[Olsr-users] problem when disconnection two network cables

[Ferry Huberts]

You can post the patch here, or on the dev list

Henning, WDYT?

On 12/06/15 15:55, Koen Swinters wrote:
> Hi all,
>
> We are using olsrd-0.6.8 in our system.
>
> I have a problem with the following setup:
>
> Node 8100 ------------- node 3
>
>       |             X                 |
>
> Node 8120 ------------- node 425
>
> Each node has a wired connection to the 3 other nodes (each node has 3
> Ethernet interfaces). Olsrd is running on each node.
>
> When I disconnect the cable between node 3 and node 8120 and after this
> the cable between node 8120 and node 425 => node 425 cannot reach node
> 8120 anymore (there is still a path via node 3 and node 8100) => the
> routing table on node 425 is not updated.
>
> Remark: when there is no physical Ethernet connection our systems
> disables the eth interface (ethx)
>
> I`ve investigated this problem and found the following problem in olsrd:
>
> ·disconnect the cable between node 3 and node 8120 => Link down between
> 3 and 8120 => disable interface
>
> oLine 371 in interfaces.c: "olsr_remove_interface(struct olsr_if* iface)"
>
> ·Line 379 in "interfaces.c":  "olsr_delete_link_entry_by_ip(&ifp->ip_addr)"
>
> §Line 411 in "link_set.c":  "olsr_delete_link_entry(link);"
>
> ·Line 375 in
> "olsr_delete_neighbor_table(&link->neighbor->neighbor_main_addr)";
>
> ·This function will delete the neighbor from the neighbor table
>
> ·(Line 177 in neighbor_table.c)
>
> ·This function sets "changes_neighborhood = true;" (Line 219 in
> neighbor_table.c)
>
> oIn "olsr_scheduler(void)" (line 486 in scheduler.c)
>
> ·function "olsr_process_changes()" (line 180 in olsr.c)
>
> ·Because "changes_neighborhood == TRUE and olsr_cnf->lq_level > 1"
> "olsr_calculate_lq_mpr() "is called
>
> ·In "olsr_calculate_lq_mpr()" (line 51 in lq_mpr.c) a new mpr is
> calculated (8100 will now be mpr for 8120) and the function
> "signal_link_changes(true);" is called => link_changes  == true
>
> ·In the next step  ANSN  is increased
>
> oAt the tc_interval  a tc message is generated with this ANSN in => the
> neighbors see a change in the ANSN number(when the packet are received)
> an will update their tables
>
> ·Link Down between node 8120 and 425
>
> oLine 371 in interfaces.c: "olsr_remove_interface(struct olsr_if* iface)"
>
> ·Line 379 in "interfaces.c":  "olsr_delete_link_entry_by_ip(&ifp->ip_addr)"
>
> §Line 411 in "link_set.c":  "olsr_delete_link_entry(link);"
>
> ·Line 375 in
> "olsr_delete_neighbor_table(&link->neighbor->neighbor_main_addr)";
>
> ·This function will delete the neighbor from the neighbor table
>
> ·(Line 177 in neighbor_table.c)
>
> ·This function sets "changes_neighborhood = true;" (Line 219 in
> neighbor_table.c)
>
> oIn "olsr_scheduler(void)" (line 486 in scheduler.c)
>
> ·function "olsr_process_changes()" (line 180 in olsr.c)
>
> ·Because "changes_neighborhood == TRUE and olsr_cnf->lq_level > 1"
> "olsr_calculate_lq_mpr() "is called
>
> ·In "olsr_calculate_lq_mpr()" (line 51 in lq_mpr.c) no new mpr is
> calculated (8100 will stay mpr for 8120) and the function
> "signal_link_changes(true);" is not called => link_changes  == false
>
> ·In the next step  ANSN  is not increased
>
> oAt the tc_interval  a tc message is generated with old ANSN in => the
> neighbors see no change in the ANSN number(when the packet are received)
> an will no update their tables
>
> Solution:
>
> ·When a neighbor is deleted from the neighbor table (line 177 in
> neighbor_table: olsr_delete_neighbor_table(const union olsr_ip_addr
> *neighbor_addr)) also call the function signal_link_changes(true);
> because there is a change in the neighbor table.
>
> I’ve tested this and it is working correct (routing tables are updated
> as expected).
>
> Where can I post this fix, or is there a better solution?
>
> Regards,
>
> koen
>
>
>

-- 
Ferry Huberts