[ovs-discuss] load:OXM_OF_ETH_DST[25..32]->NXM_NX_REG0[0..7] problem

[Ali Volkan Atli]

Hello

I am trying to implement a simple fat-tree topology using the two-level routing tables what is written in the paper (A Scalable, Commodity Data Center Network Architecture). Briefly it tries to use prefix and suffix concepts as below

Prefix
table=0,10.2.0.0/24   -> Output: 1
table=0,10.2.1.0/24   -> Output: 2
table=0, 0.0.0.0/0    -> goto_table: 1

Suffix
table=1,0.0.0.2/8     -> Output: 3
table=1,0.0.0.3/8     -> Output: 4

I know OvS does not have suffix, so I tried to load the last digit of ip into reg0, then use it in table1 but it did not work

table=0,priority=0,dl_type=0x0800,actions=load:OXM_OF_ETH_DST[25..32]->NXM_NX_REG0[0..7],goto_table=1
table=1,reg0=2,actions=output=1
table=1,reg0=3,actions=output=2

when I tried to ping from 10.0.0.2 to 10.0.1.2, the following entries are shown in dump-flows. Always "load:0", but it must have been load:2

 cookie=0x0, duration=4.640s, table=0, n_packets=0, n_bytes=0, idle_age=4, dl_type=0x88cc actions=CONTROLLER:65535
 cookie=0x0, duration=4.363s, table=0, n_packets=3, n_bytes=294, idle_age=1, priority=0,ip actions=load:0->NXM_NX_REG0[0..7],resubmit(,1)
 cookie=0x0, duration=4.378s, table=0, n_packets=0, n_bytes=0, idle_age=4, ip,nw_dst=10.0.0.2 actions=output:3
 cookie=0x0, duration=4.371s, table=0, n_packets=0, n_bytes=0, idle_age=4, ip,nw_dst=10.0.0.3 actions=output:4
 cookie=0x0, duration=4.356s, table=1, n_packets=0, n_bytes=0, idle_age=4, reg0=0x2 actions=output:1
 cookie=0x0, duration=4.349s, table=1, n_packets=0, n_bytes=0, idle_age=4, reg0=0x3 actions=output:2

Thanks in advance

- Volkan