SG300 and DHCP

[wfinley]

I've enabled DHCP on my SG300-52.  It seems to work with all clients other than the AT&T Microcell 3G.  When the microcell first powers on, it attempts to get an IP address via DHCP.  However, the SG300 logs the following:

%DHCP-W-SRVALLOC: DHCP Server cannot allocate an IP address, the length of client id is wrong

   Any suggestions?

      Wally

[Georg Pauwen]

Hello,

can you find out what the client identfier is of the Microcell ? The SG-300 expects something like the below in HEX notation:

01b60819681172

Either way, the Microcell should have a MAC address. Try to assign a static IP using its MAC address (page 297 of the attached user guide)...

https://www.cisco.com/c/dam/en/us/td/docs/switches/lan/csbms/sf30x_sg30x/administration_guide/78-19308-01.pdf

[wfinley]

Hi,

I've tried setting a static dhcp entry, but it doesn't work. The client id is 33 bytes long and is:
Option: (61) Client identifier
Length: 33
"=!ip.access-3G-A p-74547D-0027478 001"

[Georg Pauwen]

The device doesn't have a MAC address ? Have you tried setting the static entry with the MAC address ?

The MicroCell's MAC address should be listed on the bottom of the unit on a small sticker...

[wfinley]

I've attached two pictures, one is the wireshark packet capture, the other is the static entry on the SG300
[cid:image001.png@01D31DAB.F8138BC0]

[cid:image002.png@01D31DAB.F8138BC0]

[Georg Pauwen]

Attachments didn't go through and are not visible...

Have you been able to find the MAC address(es) ?

[wfinley]

Frame 4939: 348 bytes on wire (2784 bits), 348 bytes captured (2784 bits) on interface 0
Ethernet II, Src: CiscoSpv_fb:eb:be (74:54:7d:fb:eb:be), Dst: Broadcast (ff:ff:ff:ff:ff:ff)
Destination: Broadcast (ff:ff:ff:ff:ff:ff)
Address: Broadcast (ff:ff:ff:ff:ff:ff)
.... ..1. .... .... .... .... = LG bit: Locally administered address (this is NOT the factory default)
.... ...1 .... .... .... .... = IG bit: Group address (multicast/broadcast)
Source: CiscoSpv_fb:eb:be (74:54:7d:fb:eb:be)
Address: CiscoSpv_fb:eb:be (74:54:7d:fb:eb:be)
.... ..0. .... .... .... .... = LG bit: Globally unique address (factory default)
.... ...0 .... .... .... .... = IG bit: Individual address (unicast)
Type: IPv4 (0x0800)
Internet Protocol Version 4, Src: 0.0.0.0, Dst: 255.255.255.255
0100 .... = Version: 4
.... 0101 = Header Length: 20 bytes (5)
Differentiated Services Field: 0x00 (DSCP: CS0, ECN: Not-ECT)
Total Length: 334
Identification: 0x0000 (0)
Flags: 0x00
Fragment offset: 0
Time to live: 64
Protocol: UDP (17)
Header checksum: 0x79a0 [validation disabled]
[Header checksum status: Unverified]
Source: 0.0.0.0
Destination: 255.255.255.255
[Source GeoIP: Unknown]
[Destination GeoIP: Unknown]
User Datagram Protocol, Src Port: 68, Dst Port: 67
Source Port: 68
Destination Port: 67
Length: 314
Checksum: 0x06c0 [unverified]
[Checksum Status: Unverified]
[Stream index: 17]
Bootstrap Protocol (Discover)
Message type: Boot Request (1)
Hardware type: Ethernet (0x01)
Hardware address length: 6
Hops: 0
Transaction ID: 0x069bca06
Seconds elapsed: 12298
Bootp flags: 0x0000 (Unicast)
0... .... .... .... = Broadcast flag: Unicast
.000 0000 0000 0000 = Reserved flags: 0x0000
Client IP address: 0.0.0.0
Your (client) IP address: 0.0.0.0
Next server IP address: 0.0.0.0
Relay agent IP address: 0.0.0.0
Client MAC address: CiscoSpv_fb:eb:be (74:54:7d:fb:eb:be)
Client hardware address padding: 00000000000000000000
Server host name not given
Boot file name not given
Magic cookie: DHCP
Option: (53) DHCP Message Type (Discover)
Length: 1
DHCP: Discover (1)
Option: (57) Maximum DHCP Message Size
Length: 2
Maximum DHCP Message Size: 576
Option: (55) Parameter Request List
Length: 7
Parameter Request List Item: (1) Subnet Mask
Parameter Request List Item: (3) Router
Parameter Request List Item: (6) Domain Name Server
Parameter Request List Item: (12) Host Name
Parameter Request List Item: (15) Domain Name
Parameter Request List Item: (28) Broadcast Address
Parameter Request List Item: (42) Network Time Protocol Servers
Option: (60) Vendor class identifier
Length: 12
Vendor class identifier: udhcp 1.23.1
Option: (61) Client identifier
Length: 33
Option: (255) End
Option End: 255