nanog mailing list archives
Re: Transit LAN vs. Individual LANs
From: Warren Kumari <warren () kumari net>
Date: Mon, 27 Feb 2006 11:08:47 -0800
On Feb 25, 2006, at 9:23 PM, Owen DeLong wrote:
--On February 25, 2006 8:09:22 PM +0000 "Christopher L. Morrow" <christopher.morrow () verizonbusiness com> wrote:On Sat, 25 Feb 2006, Neil J. McRae wrote:An argument could be made for individual VLANs to keep things like b- cast storms isolated. But I think the additional complexity will cause more problems than it will solve.Vlans will not stop all typres of broadcast storm.So, perhaps I missed the earlier explanation, but why use switchedsegments at all? if the purpose is to connect routers to routers puttingsomething that WILL FAIL in the middle is only going to increase your labor costs later :( So, for router-router links, GE doesn't have to mean switched...Very true. In fact, GE is even easier because part of the GE standard for UTP requires it to be Auto-MDI-Sensing (MDI vs MDI-X is handled automatically in ALL compliant GE/TP interfaces).
Unfortunately it seems that not all devices actually implement MDI/MDI-X IEE Std 802.3ab-1999, 40.4.4 (Page 93) says:"Implementation of an automatic MDI/MDI-X configuration is optional for 1000BASE-T devices".
IEE Std 802.3ab-1999, 40.8,2 (Page 93) says:"Although the automatic MDI-<DI-X configuration (see 40.4.4) is not required for successful operation of 1000BASE-T, is is a functional requirement that a cross-over function be implemented in every link segment to support the operation of Auto-Negotiation"
Now, seeing as Auto-Negotiation is required, it implies that automatic MDI/MDI-X is also required -- however, certain vendors seem to ignore this....
W
Thus, you can use any eia-568[ab] cable, straight or crossed between them. (Note, USOC cables still won't work, it has to be 568a or 568b pairing) Owen -- If it wasn't crypto-signed, it probably didn't come from me.
Current thread:
- Transit LAN vs. Individual LANs Scott Weeks (Feb 24)
- Re: Transit LAN vs. Individual LANs Patrick W. Gilmore (Feb 25)
- RE: Transit LAN vs. Individual LANs Neil J. McRae (Feb 25)
- RE: Transit LAN vs. Individual LANs Christopher L. Morrow (Feb 25)
- RE: Transit LAN vs. Individual LANs Owen DeLong (Feb 25)
- Re: Transit LAN vs. Individual LANs Warren Kumari (Feb 27)
- Re: Transit LAN vs. Individual LANs goemon (Feb 27)
- RE: Transit LAN vs. Individual LANs Neil J. McRae (Feb 25)
- Re: Transit LAN vs. Individual LANs Patrick W. Gilmore (Feb 25)
- Re: Transit LAN vs. Individual LANs Mark Smith (Feb 25)
- Re: Transit LAN vs. Individual LANs Mark Smith (Feb 25)
- Re: Transit LAN vs. Individual LANs Stephen Sprunk (Feb 28)