Nick, Oliver: by flow control you mean the 'regular' Ethernet flow control using the PAUSE frame mechanism?
Olivier: I wasn't aware that remote fault detection is part of the autonegotiation. Thanks! I tested this out with two directly connected Juniper M series routers and it works exactly as you described. However, as I understand, JUNOS allows to enable auto-negotiation while at the same keep the local interface online despite the fact that link is unidirectional. I mean the [ auto-negotiation remote-fault local-interface-online ] and [ auto-negotiation remote-fault local-interface-offline ] options. For some reason, this did not work: http://s8.postimg.org/nd5zyo0mr/autoneg_and_remote_fault.png As you can see, both in case "Remote fault" "Online" or "Offline", the local interfaces go down if link becomes unidirectional. Any comments on this behavior? regards, Martin 2013/5/6, Olivier Benghozi <[email protected]>: > 1000Base-X can negotiate flow control. > > But, an interesting part of autoneg is Remote Fault Notification: one of the > fibers in your 2 fibers link breaks, and the link becomes unidirectional; > the side that sees its receiving fiber down sends a frame to notify the > other side (which didn't see anything special) that the link is down (so > this side will also show the link as "down", whereas it receives proper > signal). > Without this, when a single fiber breaks, to detect (slower) the problem and > prevent unidirectional GE links, you have to rely on protocols running at a > higher level: specialized ones (Cisco's UDLD, OAM), on routing protocols, or > on LACP (which can be used on a single link for this purpose, as would > describe http://kb.juniper.net/InfoCenter/index?page=content&id=KB13314). > > This also exists in 10GE links as Link Fault Signaling. > > > regards, > Olivier > > >> supported according to IEEE 802.3 22.2.4.4.2)? In a nutshell, why is >> auto-negotiation needed on 1000BASE-X ports? > > _______________________________________________ juniper-nsp mailing list [email protected] https://puck.nether.net/mailman/listinfo/juniper-nsp
