3750 EMI Tunneling GRE

Unanswered Question
Apr 23rd, 2007

Does some one know the maximum number of tunnel GRE that a 3750 EMI switch can support simultaneously?

Thank you

I have this problem too.
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mohammedmahmoud Mon, 04/23/2007 - 01:49

Hi there,

Kindly check out the IDB on your IOS (show idb):

Each tunnel interface definition, such as Universal Transport Interface (UTI), Generic Routing Encapsulation (GRE), Multiprotocol Label Switching Traffic Engineering (MPLS TE), or Any Transport over MPLS (AToM) consumes an HWIDB plus one SWIDB per tunnel, plus an additional SWIDB for each additional sub-interface, for example, a Frame Relay PVC, that is tunneled. The tunnel IDBs are in addition to the original interface(s) that are tunneled.

Maximum Number of Interfaces and Subinterfaces for Cisco IOS Platforms: IDB Limits


HTH, please rate if it does help,

Mohammed Mahmoud.

royalblues Mon, 04/23/2007 - 02:04


The switch does not support tunnel interfaces for unicast routed traffic. Only Distance Vector Multicast Routing Protocol (DVMRP) tunnel interfaces are supported for multicast routing.

So it is not recommended to configure GRE tunnels on 3750 unless you are using DVMRP.

Have a look at this link


HTH, rate if it does


mchakir Mon, 04/23/2007 - 02:12

Thank You Narayan,

I want use the tunnel Interfaces for only static routing. I have an simple architecture that use FH and Wimax link, so if the FH or Wimax go down the Ethernet Interface still UP, so i want to use tunnel interfaces for 60 remote site on a 3750 layer 3 swith.



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