stp-flags usage

stp-flags usage

[Maksim]

Hello,

I have such topology (where BR1 is a Linux bridges)

                            BR1
  +--------+              +-----+          +--------+
  |        |  STP+TC      |     |          |        |
  | Cisco  |  ----->  eth1|-->X |eth2      | Cisco  |
  | Switch +--------------+     +----------+ Switch |
  |        |  ----->      | --> | ----->   |        |
  +--------+   STP        +-----+  STP     +--------+

and I want to block propagation of the config STP frames only when
its bit of topology-change (TC) is set in 1 while allowing passing
other STP frames.

If I correctly understand I shall use the following rule on BR1:

# ebtables -A FORWARD -i eth1 -d BGA --stp-flags 1 -j DROP

but it does NOT seem to work: the tcpdump output on the eth2 still
shows STP config message with the TC bit.

Moreover, even the rule counters are never change:

# ebtables -L --Ln --Lc                                    
Bridge table: filter
Bridge chain: INPUT, entries: 0, policy: ACCEPT
Bridge chain: FORWARD, entries: 1, policy: ACCEPT
1. -d BGA -i eth1 --stp-flags topology-change -j DROP , pcnt = 0 -- bcnt = 0
Bridge chain: OUTPUT, entries: 0, policy: ACCEPT

always showing pcnt = 0 -- bcnt = 0.

Could somebody point out where I am going wrong?

Thanks in advance,
Maksim.