[FRR 9.x.y] isisd dumps only a half of LSP

[Vadims06]

Description

After enabling debug isis packet-dump the output shows only a half of LSP, losing the second part. The screenshot shows FRR's dump on the left and Wireshark packet dump on the right, a red line highlights missed part of LSP

It works on FRR8, but I have to use FRR9, because of isisd: IS-IS over tunnel patch enabled on FRR9 only (could you please also clarify why it's available only in FRR9?)

Correct output of debug isis packet-dump on FRR8

2023/08/29 16:48:39 ISIS: [HBVNR-SWK3N] [0x7f7ade]   83 21 01 00 19 01 00 00   00 63 01 00 10 01 00 01   ........ .c......
2023/08/29 16:48:39 ISIS: [HBVNR-SWK3N] [0x7f7ade]   00 00 00 00 00 00 00 00   00 FF FF FF FF FF FF FF   ........ ........
2023/08/29 16:48:39 ISIS: [HBVNR-SWK3N] [0x7f7ade]   FF 09 40 01 7C 01 00 10   01 00 01 00 00 00 00 01   ........ ........
2023/08/29 16:48:39 ISIS: [HBVNR-SWK3N] [0x7f7ade]   2A 4C C8 04 57 01 00 10   01 00 01 4A 00 00 00 01   .L..W... ...J....
2023/08/29 16:48:39 ISIS: [HBVNR-SWK3N] [0x7f7ade]   2A 11 10 01 2D 01 00 10   01 00 02 00 00 00 00 01   ........ ........
2023/08/29 16:48:39 ISIS: [HBVNR-SWK3N] [0x7f7ade]   2B 28 C4 01 2D 01 00 10   01 00 02 00 01 00 00 01   ........ ........
2023/08/29 16:48:39 ISIS: [HBVNR-SWK3N] [0x7f7ade]   2A 3E A1                                            ...

Version

FRRouting 9.1_git (watcher) on Linux(5.4.0-173-generic).
Copyright 1996-2005 Kunihiro Ishiguro, et al.
configured with:
    '--prefix=/usr' '--sbindir=/usr/lib/frr' '--sysconfdir=/etc/frr' '--libdir=/usr/lib' '--localstatedir=/var/run/frr' '--enable-rpki' '--enable-vtysh' '--enable-multipath=64' '--enable-vty-group=frrvty' '--enable-user=frr' '--enable-group=frr' '--enable-pcre2posix' '--enable-scripting' 'CC=gcc' 'CXX=g++'

How to reproduce

Minimal lab should include 2FRRs with established adjacency between them. Then turn on debug isis packet-dump on the first FRR and change a link cost the second FRR

FRR1

interface eth1
 ip address 20.168.13.1/24
 ip router isis lab
 ipv6 address 4ffe::192:168:13:1/127
 ipv6 router isis lab
 isis csnp-interval 600
 isis hello-interval 10
 isis network point-to-point
 no isis hello padding
exit
!
router isis lab
 net 49.0002.0200.1025.0002.00
exit
!

FRR2

!
interface eth1
 ip address 20.168.13.3/24
 ip router isis lab
 ipv6 address 4ffe::192:168:13:3/127
 ipv6 router isis lab
 isis network point-to-point
exit
!
router isis lab
 net 49.0002.0200.1001.0003.00
exit
!

FRR1

debug isis packet-dump

FRR2

conf t
int eth1
isis metric cost 11

To get the lab quickly, I can suggest to use containerlab, the topology is defined here

Expected behavior

I expect to see a full LSP packet dumped, like it works in FRR8
Correct output of debug isis packet-dump on FRR8

2023/08/29 16:48:39 ISIS: [HBVNR-SWK3N] [0x7f7ade]   83 21 01 00 19 01 00 00   00 63 01 00 10 01 00 01   ........ .c......
2023/08/29 16:48:39 ISIS: [HBVNR-SWK3N] [0x7f7ade]   00 00 00 00 00 00 00 00   00 FF FF FF FF FF FF FF   ........ ........
2023/08/29 16:48:39 ISIS: [HBVNR-SWK3N] [0x7f7ade]   FF 09 40 01 7C 01 00 10   01 00 01 00 00 00 00 01   ........ ........
2023/08/29 16:48:39 ISIS: [HBVNR-SWK3N] [0x7f7ade]   2A 4C C8 04 57 01 00 10   01 00 01 4A 00 00 00 01   .L..W... ...J....
2023/08/29 16:48:39 ISIS: [HBVNR-SWK3N] [0x7f7ade]   2A 11 10 01 2D 01 00 10   01 00 02 00 00 00 00 01   ........ ........
2023/08/29 16:48:39 ISIS: [HBVNR-SWK3N] [0x7f7ade]   2B 28 C4 01 2D 01 00 10   01 00 02 00 01 00 00 01   ........ ........
2023/08/29 16:48:39 ISIS: [HBVNR-SWK3N] [0x7f7ade]   2A 3E A1                                            ...

Actual behavior

The actual output of debug isis packet-dump on FRR9 includes only half LSP

2024/04/02 09:43:33 ISIS: [HBVNR-SWK3N] [0x7f687f]   83 1B 01 00 14 01 00 00                             ........ .
2024/04/02 09:43:33 ISIS: [HBVNR-SWK3N] [0x7f687f]   00 04 00 00 00 00 00 06                             ........ e
2024/04/02 09:43:33 ISIS: [HBVNR-SWK3N] [0x7f687f]   04 03 49 00 02 89 07 72                             ..I....r o
2024/04/02 09:43:33 ISIS: [HBVNR-SWK3N] [0x7f687f]   0A 0A 0A 04 00 86 04 0A                             ........ .
2024/04/02 09:43:33 ISIS: [HBVNR-SWK3N] [0x7f687f]   01 00 05 AF 00 00 0D 00                             ........ .
2024/04/02 09:43:33 ISIS: [HBVNR-SWK3N] [0x7f687f]   00 00 00 0D 58 14 A8 91                             ....X... .
2024/04/02 09:43:33 ISIS: [HBVNR-SWK3N] [0x7f687f]   0A 04 00 EC 17 00 00 00                             ........ .
2024/04/02 09:43:33 ISIS: [HBVNR-SWK3N] [0x7f687f]   00 00 00 01 92 01 68 01                             ......h. E
2024/04/02 09:43:33 ISIS: [R78GD-MAYNF] ISIS-Upd (vgre1): Rcvd L2 LSP 0200.1001.0004.00-00, seq 0x00000006, cksum 0x6557, lifetime 1157s, len 124, on gre1
2024/04/02 09:43:33 ISIS: [TYY20-MSXM5] ISIS-Snp (vgre1): Compare LSP 0200.1001.0004.00-00 seq 0x00000006, cksum 0x6557, lifetime 1157s
2024/04/02 09:43:33 ISIS: [SGPH7-RETTZ] ISIS-Snp (vgre1):       is newer than ours seq 0x00000005, cksum 0xb010, lifetime 908s

Additional context

No response

Checklist

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

[Vadims06]

Hi Russ (@riw777),
many thanks for introducing IS-IS over tunnel feature, I'm using this feature a lot, but how do you think if it can affect LSP output or not?.. And could you please also clarify why it's available only in FRR9 versions and not in FRR8? I'm a little bit confused by FRR versioning, I expected to see constantly increasing version number, but FRR Release 8.5.4 was released after FRR 9.1 Release, could you please explain why? Appreciate it.