DHCP Pool

[RANAJi]

DHCP Pool range 

ip dhcp pool data
network 10.60.86.0 255.255.255.128
default-router 10.60.86.2

Now if you run steag#Sh IP DHCP pool Data

Pool Data :
Utilization mark (high/low) : 100 / 0
Subnet size (first/next) : 0 / 0
Total addresses : 126
Leased addresses : 9
Excluded addresses : 86
Pending event : none
1 subnet is currently in the pool :
Current index IP address range Leased/Excluded/Total 10.60.86.77 10.60.86.1 - 10.60.86.126 9 / 86 / 126

Now if you run Sh IP ARP 

Protocol Address Age (min) Hardware Addr Type Interface
Internet 10.60.86.2 - ccef.48ed.21c2 ARPA Vlan498
Internet 10.60.86.3 24 7c5a.1c69.e258 ARPA Vlan498
Internet 10.60.86.4 0 c424.562d.0710 ARPA Vlan498
Internet 10.60.86.5 0 d8d3.8523.8304 ARPA Vlan498
Internet 10.60.86.6 0 e41f.13c4.a4ae ARPA Vlan498
Internet 10.60.86.9 0 aca8.8ecb.ae7b ARPA Vlan498
Internet 10.60.86.18 0 6c62.6d8c.196b ARPA Vlan498
Internet 10.60.86.19 0 6c62.6db2.c27c ARPA Vlan498
Internet 10.60.86.24 1 6431.50a5.3425 ARPA Vlan498
Internet 10.60.86.27 0 6c62.6db2.b22e ARPA Vlan498
Internet 10.60.86.28 3 e02a.825a.6829 ARPA Vlan498
Internet 10.60.86.30 4 5e29.da01.a293 ARPA Vlan498
Internet 10.60.86.31 30 00e4.1700.87f1 ARPA Vlan498
Internet 10.60.86.32 13 1418.77a2.e599 ARPA Vlan498
Internet 10.60.86.36 0 101f.744a.d5d6 ARPA Vlan498
Internet 10.60.86.38 0 2c76.8ae1.90da ARPA Vlan498
Internet 10.60.86.40 7 90cc.dff0.631f ARPA Vlan498
Internet 10.60.86.44 28 c018.5014.3cfb ARPA Vlan498
Internet 10.60.86.45 0 d0df.9a45.c064 ARPA Vlan498
Internet 10.60.86.46 38 7018.a746.8bb4 ARPA Vlan498
Internet 10.60.86.47 38 7018.a747.3a62 ARPA Vlan498
Internet 10.60.86.49 3 84a9.3e3f.24e3 ARPA Vlan498
Internet 10.60.86.50 11 1418.77a2.e859 ARPA Vlan498
Internet 10.60.86.51 13 f439.094b.762a ARPA Vlan498
Internet 10.60.86.52 0 6c62.6dcb.709a ARPA Vlan498
Internet 10.60.86.53 0 6c62.6dd0.b94b ARPA Vlan498
Internet 10.60.86.54 0 3c95.09fa.c417 ARPA Vlan498
Internet 10.60.86.57 0 1263.e530.7706 ARPA Vlan498
Internet 10.60.86.59 1 d0df.9a45.b441 ARPA Vlan498
Internet 10.60.86.60 0 3c95.0948.09ef ARPA Vlan498
Internet 10.60.86.61 3 f439.094b.79d8 ARPA Vlan498
Internet 10.60.86.63 0 d0df.9a5b.86a6 ARPA Vlan498
Internet 10.60.86.64 0 6c62.6dcb.44c4 ARPA Vlan498
Internet 10.60.86.65 1 fc3f.db1e.36eb ARPA Vlan498
Internet 10.60.86.66 0 6c62.6d8c.53c1 ARPA Vlan498
Internet 10.60.86.67 0 6c62.6d8f.2232 ARPA Vlan498
Internet 10.60.86.68 0 6c62.6d8f.2a89 ARPA Vlan498
Internet 10.60.86.69 0 6c62.6d8c.53b3 ARPA Vlan498
Internet 10.60.86.71 0 e41f.13c4.a4af ARPA Vlan498
Internet 10.60.86.73 0 d6c7.6419.2e5b ARPA Vlan498
Internet 10.60.86.74 0 f439.094b.76a4 ARPA Vlan498
Internet 10.60.86.75 0 84a9.3e3f.f4bc ARPA Vlan498
Internet 10.60.86.76 0 a2dc.0566.959c ARPA Vlan498
Internet 10.60.86.77 12 6c62.6d8c.4e33 ARPA Vlan498
Internet 10.60.86.78 19 f439.094b.7395 ARPA Vlan498
Internet 10.60.86.79 24 d6c7.6419.2e5b ARPA Vlan498
Internet 10.60.86.81 0 6c62.6d8c.5386 ARPA Vlan498
Internet 10.60.86.82 14 f439.094b.798e ARPA Vlan498
Internet 10.60.86.84 0 6c62.6d8f.1f72 ARPA Vlan498
Internet 10.60.86.85 0 6c62.6d8c.4ab9 ARPA Vlan498
Internet 10.60.86.86 28 6c62.6dd0.b775 ARPA Vlan498
Internet 10.60.86.89 5 6c62.6d8c.51b4 ARPA Vlan498
Internet 10.60.86.95 1 e02a.825e.bd0e ARPA Vlan498
Internet 10.60.86.96 0 6c62.6d8c.4c6e ARPA Vlan498
