Network Traffic Types

Departmental Switch Block 1

Traffic types to consider

• Network management

• Scavenger class

IP Telephony

Departmental Switch Block 1

IP Telephony

This table lists different types of traffic that may exist on the network and that should be considered before device placement and VLAN configuration.

Traffic Types

The table describes the different traffic types.

Traffic Type


Network management

Many different types of network management traffic may be present on the network. Examples include bridge protocol data units (BPDUs), Cisco Discovery Protocol (CDP) updates, Simple Network Management Protocol (SNMP) and Remote Monitoring (RMON) traffic. Some designers will assign a separate VLAN to the task of carrying certain types of network management traffic to make network troubleshooting easier.

IP telephony

There are two types of IP telephony traffic: signaling information between the end devices (for example, IP phones, and softswitches, such as Cisco CallManager) and the data packets of the voice conversation itself. Often, the data to and from IP phones will be configured on a separate VLAN for voice traffic because the designer will want to apply QoS measures to give high priority to voice traffic.

Building Cisco Multilayer Switched Networks (BCMSN) v3.0

© 2006 Cisco Systems, Inc.

Traffic Type


IP multicast

IP multicast traffic is sent from a particular source address to nonunique MAC addresses. Examples of applications that generate this type of traffic are IP/TV broadcasts and imaging software used to configure workstations and servers quickly. Multicast traffic can produce a large amount of data streaming across the network. Switches need to be configured to keep this traffic from flooding to devices that have not requested it, and routers need to ensure that multicast traffic is forwarded to the network areas where it is requested.

Normal data

This is typical application traffic related to file and print services, e-mail, Internet browsing, database access, and other shared network applications. This data may have to be treated in the same or different ways in different parts of the network, based on the volume of each type. Examples of this type of traffic are Server Message Block, Netware Core Protocol (NCP), Simple Mail Transfer Protocol (SMTP), Structured Query Language (SQL), and HTTP.

Scavenger class

Scavenger class includes all traffic with protocols or patterns that exceed their normal data flows. It is used to protect the network from exceptional traffic flows that may be the result of malicious programs executing on end-system PCs. Scavenger class is also used for less than best-effort type traffic, such as peer-to-peer traffic.

© 2006 Cisco Systems, Inc. Defining VLANs 2-15

Was this article helpful?

0 0

Post a comment