QOS: Does Traffic-Shaping count also MAC-Header in Calculation

[HUBERT RESCH]

Hi we using HFQ to shape and queue the traffic outgoing on our Ethernet WAN Interfaces

policy-map xQOS-SHAPED-10000-QUEUE-POLICY
class class-default
    shape average 9700000 97000 0
  service-policy xQOS-QUEUE-POLICY

interface GigabitEthernet0/3.1022
bandwidth 10000
encapsulation dot1Q 1022
ip address x.x.x.x 255.255.255.252
ip flow ingress
ip pim sparse-mode
ip tcp adjust-mss 1320
ip ospf authentication message-digest
ip ospf message-digest-key 10 md5 <removed>

ip ospf network point-to-point
bfd interval 200 min_rx 200 multiplier 3
crypto map MAP-GETVPN-SECURE-WAN
service-policy output xQOS-SHAPED-10000-QUEUE-POLICY
end

Now we had a discussion, if the Shaper is counting the whole Packet for the calculation including the MAC-Header or just the IP-Packet.

We made Tests filling the Line up with 64-Byte Packets, and in this case its important to know how the shaper counts it (whole packet 64Byte, IP-Packet 50Byte) because our ISP is using an Policer which is definitifely counting the whole Packet.

Does anybody know how it works really on an IOS-Box running 15.0(1)M4

Thx

Hubert

[Sudeep Khuraijam]

If you are using a layer2 vpls type service, your layer2 dot.1q encap with its IP payload, is their IP/MPLS payload so you have to take into account the layer2 overhead.  Is that what you are seeing?

[HUBERT RESCH]

For example, if you have a shaper

shape average 8000000 80000 0

and you are only (no other traffic is present) sending an 100Byte (IP-Packet without L2-Header)(800 Bits) constantly every 100 microseconds, you exactly reach the limit of the shaper( 8Mbit/s or 80000 bits per interval which is 10 milliseconds), no packet has to be dropped, all Packets are sent out to the WAN.

On the ISP-Incoming Interface the see now 8Mbit/s *1,14 (14 Byte MAC-Header , no dot1q-Tag) = 9,12 Mbit/s. So from the view of the ISP, if we would have agreed to 8Mbit/s it would be ok to drop nearly 1250 of these Packets every second.

Thats the reason why its impoortant for us to know if the shaper is countig as well the L2-Header. What I know the policer on the ISP-side does count the L2-Header.

Hubert

[Kishore Chennupati]

Hi Hubert,

please see if the following link helps,

https://supportforums.cisco.com/thread/210969

HTH,