3750 and vlans

[hugh.lancaster]

Haveing issue with DHCP server handing out IP addresses to client connected to VLAN5 interface.....

ISP Router>Firewall -(WatchGuard Drop-in mode)

I have several 3750 switches and  one acting as a L3 switch. The L3 is configured as follow:

interface Vlan1

ip address 10.100.0.4 255.255.248.0

!

interface Vlan5

ip address 10.100.8.2 255.255.248.0

ip helper-address 10.100.0.16 (This is a windows 2008 DHCP server scoped for 10.100.0.10-254 and 10.100.8.10.-254)

!

ip default-gateway 10.100.0.1

ip classless

ip route 0.0.0.0 0.0.0.0 10.100.0.1

ip http server

ip http secure-server

Here is the switch where the server resides:

interface FastEthernet1/0/10

description test VLAN5

switchport access vlan 5

switchport mode access

storm-control broadcast level 10.00

macro description cisco-desktop

spanning-tree portfast

spanning-tree bpduguard enable

If I connect a laptop to int fa1/0/10 I DO NOT get an IP address from the 10.100.0.8 scope. If I connect to another interface within the VLAN 1, I get an address from the 10.100.0.0 range.

Any help would be appreciated.

[acampbell]

Hugh,

Have you set the dhcp scopes as a superscope.

If yes then remove the superscope and leave the scopes as stand alone

Regards

Alex

[hugh.lancaster]

Have dhcp server set as super scope and don't experience any problems with VLAN1. Any reason why it would only affect vlan 5? Thanks for the reply!

[mellonr]

How are these two switches connected. For vlan 5 from the fa switch to get to the l3 switch, you'll need a trunk port connecting them that bellows vlan 5

Sent from Cisco Technical Support iPad App

[acampbell · Accepted solution]

Hugh,

The DHCP server is in VLAN 1 === 10.100.0.16

You need a seperate SCOPE definitely not under this SUPERSCOPE

When you are using multiple VLANS you can not use SUPERSCOPES

Regards

Alex

[hugh.lancaster]

I will give it a try. Here is my wireshark output.

No.     Time        Source                Destination           Protocol Info
     25 3.916883    10.100.8.2            10.100.0.16           DHCP     DHCP Discover - Transaction ID 0xa6dd94f1

Frame 25: 342 bytes on wire (2736 bits), 342 bytes captured (2736 bits)
    Arrival Time: Feb 27, 2012 10:21:48.336980000 Eastern Standard Time
    Epoch Time: 1330356108.336980000 seconds
    [Time delta from previous captured frame: 0.073777000 seconds]
    [Time delta from previous displayed frame: 0.000000000 seconds]
    [Time since reference or first frame: 3.916883000 seconds]
    Frame Number: 25
    Frame Length: 342 bytes (2736 bits)
    Capture Length: 342 bytes (2736 bits)
    [Frame is marked: False]
    [Frame is ignored: False]
    [Protocols in frame: eth:ip:udp:bootp]
    [Coloring Rule Name: UDP]
    [Coloring Rule String: udp]
Ethernet II, Src: Cisco_71:95:40 (00:1d:a2:71:95:40), Dst: Dell_42:23:c6 (00:18:8b:42:23:c6)
    Destination: Dell_42:23:c6 (00:18:8b:42:23:c6)
        Address: Dell_42:23:c6 (00:18:8b:42:23:c6)
        .... ...0 .... .... .... .... = IG bit: Individual address (unicast)
        .... ..0. .... .... .... .... = LG bit: Globally unique address (factory default)
    Source: Cisco_71:95:40 (00:1d:a2:71:95:40)
        Address: Cisco_71:95:40 (00:1d:a2:71:95:40)
        .... ...0 .... .... .... .... = IG bit: Individual address (unicast)
        .... ..0. .... .... .... .... = LG bit: Globally unique address (factory default)
    Type: IP (0x0800)
Internet Protocol, Src: 10.100.8.2 (10.100.8.2), Dst: 10.100.0.16 (10.100.0.16)
    Version: 4
    Header length: 20 bytes
    Differentiated Services Field: 0x00 (DSCP 0x00: Default; ECN: 0x00)
        0000 00.. = Differentiated Services Codepoint: Default (0x00)
        .... ..0. = ECN-Capable Transport (ECT): 0
        .... ...0 = ECN-CE: 0
    Total Length: 328
    Identification: 0x00fd (253)
    Flags: 0x00
        0... .... = Reserved bit: Not set
        .0.. .... = Don't fragment: Not set
        ..0. .... = More fragments: Not set
    Fragment offset: 0
    Time to live: 255
    Protocol: UDP (17)
    Header checksum: 0x9cce [correct]
        [Good: True]
        [Bad: False]
    Source: 10.100.8.2 (10.100.8.2)
    Destination: 10.100.0.16 (10.100.0.16)
User Datagram Protocol, Src Port: bootps (67), Dst Port: bootps (67)
    Source port: bootps (67)
    Destination port: bootps (67)
    Length: 308
    Checksum: 0x4b57 [validation disabled]
        [Good Checksum: False]
        [Bad Checksum: False]
Bootstrap Protocol
    Message type: Boot Request (1)
    Hardware type: Ethernet
    Hardware address length: 6
    Hops: 1
    Transaction ID: 0xa6dd94f1
    Seconds elapsed: 11
        [Expert Info (Note/Malformed): Seconds elapsed (11) appears to be encoded as little-endian]
            [Message: Seconds elapsed (11) appears to be encoded as little-endian]
            [Severity level: Note]
            [Group: Malformed]
    Bootp flags: 0x0000 (Unicast)
        0... .... .... .... = Broadcast flag: Unicast
        .000 0000 0000 0000 = Reserved flags: 0x0000
    Client IP address: 0.0.0.0 (0.0.0.0)
    Your (client) IP address: 0.0.0.0 (0.0.0.0)
    Next server IP address: 0.0.0.0 (0.0.0.0)
    Relay agent IP address: 10.100.8.2 (10.100.8.2)
    Client MAC address: Dell_51:39:c6 (00:15:c5:51:39:c6)
    Client hardware address padding: 00000000000000000000
    Server host name not given
    Boot file name not given
    Magic cookie: DHCP
    Option: (t=53,l=1) DHCP Message Type = DHCP Discover
        Option: (53) DHCP Message Type
        Length: 1
        Value: 01
    Option: (t=116,l=1) DHCP Auto-Configuration = AutoConfigure
        Option: (116) DHCP Auto-Configuration
        Length: 1
        Value: 01
    Option: (t=61,l=7) Client identifier
        Option: (61) Client identifier
        Length: 7
        Value: 010015c55139c6
        Hardware type: Ethernet
        Client MAC address: Dell_51:39:c6 (00:15:c5:51:39:c6)
    Option: (t=50,l=4) Requested IP Address = 10.100.1.123
        Option: (50) Requested IP Address
        Length: 4
        Value: 0a64017b
    Option: (t=12,l=9) Host Name = "HWY-11248"
        Option: (12) Host Name
        Length: 9
        Value: 4857592d3131323438
    Option: (t=60,l=8) Vendor class identifier = "MSFT 5.0"
        Option: (60) Vendor class identifier
        Length: 8
        Value: 4d53465420352e30
    Option: (t=55,l=11) Parameter Request List
        Option: (55) Parameter Request List
        Length: 11
        Value: 010f03062c2e2f1f21f92b
        1 = Subnet Mask
        15 = Domain Name
        3 = Router
        6 = Domain Name Server
        44 = NetBIOS over TCP/IP Name Server
        46 = NetBIOS over TCP/IP Node Type
        47 = NetBIOS over TCP/IP Scope
        31 = Perform Router Discover
        33 = Static Route
        249 = Private/Classless Static Route (Microsoft)
        43 = Vendor-Specific Information
    Option: (t=43,l=2) Vendor-Specific Information
        Option: (43) Vendor-Specific Information
        Length: 2
        Value: dc00
    End Option

