CONFIGURING INTERFACE TO TRANSMIT ONLY

[TARMENTANI]

We are looking to configure a C3650 to monitor sessions from a specific VLAN and send the data out through a single interface with a SFP-10G-SR. We would like the interface to solely transmit (TX) with the receive(RX) being completely physically disconnected; we will only be plugging in one (TX) of pairs into the SFP.  Any ideas?        Switching, Catalyst 3000

[Flavio Miranda]

Hi

I bit confuse you setup but as per monitor session, yes, it is possible to choose the RX TX:

# monitor session 1 source interface "int" tx|rx

[TARMENTANI]

The issue is that I only want to physically connect a strand (not the pair) of fiber.  The monitoring is going to a separate security boundary network and I want to transmit to it but not allow any data back.  The interface will not go into any state that allows just to transmit.  It seems to need to have the receive side connected which is not the desired end result.  

[Reza Sharifi]

One strand will not bring up the interface. Also, the destination device will only be receiving data and will not send anything back to the source.

HTH  

[TARMENTANI]

Yes, this is the intended design.  I want complete separation and only to send without receiving.  Is this even possible?  

[Leo Laohoo]

ACL

[TARMENTANI]

ACL to only send without receiving?   I am not tracking how your response is relevant.  

[Leo Laohoo]

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@TARMENTANI wrote:

ACL to only send without receiving?   I am not tracking how your response is relevant.  

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Physically, you cannot just use a single strand if one end is a two strand.  If the objective of this exercise is to use a single strand because there is not enough core to use, then use BX.  

If the exercise is only to deliberately use one-way-traffic only, put an ACL to stop the return traffic from happening.  

[Joseph W. Doherty]

"Physically, you cannot just use a single strand if one end is a two strand."

@Leo Laohoo. strangely, at least on the 7600, it was possible.

The company I had worked for was/is a huge video cable provider.  They only had a "need" (at the time) to transmit video down to their subscribers.  Also (at the time) 10g ports and their optics were very, very expensive.  Normally, you would expect a two strand connection between two 7600s, but this also meant, for 7600s as transit devices in the daisy chain, you need to use two ports, one for the upstream path, and one for the downstream path.  However, again, they used just one port, with one fiber stand connecting, from same port, to both the upstream and downstream neighbors.

I recall(?) this was something TAC helped them to accomplish.

[Joseph W. Doherty]

Last company I worked at did something like that, years ago, on 7600s.  From one 7600 they tx'ed to another 7600's rx.  I.e. they created a unity directional fiber daisy chain.

The head of the chain (most like your request), didn't use its rx while the last in the chain didn't use its tx.  The in between units did use both their tx and rx, but to different devices.

Unfortunately, I only recall they did do something on the interface config to allow this - don't recall "what" the config was - nor whether it would work on a 3650.

[mlund]

Hi

Maybe "no keep-alive" can work.

/Mikael

[Joseph W. Doherty]

I recall (?) there was a bit more to doing it than just "no keep-alive", although only one or a few additional interface commands.  One might try "no keep-alive".