwarding (multi-VRF) instances in customer edge (CE) devices to allow service providers to support multiple virtual private networks (VPNs) and overlap IP addresses between VPNs (requires the EMI)

•Fallback bridging for forwarding non-IP traffic between two or more VLANs

•Static IP routing for manually building a routing table of network path information

•Equal-cost routing for load balancing and redundancy

•Internet Control Message Protocol (ICMP) and ICMP Router Discovery Protocol (IRDP) for using router advertisement and router solicitation messages to discover the addresses of routers on directly attached subnets

•Protocol-Independent Multicast (PIM) for multicast routing within the network, allowing for devices in the network to receive the multicast feed requested and for switches not participating in the multicast to be pruned. Includes support for PIM sparse mode (PIM-SM), PIM dense mode (PIM-DM), and PIM sparse-dense mode.

•Multicast Source Discovery Protocol (MSDP) for connecting multiple PIM-SM domains

•Distance Vector Multicast Routing Protocol (DVMRP) tunnelling for interconnecting two multicast-enabled networks across non-multicast networks

•DHCP relay for forwarding UDP broadcasts, including IP address requests, from DHCP clients

Monitoring Features

•Switch LEDs that provide port- and switch-level status

•MAC address notification traps and RADIUS accounting for tracking users on a network by storing the MAC addresses that the switch has learned or removed

•Switched Port Analyzer (SPAN) and Remote SPAN (RSPAN) for traffic monitoring on any standard port or VLAN.

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Note An ES port cannot be a SPAN source.

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•SPAN and RSPAN support of Intrusion Detection Systems (IDS) to monitor, repel, and report network security violations

•Four groups (history, statistics, alarms, and events) of embedded RMON agents for network monitoring and traffic analysis

•Syslog facility for logging system messages about authentication or authorization errors, resource issues, and time-out events

•Layer 2 traceroute to identify the physical path that a packet takes from a source device to a destination device

•SFP module diagnostic management interface to monitor physical or operational status of an SFP module.

Default Settings After Initial Switch Configuration

The switch is designed for plug-and-play operation, requiring only that you assign basic IP information to the switch and connect it to the other devices in your network. If you have specific network needs, you can change the interface-specific and system-wide settings.

If you do not configure the switch at all, the switch operates with the default settings listed in Table 1-1. This table lists the key software features, their defaults, and where to find more information about the features.

