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Network Station - FLASH: Ethernet Network Stations attached to some Cabletron switches - problems connecting to the server
Applicable to: World-Wide
Overview:
Ethernet stations (NETWORK STATIONS) directly attached to a switch port of some Cabletron switches may have a
problem connecting to a server, after establishing a physical link to the switch.
Discussion:
This issue affects the ATX (aka ES1/ATX), ELS10-26TX prior to firmware rev 1.00.02, and FN10. Not affected are the ES1,
ELS10-26TX since firmware rev 1.00.02, ELS100-16TX, ELS100-24TX, ELS100-24TXM, and FN100.
On the affected products, the switch port is forced into Listening/Learning mode whenever a link is established on a
previously inactive (status = "BROKEN!") port. This contrasts with the unaffected products, which only invoke Spanning
Tree on a port if a BPDU (Bridge Protocol Data Unit) is received on that port.
For the duration of the Forwarding Delay time (generally 15 seconds per S.T.A. phase, for a total of 30 seconds), any attempts
of the newly attached station (client) to communicate to the network will fail. The problem arises for clients that cease their
connection attempts before the bridge port starts forwarding. The clients then fail to connect to a server.
This issue is not present when a shared media hub is used between the client and the switch, since the physical link to the
switch port has already been established, and stabilized, by the time the client is plugged into the hub.
Solution (or Circumvention):
A short-term work-around can be applied by requesting a reconnection attempt via the client's console, without physically
cycling the link on the switch port. The specific method of doing this will vary based on the protocol in question.
A more permanent resolution is to prevent affected ports from participating in Spanning Tree, by shutting off BPDU
support. This can be done in local management by typing the command: "bridge [port#] trans nobpdu" (ATX) or "bridge
[port#] nobpdu" (ELS10/FN10). This requests that the port be set to transparent bridging with no BPDU support. The
command takes effect immediately, with no interruption of switch functionality.
Since the ports in question do not contribute to bridging redundancy, shutting off Spanning Tree has no negative
side-effects. However, if the connectivity requirement of a given port changes, Spanning Tree can be re-implemented, as
desired, with the command: "bridge [port#] trans" (ATX) or "bridge [port#] on" (ELS10/FN10).
Additional information is located at the following web site:
http://www.cabletron.com/support/techtips/tk0452-9.html
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Document Category |
Technical Flashes | |
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Date Created |
19-05-99 | |
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Last Updated |
25-05-99 | |
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Revision Date |
26-06-99 | |
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Brand |
Network Computers, IBM Network Station | |
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Product Family |
AS/400 - Network Station, S/390 VM/ESA - Network Station, S/390 OS/390 - Network Station, RS/6000 - Network Station, OS/2 Warp Server - Network Station, NT Server - Network Station | |
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Machine Type |
8361, 8362, All | |
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Model |
All | |
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TypeModel |
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Retain Tip (if applicable) |
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Reverse Doclinks |