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barry
Beginner

SG300-20 Bonjour Packets being Sent after Bonjour deactivated


I have a Cisco SG300-20 Small business switch, and the IPv4 interfaces
continue to create mDNS broadcast traffic even after Bonjour has been
disabled globally.

Packets originate from the interface IP: 172.16.xx.254:5353 and have a
destination IP that is a broadcast address 224.0.0.251:5353

I have three interfaces that generate a packet about once every 10 seconds. 
This is creating alerts in other equipment that is filling up my logs.

This is a small network that is in one physical location and configuration is
static so I have no need of discovery services for anything running on the
SG300 switch.

Other than disabling Bonjour, there is nothing in the manual that seems
to relate to it.

Am I missing something, or if this is a bug?

Detailed backup information follows:

Product/Software Version Info

NAME: "1" DESCR: "SG300-20 20-Port Gigabit Managed Switch" 
PID: SRW2016-K9 VID: V04 SN: PSZ202xxxxx

SW version 1.4.7.6 ( date 07-Dec-2016 time 18:37:03 )
Boot version 1.3.5.06 ( date 21-Jul-2013 time 15:12:10 )
HW version V04

#show bonjour

Bonjour global status: disabled
Bonjour L2 interfaces port list: none

Service Admin Status Oper Status
------- ------------ -----------
csco-sb enabled enabled
http enabled enabled
https enabled enabled
ssh enabled enabled
telnet enabled disabled

Sample packet captured by wireshark:

Frame 60: 362 bytes on wire (2896 bits), 362 bytes captured (2896 bits) on interface 0
Interface id: 0 (enp0)
Encapsulation type: Ethernet (1)
Arrival Time: Mar 3, 2017 16:14:17.875849274 EST
[Time shift for this packet: 0.000000000 seconds]
Epoch Time: 1488575657.875849274 seconds
[Time delta from previous captured frame: 1.461698815 seconds]
[Time delta from previous displayed frame: 4.999822643 seconds]
[Time since reference or first frame: 43.461018609 seconds]
Frame Number: 60
Frame Length: 362 bytes (2896 bits)
Capture Length: 362 bytes (2896 bits)
[Frame is marked: False]
[Frame is ignored: False]
[Protocols in frame: eth:ethertype:ip:udp:mdns]
[Coloring Rule Name: UDP]
[Coloring Rule String: udp]
Ethernet II, Src: 00:9e:1e:xx:xx:x1 (00:9e:1e:xx:xx:x1), Dst: IPv4mcast_fb (01:00:5e:yy:yy:yb)
Destination: IPv4mcast_fb (01:00:5e:yy:yy:yb)
Address: IPv4mcast_fb (01:00:5e:yy:yy:yb)
.... ..0. .... .... .... .... = LG bit: Globally unique address (factory default)
.... ...1 .... .... .... .... = IG bit: Group address (multicast/broadcast)
Source: 00:9e:1e:xx:xx:x1 (00:9e:1e:xx:xx:x1)
Address: 00:9e:1e:xx:xx:x1 (00:9e:1e:xx:xx:x1)
.... ..0. .... .... .... .... = LG bit: Globally unique address (factory default)
.... ...0 .... .... .... .... = IG bit: Individual address (unicast)
Type: IPv4 (0x0800)
Internet Protocol Version 4, Src: 172.16.xx.254, Dst: 224.0.0.251
0100 .... = Version: 4
.... 0101 = Header Length: 20 bytes
Differentiated Services Field: 0xe0 (DSCP: CS7, ECN: Not-ECT)
1110 00.. = Differentiated Services Codepoint: Class Selector 7 (56)
.... ..00 = Explicit Congestion Notification: Not ECN-Capable Transport (0)
Total Length: 348
Identification: 0x2e4f (11855)
Flags: 0x00
0... .... = Reserved bit: Not set
.0.. .... = Don't fragment: Not set
..0. .... = More fragments: Not set
Fragment offset: 0
Time to live: 1
[Expert Info (Note/Sequence): "Time To Live" != 255 for a packet sent to the Local Network Control Block (see RFC 3171)]
["Time To Live" != 255 for a packet sent to the Local Network Control Block (see RFC 3171)]
[Severity level: Note]
[Group: Sequence]
Protocol: UDP (17)
Header checksum: 0xca52 [validation disabled]
[Good: False]
[Bad: False]
Source: 172.16.xx.254
Destination: 224.0.0.251
[Source GeoIP: Unknown]
[Destination GeoIP: Unknown]
User Datagram Protocol, Src Port: 5353 (5353), Dst Port: 5353 (5353)
Source Port: 5353
Destination Port: 5353
Length: 328
Checksum: 0x6346 [validation disabled]
[Good Checksum: False]
[Bad Checksum: False]
[Stream index: 0]
Multicast Domain Name System (response)
Transaction ID: 0x0000
Flags: 0x8000 Standard query response, No error
1... .... .... .... = Response: Message is a response
.000 0... .... .... = Opcode: Standard query (0)
.... .0.. .... .... = Authoritative: Server is not an authority for domain
.... ..0. .... .... = Truncated: Message is not truncated
.... ...0 .... .... = Recursion desired: Don't do query recursively
.... .... 0... .... = Recursion available: Server can't do recursive queries
.... .... .0.. .... = Z: reserved (0)
.... .... ..0. .... = Answer authenticated: Answer/authority portion was not authenticated by the server
.... .... ...0 .... = Non-authenticated data: Unacceptable
.... .... .... 0000 = Reply code: No error (0)
Questions: 0
Answer RRs: 1
Authority RRs: 0
Additional RRs: 0
Answers
VSDPb45501._csco-sb-vsdp._mdns._udp.local: type TXT, class IN
Name: VSDPb45501._csco-sb-vsdp._mdns._udp.local
Type: TXT (Text strings) (16)
.000 0000 0000 0001 = Class: IN (0x0001)
0... .... .... .... = Cache flush: False
Time to live: 25
Data length: 255
TXT Length: 6
TXT: type=0
TXT Length: 9
TXT: version=1
TXT Length: 21
TXT: refresh-age-timeout=0
TXT Length: 10
TXT: priority=0
TXT Length: 14
TXT: refresh-flag=0
TXT Length: 34
TXT: root-mac-address=00:9e:1e:xx:xx:x1
TXT Length: 6
TXT: cost=0
TXT Length: 26
TXT: transm-address=172.16.xx.254
TXT Length: 23
TXT: transm-interface=100049
TXT Length: 16
TXT: voice-vlan-id=10
TXT Length: 16
TXT: voice-vlan-vpt=5
TXT Length: 18
TXT: voice-vlan-dscp=46
TXT Length: 43
TXT: md5-auth=01af9cba5ed0218b0848195834e6a878ae

2 REPLIES 2
chrullrich
Beginner

The original post is a bit old now, but: To fix this, disable the Voice VLAN feature; "voice vlan state disabled".

Just take care when applying this command remotely on SG350XG switches, because it erases trunk configurations on enabled by default smart ports.