15.1. Running multiple sites with different SLAs
You can do this in several ways. Apache has some support for this with a
module, but we'll show how Linux can do this for you, and do so for other
services as well. These commands are stolen from a presentation by Jamal
Hadi that's referenced below.
Let's say we have two customers, with http, ftp and streaming audio, and we
want to sell them a limited amount of bandwidth. We do so on the server itself.
Customer A should have at most 2 megabits, customer B has paid for 5
megabits. We separate our customers by creating virtual IP addresses on our
server.
# ip address add 188.177.166.1 dev eth0
# ip address add 188.177.166.2 dev eth0 |
It is up to you to attach the different servers to the right IP address. All
popular daemons have support for this.
We first attach a CBQ qdisc to eth0:
# tc qdisc add dev eth0 root handle 1: cbq bandwidth 10Mbit cell 8 avpkt 1000 \
mpu 64 |
We then create classes for our customers:
# tc class add dev eth0 parent 1:0 classid 1:1 cbq bandwidth 10Mbit rate \
2MBit avpkt 1000 prio 5 bounded isolated allot 1514 weight 1 maxburst 21
# tc class add dev eth0 parent 1:0 classid 1:2 cbq bandwidth 10Mbit rate \
5Mbit avpkt 1000 prio 5 bounded isolated allot 1514 weight 1 maxburst 21 |
Then we add filters for our two classes:
##FIXME: Why this line, what does it do?, what is a divisor?:
##FIXME: A divisor has something to do with a hash table, and the number of
## buckets - ahu
# tc filter add dev eth0 parent 1:0 protocol ip prio 5 handle 1: u32 divisor 1
# tc filter add dev eth0 parent 1:0 prio 5 u32 match ip src 188.177.166.1
flowid 1:1
# tc filter add dev eth0 parent 1:0 prio 5 u32 match ip src 188.177.166.2
flowid 1:2 |
And we're done.
FIXME: why no token bucket filter? is there a default pfifo_fast fallback
somewhere?