Add ip6tables rule for DHCPv6 hop limit configuration#865
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Configure ip6tables mangle rule to set hop limit to 2 for DHCPv6 OUTPUT traffic from client (sport 546) to server (dport 547). This prevents VPP from dropping DHCPv6 SOLICIT/REQUEST packets when it decrements hop-limit by 1 during forwarding. Since clients generate SOLICIT/REQUEST with hop-limit=1, without this rule VPP drops the packet (ip6 ttl <= 1) with ICMP time exceeded, causing DHCPv6 lease negotiation to fail. The rule is checked for existence before adding to prevent duplicates since ip6tables does not auto-dedupe rules. The rule is also cleaned up during configuration restoration. Signed-off-by: Aritra Basu <aritrbas@cisco.com>
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sknat
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Jan 30, 2026
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Configure ip6tables
manglerule to set hop limit to 2 for DHCPv6OUTPUTtraffic from client (sport 546) to server (dport 547). This prevents VPP from dropping DHCPv6SOLICIT/REQUESTpackets when it decrements hop-limit by 1 during forwarding. Since clients generateSOLICIT/REQUESTwith hop-limit=1, without this rule, VPP drops the packet (ip6 ttl <= 1) with ICMPtime exceeded, causing DHCPv6 lease negotiation to fail.