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ap is sending a 38 digit mac add for dhcp

ino
Level 1
Level 1

i have an old c1142 (autonomous mode) which gets its ip from dhcp 

if i look at the ip dhcp bind table it is a 38 digits log mac

is there any way to use the normal 12 digit format?

in the interface settings the mac-address is set manually to a normal 12 digit one which i get / can see in the arp table

 

interface BVI1
mac-address fc99.47d5.41db   <<-- this is not what it uses for dhcp! but -->

10.0.0.3 0063.6973.636f.2d66. Infinite Manual Active Unknown
1111.2222.3333.4444.
5555.6666.7777.8888.
99

ip address dhcp
ipv6 address dhcp
ipv6 address autoconfig
ipv6 enable

5 Replies 5

Hi

 Why set the mac address manually?  Maybe  this cause the problem.

 

ino
Level 1
Level 1

its over a year i have set it up but as fare i can remember it was in the factory reset config

but at least i have set it after i couldnt figure out why this long mac for dhcp

any way i took it out and reload still the same super long mac

this seems to be the standard behavior and hope for some settings to alter it 

 

ino
Level 1
Level 1

just made a sh run as i was looking for something 

the setting is there again with a different mac

so the device it self puts it in and can not be erased

the mac for dhcp is still 38 digits and totally different

 

Rich R
VIP
VIP

It's normal for later autonomous IOS to insert the MAC config on BVI interface - usually using the same MAC as the LAN interface.

 

Provide output of "sh int bvi1" and "show int g0" (or f0 if it's fastethernet interface) from the AP?

Provide output of "show ip dhcp binding" from DHCP server?

Have you tried clearing the DHCP bindings (clear ip dhcp binding *)?

Have you collected a packet capture of the DHCP showing the AP using that MAC as you say it is?

What's displayed there is not necessarily the MAC used by the DHCP client (it's what the DHCP server has used to store and index that entry).  For example IOS DHCP server routinely prepends a type code (most often 01) to the beginning of the MAC.  This might simply be another type code it's prepended.

https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/ipaddr/command/ipaddr-cr-book/ipaddr-r1.html#wp2790763288

Hardware address

The MAC address or client identifier of the host as recorded on the DHCP server.

 

https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/ipaddr_dhcp/configuration/15-mt/dhcp-15-mt-book/config-dhcp-server.html#GUID-DEB30D2E-DEDB-43B9-AEF2-4732544E5EF0

 

ino
Level 1
Level 1
C1111#sh ip dhc bin
Bindings from all pools not associated with VRF:
IP address      Client-ID/              Lease expiration        Type       State      Interface
                Hardware address/
                User name
10.0.0.3        0063.6973.636f.2d66.    Infinite                Manual     Active     Unknown
                6339.392e.3437.6435.
                2e34.3164.622d.4256.
                31

startup-->>>
ip dhcp pool c1142
host 10.0.0.3 255.255.255.0
client-identifier 0063.6973.636f.2d66.6339.392e.3437.6435.2e34.3164.622d.4256.31
default-router 10.0.0.1
dns-server 10.10.10.10

c1142#sh int bv1
BVI1 is up, line protocol is up Hardware is BVI, address is fc99.47d5.41db (bia fc99.47d5.41db) Internet address is 10.0.0.3/24 MTU 1500 bytes, BW 54000 Kbit/sec, DLY 5000 usec, reliability 255/255, txload 1/255, rxload 1/255 Encapsulation ARPA, loopback not set Keepalive set (10 sec) ARP type: ARPA, ARP Timeout 04:00:00 Last input 00:00:00, output never, output hang never Last clearing of "show interface" counters never Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0 Queueing strategy: fifo Output queue: 0/0 (size/max) 5 minute input rate 70000 bits/sec, 8 packets/sec 5 minute output rate 70000 bits/sec, 8 packets/sec 1981510 packets input, 1659419535 bytes, 0 no buffer Received 0 broadcasts (0 IP multicasts) 0 runts, 0 giants, 0 throttles 0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort 1981511 packets output, 1659419595 bytes, 0 underruns 0 output errors, 0 collisions, 0 interface resets 0 unknown protocol drops 0 output buffer failures, 0 output buffers swapped out
GigabitEthernet0 is up, line protocol is up
  Hardware is PowerPC405ex Ethernet, address is fc99.47d5.41db (bia fc99.47d5.41db)
  Internet address will be negotiated using DHCP
  MTU 1500 bytes, BW 100000 Kbit/sec, DLY 100 usec,
     reliability 255/255, txload 1/255, rxload 1/255
  Encapsulation 802.1Q Virtual LAN, Vlan ID  1., loopback not set
  Keepalive set (10 sec)
  Full Duplex, 100Mbps, media type is T
  output flow-control is unsupported, input flow-control is unsupported
  ARP type: ARPA, ARP Timeout 04:00:00
  Last input 00:00:00, output 00:00:00, output hang never
  Last clearing of "show interface" counters never
  Input queue: 0/10013/0/0 (size/max/drops/flushes); Total output drops: 0
  Queueing strategy: fifo
  Output queue: 0/40 (size/max)
  5 minute input rate 13000 bits/sec, 11 packets/sec
  5 minute output rate 72000 bits/sec, 11 packets/sec
     2833736 packets input, 406541180 bytes, 0 no buffer
     Received 552490 broadcasts (0 IP multicasts)
     0 runts, 0 giants, 0 throttles
     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
     0 watchdog, 0 multicast, 0 pause input
     2612767 packets output, 1726701858 bytes, 0 underruns
     0 output errors, 0 collisions, 3 interface resets
     2 unknown protocol drops
     0 babbles, 0 late collision, 0 deferred
     0 lost carrier, 0 no carrier, 0 pause output
     0 output buffer failures, 0 output buffers swapped out

Have you tried clearing the DHCP bindings (clear ip dhcp binding *)? yes, tried anything what came to my mind 

 

Have you collected a packet capture of the DHCP showing the AP using that MAC as you say it is? no

but changing it in the dhcp pool setup to 12 digit instead of the current 38 and i get no ip

at least not the one i want (manual see top of message) just one from the pool 

 

ip dhcp pool V7
network 10.0.0.0 255.255.255.0
bootfile boot\ipxe\ipxe.efi
next-server 10.0.0.6
dns-server 10.0.0.6
default-router 10.0.0.1
netbios-name-server 10.0.0.6
lease 0 0 1

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