ASR920 MPLS label Switching over GRE

[Alireza Soltanian]

Hi

Currently we purchased ASR920. I did some tests on it. In one of my tests, I have three routers:

C2821----ASR920----C7200

I have GRE tunnel between C2821 and ASR920 and I have Layer-2 connectivity between ASR920 and C7200. I also have OSPF and MPLS in action on all links.

The case is when the network was converged on OSPF and MPLS, I cannot do normal icmp source-ping  Loop1 of C7200 from C2821 Loop1 and vice-versa.

When I change the connection between ASR920 and C7200 to GRE tunnel everything works fine.

I also must mention when I break the LSP path with disabling MPLS on interfaces, the connectivity works fine too.

It seems in Control Plane everything works properly:

1) OSPF is converged.

2) LDP is converged and MPLS LFIB looks fine.

But in Data plane when ASR920 is doing MPLS label switching it cannot placed un-Tunneled packets inside GRE header and vice-versa.

When the Layer-2 connection between ASR920 and C7200 is changed to GRE, MPLS switching works fine since incoming packets and outgoing packets both have GRE header.(From/To both C7200 and C2821)

Any idea to solve this issue?

Thank you

Alireza Soltanian

[Vinit Jain]

Hello Alireza

Could you please share the below output in non-working condition from ASR920 router:

- show mpls for <C2821_loopback>

- show mpls for <C7200_loopback>

- show ip route <2821_loop>

- show ip route <c7200_loop>

Also, please share the configuration from all the 3 routers in a file.

Regards

Vinit

[Vasilii Mikhailovskii]

Just a note for anybody reading the article - GRE is not supported on ASR920 (effective Feb 2017).

[vamikhai]

Just an update to avoid confusion:

 - GRE tunnels on ASR920 are still NOT supported;

 - mVPN GRE (profile 0) is supported on ASR920 under certain conditions - pleasesee more details on the link https://www.cisco.com/c/en/us/td/docs/routers/asr920/configuration/guide/ipmcast/ipmulti-xe-3-14-asr920-book/ipmulti-xe-3-14-asr920-book_chapter_0111.html#GUID-EE855CF2-DD71-4961-8ADE-D4D983128510

[Vasilii Mikhailovskii]

Support for GRE on ASR920 may come with 16.10.1 (tentative release is the middle of November 2018).

Best regards,

[abgromov]

16.10.1  release notes  does not contain any information about GRE support.

https://content.cisco.com/platform_home.sjs?platform=Cisco%20ASR%20920%20Series%20Aggregation%20Services%20Router&release=OS%20XE%20Gibraltar%2016.10.x

Is this feature in the roadmap?

[vamikhai]

Looks like the support was shifted to 16.11:

Starting Cisco IOS XE release 16.11.x, unicast GRE tunnel supports IPv4 as transport protocol and payload protocol of also type IPv4.