No Mac Address on Switch port

[nygenxny123]

Is it possible for a server not to advertise its mac address?

The reason I ask is that we have

a tumbleweed server attatched to our

switch..

The gig port shows up up

however no mac-address is being displayed

when issue the command sh-mac-address int gig 0/3

GigabitEthernet0/3 is up, line protocol is up (connected)

Hardware is Gigabit Ethernet, address is 0018.b985.c403 (bia 0018.b985.c403)

Description: "connection to tumbleweed"

MTU 1500 bytes, BW 100000 Kbit, DLY 100 usec,

reliability 255/255, txload 1/255, rxload 1/255

Encapsulation ARPA, loopback not set

Keepalive set (10 sec)

Full-duplex, 100Mb/s, media type is 10/100/1000BaseTX

MC5.1#sh mac-address-table interface gigabitEthernet 0/3

Mac Address Table

-------------------------------------------

Vlan Mac Address Type Ports

---- ----------- -------- -----

MC5.1#

At this point..we can not ping the server..but i can ping the gateway of the server from the switch

[Richard Burts]

John

I have looked at the link that you posted and here is the very first sentence:"The address table is built by using the source address of the frames received."

Everything else was about how we might get the destination station to send something. The only way the switch learns the MAC is when the host on the port sends something. To say anything different is to be at least slightly wrong.

HTH

Rick

[nygenxny123]

this has turned into a very good thread..

Here is the config on the switch

10.1.13.30

255.255.252.0

10.1.12.1

Here is the config for the port it is connected to

interface GigabitEthernet0/3

description "connection to tumbleweed"

switchport access vlan 12

speed 100

duplex full

there is a trunk back to the router

this is the config on the router

interface FastEthernet0/0.12

encapsulation dot1Q 12

ip address 10.1.14.3 255.255.254.0 secondary

ip address 10.1.12.3 255.255.254.0

no snmp trap link-status

standby 12 ip 10.1.12.1

standby 12 ip 10.1.14.1 secondary

standby 12 preempt

the only issue i see is diff. subnet mask.

[Richard Burts]

Richard

It is a little ambiguous where this comes from:

10.1.13.30

255.255.252.0

10.1.12.1

I would assume that it is the address of the management interface for the switch, its mask, and its default gateway. Can you confirm that (or providing the configuration detail of it might be even better)?

The apparent mismatch in mask between the switch and the router may or may not be a problem. They both describe an address space that starts at 10.1.12.0 and extends through 10.1.15.255. We would need some additional details, especially of how hosts in the VLAN were configured to know if the mask is part of the problem.

The main thing that we do not have yet is the config details of the server. Can you get the server folks to provide the output of ipconfig (or similar command if the server is not Windows)?

The previous suggestion about checking for possible mismatch in speed or duplex is a good suggestion.

If attempts to get the server MAC address by ping have not been successful, you might try something different to see if we can get it. If the server folk would disable the NIC/interface and then re-enable it, then the server might send a gratuitous ARP from which the switch might learn the MAC. Or perhaps having the server attempt to ping to some destination would cause it to send a frame to the switch.

HTH

Rick

[John Blakley]

Is the 10.1.13.30 the address for the server? If so, it should be changed to 10.1.12.30.

HTH,

John

[Leo Laohoo]

What's the IP config of the server?

What is the configuration for VLAN 12 on the switch?

Has this Tumbleweed server ever worked before? If so, what changes were done that broke it?

Can you try the command "sh controller ethernet GigabitEthernet0/3"?

Thanks.

[nygenxny123]

well it turned out to be a server issue..we think..

we got a separate hub....placed a laptop on it and the server...

the laptop was able to ping the server

so we placed the laptop on the switchport with the config of the server

10.1.13.30

255.255.252.0

10.1.12.1

and the switch config being

interface Vlan1

ip address 10.1.1.35 255.255.255.0

no ip route-cache

!

ip default-gateway 10.1.1.1

and WE WERE able to ping the laptop

[darcwing7]

A possible consideration:

You will need to verify the configuration of both the server and the VLAN gateway. If the subnet mask does not match then the ARPs will not be sent to the correct address. If the server receives a packet addressed to an address that is not it's address or it's broadcast address (based on the subnet mask) it will ignore the packet and therefore not respond to ARP requests. Without that response, the CAM table will not be updated.