N2048 - DHCP Relay not functioning after outage (help please!)

It could be possible that some parts of the configuration were not saved to the startup configuration. Does your configuration currently have ip helper enabled on it? Can you post up your current running configuration? What firmware is the switch on?

console(config)# ip helper enable

console(config)# ip helper {DHCP server IP} dhcp

Hello.

I am having this same problem.  Is someone watching this thread that could help if I post my information?

Please, feel free to post up information about what you are seeing and I can help out.

<189> Jul 17 10:25:44 192.168.1.241-1 TRAPMGR[dot1s_task]: traputil.c(763) 175323 %% NOTE Spanning Tree Topology Change Received: MSTID: 0 Gi1/0/24
<189> Jul 17 10:25:42 192.168.1.241-1 TRAPMGR[dot1s_task]: traputil.c(763) 175322 %% NOTE Spanning Tree Topology Change Received: MSTID: 0 Gi1/0/24
<189> Jul 17 10:25:40 192.168.1.241-1 TRAPMGR[dot1s_task]: traputil.c(763) 175321 %% NOTE Spanning Tree Topology Change Received: MSTID: 0 Gi1/0/24
<188> Jul 17 10:25:40 192.168.1.241-1 DHCP_SNP[dtlTask]: ds_util.c(1783) 175320 %% WARN DHCP packet: op Request, htype 1, hlen 6, hops 0, xid 3107306137, secs 10, ciaddr 10.111.133.56, yiaddr 0.0.0.0, server 0.0.0.0, giaddr 0.0.0.0, chaddr 00:18:B9:35:BA:99.
<188> Jul 17 10:25:40 192.168.1.241-1 DHCP_SNP[dtlTask]: ds_util.c(1741) 175319 %% WARN IP packet: ver/hlen 0x45, tos 96, len 348, id 39131, flags/offset   00, ttl 64, proto 17, src 10.111.133.56, dst 255.255.255.255.
<188> Jul 17 10:25:40 192.168.1.241-1 DHCP_SNP[dtlTask]: ds_util.c(1708) 175318 %% WARN Ethernet header: dest FF:FF:FF:FF:FF:FF, src 00:18:B9:35:BA:99, type/len 0x8100.
<188> Jul 17 10:25:40 192.168.1.241-1 DHCP_SNP[dtlTask]: ds_main.c(2860) 175317 %% WARN interface Gi1/0/19 vlanId 2
<188> Jul 17 10:25:40 192.168.1.241-1 DHCP_SNP[dtlTask]: ds_main.c(2860) 175316 %% WARN DHCP L2 Relay dropping client msg without Option-82rx'ed on L2 Relay trusted
<188> Jul 17 10:25:40 192.168.1.241-1 DHCP_SNP[dtlTask]: ds_util.c(1783) 175315 %% WARN DHCP packet: op Request, htype 1, hlen 6, hops 0, xid 220306, secs 7168, ciaddr 0.0.0.0, yiaddr 0.0.0.0, server 0.0.0.0, giaddr 0.0.0.0, chaddr 34:17:EB:AD:B9:53.
<188> Jul 17 10:25:40 192.168.1.241-1 DHCP_SNP[dtlTask]: ds_util.c(1741) 175314 %% WARN IP packet: ver/hlen 0x45, tos 0, len 328, id 4, flags/offset   00, ttl 64, proto 17, src 0.0.0.0, dst 255.255.255.255.
<188> Jul 17 10:25:40 192.168.1.241-1 DHCP_SNP[dtlTask]: ds_util.c(1708) 175313 %% WARN Ethernet header: dest FF:FF:FF:FF:FF:FF, src 34:17:EB:AD:B9:53, type/len 0x8100.
<188> Jul 17 10:25:40 192.168.1.241-1 DHCP_SNP[dtlTask]: ds_main.c(2860) 175312 %% WARN interface Gi1/0/24 vlanId 1
<188> Jul 17 10:25:40 192.168.1.241-1 DHCP_SNP[dtlTask]: ds_main.c(2860) 175311 %% WARN DHCP L2 Relay dropping client msg without Option-82rx'ed on L2 Relay trusted

Since everyone has gone silent, I'm experiencing the same thing. There was a power outage, now I can't get the phones on the switch back up. I'm a novice at this, but my impression is that the packets aren't being appended with option 82, but I've tried everything I can find to try to enable it. Phones are on 17, 19, and 21. Uplink is 24.

