Inbound GRE configuration Guide - #1114
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| sidebar_label: GRE Cloud Peering | ||
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| Cloud security and SD-WAN services — such as Akamai — commonly terminate customer traffic over Generic Routing Encapsulation (GRE) tunnels and monitor tunnel liveness by sending inbound ICMP echo requests (health checks) to the customer end of each tunnel. As described in [Native GRE Tunnels](config_gre_tunnel.md), an SSR `gre-tunnel` network-interface does not answer these inbound ICMP probes on its own, so the far-end service can mark an otherwise healthy tunnel as down. |
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Is there a need to call out the other vendor? I feel this can be left as a "generic third party security appliance" or something like that.
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It can be left completely generic, although I find that specific examples are better for associating reference docs.
| ## Overview | ||
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| SSR native GRE (`type gre-tunnel`) does not pass inbound ICMP echo requests to the Linux stack, so a health-checking peer receives no reply. The workaround is to create a `host`-type device interface (KNI) with the same IP address as the GRE tunnel's `internal-address`. The Linux host stack answers the ICMP echo replies, and SSR services steer inbound GRE and ICMP traffic into that host interface. | ||
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The term host-type device interface is used several times in this document and it is ambiguous. Can you please clarify for me? Is it a device interface acting like a host? Is it supposed to be host-type device-interface? Is it just a host device-interface that AI keeps trying to classify?
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A device-interface can be defined as a type depending on its purpose. From the 128T datamodel:
leaf type {
type enumeration {
enum ethernet {
description
"A physical ethernet interface.";
}
enum kni {
status obsolete;
description
"A logical interface to VM, host process, or container instance.";
}
enum pppoe {
description
"An interface using the Point-to-Point Protocol over Ethernet (PPPoE).";
}
enum host {
description
"A logical interface to the host system.";
}
enum bridged {
description
"A logical interface bridged to a target interface.";
}
enum lte {
description
"An interface using LTE.";
}
enum t1 {
description
"An interface using a T1 card.";
}
enum bond {
description
"An aggregated group of ethernet interfaces.";
}
enum conduit {
description
"An interface which is used as a connection to a switch device.";
t128-internal:visibility hidden;
}
}
Chr1st0ph3rTurn3r
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August 13, 2026 18:06
Chr1st0ph3rTurn3r
approved these changes
Aug 13, 2026
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