ospf6d / OSPFv3: Post graceful-restart grace lsa flush failed on the GR-Restarter

[rchandrans]

Description

OSPFv3 Graceful-restart grace lsa flush failed on the GR-Restarter. Post restart, after all adjacencies are re-established on the restarting node grace lsa flush(grace lsa maxage send) failed.

Version

FRRouting 8.2.2 (node1).
Copyright 1996-2005 Kunihiro Ishiguro, et al.
configured with:
    '--build=x86_64-linux-gnu' '--prefix=/usr' '--includedir=${prefix}/include' '--mandir=${prefix}/share/man' '--infodir=${prefix}/share/info' '--sysconfdir=/etc' '--localstatedir=/var' '--disable-option-checking' '--disable-silent-rules' '--libdir=${prefix}/lib/x86_64-linux-gnu' '--libexecdir=${prefix}/lib/x86_64-linux-gnu' '--disable-maintainer-mode' '--localstatedir=/var/run/frr' '--sbindir=/usr/lib/frr' '--sysconfdir=/etc/frr' '--with-vtysh-pager=/usr/bin/pager' '--libdir=/usr/lib/x86_64-linux-gnu/frr' '--with-moduledir=/usr/lib/x86_64-linux-gnu/frr/modules' '--disable-dependency-tracking' '--disable-rpki' '--disable-scripting' '--with-libpam' '--enable-doc' '--enable-doc-html' '--enable-snmp' '--enable-fpm' '--enable-iptrackd' '--disable-protobuf' '--disable-zeromq' '--disable-isisd' '--disable-eigrpd' '--disable-ldpd' '--disable-ripd' '--disable-ripngd' '--disable-babeld' '--disable-vrrpd' '--disable-fabricd' '--enable-ospfapi' '--disable-ospfclient' '--disable-bgp-vnc' '--disable-pbrd' '--disable-nhrpd' '--disable-watchfrr' '--enable-multipath=256' '--enable-user=frr' '--enable-group=frr' '--enable-vty-group=frrvty' '--enable-configfile-mask=0640' '--enable-logfile-mask=0640' 'build_alias=x86_64-linux-gnu' 'PYTHON=python3

How to reproduce

GR configuration

1. There are 2 nodes(node1---node2) connected back-to-back over a single link and ospfv3 is enabled on the interface
2. node1 is configured with "graceful-restart grace period 600"
3. node2 is configured with "graceful-restart helper enable"
4. on node-1, ospf6d is restarted which will originate grace-lsa on the link
5. on node-2, ospf neighbor will receive grace lsa and will become a GR-Helper
6. post restart ospf6d does graceful restart procedures
   6a. receives pre-restart lsa's from the helper and installs the lsa's(both self originated and non-self originated)
   6b. after all adjacanceis are re-established exits GR and re-originates all self-originated LSA's
   6c. flush grace-lsa's and send max-age lsa to helper so that helper exits GR-helper

Expected behavior

GR-restarter(node-1) grace lsa flush should not fail. grace-lsa maxage should be sent out after and the gr-helper(node-2) should exit GR successfully

Actual behavior

• GR-restarter(node-1) grace lsa flush fails
  1.pre-restart and post-restart ospfv3 interface if-index are different.
  2.graceful-restart is successful at the gr-restarter(node-1) but the grace-lsa flush fails because of different if-index used in the grace lsa lookup.
  3.gr-helper is waiting for the grace lsa flush (max-age grace-lsa from the gr-restarter) to exit GR-helper
  4.gr-restarter is exiting gr successfully and re-originates all the lsa's
  5.The re-originated router-lsa is causing a topology-change on the gr-helper (strict lsa check enabled)
  or a grace timer expiry ( if strict lsa check is disabled), in both case a unsuccesful graceful-restart on the gr-helper

Additional context

I added some debugs in my environment to understand the problem better. OSPFv3 link state id for the link-lsa and grace-lsa are derived from the interface ifindex, and the assumption is that ifindex would be same after process restart(which is incorrect in this case?)

node-1(rtrid: 192.x.x.x) ----[Ethernet1]----- node-2(rtrid: 193.x.x.x)

/pre-restart/
ospf6d[301]: [VG0KG-PBTHZ] Originate Grace-LSA for Interface Ethernet1
ospf6d[301]: [TQB4M-JQ72Z] LSA Originate:
ospf6d[301]: [GNRNM-HX7W3] [Grace Id:0.0.1.218 Adv:192.x.x.x]
ospf6d[301]: [HA4BY-46K3Y] Age: 0 SeqNum: 0x80000001 Cksum: e0fa Len: 36
ospf6d[301]: [ZGT86-07C95] ospf6_install_lsa Install LSA: [Grace Id:0.0.1.218 Adv:192.x.x.x] age 0 seqnum 80000001 in LSDB.
/*pre-restart interface ifindex is 74 */
ospf6d[301]: [KAY2X-SAB58] ospf6_interface_lsdb_hook_add LSA: [Grace Id:0.0.1.218 Adv:192.x.x.x] age 0 seqnum 80000001 to oi(Ethernet1,74) LSDB.

/post-restart/
ospf6d[368]: [M3K4C-7HG7V] LSA Receive from 193.x.x.x%Ethernet1
ospf6d[368]: [GNRNM-HX7W3] [Link Id:0.0.1.218 Adv:192.x.x.x]
ospf6d[368]: [HA4BY-46K3Y] Age: 329 SeqNum: 0x80000001 Cksum: 3d50 Len: 56
ospf6d[368]: [Z8A48-ZTKMJ] Install, Flood, Possibly acknowledge the received LSA
ospf6d[368]: [ZGT86-07C95] ospf6_install_lsa Install LSA: [Link Id:0.0.1.218 Adv:192.x.x.x] age 329 seqnum 80000001 in LSDB.
/*post-restart interface ifindex is 73 */
ospf6d[368]: [KAY2X-SAB58] ospf6_interface_lsdb_hook_add LSA: [Link Id:0.0.1.218 Adv:192.x.x.x] age 329 seqnum 80000001 to oi(Ethernet1,73) LSDB.
ospf6d[368]: [RTGCS-FBH35] GR: exiting graceful restart[vrf default]: all adjacencies were reestablished
/*grace-lsa is being looked up with current ifindex/link-state-id 73 , but grace lsa is actually present in the interface LSDB with pre-restart ifindex/link-state-id 74 as received from the gr-helper */
ospf6d[368]: [Y052T-0BR52] ospf6_gr_flush_grace_lsas: GR: Grace-LSA not found [intf Ethernet1 ifdx 73 rtrid 192.x.x.x] [area 0.0.0.0] [vrf :default]

Checklist

• I have searched the open issues for this bug.
• I have not included sensitive information in this report.