IP Arp on 6500

[marshyrob]

Hello

I have a Cisco 6509 switch configured and working how it should. I wanted to look up an IP address to find out what port its plugged into, but when I look at the IP ARP table and it only shows a few entries?

I have nearly 300 servers plugged into this switch so why does the ARP table only show about 10 entries? The mac address table shows many entries as expected.

Any help would be appreciated.

Thanks

 

[unclerico]

is this switch the gateway for the particular host taht you are trying to discover??

I hate all Uppercase... I don't want my groups to seem angry at me all the time! =)
- ColdFlame (vbscript forum)

 

[North323]

the 6509 is a layer 2 switch and will only show ARP of directrly connected IP addresses like vlan IP. You see all the MAC's because thats layer 2.

 

[marshyrob]

Hello

Managed to sort it, the switch in question plugs into another 6500 that is the CORE switch, this has all the routing and layer 3 VLAN configuration on it. So i needed to look at the IP ARP entries on the CORE switch and that gave me the IP and MAC, then on the access switch i looked at the MAC-ADDRESS TABLE for the MAC that i identified on the CORE and i find my port!

North323 - This 6509 is a layer 3 switch as it has a sup blade and is configured for IP routing.

Cheers

Rob

 

[North323]

what is your ARP timeout set at? is this CAT OS?

Vlan40 is up, line protocol is up
Hardware is Cat6k RP Virtual Ethernet, address is 00d0.0050.33fc (bia 00d0.005
0.33fc)
Internet address is 40.40.40.3/24
MTU 1500 bytes, BW 1000000 Kbit, DLY 10 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive not supported
ARP type: ARPA, ****ARP Timeout 04:00:00*****
Last input 00:00:00, output 00:01:44, output hang never
Last clearing of "show interface" counters never
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0

 

[VinceWhirlwind]

If you ping the servers from the 6509 itself, it should populate its ARP table with their details.

This is why before doing a switchport map I always do a ping sweep of the subnets that are on it.

 

[marshyrob]

Thanks chaps ive now sorted it as ive described above. I used to do as you suggested VinceWhirlwind but that does not work after a ping the entry is still not there.

Basically the 6509 is acting as a layer 2 switch passing the routing upto the Core 6513 switch which has all the arp entries in. So i just look on the 6513 for the arp entry and then find that MAC on the 6509, which tells me the port.

Cheers

 

[North323]

so North323 was right?
North323 (TechnicalUser)
11 Aug 09 8:24
the 6509 is a layer 2 switch and will only show ARP of directrly connected IP addresses like vlan IP. You see all the MAC's because thats layer 2.

 

[VinceWhirlwind]

If you look at it very pedantically, he wasn't right.

The following is not a true statement:
"the 6509 is a Layer 2 switch"

This statement *is* true:
"marshyrob's 6509 is acting as a Layer 2 switch", (which is presumably what you meant)...

And your 6509 *should* populate its ARP table when you ping directly connected devices - it probably depends on what the 6509 is using as its source address - maybe you use a *management* VLAN and the servers are in a different VLAN to the switch's own IP address?

 

[marshyrob]

Thats correct the switch is on a vlan thats different from the servers vlan.

Makes sense now.

Thanks for everyones input its appreciated.

 

[kcbell]

I am working on a 3750 switch and tried to add the following to the interface Fa1/0/44.

auto qos voip cisco-phone

then I got the following error message. I am running
C3750 Software (C3750-IPBASEK9-M), Version 12.2(44)SE,

I know this is qos for Cisco phone. How do I remedy this problem? I am not upgrading the IOS to a newer version. I am just adding the QOS to the Interface. Thanks!

AutoQoS Error while generating commands on Fa1/0/44.
policy map AutoQoS-Police-CiscoPhone not configured
AutoQoS Error: ciscophone input service policy was not properly applied
Warning: if upgrading from a previous release, and there is already auto qos voip cisco-phone configured on other interfaces, you may need to first delete those auto qos configurations and re-apply them on those interfaces.
policy map AutoQoS-Police-CiscoPhone not configured

 

[kcbell]

I am sorry folks. I meant to post the above as a new question.