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This patch changes the way the link local address is configured in VPP. Previously we were going through the addresses configured on the uplink in linux prior to starting VPP, extracting the Linklocal and using is as-is in VPP. This patch makes it so that we first create the tap interface in linux, wait for it to get a linklocal address and use the new one as a Link local in VPP. This addresses a conflict where linux will compute two different LL addresses for the real uplink - prior to VPP starting - and the tuntap replacing it - after VPP started. This due to the fact that the computation [0] includes idev->dev->perm_addr which is unset in tuntap but is in hardware drivers. Another reason for this design is that VPP does not currently support multiple LL addresses for a given interface. [0] https://github.com/torvalds/linux/blob/master/net/ipv6/addrconf.c#L3337C12-L3337C40 Signed-off-by: Nathan Skrzypczak <nathan.skrzypczak@gmail.com>
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aritrbas
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Feb 6, 2026
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This patch changes the way the link local address is configured in VPP. Previously we were going through the addresses configured on the uplink in linux prior to starting VPP, extracting the Linklocal and using is as-is in VPP.
This patch makes it so that we first create the tap interface in linux, wait for it to get a linklocal address and use the new one as a Link local in VPP.
This addresses a conflict where linux will compute two different LL addresses for the real uplink - prior to VPP starting - and the tuntap replacing it
Another reason for this design is that VPP does not currently support multiple LL addresses for a given interface.
[0] https://github.com/torvalds/linux/blob/master/net/ipv6/addrconf.c#L3337C12-L3337C40