Outlines the differences between bind and unbind modes for loopback interfaces, clarifying their impact on interface configuration and traffic forwarding.
The difference between the bind mode and the unbind mode for loopback TLOC is that in a bind mode the passthrough traffic is dropped because the bound physical interface is treated as a TLOC by itself. In an unbind mode, the passthrough traffic is allowed.
Bind mode
A Cisco IOS XE Catalyst SD-WAN device has Loopback1 and Loopback2 configured as TLOCs and bound to the physical interface GigabitEthernet1. The device also has another interface, Loopback3, which is not configured as a TLOC.
Physical interface GigabitEthernet1 will be treated as a TLOC interface for incoming VPN 0.
In this example:
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If the traffic is destined for Loopback1, implicit ACL rules of Loopback1 are applied.
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If the traffic is destined for Loopback2, implicit ACL rules of Loopback2 are applied.
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If the traffic is destined for Loopback3 on GigabitEthernet1, traffic is allowed.
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If the traffic is destined for another device passing through GigabitEthernet1, it is dropped.
If the bound interface, GigabitEthernet1, is also configured as a TLOC, the traffic to Loopback3 will be subjected to implicit ACL rules on GigabitEthernet1.
Unbind mode
A Cisco IOS XE Catalyst SD-WAN device has Loopback1 configured as a TLOC and is in unbind mode. Loopback2 is not configured as a TLOC. The device also has GigabitEthernet1 interface, which is configured as a TLOC, and GigabitEthernet4 interface, which is not configured as a TLOC.
In this example:
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If the traffic destined for Loopback1 arrives at GigabitEthernet1, the Loopback1 implicit ACL rules are applied. If the traffic is destined for GigabitEthernet1, the GigabitEthernet1 implicit ACL rules are applied.
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If the traffic destined for Loopback1 arrives at GigabitEthernet4, the Loopback1 implicit ACL rules are applied. If the traffic is destined for GigabitEthernet4, traffic is allowed.
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If the traffic destined for Loopback2 arrives on GigabitEthernet1, the GigabitEthernet1 implicit ACL rules are applied. If the traffic is destined for another device passing through GigabitEthernet1, it is dropped.
If the traffic is destined for another device passing through GigabitEthernet4, the traffic is forwarded.