DECnet over GRE tunnel with FiberOptic leased-line

Mar 29, 2006 6 Replies

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sali 20 years ago

Hi All,

I have a problem in tunneling DECNET traffic over GRE using FiberOptic leased-line as the media in the middle of the network.

DECNET terminal - router - layer3 switch - FiberOptic - layer3 switch - router - DECNET server

Although the DECNET packet is smaller the link mtu, I guess, I've try to enable tunnel PMTUD (tunnel path-mtu-discovery) and configure ip mtu

1476 in the tunnel interface.

Then I tried to modify the DF-bit using ip policy route-map in the tunnel interface. It still doesn't work.

Has anyone ever experience this problem?

Does it have something to do with the GRE Tunnel latency?

Regards, Sali

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Merv 20 years ago

Is IP working over the GRE tunnel ?

Does CDP flow over the tunnel ?

Post a sanitized configs of both routers and the post the output from both routers for

sh version

sh decnet
sh decnet interface

sh decnet route
sh decnet nei

Are Decnet hellos being exchanged over the tunnel ?

debug decnet adj

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Merv 20 years ago

Do you have "decnet cost x" configured on tunnel interfaces ?

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Neil Cherry 20 years ago

This wouldn't be LAT would it? That won't work (LAT) without configuring bridging on the tunnel. In the later IOS releases bridging isn't supported (but can be configured) on the GRE tunnel interface.

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Merv 20 years ago

If it is LAT, then LAT to TCP protocol translation should be used

see Cisco doc

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Neil Cherry 20 years ago

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The only problem with that is it very resource intensive (memory and CPU) and it doesn't support LAST and LAVC (sp?). It does work very well.

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Merv 20 years ago

Well if the OP is trying to run vax cluster traffic over the Internet then all bets are off ...

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