3750 ARP Problem

[infosateng]

Hello Experts

I have 3 stacked 3750 Switches (WS-C3750-48TS, IOS c3750-ipservicesk9-mz.122-53.SE1) and I've started getting alerts that some of the connected servers are down, and a short time later that they are Up.  The alerts I get are not for all the servers, just ones on a partitular VLAN and not all the servers on this VLAN.  I think its an ARP problem as if I get alerts for 8 servers in a day and then I do a continuous ping to the these servers, I don't get any alerts any more, and the alerts move to different servers on the same VLAN.  I set the arp timeout on the VLAN interface to 1, but this didn't fix the problem.  Any idea how I can fix this.

Thanks

[Richard Burts]

Setting the arp timeout to 1 is probably too short. Frequently on a switch like the 3750 people may set the arp timout to 300 seconds so that it agrees with the timeout for the entries in the mac address table.

HTH

Rick

[infosateng]

Hi Rick

Thanks for the advise, but after changing the timeout to 300, I still have the same problem.

Thanks

[Richard Burts]

Without additional information I do not know what else to suggest. Do I understand correctly that the problems are happening on a particular vlan and not on others? If so then perhaps we can find out what is different about that vlan. Perhaps you could post the config of the switch with an indication about which vlan is experiencing the problems.

HTH

Rick

[infosateng]

Hi Rick

I am having problems to VLAN 92.  The config  below

!

switch 1 provision ws-c3750-48ts

switch 2 provision ws-c3750-48ts

switch 3 provision ws-c3750-48ts

system mtu routing 1500

authentication mac-move permit

ip subnet-zero

no ip source-route

ip routing

!

!

ip multicast-routing distributed

!

!

!

spanning-tree mode pvst

spanning-tree etherchannel guard misconfig

spanning-tree extend system-id

!

vlan internal allocation policy ascending

!

ip tcp synwait-time 10

!

!

!

interface Port-channel1

description Network 1 Path Redundancy

switchport access vlan 444

switchport mode access

speed 100

duplex full

!

interface Port-channel2

description Switch 2 Redundancy

switchport access vlan 92

switchport mode access

speed 100

duplex full

!

interface Port-channel3

description Switch 3 Redundancy

switchport access vlan 92

switchport mode access

speed 100

duplex full

!

interface Port-channel4

description Switch 4 Redundancy

switchport access vlan 92

switchport mode access

speed 100

duplex full

!

interface Port-channel5

description Switch 5 Redundancy

switchport access vlan 92

switchport mode access

speed 100

duplex full

!

interface FastEthernet1/0/1

!

interface FastEthernet1/0/2

description Connection to Management VLAN

switchport access vlan 10

speed 100

duplex full

!

interface FastEthernet1/0/3

!

interface FastEthernet1/0/4

!

interface FastEthernet1/0/5

switchport access vlan 82

speed 100

duplex full

!

interface FastEthernet1/0/6

switchport access vlan 92

speed 100

duplex full

!

interface FastEthernet1/0/7

!

interface FastEthernet1/0/8

!

interface FastEthernet1/0/9

!

interface FastEthernet1/0/10

description Server VLAN 82

switchport access vlan 82

speed 100

duplex full

spanning-tree portfast

!

interface FastEthernet1/0/11

description Server VLAN 82

switchport access vlan 82

speed 100

duplex full

spanning-tree portfast

!

interface FastEthernet1/0/12

description Server VLAN 82

switchport access vlan 82

speed 100

duplex full

spanning-tree portfast

!

interface FastEthernet1/0/13

description Server VLAN 82

switchport access vlan 82

speed 100

duplex full

spanning-tree portfast

!

interface FastEthernet1/0/14

description Server VLAN 82

switchport access vlan 82

speed 100

duplex full

spanning-tree portfast

!

interface FastEthernet1/0/15

!

interface FastEthernet1/0/16

!

interface FastEthernet1/0/17

description Server VLAN 82

switchport access vlan 82

speed 100

duplex full

spanning-tree portfast

!

interface FastEthernet1/0/18

description Server VLAN 82

switchport access vlan 82

speed 100

duplex full

spanning-tree portfast

!

interface FastEthernet1/0/19

description Server VLAN 82

switchport access vlan 82

speed 100

duplex full

spanning-tree portfast

!

interface FastEthernet1/0/20

!

interface FastEthernet1/0/21

description Server VLAN 82

switchport access vlan 82

speed 100

duplex full

spanning-tree portfast

!

interface FastEthernet1/0/22

!

interface FastEthernet1/0/23

description Server VLAN 82

switchport access vlan 82

speed 100

duplex full

spanning-tree portfast

!

