3850 GRE Support in Hardware?

[a.mallory]

Does anybody know if the 3850 will support GRE in hardware, if so, is there a document that says so? I have been unable to locate any information so far. The 3850 will allow you to configure it, but I need to know if this will be processed in hardware or not.

Thanks in advance for any information!

[Haihua Rong · Accepted solution]

Hello Andrew,

The feature is supported and processed on hardware, here is a brief statement for this platform:

“GRE tunnel encapsulation and deencapsulation for multicast packets are handled by the hardware. Each hardware-assisted tunnel must have a unique source. Hardware-assisted tunnels cannot share a source even if the destinations are different. You should use secondary addresses on loopback interfaces or create multiple loopback interfaces to ensure that the hardware-assisted tunnels do not share a source.”

http://www.cisco.com/en/US/docs/ios-xml/ios/interface/command/ir-xe-3se-3850-cr-book_chapter_01110.html

Haihua

[Haihua Rong · Accepted solution]

Hello Andrew,

Nevertheless there is a defect:

https://tools.cisco.com/bugsearch/bug/CSCtz13264

3850: Remove CLIs used to configure GRE tunnel - may cause crash

CSCtz13264

So GRE on Cat3k, including 3850 is unsupported feature.

You may want to reconsider your design and terminate GRE on IOS Router and GRE supported switch.

Haihua

[omvanderwiele]

Just to update this old post that I just found using Google... GRE is now supported in Hardware with the right SW version. From the release notes in 3.7E

http://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst3850/software/release/3e/release_notes/rn-3dot7e-3850.html

What’s New in Cisco IOS XE Release 3.7.2E

• GRE tunneled packets switched on hardware—Support for forwarding GRE tunneled packets on the switch hardware.

[alnajaba]

Hello, For me the statement

"GRE tunneled packets switched on hardware—Support for forwarding GRE tunneled packets on the switch hardware."

does not sound like the tunnel is HW processed,  it sounds for me like " if this switch is in the middle and a GRE tunnel cross trough the device  is capable to HW process the tunnel traffic".

But, for me the origial question remains, what about if this Switch is the start/end of the tunnel?