leblanc
asked on
3750 QoS
I have QoS configured on several 3750s. I have Cisco VoIP phones connected to the switches. I also have voice vlan configured on the access switches.
My questions are follow:
- I have the QoS commands below at the global configuration mode. What happens if I don't have those QoS commands? Why do you need cos to dscp mapping?
mls qos map cos-dscp 0 8 16 24 32 46 48 56
mls qos srr-queue output cos-map queue 1 threshold 3 5
mls qos srr-queue output cos-map queue 2 threshold 1 2 4
...
- I have the command below on the interface. Why do I need to mark the packets as the Cisco phone already marked the packets and I use voice vlan?
policy-map lan-in
class voice
set dscp ef
class callsig
set dscp cs3
...
interface FastEthernet1/0/1
switchport access vlan 10
switchport mode access
switchport voice vlan 20
service-policy input lan-in
speed 100
duplex full
srr-queue bandwidth share 1 70 25 5
srr-queue bandwidth shape 30 0 0 0
priority-queue out
- Do I have to have the two srr-queue bandwith commands below on int fa1/0/1
interface FastEthernet1/0/1
...
srr-queue bandwidth share 1 70 25 5
srr-queue bandwidth shape 30 0 0 0
...
My questions are follow:
- I have the QoS commands below at the global configuration mode. What happens if I don't have those QoS commands? Why do you need cos to dscp mapping?
mls qos map cos-dscp 0 8 16 24 32 46 48 56
mls qos srr-queue output cos-map queue 1 threshold 3 5
mls qos srr-queue output cos-map queue 2 threshold 1 2 4
...
- I have the command below on the interface. Why do I need to mark the packets as the Cisco phone already marked the packets and I use voice vlan?
policy-map lan-in
class voice
set dscp ef
class callsig
set dscp cs3
...
interface FastEthernet1/0/1
switchport access vlan 10
switchport mode access
switchport voice vlan 20
service-policy input lan-in
speed 100
duplex full
srr-queue bandwidth share 1 70 25 5
srr-queue bandwidth shape 30 0 0 0
priority-queue out
- Do I have to have the two srr-queue bandwith commands below on int fa1/0/1
interface FastEthernet1/0/1
...
srr-queue bandwidth share 1 70 25 5
srr-queue bandwidth shape 30 0 0 0
...
ASKER
What if I don't have these commands on the global interface?
mls qos map cos-dscp 0 8 16 24 32 46 48 56
mls qos srr-queue output cos-map queue 1 threshold 3 5
mls qos srr-queue output cos-map queue 2 threshold 1 2 4
mls qos map cos-dscp 0 8 16 24 32 46 48 56
mls qos srr-queue output cos-map queue 1 threshold 3 5
mls qos srr-queue output cos-map queue 2 threshold 1 2 4
SOLUTION
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ASKER CERTIFIED SOLUTION
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ASKER
That is I wanted to know. I configure those QoS commands if I need to customize my QoS. That is the key.
" all you need to do is match the marking in your class map" or I can just do trust dscp. Correct?
" all you need to do is match the marking in your class map" or I can just do trust dscp. Correct?
SOLUTION
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ASKER
Yes. But I can remove the policy-map statement and service-policy input lan-in statement because I already have trust dscp. Correct? My QoS still works. What I am trying to do is to keep things simple,
SOLUTION
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So,
COS = Layer2
DSCP = Layer3