Cisco 2950SX 48 SI - Catalyst Switch Технічний паспорт - Сторінка 4

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a RADIUS server allows dynamic port-based user authentication. In addition, 802.1x can coexist with port security

on a per-port basis. Security features can be deployed using Cisco CMS software security wizards, which ease the

deployment of security features that restrict user access to a server or portion of the network or restrict the

applications used in certain areas of the network.

Network Control

Cisco Catalyst 2950SX-48, 2950T-48, 2950SX-24, 2950-24, and 2950-12 switches deliver LAN-edge QoS,

supporting two modes of reclassiﬁcation. One mode—based on the IEEE 802.1p standard—honors the

class-of-service (CoS) value at the ingress point and assigns the packet to the appropriate queue. In the second mode,

packets can be reclassiﬁed based on a default CoS value assigned to the ingress port by the network administrator.

In the case of frames that arrive without a CoS value (such as untagged frames), these Cisco Catalyst 2950 Series

switches support classiﬁcation based on a default CoS value per port assigned by the network administrator. After

the frames have been classiﬁed or reclassiﬁed using one of the above modes, they are assigned to the appropriate

queue at the egress. Cisco Catalyst 2950 Series switches support four egress queues, which allow the network

administrator to be more discriminating and granular in assigning priorities for the various applications on the LAN.

Strict Priority Scheduling conﬁguration ensures that time-sensitive applications, such as voice, always follow an

expedited path through the switch fabric. Weighted Round Robin (WRR) scheduling, another signiﬁcant

enhancement, ensures that lower-priority trafﬁc receives attention without comprising the priority settings

administered by a network manager. These features allow network administrators to prioritize mission-critical,

time-sensitive trafﬁc, such as voice (IP telephony trafﬁc), enterprise resource planning (Oracle, SAP, etc.), and

computer-assisted design and manufacturing, over less time-sensitive applications such as FTP or e-mail (Simple Mail

Transfer Protocol).

Network Availability

To provide efﬁcient use of resources for bandwidth-hungry applications like multicasts, Cisco Catalyst 2950 Series

switches support Internet Group Management Protocol Version 3 (IGMPv3) snooping in hardware. Through the

support and conﬁguration of IGMP snooping through the Cisco CMS software, these Cisco Catalyst 2950 Series

switches deliver outstanding performance and ease of use in administering and managing multicast applications on

the LAN.

The IGMPv3 snooping feature allows the switch to "listen in" on the IGMP conversation between hosts and routers.

When a switch hears an IGMP join request from a host for a given multicast group, the switch adds the host's port

number to the group destination address list for that group. And when the switch hears an IGMP leave request, it

removes the host's port from the content-addressable memory (CAM) table entry.

Multicast VLAN Registration (MVR) is designed for applications using wide-scale deployment of multicast trafﬁc

across an Ethernet ring-based service provider network (for example, the broadcast of multiple television channels

over a service-provider network). MVR allows a subscriber on a port to subscribe and unsubscribe to a multicast

stream on the networkwide multicast VLAN.

Per VLAN Spanning Tree Plus (PVST+) allows users to implement redundant uplinks while also distributing trafﬁc

loads across multiple links. This is not possible with standard Spanning Tree Protocol implementations. Cisco

UplinkFast technology ensures immediate transfer to the secondary uplink, much better than the traditional 30- to

60-second convergence time. This is yet another enhancement of the Spanning Tree Protocol implementation. An

Cisco Systems, Inc.

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