interface FastEthernet1/0/24

description Server VLAN 82

switchport access vlan 82

speed 100

duplex full

spanning-tree portfast

!

interface FastEthernet1/0/25

description Server VLAN 82

switchport access vlan 82

speed 100

duplex full

spanning-tree portfast

!

interface FastEthernet1/0/26

!

interface FastEthernet1/0/27

!

interface FastEthernet1/0/28

!

interface FastEthernet1/0/29

!

interface FastEthernet1/0/30

!

interface FastEthernet1/0/31

description Server VLAN 92

switchport access vlan 92

speed 100

duplex full

spanning-tree portfast

!

interface FastEthernet1/0/32

description Server VLAN 92

switchport access vlan 92

speed 100

duplex full

spanning-tree portfast

!

interface FastEthernet1/0/33

description Server VLAN 92

switchport access vlan 92

speed 100

duplex full

spanning-tree portfast

!

interface FastEthernet1/0/34

!

interface FastEthernet1/0/35

description Server VLAN 92

switchport access vlan 92

speed 100

duplex full

spanning-tree portfast

!

interface FastEthernet1/0/36

!

interface FastEthernet1/0/37

description Server VLAN 92

switchport access vlan 92

speed 100

duplex full

spanning-tree portfast

!

interface FastEthernet1/0/38

description Server VLAN 92

switchport access vlan 92

speed 100

duplex full

spanning-tree portfast

!

interface FastEthernet1/0/39

description Server VLAN 92

switchport access vlan 92

speed 100

duplex full

spanning-tree portfast

!

interface FastEthernet1/0/40

!

interface FastEthernet1/0/41

!

interface FastEthernet1/0/42

description Connection Switch 2 Fe0/2

switchport access vlan 92

switchport mode access

speed 100

duplex full

channel-group 2 mode on

!

interface FastEthernet1/0/43

description Connection to Switch 3 Fe0/2

switchport access vlan 92

switchport mode access

speed 100

duplex full

channel-group 3 mode on

!

interface FastEthernet1/0/44

!

interface FastEthernet1/0/45

!

interface FastEthernet1/0/46

!

interface FastEthernet1/0/47

!

interface FastEthernet1/0/48

!

interface GigabitEthernet1/0/1

!

interface GigabitEthernet1/0/2

!

interface GigabitEthernet1/0/3

!

interface GigabitEthernet1/0/4

!

interface FastEthernet2/0/1

description Connection to Network 1

switchport access vlan 444

switchport mode access

speed 100

duplex full

!

interface FastEthernet2/0/2

!

interface FastEthernet2/0/3

!

interface FastEthernet2/0/4

!

interface FastEthernet2/0/5

!

interface FastEthernet2/0/6

!

interface FastEthernet2/0/7

!

interface FastEthernet2/0/8

!

interface FastEthernet2/0/9

!

interface FastEthernet2/0/10

description Server VLAN 82

switchport access vlan 82

speed 100

duplex full

spanning-tree portfast

!

interface FastEthernet2/0/11

description Server VLAN 82

switchport access vlan 82

speed 100

duplex full

spanning-tree portfast

!

interface FastEthernet2/0/12

description Server VLAN 82

switchport access vlan 82

speed 100

duplex full

spanning-tree portfast

!

interface FastEthernet2/0/13

description Server VLAN 82

switchport access vlan 82

speed 100

duplex full

spanning-tree portfast

!

interface FastEthernet2/0/14

description Server VLAN 82

switchport access vlan 82

speed 100

duplex full

spanning-tree portfast

!

interface FastEthernet2/0/15

!

interface FastEthernet2/0/16

!

interface FastEthernet2/0/17

description Server VLAN 82

switchport access vlan 82

speed 100

duplex full

spanning-tree portfast

!

interface FastEthernet2/0/18

description Server VLAN 82

switchport access vlan 82

speed 100

duplex full

spanning-tree portfast

!

interface FastEthernet2/0/19

description Server VLAN 82

switchport access vlan 82

speed 100

duplex full

spanning-tree portfast

!

interface FastEthernet2/0/20

description Server VLAN 82

switchport access vlan 82

speed 100

duplex full

spanning-tree portfast

!

interface FastEthernet2/0/21

description Server VLAN 82

switchport access vlan 82

speed 100

duplex full

spanning-tree portfast

!

interface FastEthernet2/0/22

!

interface FastEthernet2/0/23

description Server VLAN 82

switchport access vlan 82

speed 100

duplex full

spanning-tree portfast

!

interface FastEthernet2/0/24

!

interface FastEthernet2/0/25

description Server VLAN 82

switchport access vlan 82

speed 100

duplex full

spanning-tree portfast

!