Table 1-1 Default Settings After Initial Switch Configuration 

Feature		Default Setting	More information in...
Switch IP address, subnet mask, and default gateway		0.0.0.0	"Assigning the Switch IP Address and Default Gateway"
Domain name		None
Passwords		None defined	"Administering the Switch"
TACACS+		Disabled
RADIUS		Disabled
System name and prompt		Switch
NTP		Enabled
DNS		Enabled
802.1x		Disabled	"Configuring IEEE 802.1x Port-Based Authentication"
DHCP
	DHCP client	Enabled (only if the device acting as a DHCP server is configured and is enabled)	"Assigning the Switch IP Address and Default Gateway" "Configuring DHCP Features and IP Source Guard"
	DHCP server
	DHCP relay agent	Enabled (only if the device is acting as a DHCP relay agent is configured and is enabled)
Port parameters
	Operating mode	Layer 2 (switchport)	"Configuring Interface Characteristics"
	Port enable state	All ports are enabled.
	Interface speed and duplex mode	Autonegotiate
	Auto MDIX	Disabled
	Flow control	Off
VLANs
	Default VLAN	VLAN 1	Chapter 12, "Configuring VLANs"
	VLAN trunking	Dynamic auto (DTP)
	Trunk encapsulation	Negotiate
	VTP mode	Server	Chapter 13, "Configuring VTP"
	VTP version	1
	Voice VLAN	Disabled	Chapter 15, "Configuring Voice VLAN"
	Private VLANs	None configured.	Chapter 14, "Configuring Private VLANs"
	Dynamic ARP inspection	Disabled on all VLANs	"Configuring Dynamic ARP Inspection"
Tunneling
	802.1Q tunneling	Disabled	Chapter 16, "Configuring IEEE 802.1Q and Layer 2 Protocol Tunneling"
	VLAN mapping	Disabled
	Layer 2 protocol tunneling	Disabled
Spanning Tree Protocol
	STP	PVST+ enabled on VLAN 1	Chapter 17, "Configuring STP"
	MSTP	Disabled	Chapter 18, "Configuring MSTP"
	Optional spanning-tree features	Disabled	Chapter 19, "Configuring Optional Spanning-Tree Features"
Flex Links		Not configured	"Configuring Flex Links and the MAC Address-Table Move Update Feature"
DHCP snooping		Disabled	"Configuring DHCP Features and IP Source Guard"
IP source guard		Disabled	"Configuring DHCP Features and IP Source Guard"
IGMP snooping
	IGMP snooping	Enabled	"Configuring IGMP Snooping and MVR"
	IGMP filters	None applied
	MVR	Disabled
IGMP throttling
	IGMP throttling	Deny	"Configuring IGMP Snooping and MVR"
Port-based Traffic
	Broadcast, multicast, and unicast storm control	Disabled	Chapter 24, "Configuring Port-Based Traffic Control"
	Protected ports	None defined
	Unicast and multicast traffic flooding	Not blocked
	Secure ports	None configured
CDP		Enabled	"Configuring CDP"
UDLD		Disabled	Chapter 26, "Configuring UDLD"
SPAN and RSPAN		Disabled	Chapter 27, "Configuring SPAN and RSPAN"
RMON		Disabled	Chapter 28, "Configuring RMON"
Syslog messages		Enabled; displayed on the console	"Configuring System Message Logging"
SNMP		Enabled; Version 1	Chapter 30, "Configuring SNMP"
ACLs		None configured	"Configuring Network Security with ACLs"
QoS		Disabled	Chapter 32, "Configuring QoS"
EtherChannels		None configured	"Configuring EtherChannels and Link-State Tracking"
IP unicast routing
	IP routing (and routing protocols)	Disabled	"Configuring IP Unicast Routing"
	Multi-VRF-CE	Disabled
MPLS services
	Label switching	Globally enabled; disabled per interface	Chapter 37, "Configuring MPLS and EoMPLS"
	EoMPLS	Not configured
	MPLS QoS	Disabled
	H-VPLS	No VFIs configured
HSRP groups		None configured	"Configuring HSRP"
IP multicast routing		Disabled on all interfaces	Chapter 38, "Configuring IP Multicast Routing"
MSDP		Disabled	Chapter 39, "Configuring MSDP"
Fallback bridging		Not configured	"Configuring Fallback Bridging"
Ethernet OAM
	CFM	Disabled globally, enabled per interface	Chapter 36, "Configuring Ethernet CFM and E-LMI"
	E-LMI	Disabled globally

Network Configuration Examples

This section provides network configuration concepts and includes examples of using the switch to create dedicated network segments and interconnecting the segments through Fast Ethernet and Gigabit Ethernet connections.

•"Multidwelling or Ethernet-to-the Subscriber Network" section

•"Layer 2 VPN Application" section

•"Layer 3 VPN Application" section

Multidwelling or Ethernet-to-the Subscriber Network

Figure 1-1 shows a Gigabit Ethernet ring for a residential location serving multitenant units using Catalyst 3750 Metro switches connected through 1000BASE-X SFP module ports. Catalyst 3750 Metro switches used as residential switches provide customers with high-speed connections to the service provider point-of presence (POP). Catalyst 2950 Long-Reach Ethernet (LRE) switches also can be used as residential switches for customers requiring connectivity through existing phone lines. The Catalyst 2950 LRE switches can then connect to another residential switch, such as a Catalyst 3750 Metro switch. For more information about the Catalyst LRE switches and LRE information, see the Catalyst 2950 LRE documentation set.

All ports on the residential switches (and Catalyst 2950 LRE switches if they are included) are configured as 802.1Q trunks with Private VLAN Edge (protected port) and STP root guard features enabled. The protected-port feature provides security and isolation between ports on the switch, ensuring that subscribers cannot view packets destined for other subscribers. STP root guard prevents unauthorized devices from becoming the STP root switch. All ports have IGMP snooping or CGMP enabled for multicast traffic management. ACLs on the uplink ports to the aggregating switches provide security and bandwidth management.

The aggregating switches and routers have HSRP enabled for load balancing and redundant connectivity to guarantee mission-critical traffic. This ensures connectivity to the Internet, WAN, and mission-critical network resources in case one of the routers or switches fails.