-log-

!Current Configuration:
!Software Capability "Stack Limit = 12, VLAN Limit = 4093"
!Image File "N2000Stdv6.5.1.6"
!System Description "Dell EMC Networking N2024P, 6.5.1.6, Linux 3.6.5-e3cd5a07"
!System Software Version 6.5.1.6
!
configure
gvrp enable
vlan 2
exit
vlan 2
name "PHONE"
vlan association subnet 10.111.133.0 255.255.255.0
exit
clock timezone -7 minutes 0 zone "PDT"
stack
member 1 2    ! N2024P
exit
no logging console
exit
ip dhcp relay information option
interface vlan 1
ip address 192.168.1.241 255.255.255.0
ip helper-address discard dhcp
exit
interface vlan 2
ip helper-address 69.168.202.34 domain
ip helper-address 10.111.133.254 dhcp
ip dhcp relay information option-insert
exit
ip default-gateway 192.168.1.1
no isdp enable
application install SupportAssist auto-restart start-on-boot
ip dhcp snooping
ip dhcp snooping vlan 2
dhcp l2relay
dhcp l2relay vlan 1-2
dhcp l2relay circuit-id vlan 2
!
interface Gi1/0/1
gvrp enable
exit
!
interface Gi1/0/5
switchport voice detect auto
dhcp l2relay
dhcp l2relay trust
gvrp enable
switchport mode general
switchport general pvid 2
switchport general allowed vlan add 2 tagged
exit
!
interface Gi1/0/11
switchport voice detect auto
dhcp l2relay
dhcp l2relay trust
gvrp enable
switchport mode trunk
switchport general pvid 2
switchport general allowed vlan add 2 tagged
switchport trunk native vlan 2
exit
!
interface Gi1/0/17
dhcp l2relay
dhcp l2relay trust
switchport general pvid 2
switchport general acceptable-frame-type tagged-only
switchport general allowed vlan add 2 tagged
switchport access vlan 2
exit
!
interface Gi1/0/19
dhcp l2relay
dhcp l2relay trust
switchport general pvid 2
switchport general acceptable-frame-type tagged-only
switchport access vlan 2
exit
!
interface Gi1/0/21
dhcp l2relay
switchport general pvid 2
switchport general acceptable-frame-type tagged-only
switchport access vlan 2
exit
!
interface Gi1/0/23
switchport voice detect auto
switchport mode general
switchport general allowed vlan add 2 tagged
switchport voice vlan 2
exit
!
interface Gi1/0/24
dhcp l2relay
dhcp l2relay trust
switchport mode general
switchport general allowed vlan add 2 tagged
exit
snmp-server engineid local 800002a203f8b15649188e
snmp-server community "public" rw
no hiveagent
exit

Do you have a backup of the working configuration? Something you can compare the current config with? This would help to identify any changes that were not saved to the startup config before the power outage.

Do the phones have any workstations plugged into them? The ports you are working with are configured for a single untagged VLAN.

interface Gi1/0/19

dhcp l2relay

dhcp l2relay trust

switchport general pvid 2

switchport general acceptable-frame-type tagged-only

switchport access vlan 2

While other interfaces are configured a little different.

interface Gi1/0/5

switchport voice detect auto

dhcp l2relay

dhcp l2relay trust

gvrp enable

switchport mode general

switchport general pvid 2

switchport general allowed vlan add 2 tagged

Are these all the same phone models? Or is it a mixed environment? If you plug a workstation into these ports, is the workstation able to ping throughout the network?

Is there a specific reason you are running the VLAN association command?

vlan association subnet 10.111.133.0 255.255.255.0

I have seen this cause more head scratching than anything, and is something that usually ends up being removed.

No, we're kind of working blind. The previous admin wasn't big on backups or documentation.

It's just the phones on 17, 19, and 21. No workstation with them.

There's nothing on 5. A holdover configuration from something previous, I guess.

"Is there a specific reason you are running the VLAN association command?"  No, just found it that way.

Remove the VLAN association.