Internet 10.60.86.97 7 6c62.6db2.bbc8 ARPA Vlan498
Internet 10.60.86.98 6 f439.094b.7c69 ARPA Vlan498
Internet 10.60.86.100 0 6c62.6db2.b541 ARPA Vlan498
Internet 10.60.86.103 0 70c9.4ed5.42e5 ARPA Vlan498
Internet 10.60.86.105 0 6c62.6d8c.5746 ARPA Vlan498
Internet 10.60.86.106 7 f439.094b.7df5 ARPA Vlan498
Internet 10.60.86.107 2 6c62.6d8c.5393 ARPA Vlan498
Internet 10.60.86.108 33 c018.5014.394a ARPA Vlan498
Internet 10.60.86.109 35 3c6a.a713.8995 ARPA Vlan498
Internet 10.60.86.111 18 f439.094b.76e4 ARPA Vlan498
Internet 10.60.86.112 36 5cb9.0141.d789 ARPA Vlan498
Internet 10.60.86.113 0 9829.a659.c5e7 ARPA Vlan498
Internet 10.60.86.114 9 f439.094b.8074 ARPA Vlan498
Internet 10.60.86.115 7 645d.86c4.2c69 ARPA Vlan498
Internet 10.60.86.116 0 84a9.3e3f.7498 ARPA Vlan498
Internet 10.60.86.118 19 9608.4b64.7d6f ARPA Vlan498
Internet 10.60.86.121 3 6c62.6d8f.1f35 ARPA Vlan498
Internet 10.60.86.122 14 90cc.dff1.1fd5 ARPA Vlan498
Internet 10.60.86.123 1 229c.7ae9.a3d2 ARPA Vlan498
Internet 10.60.86.124 8 f439.094b.750a ARPA Vlan498
Internet 10.60.86.125 3 f439.094b.7481 ARPA Vlan498
Internet 10.60.86.126 1 f439.094b.731a ARPA Vlan498
Internet 10.60.86.129 28 588d.09c0.397f ARPA Vlan497
Internet 10.60.86.130 - ccef.48ed.21c1 ARPA Vlan497
Internet 10.60.86.141 27 c471.fe91.0323 ARPA Vlan497
Internet 10.60.86.142 3 c471.fe91.0810 ARPA Vlan497
Internet 10.60.86.143 27 c471.fe91.08a4 ARPA Vlan497
Internet 10.60.86.144 4 7081.0522.3567 ARPA Vlan497
Internet 10.60.86.145 27 7081.0522.33e1 ARPA Vlan497
Internet 10.60.86.146 8 c471.fe90.ea0b ARPA Vlan497
Internet 10.60.86.147 26 c471.fe91.08a2 ARPA Vlan497
Internet 10.60.86.148 38 0056.2b62.03b5 ARPA Vlan497
Internet 10.60.86.149 27 c471.fe91.0623 ARPA Vlan497
Internet 10.60.86.150 27 c471.fe91.089a ARPA Vlan497
Internet 10.60.86.151 4 5ce1.7611.2524 ARPA Vlan497
Internet 10.60.86.152 38 0056.2b63.d199 ARPA Vlan497
Internet 10.60.86.153 27 7081.0522.4320 ARPA Vlan497
Internet 10.60.86.155 14 c471.fe91.0824 ARPA Vlan497
Internet 10.60.86.156 4 c471.fe91.0187 ARPA Vlan497
Internet 10.60.86.157 27 6400.f17d.f323 ARPA Vlan497
Internet 10.60.86.158 27 7081.0522.5bd7 ARPA Vlan497
Internet 10.60.86.160 26 c471.fe91.0a82 ARPA Vlan497
Internet 10.60.86.161 6 c471.fe91.01af ARPA Vlan497
Internet 10.60.86.162 27 7081.0522.358d ARPA Vlan497
Internet 10.60.86.164 12 c471.fe91.081f ARPA Vlan497
Internet 10.60.86.165 26 c471.fe91.082f ARPA Vlan497
Internet 10.60.86.168 38 5ce1.7611.2653 ARPA Vlan497
Internet 10.60.86.169 0 c471.fe91.0af6 ARPA Vlan497
Internet 10.60.86.170 38 0056.2b62.03aa ARPA Vlan497
Internet 10.60.86.171 31 7081.0522.5bd0 ARPA Vlan497
Internet 10.60.86.172 5 7081.0522.35a4 ARPA Vlan497
Internet 10.60.86.173 38 0076.86ed.47b4 ARPA Vlan497
Internet 10.60.86.174 28 0056.2b63.d195 ARPA Vlan497
Internet 10.60.86.175 3 0056.2b62.03aa ARPA Vlan497
Internet 10.60.86.177 38 0056.2b63.d054 ARPA Vlan497
Internet 10.60.86.180 1 7081.0522.35a0 ARPA Vlan497
Internet 10.60.86.181 38 0056.2b63.d167 ARPA Vlan497
Internet 10.60.86.183 24 0056.2b62.01dd ARPA Vlan497
Internet 10.60.86.185 3 c471.fe91.082c ARPA Vlan497
Internet 169.254.24.231 23 f439.094b.76a4 ARPA Vlan498
Internet 169.254.103.147 36 84a9.3e3f.f4bc ARPA Vlan498
Internet 169.254.177.95 28 6c62.6d8c.53c1 ARPA Vlan498
Internet 169.254.248.6 36 6c62.6dd0.b775 ARPA Vlan498