interface FastEthernet2/0/26

!

interface FastEthernet2/0/27

!

interface FastEthernet2/0/28

!

interface FastEthernet2/0/29

!

interface FastEthernet2/0/30

!

interface FastEthernet2/0/31

description Server VLAN 92

switchport access vlan 92

speed 100

duplex full

spanning-tree portfast

!

interface FastEthernet2/0/32

description Server VLAN 92

switchport access vlan 92

speed 100

duplex full

spanning-tree portfast

!

interface FastEthernet2/0/33

description Server VLAN 92

switchport access vlan 92

speed 100

duplex full

spanning-tree portfast

!

interface FastEthernet2/0/34

description Server VLAN 92

switchport access vlan 92

speed 100

duplex full

spanning-tree portfast

!

interface FastEthernet2/0/35

description Server VLAN 92

switchport access vlan 92

speed 100

duplex full

spanning-tree portfast

!

interface FastEthernet2/0/36

!

interface FastEthernet2/0/37

description Server VLAN 92

switchport access vlan 92

speed 100

duplex full

spanning-tree portfast

!

interface FastEthernet2/0/38

!

interface FastEthernet2/0/39

description Server VLAN 92

switchport access vlan 92

speed 100

duplex full

spanning-tree portfast

!

interface FastEthernet2/0/40

!

interface FastEthernet2/0/41

!

interface FastEthernet2/0/42

description Connection to Switch 2

switchport access vlan 92

switchport mode access

speed 100

duplex full

channel-group 2 mode on

!

interface FastEthernet2/0/43

description Connection to Switch 3

switchport access vlan 92

switchport mode access

speed 100

duplex full

channel-group 3 mode on

!

interface FastEthernet2/0/44

description Connection Switch 4

switchport access vlan 92

switchport mode access

speed 100

duplex full

channel-group 4 mode on

!

interface FastEthernet2/0/45

description Connection to Switch 5

switchport access vlan 92

switchport mode access

speed 100

duplex full

channel-group 5 mode on

!

interface FastEthernet2/0/46

description Management VLAN

switchport access vlan 10

switchport mode access

spanning-tree portfast

!

interface FastEthernet2/0/47

description Management VLAN

switchport access vlan 10

speed 100

duplex full

spanning-tree portfast

!

interface FastEthernet2/0/48

description FW 1

switchport access vlan 333

spanning-tree portfast

!

interface GigabitEthernet2/0/1

!

interface GigabitEthernet2/0/2

!

interface GigabitEthernet2/0/3

!

interface GigabitEthernet2/0/4

!

interface FastEthernet3/0/1

description Connection to Network 1

switchport access vlan 444

switchport mode access

speed 100

duplex full

channel-group 1 mode on

!

interface FastEthernet3/0/2

no cdp enable

!

interface FastEthernet3/0/3

no cdp enable

!

interface FastEthernet3/0/4

no cdp enable

!

interface FastEthernet3/0/5

no cdp enable

!

interface FastEthernet3/0/6

no cdp enable

!

interface FastEthernet3/0/7

no cdp enable

!

interface FastEthernet3/0/8

no cdp enable

!

interface FastEthernet3/0/9

no cdp enable

!

interface FastEthernet3/0/10

description Server VLAN 82

switchport access vlan 82

speed 100

duplex full

no cdp enable

spanning-tree portfast

!

interface FastEthernet3/0/11

description Server VLAN 82

switchport access vlan 82

speed 100

duplex full

no cdp enable

spanning-tree portfast

!

interface FastEthernet3/0/12

description Server VLAN 82

switchport access vlan 82

speed 100

duplex full

no cdp enable

spanning-tree portfast

!

interface FastEthernet3/0/13

description Server VLAN 82

switchport access vlan 82

speed 100

duplex full

no cdp enable

spanning-tree portfast

!

interface FastEthernet3/0/14

description Server VLAN 82

switchport access vlan 82

speed 100

duplex full

no cdp enable

spanning-tree portfast

!

interface FastEthernet3/0/15

no cdp enable

!

interface FastEthernet3/0/16

no cdp enable

!

interface FastEthernet3/0/17

description Server VLAN 82

switchport access vlan 82

speed 100

duplex full

no cdp enable

spanning-tree portfast

!

interface FastEthernet3/0/18

no cdp enable

!

interface FastEthernet3/0/19

description Server VLAN 82

switchport access vlan 82

speed 100

duplex full

no cdp enable

spanning-tree portfast

!

interface FastEthernet3/0/20

description Server VLAN 82

switchport access vlan 82

speed 100

duplex full

no cdp enable

spanning-tree portfast

!