# int vlan 2
# no ip association subnet 10.111.133.0 255.255.255.0
 

Remove DHCP l2relay trust from the phone facing interfaces.

# int gi1/0/19

# no dhcp l2relay trust
 

Globally enable ip helper.

# ip helper enable

Then test again, see if the behavior changes at all.

After that change, I am no longer seeing the:

WARN DHCP L2 Relay dropping client msg without Option-82rx'ed on L2 Relay trusted

error for those interfaces, however they are still not able to reach their DHCP server.

Glad to hear the messages went away. If you plug a client with a static IP into one of the phone ports, is that client able to ping the DHCP server at 10.111.133.254? This will just help ensure that the communication path between the port and the DHCP server is good.

Plugged my workstation into gi/21
Not able to establish any connection
Changed PVID for gi/21 to 1
Connection established

"ping 100.111.133.254

Pinging 100.111.133.254 with 32 bytes of data:
Reply from 130.94.195.173: Destination net unreachable."

"Tracing route to dyn-130-194-195-173.its.monash.edu.au [130.194.195.173]
over a maximum of 30 hops:

  1    <1 ms    <1 ms    <1 ms  192.168.1.1
  2    31 ms     1 ms    <1 ms  noname.netfortris.com [69.168.194.33]
  3     4 ms     4 ms     4 ms  10.249.11.149
  4     4 ms     4 ms     4 ms  172.30.249.53
  5     4 ms     4 ms     4 ms  noname.netfortris.com [69.170.160.92]
  6     4 ms     4 ms     4 ms  vlan15.la-bdr1.netfortris.net [66.43.97.245]
  7     5 ms     5 ms     5 ms  ge-100-0-0-18.r01.lsanca07.us.bb.gin.ntt.net [130.94.195.173]
  8     4 ms     4 ms     5 ms  ae-3.r23.lsanca07.us.bb.gin.ntt.net [129.250.4.106]
  9    17 ms    13 ms    13 ms  ae-12.r22.snjsca04.us.bb.gin.ntt.net [129.250.4.150]
 10    12 ms    16 ms    12 ms  ae-19.r01.snjsca04.us.bb.gin.ntt.net [129.250.3.27]
 11    12 ms    12 ms    13 ms  ae-1.a00.snjsca04.us.bb.gin.ntt.net [129.250.2.228]
 12   155 ms   155 ms   155 ms  xe-0-0-12-3.a00.snjsca04.us.ce.gin.ntt.net [128.241.219.154]
 13   155 ms   155 ms   155 ms  xe-1-0-1.pe1.msct.nsw.aarnet.net.au [202.158.194.161]
 14   155 ms   156 ms   155 ms  et-3-3-0.pe1.rsby.nsw.aarnet.net.au [113.197.15.156]
 15   156 ms   157 ms   156 ms  xe-1-1-0.pe1.eskp.nsw.aarnet.net.au [113.197.15.199]
 16   168 ms   168 ms   168 ms  et-5-3-0.pe1.wmlb.vic.aarnet.net.au [113.197.15.9]
 17   168 ms   168 ms   169 ms  et-0-1-0.pe1.nbpk.vic.aarnet.net.au [113.197.15.27]
 18   169 ms   168 ms   169 ms  xe-5-0-6-211.pe1.nbpk.vic.aarnet.net.au [138.44.64.221]
 19   169 ms   169 ms   169 ms  core-gw1-v520.net.monash.edu.au [130.194.28.81]
 20   169 ms   169 ms   169 ms  south-gw1-e2-1.net.monash.edu.au [130.194.29.136]
 21   172 ms   168 ms   168 ms  dyn-130-194-195-173.its.monash.edu.au [130.194.195.173]"

In your config you have ip helper pointing to 10.111.133.254. But in your ping testing you pinged 100.111.133.254. Can you confirm the IP of the DHCP address? Where in the network does the DHCP server reside? Do you have any other switches that have VLAN 2 devices?

Oops, yes, 10.111.133.254 is correct. The DHCP server is external, hosted by our VoIP provider.

Ping to the *correct* address times out.

Pinging 10.111.133.254 with 32 bytes of data:
Request timed out.
Request timed out.
Request timed out.
Request timed out.

We do have other switches, that are working with VLAN 2, but don't have access to the configurations at this time. Again, a gift from the previous admin.