Now If you Closely Check ARP Table you can find that table is not complete many IP Missing in this table.

IF we calculate Data Pool IP Address 126 (Exculed 86 Lease 9 = 95 + 17 manual exclude from Pool = 112) still 14 left unassigned but DHCP is Assigning false IP Address to Client . Can anyone help me to resolve the Issue.

On Daily basis we r running Below Commands

Clear ARP

Clear IP DHCP Binding *

Clear MAc Address-table Dynamic 

or Reload when issue didn't resolve  

[marce1000]

  - The arp-table does not have to match the leased-addresses because arp entries can expire if 'not used' or 'idle'

 M.

[RANAJi]

Internet 169.254.24.231 23 f439.094b.76a4 ARPA Vlan498
Internet 169.254.103.147 36 84a9.3e3f.f4bc ARPA Vlan498
Internet 169.254.177.95 28 6c62.6d8c.53c1 ARPA Vlan498
Internet 169.254.248.6 36 6c62.6dd0.b775 ARPA Vlan498

Dear Marc what About these false entry Why IP was not Assigned by DHCP , Shall we assigned manual IP to all Host to resolve issue permanently 

[balaji.bandi]

Waht is this Device, and what IOS Code running here :

what i see the issue, May be due to Lease time expiry, if the client with same MAC with in the lease time he get the IP address what he was allocaed before, but iif the Unique clients coming in, you do not have sufficiend pool of IP address cater that buffer.

If the Clients Fixed ? Do you have dynamic users like hot desk ?

i would suggest to set a lease time 8 hours (thinking the working hours, lease expirty ) - or increase the scope to /24 or more depends on outcome where possible,.

Internet 169.254.24.231 23 f439.094b.76a4 ARPA Vlan498
Internet 169.254.103.147 36 84a9.3e3f.f4bc ARPA Vlan498
Internet 169.254.177.95 28 6c62.6d8c.53c1 ARPA Vlan498
Internet 169.254.248.6 36 6c62.6dd0.b775 ARPA Vlan498

This is not Assigned by DHCP, this is link Local address.

