MLS QOS has been one of the greatest fear for my CCIE RS exam. I’ve read it several times, labbed it more than 3 times, but still I just cannot understand it. Then I decided to write my own notes to teach myself and hopefully any of you mere mortals like me.

I’ll start with this Classification and Marking and let see how deep the rabbit hole goes for the next few parts.

Enjoy!
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Just say that we have these three sites connected to the main hub R1. R1 – R2 is running EIGRP 12 and R1 – R3 is running EIGRP 13. R1 – R4 runs no routing protocol and R4 uses default route pointing to R1 Fa2/0 interface 14.14.14.1.

Initial configuration below

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• Proxy ARP (Cisco Page)
• To check whether an interface is using Proxy ARP or not.

  Rack10R6#sh ip int f0/0.146 | i ARP
    Proxy ARP is enabled
    Local Proxy ARP is disabled
  

• To enable/disable Proxy ARP on the interface

  Rack10R6(config)#int f0/0.146
  Rack10R6(config-subif)#no ip proxy-arp 
  Rack10R6(config-subif)#do sh ip int f0/0.146 | i ARP
    Proxy ARP is disabled
    Local Proxy ARP is disabled
  

• To disable Proxy ARP from the global configuration (Proxy ARP is enabled by default)

  Rack10R6(config)#ip arp proxy disable 
  Rack10R6(config)#do sh ip int f0/0.146 | i ARP
    Proxy ARP is disabled (Globally)
    Local Proxy ARP is disabled
  

When you configure switchport access vlan 20 on an interface:

• This will make the interface become a layer 2 switchport or non-routeable port.
• There is no 802.1q/ISL tagging involvement in this port as the traffic will be received and sent as untagged.
• Because there is no tagging involved, the port has no clue what VLAN this frame should be. Therefore, any packets passing this port is assumed to belong to the VLAN assigned to this port. In this case vlan 20.
• If you add the configuration with switchport mode access this will make the interface turned to nontrunking permanently and also negotiates or telling the other end of the link to be a nontrunk link. This interface will permanently become nontrunk interface regardless the other end is trunk or nontrunk link. With this in mind, if one port is configured with switchport mode access and other end port happens to be configured with switchport mode dynamic auto or switchport mode dynamic desirable
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Catalyst QOS Port-Based Policing Cannot Co-exist with Vlan-based Classification.

SW1#sh ver | i cisco

http://www.cisco.com/wwl/export/crypto/tool/stqrg.html

export@cisco.com.
cisco WS-C3560-24TS (PowerPC405) processor (revision D0) with 122880K/8184K bytes of memory.

SW1#conf t
Enter configuration commands, one per line.  End with CNTL/Z.
SW1(config)#
SW1(config)#no policy-map PM_QOS
SW1(config)#
SW1(config)#ip access-list ext ACL_IP
SW1(config-ext-nacl)# permit ip any any
SW1(config-ext-nacl)#exit
SW1(config)#
SW1(config)#class-map CM_IP
SW1(config-cmap)# match access-group name ACL_IP
SW1(config-cmap)#exit
SW1(config)#
SW1(config)#no policy-map PM_QOS
SW1(config)#policy-map PM_QOS
SW1(config-pmap)# class class-default
SW1(config-pmap-c)#  police 128000 125000 exceed-action drop
SW1(config-pmap-c)# exit
SW1(config-pmap)#exit
SW1(config)#
SW1(config)#int f0/1
SW1(config-if)# service-policy in PM_QOS
%QoS: policymap is not attachable to vlan-based interface
Service Policy attachment failed
SW1(config-if)#exit
SW1(config)#exit
SW1#
*Mar  1 09:26:17.854: %SYS-5-CONFIG_I: Configured from console by console
SW1#sh run int f0/1
Building configuration...

