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Cisco ONS 15454 Series Multiservice Provisioning Platforms

Field Notice 13171: ONS 15454 and ONS 15327: E-Series Ethernet Line Card Packet Forwarding Limitations


Updated March 11, 2002

April 18, 2001


Products Affected

Product

Top Assembly

Printed Circuit Assembly

HW Rev.

Part Number

Rev.

Part Number

Rev.

15454-E1000-2-G

All

All

All

All

All

15454-E1000-2

All

All

All

All

All

15454-E100T-12

All

All

All

All

All

15454-E100T-G

All

All

All

All

All

15327-E10/100T-4

All

All

All

All

All

Problem Description

Unicast packet loss can occur when Broadcast or Multicast traffic is present.

The effect of this issue varies by E-series card, circuit size, and software revision. See the table below for a summary.

For ONS 15454 Software Release 2.2.1 and earlier and ONS 15327 Software Release 1.0.0, traffic loss of approximately one percent may be caused by Multicast and Unknown-DA traffic of 100 frames per second (fps). Higher Multicast and Unknown-DA traffic rates may cause higher traffic loss.

It is strongly suggested that customers using E-sereies cards upgrade to ONS 15454 Software Release 2.2.2 or ONS 15327 Software Release 1.0.1 or later.

For ONS 15454 Software Release 2.2.2 and ONS 15327 Software Release 1.0.1 and later releases, no traffic loss will occur with all Multicast and Unknown-DA frames at a rate of 9000 fps when using 15454-E100T-12 or 15327-E10/100T-4 cards, with STS-1 or STS-3c circuit sizes.

When using STS-6c or STS-12c circuit sizes, or any circuit size on the 15454-E1000T-2 card, with any software release, only Multicast traffic sent by control protocols should be used. Multicast rates of 100 fps using unknown Multicast addresses may cause traffic loss of approximately one percent. Higher Multicast and Unknown-DA traffic rates may cause higher traffic loss.

In order to reduce the severity and occurance of this issue for control protocols, a limited number of common control protocols have been given special handling to work around the issue. As a result, these control protocols will cause no loss of traffic, even when the control protocol packet rates exceed 100 fps.

This matrix provides a guide to what is supported for each circuit type according to the card type:

Product ID

STS-1 Multicast Support

STS-3c Multicast Support

STS-6c Multicast Support

STS-12c Multicast Support

15454-E100T-12 15454-E100T-G

9000 FPS (All Applications)

9000 FPS (All Applications)

9000 FPS ("zero-loss protocols")

9000 FPS ("zero-loss protocols")

15327-E10/100T-4

9000 FPS (All Applications)

9000 FPS (All Applications)

9000 FPS ("zero-loss protocols")

9000 FPS ("zero-loss protocols")

15454-E1000-215454-E1000-2-G

9000 FPS ("zero-loss protocols")

9000 FPS ("zero-loss protocols")

9000 FPS ("zero-loss protocols")

9000 FPS ("zero-loss protocols")

Note:?9000 FPS using 1500 byte packets is the equivalent of 108 Mbps.

Protocols with Zero-Loss Workaround

Protocol

15454 Release

15327 Release

Broadcast MAC (used by many protocols)

R2.2.1

R1.0.0

Open Shortest Path First (OSPF)

R2.2.2

R1.0.1

Cisco Discovery Protocol (CDP)

R2.2.2

R1.0.1

Per-VLAN Spanning Tree (PVST)

R2.2.2

R1.0.1

Interior Gateway Routing Protocol (IGRP)

R2.2.2

R1.0.1

Enhanced Interior Gateway Routing Protocol (EIGRP)

R2.2.2

R1.0.1

Internet Group Management Protocol (IGMP)

R2.2.2

R1.0.1

Hot Standby Routing Protocol (HSRP)

R3.0.3

R3.3.0

Note:?All other control protocols are supported, however, a small amount of packet loss may occur (less than one percent in most cases, based on an expected control protocol frame rate of less than 100 fps).

Background

It is common for the performance of many ethernet chipsets to be reduced when broadcasting unknown-destination frames. This generally is not an issue because the destination of the MAC addresses involved is quickly learned and frames are then switched to a known-destination. Limiting the forwarding rate of unknown-destination frames was also historically considered a good practice in order to prevent storms which might be created by other equipment malfunctions or network problems. Because of this expected behavior in handling unknown-destination frames, issues related to handling of unknown-destination frames were not discovered in initial testing of the E100 and E1000 cards.

Various software changes to work around these issues have been implemented.

On low-speed ports, including Fast Ethernet, STS-1, and STS-3c, a way was found to completely solve the issue for all packets with unknown-destination and Multicast packet rates as high as 9000 fps. This change was introduced in ONS 15454 Software Release 2.2.2 and ONS 15327 Software Release 1.0.1.

For high-speed ports, including Gigabit Ethernet, STS-6c, STS-12c, the issue has proven more difficult to solve. Special handling of a few standard Multicast MAC addresses utilized by common control protocols has been accomplished, solving the issues for these specific control protocols. These changes were introduced in various ONS 15454 software releases as indicated in the problem description.

General unknown-destination packet handling on high speed ports, including Gigabit Ethernet, STS-6c, STS-12c, continues to cause some traffic loss.

Problem Symptoms

Unicast packet loss can occur when Flood or Multicast traffic is present. This is particularly apparent when using applications based on the UDP protocol, including ping, traceroute, and snmp.

Workaround/Solution

If you are creating a network using E-series cards to support Multicast applications or applications extremely sensitive to packet loss, such as applications based on the UDP protocol, limit the network design to use only 15454-E100T-12 and 15327-E100-4 cards, only STS-1 and STS-3c circuit sizes, and use a minimum software release of 2.2.2 for the ONS 15454 and 1.0.1 for the ONS 15327.

If you have specific concerns regarding applications supported by the 15454-E100T-12, 15327-E100-4 or 15454-E1000-2, please contact your sales team or the Technical Assistance Center (TAC) for more details.

DDTS

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DDTS

Description

CSCdr94172

Multicast/Broadcast Limitation of E100 and E1000 Platform.

For More Information

If you require further assistance, or if you have any further questions regarding this field notice, please contact the Cisco Systems Technical Assistance Center (TAC) by one of the following methods:

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