The host boots up and looks for DHCP servers on the network. However, the DHCP server is down and can’t respond to the host. After some time (from a couple of seconds to a couple of minutes, depending on the operating system) the client auto-configures itself with an address from the APIPA rang.

when i looking at your VLAN you have different VLAN in the show ip ARP table, so we need Full conffiguraiton of the device and more about environment where you working to suggest best here.

If you looking to assign static IP that is good Idea, if you know the clients fixed, how about Dynamic Clients.

If you looking to do this on Cisco Device you need to create profiles for each user as identifier, your line of code become more complex.

To avoide this situation, get DHCP Server (Linux or Windows based, out of the cisco gear, so you can easily manange the scope with static or dynamic entry)

make sure static entries always exclude from Pool do get out of conflicts.

[RANAJi]

Many IP address in DHCP Pool Data are available and still not Assigned to Client , If you check ARP Table there are so many IP address missing and if we assign  these missing IP Client it Work, Didn't Show any Conflict.

This what I am looking from all of you why DHCP unable to assign complete pool List ?

version 15.0
no service pad
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname Data
!
boot-start-marker
boot-end-marker

!
no aaa new-model
switch 1 provision ws-c3750x-48
system mtu routing 1500
ip routing
!
ip dhcp excluded-address 10.60.86.1 10.60.86.17
ip dhcp excluded-address 10.60.86.129 10.60.86.140
!
ip dhcp pool Data
network 10.60.86.0 255.255.255.128
default-router 10.60.86.2
dns-server 10.60.86.6 8.8.8.8 156.154.70.1 218.248.255.196
lease 7
!
ip dhcp pool DataVOIP
network 10.60.86.128 255.255.255.128
default-router 10.60.86.130
option 150 ip 10.60.37.36 10.60.37.42
lease 7
!
!
ip domain-list Data
!
!
crypto pki trustpoint TP-self-signed-1223500160
enrollment selfsigned
subject-name cn=IOS-Self-Signed-Certificate-1223500160
revocation-check none
rsakeypair TP-self-signed-1223500160
!
!
crypto pki certificate chain TP-self-signed-1223500160
certificate self-signed 01
3082023D 308201A6 A0030201 02020101 300D0609 2A864886 F70D0101 04050030
31312F30 2D060355 04031326 494F532D 53656C66 2D536967 6E65642D 43657274
69666963 6174652D 31323233 35303031 3630301E 170D3933 30333031 30303031
33305A17 0D323030 31303130 30303030 305A3031 312F302D 06035504 03132649
4F532D53 656C662D 5369676E 65642D43 65727469 66696361 74652D31 32323335
30303136 3030819F 300D0609 2A864886 F70D0101 01050003 818D0030 81890281
8100B367 9B50916C 97DCA987 DCC94AA3 CAC09807 5FFD415A 321E2575 B08BF0D8
24765883 DD3FE2ED 67E47825 ECC33E16 1E8B7CCD 6A715E90 A423A284 84233167
27AC62C9 CA569F82 797B6FCD 97FC8B07 5AE69D25 7A0D9DF4 F510CBB9 D9DDCA38
A35548D2 09AD4F29 1EC3E3C7 029A2B63 E8F8C312 0F91591D 37EF2B73 DBDFD65F
04210203 010001A3 65306330 0F060355 1D130101 FF040530 030101FF 30100603
551D1104 09300782 05737465 6167301F 0603551D 23041830 16801468 319357B2
71D3B341 B9D09F58 AF31C339 94E38730 1D060355 1D0E0416 04146831 9357B271
D3B341B9 D09F58AF 31C33994 E387300D 06092A86 4886F70D 01010405 00038181
0031D894 51811FE0 BDE841AE D326CA4F 973366E3 293F86C5 C4355289 0411A472
5FC95679 6DAD89B9 90E7BD61 FD9C18A5 9B958922 524E5876 460695B9 D2F80C55
75FE76B6 6A45967F BEC43687 241DC538 2E6F69C0 16132B35 7B056CCE 52AAA9CB
5B016641 4A3E3087 6DB52E72 B3B8E6A3 DFA10BEB EC4C65B4 9025A76D B6E0E171 88
quit
!
!
!
spanning-tree mode pvst
spanning-tree extend system-id
!
!
!
!
vlan internal allocation policy ascending
!
!
!
!
!
!
interface FastEthernet0
no ip address
no ip route-cache
shutdown
!
interface GigabitEthernet1/0/1
description CONNECTED TO ASA-5520 FOR HMEL-DATA
switchport access vlan 498
!
interface GigabitEthernet1/0/2
switchport access vlan 498
switchport voice vlan 497
spanning-tree portfast
!
interface GigabitEthernet1/0/3
switchport access vlan 498
switchport voice vlan 497
spanning-tree portfast
!
interface GigabitEthernet1/0/4
switchport access vlan 498
switchport voice vlan 497
spanning-tree portfast
!
interface GigabitEthernet1/0/5
switchport access vlan 498
switchport voice vlan 497
spanning-tree portfast
!
interface GigabitEthernet1/0/6
switchport access vlan 498
switchport voice vlan 497
spanning-tree portfast
!
interface GigabitEthernet1/0/7
switchport access vlan 498
switchport voice vlan 497
spanning-tree portfast
!
interface GigabitEthernet1/0/8
switchport access vlan 498
switchport voice vlan 497
spanning-tree portfast
!
interface GigabitEthernet1/0/9
switchport access vlan 498
switchport voice vlan 497
spanning-tree portfast