Current configuration : 81 bytes
!
interface FastEthernet0/1
 switchport access vlan 146
 mls qos vlan-based
end

SW1#conf t
Enter configuration commands, one per line.  End with CNTL/Z.
SW1(config)#int f0/1
SW1(config-if)#no mls qos vlan-based
SW1(config-if)#^Z
SW1#
*Mar  1 09:26:35.545: %SYS-5-CONFIG_I: Configured from console by console
SW1#conf t
Enter configuration commands, one per line.  End with CNTL/Z.
SW1(config)#int f0/1
SW1(config-if)# service-policy in PM_QOS
SW1(config-if)#exit
SW1(config)#exit
SW1#
*Mar  1 09:26:47.550: %SYS-5-CONFIG_I: Configured from console by console
SW1#sh poli
SW1#sh policy-map int f0/1
 FastEthernet0/1 

  Service-policy input: PM_QOS

    Class-map: class-default (match-any)
      0 packets, 0 bytes
      5 minute offered rate 0 bps, drop rate 0 bps
      Match: any 
        0 packets, 0 bytes
        5 minute rate 0 bps
SW1#

This article explains prefix-list in a very easy way to understand.

Legacy Frame Relay Traffic Shaping

int s0/0/0
 band 1536
 frame-relay traffic-shaping
 frame-relay interface-dlci 513
  class MC_513
 frame-relay interface-dlci 504
  class MC_504
 exit
exit

map-class frame-relay MC_513
 frame-relay cir 128000
 frame-relay bc  6400
 frame-relay be  51200
 frame-relay mincir 96000
 frame-relay adaptive-shaping becn
map-class frame-relay MC_504
 frame-relay cir 512000
 frame-relay bc  25600
 frame-relay be  0
 frame-relay mincir 384000
 frame-relay adaptive-shaping becn
exit

Class-Based Generic Traffic Shaping for Frame Relay

class-map CM_DLCI_513
 match fr-dlci 513
class-map CM_DLCI_504
 match fr-dlci 504
exit

policy-map PM_FRTS
 class CM_DLCI_513
  shape average 128000 6400 0
  shape adaptive 96000
 class CM_DLCI_504
  shape average 512000 25600 51200
  shape adaptive 384000  
 exit
exit

int s0/0/0
 bandwidth 1536
 no frame-relay traffic-shaping
 service-policy output PM_FRTS
exit

MQC-based Frame Relay Traffic Shaping

int s0/0/0
 band 1536
 no frame-relay traffic-shaping
 frame-relay interface dlci 513
  class MC_513
 frame-relay interface dlci 504
  class MC_504
 exit
exit

map-class frame-relay MC_513
 service-policy out PM_513
map-class frame-relay MC_504
 service-policy out PM_504
exit

policy-map PM_513
 class class-default
  shape average 128000 6400 0
  shape adaptive 96000 ! automatically adapt to BECN
 exit
exit

policy-map PM_504
 class class-default
  shape average 512000 25600 51200
  shape adaptive 384000 ! automatically adapt to BECN
 exit
exit

Notes.
Bc = CIR (in bits per seconds) * (Tc/1000)
(Bc + Be) / (Tc/1000) = AIR

Example.

Bc = CIR (in bits per seconds) * (Tc/1000)
Bc = 512000 * 50/1000
Bc = 512000 * 0.05
Bc = 25600

(Bc + Be) / (Tc/1000) = AIR
(25600 + Be) / 0.05 = 1536000
Be = (1536000 * 0.05) – 25600
Be = 51200

Note – 30 December 2011.
For MQC-based Frame Relay Traffic Shaping, inside the policy-map, command shape average needs to be applied first.

ROUTER(config)#policy-map PM_513
ROUTER(config-pmap)# class class-default
ROUTER(config-pmap-c)#  shape adaptive 256000
Traffic Shaping must be enabled on this class before the command can be issued
ROUTER(config-pmap-c)# shape average 384000
ROUTER(config-pmap-c)#shape adaptive 256000