interface FastEthernet3/0/21

description Server VLAN 82

switchport access vlan 82

speed 100

duplex full

no cdp enable

spanning-tree portfast

!

interface FastEthernet3/0/22

description Server VLAN 82

switchport access vlan 82

speed 100

duplex full

no cdp enable

spanning-tree portfast

!

interface FastEthernet3/0/23

description Server VLAN 82

switchport access vlan 82

speed 100

duplex full

no cdp enable

spanning-tree portfast

!

interface FastEthernet3/0/24

no cdp enable

!

interface FastEthernet3/0/25

description Server VLAN 82

switchport access vlan 82

speed 100

duplex full

no cdp enable

spanning-tree portfast

!

interface FastEthernet3/0/26

no cdp enable

!

interface FastEthernet3/0/27

no cdp enable

!

interface FastEthernet3/0/28

no cdp enable

!

interface FastEthernet3/0/29

no cdp enable

!

interface FastEthernet3/0/30

no cdp enable

!

interface FastEthernet3/0/31

description Server VLAN 92

switchport access vlan 92

speed 100

duplex full

no cdp enable

spanning-tree portfast

!

interface FastEthernet3/0/32

no cdp enable

!

interface FastEthernet3/0/33

description Server VLAN 92

switchport access vlan 92

speed 100

duplex full

no cdp enable

spanning-tree portfast

!

interface FastEthernet3/0/34

description Server VLAN 92

switchport access vlan 92

speed 100

duplex full

no cdp enable

spanning-tree portfast

!

interface FastEthernet3/0/35

description Server VLAN 92

switchport access vlan 92

speed 100

duplex full

no cdp enable

spanning-tree portfast

!

interface FastEthernet3/0/36

description Server VLAN 92

switchport access vlan 92

speed 100

duplex full

no cdp enable

spanning-tree portfast

!

interface FastEthernet3/0/37

description Server VLAN 92

switchport access vlan 92

speed 100

duplex full

no cdp enable

spanning-tree portfast

!

interface FastEthernet3/0/38

no cdp enable

!

interface FastEthernet3/0/39

description Server VLAN 92

switchport access vlan 92

speed 100

duplex full

no cdp enable

spanning-tree portfast

!

interface FastEthernet3/0/40

no cdp enable

!

interface FastEthernet3/0/41

no cdp enable

!

interface FastEthernet3/0/42

no cdp enable

!

interface FastEthernet3/0/43

no cdp enable

!

interface FastEthernet3/0/44

description Connection to Switch 4

switchport access vlan 92

switchport mode access

speed 100

duplex full

channel-group 4 mode on

!

interface FastEthernet3/0/45

description Connection to Switch 5

switchport access vlan 92

switchport mode access

speed 100

duplex full

channel-group 5 mode on

!

interface FastEthernet3/0/46

description Management VLAN

switchport access vlan 10

switchport mode access

spanning-tree portfast

!

interface FastEthernet3/0/47

description Management VLAN

switchport access vlan 10

speed 100

duplex full

no cdp enable

spanning-tree portfast

!

interface FastEthernet3/0/48

description FW 2

switchport access vlan 333

no cdp enable

spanning-tree portfast

!

interface GigabitEthernet3/0/1

no cdp enable

!

interface GigabitEthernet3/0/2

no cdp enable

!

interface GigabitEthernet3/0/3

no cdp enable

!

interface GigabitEthernet3/0/4

no cdp enable

!

interface Vlan1

no ip address

shutdown

!

interface Vlan10

description Management

ip address 10.0.10.12 255.255.255.0

no ip redirects

no ip unreachables

no ip proxy-arp

!

interface Vlan82

description Server VLAN 82

ip address 10.2.12.1 255.255.255.0

ip pim dense-mode

ip igmp query-interval 125

no ip mroute-cache

!

interface Vlan92

description Server VLAN 92

ip address 10.2.20.1 255.255.255.0

arp timeout 300

!

interface Vlan444

description Network 1

ip address 10.8.8.1 255.255.255.252

!

interface Vlan333

description FW

ip address 10.8.2.249 255.255.255.248

no ip redirects

no ip unreachables

no ip proxy-arp

ip pim dense-mode

ip igmp query-interval 125

no ip mroute-cache

!

router rip

version 2

passive-interface Vlan444

passive-interface Vlan333

network 10.0.0.0

!

ip classless

ip route 0.0.0.0 0.0.0.0 10.8.2.250

ip route 10.0.5.0 255.255.255.0 10.0.10.1

ip route 10.10.4.0 255.255.254.0 10.0.10.1

ip route 10.254.202.2 255.255.255.255 10.8.8.2

ip route 10.254.200.0 255.255.255.240 10.8.8.2