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FIB: default route not found in FIB #4543

Closed miri64 closed 8 years ago

miri64 commented 8 years ago

When testing #4144 with a border router setup, I set up the interfaces as follows:

ifconfig
2015-12-23 15:00:24,042 - INFO # Iface  5   HWaddr: 65:b2  Channel: 26  Page: 0  NID: 0x23  TX-Power: 0dBm  State: IDLE CSMA Retries: 4 
2015-12-23 15:00:24,048 - INFO #            Long HWaddr: 5a:55:68:6c:25:35:65:b2 
2015-12-23 15:00:24,054 - INFO #            AUTOACK  CSMA  MTU:1280  HL:64  6LO  RTR  RTR_ADV  IPHC  
2015-12-23 15:00:24,057 - INFO #            Source address length: 8
2015-12-23 15:00:24,059 - INFO #            Link type: wireless
2015-12-23 15:00:24,064 - INFO #            inet6 addr: ff02::1/128  scope: local [multicast]
2015-12-23 15:00:24,070 - INFO #            inet6 addr: fe80::5855:686c:2535:65b2/64  scope: local
2015-12-23 15:00:24,076 - INFO #            inet6 addr: ff02::1:ff35:65b2/128  scope: local [multicast]
2015-12-23 15:00:24,081 - INFO #            inet6 addr: ff02::2/128  scope: local [multicast]
2015-12-23 15:00:24,082 - INFO #            
2015-12-23 15:00:24,087 - INFO # Iface  6   HWaddr: 00:04:25:19:1a:3e  State: IDLE
2015-12-23 15:00:24,091 - INFO #            MTU:1500  HL:64  RTR  RTR_ADV  
2015-12-23 15:00:24,094 - INFO #            Source address length: 6
2015-12-23 15:00:24,096 - INFO #            Link type: wired
2015-12-23 15:00:24,102 - INFO #            inet6 addr: ff02::1/128  scope: local [multicast]
2015-12-23 15:00:24,108 - INFO #            inet6 addr: fe80::204:25ff:fe19:1a3e/64  scope: local
2015-12-23 15:00:24,114 - INFO #            inet6 addr: ff02::1:ff19:1a3e/128  scope: local [multicast]
2015-12-23 15:00:24,119 - INFO #            inet6 addr: ff02::2/128  scope: local [multicast]
2015-12-23 15:00:24,120 - INFO #            
ifconfig 6 add abcd::204:25ff:fe19:1a3e/16
fibroute add :: via fe80::xxxx:xxxx:xxxx:xxxx dev 6 # link local of linux machine
ping6 abcd::xxxx:xxxx:xxxx:xxxx

and got ping timeouts. Further debugging showed, that fib_get_next_hop() did not find the default route as specified, but (I don't know exactly why) the packets where send over the 6LoWPAN.

OlegHahm commented 8 years ago

What is fibroute saying?

miri64 commented 8 years ago 
fibroute
2015-12-23 14:54:58,239 - INFO # > fibroute
2015-12-23 14:54:58,251 - INFO # Destination                             Flags        Next Hop                                Flags      Expires          Interface
2015-12-23 14:54:58,262 - INFO # ::                                      0x00000000 H fe80::xxxx:xxxx:xxxx:xxxx               0x00000000 NEVER            6
cgundogan commented 8 years ago

I think your flags for the fib entry are wrong. FIB_FLAG_NET_PREFIX must be set for the :: route, I believe.

cgundogan commented 8 years ago

It should be sufficient to set only the destination flags of the fib entry

miri64 commented 8 years ago

how do I do that with the fibroute command?

cgundogan commented 8 years ago

usage: fibroute add <destination> via <next hop> [dev <device>] [lifetime <lifetime>]

cgundogan commented 8 years ago

hmm, doesn't seem to work from within the shell then

miri64 commented 8 years ago

Okay, with the flag set (I set it statically in the command), it is at least not send over 6Lo anymore and the FIB seems to find the entry. I still get timeouts, but they are probably related to a broken ND.

miri64 commented 8 years ago

When I set the next hop in the fib to the GUA of the linux host it works. Fine for me :-)

miri64 commented 8 years ago

(the back-translation of 6Lo-ND of ll addresses is the problem)

cgundogan commented 8 years ago

@BytesGalore I also encountered this problem several times. If you add the default route via the fibroute shell command then it is not possible to ping6 between two nodes. I assume it has to do with the destination flag of the default route entry. Because RPL sets the destination flag of the default route to be FIB_FLAG_NET_PREFIX. Pinging works then.

OlegHahm commented 8 years ago

Is this flag new? I remember that default routes used to work last summer.

BytesGalore commented 8 years ago

@cgundogan yes the problem is that the FIB_FLAG_NET_PREFIX is not set by the fibroute command, the capital H behind the flags indicates the destination is flagged as a host.

cgundogan commented 8 years ago

@BytesGalore what would be the best solution to solve this? Is it possible to infer from the given ipv6 address if the FIB_FLAG_NET_PREFIX should be set automatically (somehow without making the fib specific to IPv6)

BytesGalore commented 8 years ago

Try #4584 :)

BytesGalore commented 8 years ago

At least it will allow to set the default route using the fibroute command. With #4279 there will be the proper way to set the prefix.

cgundogan commented 8 years ago

fixed by #4584