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Have a Debian 10 Linux and ZTE ZXR10 5960 L3 switch as a router on the network. The problem is that Linux send Router Solicitation (RS) packet without "Source link-layer address" as ICMPv6 type 133 option. ZTE ignore this RS packet and don't send Router Advertisment (RA). As a result - large intervals (up to 10 minutes) of receiving IPv6 address/DNS servers on Linux host via DHCP. There is no such problem with Cisco L3 switch as a router - it's send RA imediatly after receiving RS.

Default RA interval on ZTE is 600 seconds. The one way I can fix RS/RA exchange is to set RA interval to 60 seconds or less.

Is there any Linux kernel parameter to specify to include "Source link-layer address" as option at ICMPv6 type 133? How can I fix the problem correctly?

According RFC 4861:

A router might process Router Solicitations as follows:

...

If there is no existing Neighbor Cache entry for the solicitation's sender, the router creates one, installs the link- layer address and sets its reachability state to STALE as specified in Section 7.3.3. If there is no existing Neighbor Cache entry and no Source Link-Layer Address option was present in the solicitation, the router may respond with either a multicast or a unicast router advertisement.

dshykuts
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  • What did ZTE say about this? It seems like the problem is with their switch. The source link-layer address is supposed to be omitted at this stage. See RFC 4861 section 4.1. – Michael Hampton Feb 01 '21 at 15:32
  • ZTE say that, according RFC 4861 6.2 "The router MAY respond with either a multicast or a unicast router advertisement but not SHOULD." According to RFC 4861 4.1 "Source link-layer address. The link-layer address of the sender, if known. MUST NOT be included if the Source Address is the unspecified address. Otherwise, it SHOULD be included on link layers that have addresses." – dshykuts Feb 01 '21 at 18:43
  • Yes, but they are not sending a multicast or a unicast router advertisement. They are sending nothing. Not responding is not one of the allowed options. And of course it makes absolutely no sense for the router to not respond in this scenario. – Michael Hampton Feb 01 '21 at 18:46

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