!
interface GigabitEthernet1/0/10
switchport access vlan 498
switchport voice vlan 497
spanning-tree portfast
!
interface GigabitEthernet1/0/11
switchport access vlan 498
switchport voice vlan 497
spanning-tree portfast
!
interface GigabitEthernet1/0/12
switchport access vlan 498
switchport voice vlan 497
spanning-tree portfast
!
interface GigabitEthernet1/0/13
switchport access vlan 498
switchport voice vlan 497
spanning-tree portfast
!
interface GigabitEthernet1/0/14
switchport access vlan 498
switchport voice vlan 497
spanning-tree portfast
!
interface GigabitEthernet1/0/15
switchport access vlan 498
switchport voice vlan 497
spanning-tree portfast
!
interface GigabitEthernet1/0/16
switchport access vlan 498
switchport voice vlan 497
spanning-tree portfast
!
interface GigabitEthernet1/0/17
switchport access vlan 498
switchport voice vlan 497
spanning-tree portfast
!
interface GigabitEthernet1/0/18
switchport access vlan 498
switchport voice vlan 497
spanning-tree portfast
!
interface GigabitEthernet1/0/19
switchport access vlan 498
switchport voice vlan 497
spanning-tree portfast
!
interface GigabitEthernet1/0/20
switchport access vlan 498
switchport voice vlan 497
spanning-tree portfast
!
interface GigabitEthernet1/0/21
switchport access vlan 498
switchport voice vlan 497
spanning-tree portfast
!
interface GigabitEthernet1/0/22
switchport access vlan 498
switchport voice vlan 497
spanning-tree portfast
!
interface GigabitEthernet1/0/23
switchport access vlan 498
switchport voice vlan 497
spanning-tree portfast
!
interface GigabitEthernet1/0/24
switchport access vlan 498
switchport voice vlan 497
spanning-tree portfast
!
interface GigabitEthernet1/0/25
switchport access vlan 498
switchport voice vlan 497
spanning-tree portfast
!
interface GigabitEthernet1/0/26
switchport access vlan 498
switchport voice vlan 497
spanning-tree portfast
!
interface GigabitEthernet1/0/27
switchport access vlan 498
switchport voice vlan 497
spanning-tree portfast
!
interface GigabitEthernet1/0/28
switchport access vlan 498
switchport voice vlan 497
spanning-tree portfast
!
interface GigabitEthernet1/0/29
switchport access vlan 498
switchport voice vlan 497
spanning-tree portfast
!
interface GigabitEthernet1/0/30
switchport access vlan 498
switchport voice vlan 497
spanning-tree portfast
!
interface GigabitEthernet1/0/31
switchport access vlan 498
switchport voice vlan 497
spanning-tree portfast
!
interface GigabitEthernet1/0/32
switchport access vlan 498
switchport voice vlan 497
spanning-tree portfast
!
interface GigabitEthernet1/0/33
switchport access vlan 498
switchport voice vlan 497
spanning-tree portfast
!
interface GigabitEthernet1/0/34
switchport access vlan 498
switchport voice vlan 497
spanning-tree portfast
!
interface GigabitEthernet1/0/35
switchport access vlan 498
switchport voice vlan 497
spanning-tree portfast
!
interface GigabitEthernet1/0/36
switchport access vlan 498
switchport voice vlan 497
spanning-tree portfast
!
interface GigabitEthernet1/0/37
switchport access vlan 498
switchport voice vlan 497
spanning-tree portfast
!
interface GigabitEthernet1/0/38
switchport access vlan 498
switchport mode access
switchport voice vlan 497
spanning-tree portfast
!
interface GigabitEthernet1/0/39
switchport access vlan 498
switchport voice vlan 497
spanning-tree portfast
!
interface GigabitEthernet1/0/40
switchport access vlan 498
switchport voice vlan 497
spanning-tree portfast
!
interface GigabitEthernet1/0/41
switchport access vlan 498
switchport voice vlan 497
spanning-tree portfast
!
interface GigabitEthernet1/0/42
switchport access vlan 498
switchport voice vlan 497
spanning-tree portfast
!
interface GigabitEthernet1/0/43
switchport access vlan 498
switchport voice vlan 497
spanning-tree portfast
!
interface GigabitEthernet1/0/44
switchport access vlan 498
switchport voice vlan 497
spanning-tree portfast
!
interface GigabitEthernet1/0/45
switchport access vlan 498
switchport voice vlan 497
spanning-tree portfast
!
interface GigabitEthernet1/0/46
switchport access vlan 498
switchport voice vlan 497
spanning-tree portfast
!
interface GigabitEthernet1/0/47
description CONNETED TO HMEL LAN FOR VOIP
switchport access vlan 497
!
interface GigabitEthernet1/0/48
description CONNECTED TO HMEL SWITCH FOR DATA
switchport access vlan 498
!
interface GigabitEthernet1/1/1
!
interface GigabitEthernet1/1/2
!
interface GigabitEthernet1/1/3
!
interface GigabitEthernet1/1/4
!
interface TenGigabitEthernet1/1/1
!
interface TenGigabitEthernet1/1/2
!
interface Vlan1
no ip address
!
interface Vlan497
ip address 10.60.86.130 255.255.255.128
!
interface Vlan498
ip address 10.60.86.2 255.255.255.128

