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Paxy
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IPv6 Routing table - somethings does not sounds right

Thu Apr 23, 2015 4:50 pm

Is it possible that Mirkotik FW still have issues with basic IPv6 routing procedures ?
My guess is that I am doing something wrong but maybe is an issue.

With recent FW 6.28 you can see on img thing that bother me.
Image
https://www.dropbox.com/s/ncsek0qssg1tv ... 1.png?dl=0

Ping to host 2001:470:6ab5:1::1 shows in traceroute as forwarder to default gw even if there is more specific routes (2001:470:6ab5::/48, and even 2001:470:6ab5:1::1/128).
 
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ZeroByte
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Re: IPv6 Routing table - somethings does not sounds right

Thu Apr 23, 2015 7:40 pm

Do you have route marks involved?
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Re: IPv6 Routing table - somethings does not sounds right

Thu Apr 23, 2015 8:20 pm

Do you have route marks involved?
No, IPv6 is clean installation, just Tunnel, addresses and routes are configured.
 
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ZeroByte
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Re: IPv6 Routing table - somethings does not sounds right

Thu Apr 23, 2015 9:22 pm

Try using the link-local address of the other router for your next hop.
(I'm still pretty new to IPv6 myself, but it seems that link-local next hops are preferred)
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Re: IPv6 Routing table - somethings does not sounds right

Thu Apr 23, 2015 10:33 pm

Hmm, strange thing.
Could not ping other side on link via link-local address. Routing table did not include any record about link-local addresses.
Also it refuses to accept static route via link-local address.

Then I configured OSPFv3 (but for two routers it should not be required). Pings started to work and I got route like:
2001:470:6ab5:1::/64 pointing to fe80::d6ca:6dff:fefa:1d79%VRRP
Notice this %Interface looks like it is the main reason of this problem.

After that I have removed OPSFv3 and just added static route like this, and routing works just fine.
Solution: Next hop should be link-local address with % symbol and interface name in same line
 
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Re: IPv6 Routing table - somethings does not sounds right

Thu Apr 23, 2015 11:00 pm

Sorry - I should have mentioned that fact.
With link-local, it's required because it's not enough to give some link-local address to ping - you have to also specify on which interface - because EVERY interface contains an address in fe80::/16 - the routing table is not enough to answer the question about where to send the packet.
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Re: IPv6 Routing table - somethings does not sounds right

Fri Apr 24, 2015 11:40 am

Here is some best practice explanation about Next-hop for IPv6
In IPv6, fe80::/10 is reserved for this purpose, though link-local addresses are always configured with a fe80::/64 prefix. The concept of a link-local address is much more heavily used in IPv6, and one very popular use case is in next-hop determination. While it’s possible to use Global Unicast addresses, such as anything in the 2000::/3 block, it’s also a very popular use case to use link-local addreses to get packets to a next-hop router.
http://keepingitclassless.net/2013/03/i ... practices/

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