Measuring Performance

[Contents] [Prev] [Next] [Index] [Report an Error]

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 28).

Table 28: 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	hrStorageSize – hrStorageUsed
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 7.)

Figure 7: Network Behavior During Congestion

Image g017048.gif

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:


            
               firewall {
               
                  
                     filter f1 {
                     
                        
                           term t1 {
                           
                              
                                 from {
                                 dscp af11;
                                 }
                              
                           
                           
                              
                                 then {
                                 # Assured forwarding class 1 drop profile 1 count inbound-af11;
                                 accept;
                                 }
                              
                           
                           }
                        
                     
                     }
                  
               
               }

For example, Table 29 shows additional filters used to match the other classes.

Table 29: 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 30.

Table 30: 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 31.)

Table 31: 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 32.

Table 32: 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:


            
               Dropped = Inbound Counter – Outbound Counter

You can also select counters from the CoS MIB, as shown in Table 33.

Table 33: 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

[Contents] [Prev] [Next] [Index] [Report an Error]