[balaji.bandi]

Look at the config high level i did not see any findings something wrong (other than lease time 7 days ?)

Sure you have enough scope available for the clients to connect and DHCP.  Is the issue directly connected devices ? or any daisy chain switches connected ( as per the config did not show any trunk config )

you have 48 ports ?   you have 100+ ARP entries ? where they coming from even you take Switch and Phone  48 x 2 = 96ARP Entries maximum.

when the user not getting lease , quick way is to run dhcp debug and see what is process taking place ?  (debug ip dhcp server packets)

other option i do not consider - but if possible uplift any stable IOS available to upgrade and test.

[Richard Burts]

The original poster seems to believe that there is a problem. I am not seeing anything in the discussion so far that clearly shows any problem. The original poster seems to believe that the content of the arp table is a valid way to check on addresses that have been assigned by DHCP. This logic is not correct. The arp table is a valid way to see what addresses are currently active (or perhaps have recently been active) but is not a way to check on what addresses have been assigned.

I will suggest a couple of scenarios that may help to explain the behavior:

- a user PC booted up and obtained an IP address via DHCP. That IP address was in the arp table for a period of time. The user left the office and powered down the PC. After a period of time (4 hours by default) the IP address was removed from the arp table. The address assignment was valid but no longer generates an arp entry.

- a user PC booted up and obtained an IP address via DHCP. After a period of time the lease expired and for some reason the PC was assigned a different IP address from the pool. Now the arp table will reflect the new address assignment but not the previous (valid but expired) address.

If there is some problem then we need an explanation of what the problem is. But differences between what shows up in the arp table and what was assigned by DHCP is not a problem.

[marce1000]

 - These are link-local addresses , ignore them in  the arp-table, for the rest use DHCP as much as possible.

 M.