When an end station in one VLAN needs to communicate with an end station in another VLAN, a router or switch routes the traffic to the appropriate destination VLAN, providing inter-VLAN routing. VLAN access control lists (VLAN maps) provide intra-VLAN security and prevent unauthorized users from accessing critical pieces of the network.

In addition to inter-VLAN routing, the switch QoS mechanisms such as DSCP prioritize the different types of network traffic to deliver high-priority traffic in a predictable manner. If congestion occurs, QoS drops low-priority traffic to allow delivery of high-priority traffic.

The routers also provide firewall services, Network Address Translation (NAT) services, voice-over-IP (VoIP) gateway services, and WAN and Internet access.

Figure 1-1 Catalyst 3750 Metro Switches in a Multidwelling Configuration

Layer 2 VPN Application

You can use Catalyst 3750 Metro switches to form Layer 2 VPNs so that customers at different locations can exchange information through a service-provider network, without requiring dedicated connections. IEEE 802.1Q and Layer 2 protocol tunneling are features designed for service providers who carry traffic of multiple customers across their networks and are required to maintain the VLAN and Layer 2 protocol configurations of each customer without impacting the traffic of other customers.

The Catalyst 3750 Metro switches are used as the provider edge customer-located equipment (PE-CLE) in customer sites at the both edges of the provider network connected to customer premises equipment (CPE) switches. The PE switches tag packets entering the service-provider network with the customer VLAN ID. VLAN mapping translates each customer VLAN ID to a service-provider VLAN ID for transport across the service-provider network. At the egress PE interface, the egress PE switch restores the original VLAN ID numbers for the customer's network.

The service provider can use 802.1Q tunneling or EoMPLS to provide Layer 2 VPN services. If the service-provider network is an MPLS cloud, and EoMPLS is configured as the point-to-point protocol, MPLS tags are added at the PE-CLE ES port that connects to the MPLS network. The MPLS tags are removed at the ES port of the remote PE-CLE device.

See Chapter 16, "Configuring IEEE 802.1Q and Layer 2 Protocol Tunneling," and Chapter 37, "Configuring MPLS and EoMPLS," for more information on configuring these features.

Figure 1-2 Layer 2 VPN Configuration

Layer 3 VPN Application

Layer 3 VPN services can use multi-VRF-CE or MPLS VPNs to deploy and administer scalable Layer 3 VPN services to business customers. A Layer 3 VPN is a secure IP-based network that shares resources on one or more physical networks. It contains geographically dispersed sites that can communicate securely over a shared backbone.

Figure 1-3 shows an end-to-end MPLS VPN network with MPLS extending from customer site to customer site. The CE devices (which can be Catalyst 3750 Metro switches or other Layer 3 switches) use a routing protocol, such as RIP, EBGP, OSPF, IS-IS, or static routing, to forward packets from customer VPNs to the Catalyst 3750 Metro PE-CLE devices at the edge of the MPLS network. The PE-CLE device is configured with multiprotocol BGP (MP-BGP) and a route distinguisher that is associated with the customer's VPN. The PE-CLE device converts this information to a VPN-IPv4 format and adds layer distribution protocol (LDP) labels to establish VPN routes.

VPN routes are distributed over the MPLS network using MP-BGP, which also distributes the labels associated with each VPN route. MPLS VPN depends on VPN routing and forwarding (VRF) support to isolate the routing domains from each other.

When an MPLS-VPN packet is received on a port, the CE switch looks up the labels in the routing table to determine what to do with the packet. A PE-CLE router binds a label to each customer prefix learned from a CE device and includes the label in the prefix that it advertises to other PE-CLE routers. When a PE-CLE router forwards a packet across the provider network, it labels the packet with the label learned from the destination router. When the destination router receives the labeled packet, it examines the label and uses it to direct the packet to the correct CE device.

Only the PE-CLE routers at each end of the MPLS network maintain the VPN routes for VPN members. Provider routers in the core network do not maintain the VPN routes. This ensures the security of customer VPNs and isolates them from other customer packets that are carried across the service-provider MPLS network.

Figure 1-3 MPLS VPN Configuration

See Chapter 37, "Configuring MPLS and EoMPLS," for more information on configuring MPLS VPN.

Where to Go Next

Before configuring the switch, review these sections for startup information:

•"Using the Command-Line Interface"

•"Assigning the Switch IP Address and Default Gateway"

•Chapter 5, "Configuring Cisco IOS CNS Agents"