Routing

Hi Experts

I am really much confused in getting the concepts of policer types in JUNOS. Can any one explain this in simple words. Please don not give the links for JUNOS documentation 🙂

1- Physical interface policer

2- Logical interface policer

3- bandwidth policer

4- Hierarchical policer

Thanks

Hi

Is there any one?

Hi,

"Physical Policers" are used when you want to limit the traffic at IFD level, assuming you don't have any
IFLs.

In case you have multiple IFLs in one IFD with the usage of VLANs (ethernet)/ DLCI (sonet), and you want to limit the traffic differently for each logical interfaces, then you use "Logical Interface Policer". This is also used when you want to rate limit the traffic irrespective of the traffic type (families).

If you want single policer to cater the same traffic metering for interfaces based on their individual speeds, you can use "Bandwidth Policers". With the static values used in non-bandwdith policers, it may not be feasible for all interfaces running at different speed.

Hierarchy Policers is little different and it is Layer-2 policer. Basically with policers non-conforming traffic would be metered irrespective of their preference. In cases where the trafffic is mix of High Priority (EF) and Low priority, one would like to dedicate some bandwdith of the total policer for EF traffic and remaining bandwidth for non-EF traffic. With Hierarchy Policers user defines Premium Policer for EF traffic and an Aggregate Polcier for all traffic. So eventually the Premium policer bandwidth is the guranteed subset of Aggregate Polcier bandwdith.

Hope this helps you.

Regards
Surya Prakash

Thanks for the reply. So it means:

1- If I want to apply the policer on the physical interface for all aggregate traffic then I will use the "Physical Interface Policer"

2- If I want to apply the different policers for each logical interface of same physical interface then I will use "Logical Interface Policer"

3- If I want to apply the single policer to different interface of varying speed then I would use "Bandwidth Policer"

4- If I want to dedicate some of the bandwidth of policer to some traffic and rest to the aggregate traffic then I would use "Hierarchy Policer"

Below are my two more questions:

1- What is "interface-specific" in the policer configuration?

2- If I have one physical interface and only unit 0 and I want to apply the policer to all families then I would use physical or logical interface policer?

Thanks for your time

Hi,

1- What is "interface-specific" in the policer configuration?

[Surya] I believe you are referring to the "interface-specific" knob in firewall. If so, then it helps to keep different counters instances for each interfaces . Otherwise it would be an aggregate count for all interfaces which uses same FW/Policer.

2- If I have one physical interface and only unit 0 and I want to apply the policer to all families then I would use physical or logical interface policer?

[Surya] In this case, you use logical-interface policer.

Regards

Surya Prakash

Thanks... Just last thing:

If I have one physical interface and only unit 0 and I want to apply the policer to only inet family then I would use physical or logical interface policer?

Thanks