EAPS and oneway traffic

Userlevel 1
Question around oneway traffic patterns in a ring design

Say I have a ring of 4 switches interconnected with WDM equipment over dualfiberpairs

Between switch 1 and 2 I loose the link, so the switch flags the port as down Local fault.
However the WDM equipment manages to have one TX/RX active in one direction only. But the switch acts as if the ring is down and opens the secondary port on the master.

In this scenario traffic would still arrive at the masters secondary port but just one-way.

My question around this. Would this cause a loop ?
Switch 1 would still receive all the traffic from switch 2 but it could not send anything back since its one-way traffic only.

Makes sense?

2 replies

Userlevel 6
Andreas, If the Transit switches see the link as down, they will not pass any traffic through it. You can check the state of a switch with the command show eaps It should show something like this eaps.sw1.1 # show eaps EAPS Enabled: Yes EAPS Fast-Convergence: Off EAPS Display Config Warnings: On EAPS Multicast Add Ring Ports: Off EAPS Multicast Send IGMP and MLD Query: On EAPS Multicast Temporary Flooding: Off EAPS Multicast Temporary Flooding Duration: 15 sec Number of EAPS instances: 2 # EAPS domain configuration : ---------------------------------------------------------------------------------- Domain State Mo En Pri Sec Control-Vlan VID Count Prio ---------------------------------------------------------------------------------- r1 Links-Up T Y 1 2 c1 (4001) 1 N r2 Links-Down T Y 2 3 c2 (4002) 1 N ---------------------------------------------------------------------------------- Flags : (!) CFM Down *
Userlevel 6

If you are running EXOS v15.2 or higher, you can configure EAPS to use CFM to check link health.

That way, EAPS will consider the link as up only if both switches can excange CFM messages correctly.