Unable to limit tcp bandwidth using tc in QoS for localhost

Question

I am trying to connect few bitcoind instance running on different ports on my local machine and control the bandwidth between those connections. I used the tc utility as following:

#network interface on which to limit traffic
IF="lo"
#limit of the network interface in question
LINKCEIL="1gbit"
#limit outbound Bitcoin protocol traffic to this rate
LIMIT="80bps"

#delete existing rules
tc qdisc del dev ${IF} root

#add root class
tc qdisc add dev ${IF} root handle 1: htb default 10

#add parent class
tc class add dev ${IF} parent 1: classid 1:1 htb rate ${LINKCEIL} ceil ${LINKCEIL}

#add our two classes. one unlimited, another limited
tc class add dev ${IF} parent 1:1 classid 1:10 htb rate ${LINKCEIL} ceil ${LINKCEIL} prio 0
tc class add dev ${IF} parent 1:1 classid 1:11 htb rate ${LIMIT} ceil ${LIMIT} prio 1

#add handles to our classes so packets marked with <x> go into the class with "... handle <x> fw ..."
tc filter add dev ${IF} parent 1: protocol ip prio 1 handle 1 fw classid 1:10
tc filter add dev ${IF} parent 1: protocol ip prio 2 handle 2 fw classid 1:11

#   --set-mark marks packages matching these criteria with the number "2"
#   these packages are filtered by the tc filter with "handle 2"
#   this filter sends the packages into the 1:11 class, and this class is limited to ${LIMIT}

for ((i = 1; i <= 10; i++))
do
    iptables -t mangle -A OUTPUT -p tcp -m tcp --dport $((18440 + $i)) -j MARK --set-mark 0x2
    iptables -t mangle -A OUTPUT -p tcp -m tcp --sport $((18440 + $i)) -j MARK --set-mark 0x2
done

I have modified the script from the original version: https://github.com/bitcoin/bitcoin/blob/master/contrib/qos/tc.sh

As show in the picture below, the connection for port 18444 is reporting a rate of 128 B/s which is way more than the set LIMIT of 80bps(80 Bytes/second).

Please point me in the right direction, if I am missing out something. I am using tcptrack to monitor the port connections.