Measuring Performance

 

The performance of a service provider’s network is usually defined as how well it can support services, and is measured with metrics such as delay and utilization. We suggest that you monitor the following performance metrics using applications such as InfoVista Service Performance Management or Concord Network Health (see Table 1).

Table 1: Performance Metrics

Metric:

Average delay

Description

Average round-trip time (in milliseconds) between two measurement points.

MIB name

DISMAN-PING-MIB (RFC 2925)

Variable name

pingResultsAverageRtt

Variable OID

pingResultsEntry.6

Frequency (mins)

15 (or depending upon ping test frequency)

Allowable range

To be baselined

Managed objects

Each measured path in the network

Metric:

Interface utilization

Description

Utilization percentage of a logical connection.

MIB name

IF-MIB

Variable name

(ifInOctets & ifOutOctets) * 8 / ifSpeed

Variable OID

ifTable entries

Frequency (mins)

60

Allowable range

To be baselined

Managed objects

All operational interfaces in the network

Metric:

Disk utilization

Description

Utilization of disk space within the Juniper Networks router

MIB name

HOST-RESOURCES-MIB (RFC 2790)

Variable name

hrStorageSizehrStorageUsed

Variable OID

hrStorageEntry.5 – hrStorageEntry.6

Frequency (mins)

1440

Allowable range

To be baselined

Managed objects

All Routing Engine hard disks

Metric:

Memory utilization

Description

Utilization of memory on the Routing Engine and FPC.

MIB name

JUNIPER-MIB (Juniper Networks enterprise Chassis MIB)

Variable name

jnxOperatingHeap

Variable OID

Table for each component

Frequency (mins)

60

Allowable range

To be baselined

Managed objects

All Juniper Networks routers

Metric:

CPU load

Description

Average utilization over the past minute of a CPU.

MIB name

JUNIPER-MIB (Juniper Networks enterprise Chassis MIB)

Variable name

jnxOperatingCPU

Variable OID

Table for each component

Frequency (mins)

60

Allowable range

To be baselined

Managed objects

All Juniper Networks routers

Metric:

LSP utilization

Description

Utilization of the MPLS label-switched path.

MIB name

MPLS-MIB

Variable name

mplsPathBandwidth / (mplsLspOctets * 8)

Variable OID

mplsLspEntry.21 and mplsLspEntry.3

Frequency (mins)

60

Allowable range

To be baselined

Managed objects

All label-switched paths in the network

Metric:

Output queue size

Description

Size, in packets, of each output queue per forwarding class, per interface.

MIB name

JUNIPER-COS-MIB

Variable name

jnxCosIfqQedPkts

Variable OID

jnxCosIfqStatsEntry.3

Frequency (mins)

60

Allowable range

To be baselined

Managed objects

For each forwarding class per interface in the network, once CoS is enabled.

This section includes the following topics:

Measuring Class of Service

You can use class-of-service (CoS) mechanisms to regulate how certain classes of packets are handled within your network during times of peak congestion. Typically you must perform the following steps when implementing a CoS mechanism:

  • Identify the type of packets that is applied to this class. For example, include all customer traffic from a specific ingress edge interface within one class, or include all packets of a particular protocol such as voice over IP (VoIP).

  • Identify the required deterministic behavior for each class. For example, if VoIP is important, give VoIP traffic the highest priority during times of network congestion. Conversely, you can downgrade the importance of Web traffic during congestion, as it may not impact customers too much.

With this information, you can configure mechanisms at the network ingress to monitor, mark, and police traffic classes. Marked traffic can then be handled in a more deterministic way at egress interfaces, typically by applying different queuing mechanisms for each class during times of network congestion. You can collect information from the network to provide customers with reports showing how the network is behaving during times of congestion. (See Figure 1.)

Figure 1: Network Behavior During Congestion
Network Behavior During Congestion

To generate these reports, routers must provide the following information:

  • Submitted traffic—Amount of traffic received per class.

  • Delivered traffic—Amount of traffic transmitted per class.

  • Dropped traffic—Amount of traffic dropped because of CoS limits.

The following section outlines how this information is provided by Juniper Networks routers.

Inbound Firewall Filter Counters per Class

Firewall filter counters are a very flexible mechanism you can use to match and count inbound traffic per class, per interface. For example:

For example, Table 2 shows additional filters used to match the other classes.

Table 2: Inbound Traffic Per Class

DSCP Value

Firewall Match Condition

Description

10

af11

Assured forwarding class 1 drop profile 1

12

af12

Assured forwarding class 1 drop profile 2

18

af21

Best effort class 2 drop profile 1

20

af22

Best effort class 2 drop profile 2

26

af31

Best effort class 3 drop profile 1

Any packet with a CoS DiffServ code point (DSCP) conforming to RFC 2474 can be counted in this way. The Juniper Networks enterprise-specific Firewall Filter MIB presents the counter information in the variables shown in Table 3.

Table 3: Inbound Counters

Indicator Name

Inbound Counters

MIB

jnxFirewalls

Table

jnxFirewallCounterTable

Index

jnxFWFilter.jnxFWCounter

Variables

jnxFWCounterPacketCount

jnxFWCounterByteCount

Description

Number of bytes being counted pertaining to the specified firewall filter counter

SNMP version

SNMPv2

This information can be collected by any SNMP management application that supports SNMPv2. Products from vendors such as Concord Communications, Inc., and InfoVista, Inc., provide support for the Juniper Networks Firewall MIB with their native Juniper Networks device drivers.

Monitoring Output Bytes per Queue

You can use the Juniper Networks enterprise ATM CoS MIB to monitor outbound traffic, per virtual circuit forwarding class, per interface. (See Table 4.)

Table 4: Outbound Counters for ATM Interfaces

Indicator Name

Outbound Counters

MIB

JUNIPER-ATM-COS-MIB

Variable

jnxCosAtmVcQstatsOutBytes

Index

ifIndex.atmVclVpi.atmVclVci.jnxCosFcId

Description

Number of bytes belonging to the specified forwarding class that were transmitted on the specified virtual circuit.

SNMP version

SNMPv2

Non-ATM interface counters are provided by the Juniper Networks enterprise-specific CoS MIB, which provides information shown in Table 5.

Table 5: Outbound Counters for Non-ATM Interfaces

Indicator Name

Outbound Counters

MIB

JUNIPER-COS-MIB

Table

jnxCosIfqStatsTable

Index

jnxCosIfqIfIndex.jnxCosIfqFc

Variables

jnxCosIfqTxedBytes

jnxCosIfqTxedPkts

Description

Number of transmitted bytes or packets per interface per forwarding class

SNMP version

SNMPv2

Dropped Traffic

You can calculate the amount of dropped traffic by subtracting the outbound traffic from the incoming traffic:

You can also select counters from the CoS MIB, as shown in Table 6.

Table 6: Dropped Traffic Counters

Indicator Name

Dropped Traffic

MIB

JUNIPER-COS-MIB

Table

jnxCosIfqStatsTable

Index

jnxCosIfqIfIndex.jnxCosIfqFc

Variables

jnxCosIfqTailDropPkts

jnxCosIfqTotalRedDropPkts

Description

The number of tail-dropped or RED-dropped packets per interface per forwarding class

SNMP version

SNMPv2