Summary
When using a transit VLAN with IP Proxy ARP implemented and a Static Route pointing to a VE interface as the Next Hop, ARP entries from Source/Destination VLANs are not being learned as expected
Background
In a typical environment where IP Proxy ARP is not in use, ARP entries should not be learned for addresses that fall outside of the configured prefix range. Changes made in SLXOS-77770 (SLX-OS 20.7.2, 20.7.1b) caused ARP Reply messages for addresses outside of the configured prefix to be dropped incorrectly when using IP Proxy ARP with a Static Route pointing to a VE interface as the Next Hop.
Impact
This can cause network impact for traffic expected to traverse a transit VLAN configured for IP Proxy ARP
Products Affected
SLX 9740, SLX 9640, SLX 9540, SLX 9250, SLX 9150, Extreme 8820, Extreme 8720, Extreme 8520
Software Affected
SLX-OS 20.7.1b, SLX-OS 20.7.2, SLX-OS 20.7.2a
Symptoms
In this situation, the ARP Request and Reply will still be transmitted as expected with IP Proxy ARP, however SLX-OS will drop the ARP Reply upon receipt causing traffic to no longer traverse the transit VLAN
Workaround
Changing the IP Route to point to the L3 IP Address of Next Hop rather than the VE Interface will restore traffic
Solution
The software fix is targeted for a future SLX-OS 20.7.3 or higher release.
Please check the release notes once the software release is available to ensure that Defect ID: SLXOS-78634 is included.
Please see the full Field Notice here for more details and future updates.
