[f-nsp] Multicast is being switched by LP CPU on MLXe?

[Alexander Shikoff]

Hello!

I have some VLANs configured between certain ports on MLXe box (MLXe-16, 5.7.0e).
All ports are in 'no route-only' mode. For example:

telnet at lsr1-gdr.ki(config)#show vlan 720

PORT-VLAN 720, Name V720, Priority Level 0, Priority Force 0, Creation Type STATIC
Topo HW idx    : 65535    Topo SW idx: 257    Topo next vlan: 0
L2 protocols   : NONE
Statically tagged Ports    : ethe 7/1 ethe 9/5 ethe 10/6 ethe 11/6 ethe 13/3 
Associated Virtual Interface Id: NONE
----------------------------------------------------------
Port  Type      Tag-Mode  Protocol  State     
7/1   TRUNK     TAGGED    NONE      FORWARDING
9/5   TRUNK     TAGGED    NONE      FORWARDING
10/6  TRUNK     TAGGED    NONE      FORWARDING
11/6  TRUNK     TAGGED    NONE      FORWARDING
13/3  PHYSICAL  TAGGED    NONE      FORWARDING
Arp Inspection: 0
DHCP Snooping: 0
IPv4 Multicast Snooping: Enabled - Passive
IPv6 Multicast Snooping: Disabled

No Virtual Interfaces configured for this vlan



As you may notice, passive multicast snooping is enabled on that VLAN.
The problem is that multicast traffic is being switched by LP CPU,
causing high CPU utilization and packet loss.

It is clearly seen on rconsole:

LP-11#debug packet capture rx include src-port me/6 vlan-id 720 dst-address 233.191.133.96
[...]
**********************************************************************
[ppcr_tx_packet] ACTION: Forward packet using fid 0xa06d
[ppcr_rx_packet]: Packet received
Time stamp : 56 day(s) 20h 48m 05s:,
TM Header: [ 0564 0aa3 0080 ]
Type: Fabric Unicast(0x00000000) Size: 1380 Class: 0 Src sys port: 2723
Dest Port: 0  Drop Prec: 2 Ing Q Sig: 0 Out mirr dis: 0x0 Excl src: 0 Sys mc: 0
**********************************************************************
Packet size: 1374, XPP reason code: 0x000095cc
00: 05f0 0003 5c50 02d0-7941 fffe 8000 0000  FID     = 0x05f0
10: 0100 5e3f 85b0 e4d3-f17d a7c5 0800 4516  Offset  = 0x10
20: 0540 0000 4000 7e11-f89f b060 df26 e9bf  VLAN    = 720(0x02d0)
30: 85b0 04d2 04d2 052c-0000 4701 3717 8134  CAM     = 0x0ffff(R)
40: 01d0 92de c56f 18f6-dc4f 8d00 1273 cdb3  SFLOW   = 0
50: c3ff 3da8 2600 5a37-cfbe 993f dbfd c927  DBL TAG = 0
60: 8000 8290 ef9b 7638-9089 9a50 5000 8611
70: 2026 0079 8de2 a404-1013 dffd 04e0 1404
Pri CPU MON SRC   PType US BRD DAV SAV DPV SV ER TXA SAS Tag MVID
0   0   0   11/6  3     0  1   0   1   1   1  0  0   0   1   0

176.96.223.38 -> 233.191.133.176 UDP [1234 -> 1234] 
**********************************************************************

As far as I understand documentation that should not happen.
The situation remains the same if I disable IGMP snooping.

Any ideas/suggestions is kindly appreciated!

Thanks in advance.

-- 
MINO-RIPE