Re: Single subnet
Steve Deering <deering@pescadero.stanford.edu> Sun, 20 May 1990 00:04 UTC
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Date: Sat, 19 May 1990 16:20:00 -0000
From: Steve Deering <deering@pescadero.stanford.edu>
Subject: Re: Single subnet
To: Dave Katz <katz@merit.edu>
Cc: fddi@merit.edu
Message-Id: <90/05/19
In-Reply-To: Dave Katz's message of Sat, 19 May 90 180251 EST
Status: O
> > Will CLNP routers detect the wrap->thru transition and use > > that to trigger a solicitation for ES Hellos? > > Yes, in that IS-IS uses the loss of an IS on a subnetwork to trigger > this function. If all the ISs are dual-MACed, unwrapping does not cause any ISs to disappear from either of the two resulting subnetworks. So, for this to work, it would have to be the loss of an IS *at a specific MAC address* that triggers the solicitation of ES configuration. Is that the case? Also, if there is only one (dual-MAC) IS attached to the FDDI network, it would have to detect the loss of connectivity between its *own* two MACs, and use that to trigger ES solicitation. Is that the case? I presume that the FDDI MAC or PHY layer detects unwrap events. Can they or should they not be signalled upward as "change of topology" events? > However, asking for ES Hellos doesn't help get rid > of the ones you can't reach any more. The spec calls for reducing > the remaining holding time on ES adjacencies, but when you add > it all up, it can take up to 239 (!) seconds to lose old ES adjacencies. But that's the main problem, right? An IS may continue to send packets to a single-MAC ES via the "wrong" ring for that length of time after an unwrap event. (I suppose a fancy IS would load split across the two rings, so half the packets would get through. Are the transport protocols expected to cope with that?) > These timers can be cranked down, however. Sounds like a good idea! Steve
- Single subnet Dave Katz
- Re: Single subnet Steve Deering
- Re: Single subnet Dave Katz
- Re: Single subnet Steve Deering
- Re: Single subnet Vernon Schryver
- Re: Single subnet Steve Deering
- Re: Single subnet Dave Katz
- Re: Single subnet Vernon Schryver
- Re: Single subnet Steve Deering
- Re: Single subnet Dave Katz
- Re: Single subnet Dave Katz