QoS for OSPF and MPLS

[jm-barreto]

Greetings

I want to create class and policy-map that prioritize ospf and mpls traffic on links that are congested. This is for backbone links, not for links facing CE. I will appreciate if there any configuration sample or documentation that you can share.

Thanks

[jm-barreto]

I got this sample configuration, i want to validate if this is viable.

ipv4 access-list OSPF_ACL
10 permit ospf any any

ipv4 access-list MPLS_ACL
10 permit mpls any any

class-map match-any OSPF_CLASS
match access-group name OSPF_ACL

class-map match-any MPLS_CLASS
match access-group name MPLS_ACL

policy-map QOS_POLICY
class OSPF_CLASS
set dscp af31
bandwidth percent 5
priority level 1

class MPLS_CLASS
set dscp af32
bandwidth percent 5

interface GigabitEthernet0/0/0/0
service-policy input QOS_POLICY

[M02@rt37]

Hello @jm-barreto,

If your gig is the interface facing your Backbone and mpls is activated on it, I think you have to configure/adjust EXP.

If a packet is encapsulated in MPLS, the MPLS payload cannot be checked for other protocols such as IP for classification or marking. Only MPLS EXP marking affects packets encapsulated by MPLS.

https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/qos_classn/configuration/xe-16/qos-classn-xe-16-book/qos-classn-mrkg-mpls-exp.html

[Giuseppe Larosa]

Hello @jm-barreto ,

there are several issues in your proposed configuration the main point has been been noted by M02@rt37 .

MPLS frames have the EXP field to be used for marking and QoS.

In addition to this note, the proposed configuration using priority and bandwidth commands means CBWFQ with LLQ and it works only in the outbound direction. You cannot apply it inbound it is not supported.

CBWFQ with LLQ is a queuing system and applied to outbond only.

You can match on OSPF but be aware that OSPF packets are already marked with DSCP CS6 so you shouldn't remark them.

Hope to help

Giuseppe