chassis-packet: Update arp_update script for FAILED and STALE check (#16311)
1. Fixing an issue with FAILED entry resolution retry.
Neighbor entries in arp table may sometimes enter a FAILED state when the far end is down and reports the state as follows:
2603:10e2:400:3::1 dev PortChannel19 router FAILED
While the arp_update script handles the entries for FAILED in the following format, the above was not handled due to the token location (extra router keyword at index 4):
2603:10e2:400:3::1 dev PortChannel19 FAILED
The former format may appear if an arp resolution is tried on a link that is known but the far end goes down, e.g., pinging a STALE entry while the far end is down.
2. Refreshing STALE entries to make sure the far end is reachable.
STALE entries for some backend ports may appear in chassis-packet when no traffic is received for a while on the port. When the far end goes down, it is expected for BFD to stop sending packets on the session for which the far end is not reachable. But as the entry is known as stale, on the Cisco chassis, BFD keeps sending packets. Refreshing the stale entry will keep active links as reachable in the neighbor table while the entries for the far end down will enter a failed state. FAILED state entries will be retired and entered reachable when far end comes back up.
* To resolve NEIGH table entries present in CONFIG_DB. Without this change arp/ndp entries which we wish to resolve, and configured via CONFIG_DB are not resolved.
Why I did it
Fixes#14179
chassis-packet: missing arp entries for static routes causing high orchagent cpu usage
It is observed that some sonic-mgmt test case calls sonic-clear arp, which clears the static arp entries as well. Orchagent or arp_update process does not try to resolve the missing arp entries after clear.
How I did it
arp_update should resolve the missing arp/ndp static route
entries. Added code to check for missing entries and try ping if any
found to resolve it.
How to verify it
After boot or config reload, check ipv4 and ipv4 neigh entries to make sure all static route entries are present
manual validation:
Use sonic-clear arp and sonic-clear ndp to clear all neighbor entries
run arp_update
Check for neigh entries. All entries should be present.
Testing on T0 setup route/for test_static_route.py
The test set the STATIC_ROUTE entry in conifg db without ifname:
sonic-db-cli CONFIG_DB hmset 'STATIC_ROUTE|2.2.2.0/24' nexthop 192.168.0.18,192.168.0.25,192.168.0.23
"STATIC_ROUTE": {
"2.2.2.0/24": {
"nexthop": "192.168.0.18,192.168.0.25,192.168.0.23"
}
},
Validate that the arp_update gets the proper ARP_UPDATE_VARDS using arp_update_vars.j2 template from config db and does not crash:
{ "switch_type": "", "interface": "", "pc_interface" : "PortChannel101 PortChannel102 PortChannel103 PortChannel104 ", "vlan_sub_interface": "", "vlan" : "Vlan1000", "static_route_nexthops": "192.168.0.18 192.168.0.25 192.168.0.23 ", "static_route_ifnames": "" }
validate route/test_static_route.py testcase pass.
arp_update should resolve the missing arp/ndp static route
entries. Added code to check for missing entries and try ping to
resolve the missing entry.
Why I did it
Fixes#14179
chassis-packet: missing arp entries for static routes causing high orchagent cpu usage
It is observed that some sonic-mgmt test case calls sonic-clear arp, which clears the static arp entries as well. Orchagent or arp_update process does not try to resolve the missing arp entries after clear.
How I did it
arp_update should resolve the missing arp/ndp static route
entries. Added code to check for missing entries and try ping if any
found to resolve it.
How to verify it
After boot or config reload, check ipv4 and ipv4 neigh entries to make sure all static route entries are present
manual validation:
Use sonic-clear arp and sonic-clear ndp to clear all neighbor entries
run arp_update
Check for neigh entries. All entries should be present.
Signed-off-by: anamehra <anamehra@cisco.com>
Fix the issue where arp_update will not ping some of the ip's even
though they are in failed state since grep of that ip on ip neigh show
command does not do exact word match and can return multiple match.
After pinging any failed IPv6 neighbor entries, set the remaining failed/incomplete entries to a permanent INCOMPLETE state. This manual setting to INCOMPLETE prevents these entries from automatically transitioning to FAILED state, and since they are now incomplete any subsequent NA messages for these neighbors is able to resolve the entry in the cache.
Signed-off-by: Lawrence Lee <lawlee@microsoft.com>
In arp_update, check for FAILED or INCOMPLETE kernel neighbor entries and manually ping them to try and resolve the neighbor
Signed-off-by: Lawrence Lee <lawlee@microsoft.com>
What I did:
Following changes done for packet based chassis:-
1> Run arp_update on LC's to resolve static route nexthops over backend
port-channel interfaces.
2> On Supervisor make sure arp_update exit gracefully
Fix#7968
Issue is detected on SONiC.20201231.11
In test_static_route.py::test_static_route_ecmp static routes are configured, but neighbors are not resolved after config reload even after 10 minutes.
It looks like the arp_update script is starting to ping when Vlan1000 is not fully configured.
When issue is reproduced, stuck ping6 process is observed in swss container :
USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND
root 180 0.1 0.0 6296 1272 pts/0 S 17:03 0:03 ping6 -I Vlan1000 -n -q -i 0 -c 1 -W 0 ff02::1
And when arp_update script successfully resolves neighbors, we observe sleep 300 instead of ping process
#### Why I did it
* `arp_update` fails to ping those neighbors over vlan sub interfaces.
#### How I did it
* modify `arp_update_vars.j2` to get vlan sub interfaces with ipv6 addresses assigned.
* modify `arp_update` to send ipv6 pings over those retrieved vlan sub interfaces.
Signed-off-by: Longxiang Lyu <lolv@microsoft.com>
This PR limited the number of calls to sonic-cfggen to one call
per iteration instead of current 3 calls per iteration.
The PR also installs jq on host for future scripts if needed.
signed-off-by: Tamer Ahmed <tamer.ahmed@microsoft.com>
* Fix potential blackholing/looping traffic and refresh ipv6 neighbor to avoid CPU hit
In case ipv6 global addresses were configured on L3 interfaces and used for peering,
and routing protocol was using link-local addresses on the same interfaces as prefered nexthops,
the link-local addresses could be aged out after a while due to no activities towards the link-local
addresses themselves. And when we receive new routes with the link-local nexthops, SONiC won't insert
them to the HW, and thus cause looping or blackholing traffic.
Global ipv6 addresses on L3 interfaces between switches are refreshed by BGP keeplive and other messages.
On server facing side, traffic may hit fowarding plane only, and no refresh for the ipv6 neighbor entries regularly.
This could age-out the linux kernel ipv6 neighbor entries, and HW neighbor table entries could be removed,
and thus traffic going to those neighbors would hit CPU, and cause traffic drop and temperary CPU high load.
Also, if link-local addresses were not learned, we may not get them at all later.
It is intended to fix all above issues.
Changes:
Add ndisc6 package in swss docker and use it for ipv6 ndp ping to update the neighbors' state on Vlan interfaces
Change the default ipv6 neighbor reachable timer to 30mins
Add periodical ipv6 multicast ping to ff02::11 to get/refresh link-local neighbor info.
* Fix review comments:
Add PORTCHANNEL_INTERFACE interface for ipv6 multicast ping
format issue
* Combine regular L3 interface and portchannel interface for looping
* Add ndisc6 package to vs docker