No.     Time        Source                Destination           Protocol Info
     26 3.917053    10.100.0.16           10.100.8.2            DHCP     DHCP Offer    - Transaction ID 0xa6dd94f1

Frame 26: 344 bytes on wire (2752 bits), 344 bytes captured (2752 bits)
    Arrival Time: Feb 27, 2012 10:21:48.337150000 Eastern Standard Time
    Epoch Time: 1330356108.337150000 seconds
    [Time delta from previous captured frame: 0.000170000 seconds]
    [Time delta from previous displayed frame: 0.000170000 seconds]
    [Time since reference or first frame: 3.917053000 seconds]
    Frame Number: 26
    Frame Length: 344 bytes (2752 bits)
    Capture Length: 344 bytes (2752 bits)
    [Frame is marked: False]
    [Frame is ignored: False]
    [Protocols in frame: eth:ip:udp:bootp]
    [Coloring Rule Name: Checksum Errors]
    [Coloring Rule String: cdp.checksum_bad==1 || edp.checksum_bad==1 || ip.checksum_bad==1 || tcp.checksum_bad==1 || udp.checksum_bad==1 || mstp.checksum_bad==1]
Ethernet II, Src: Dell_42:23:c6 (00:18:8b:42:23:c6), Dst: Cisco_71:95:40 (00:1d:a2:71:95:40)
    Destination: Cisco_71:95:40 (00:1d:a2:71:95:40)
        Address: Cisco_71:95:40 (00:1d:a2:71:95:40)
        .... ...0 .... .... .... .... = IG bit: Individual address (unicast)
        .... ..0. .... .... .... .... = LG bit: Globally unique address (factory default)
    Source: Dell_42:23:c6 (00:18:8b:42:23:c6)
        Address: Dell_42:23:c6 (00:18:8b:42:23:c6)
        .... ...0 .... .... .... .... = IG bit: Individual address (unicast)
        .... ..0. .... .... .... .... = LG bit: Globally unique address (factory default)
    Type: IP (0x0800)
Internet Protocol, Src: 10.100.0.16 (10.100.0.16), Dst: 10.100.8.2 (10.100.8.2)
    Version: 4
    Header length: 20 bytes
    Differentiated Services Field: 0x00 (DSCP 0x00: Default; ECN: 0x00)
        0000 00.. = Differentiated Services Codepoint: Default (0x00)
        .... ..0. = ECN-Capable Transport (ECT): 0
        .... ...0 = ECN-CE: 0
    Total Length: 330
    Identification: 0x250f (9487)
    Flags: 0x02 (Don't Fragment)
        0... .... = Reserved bit: Not set
        .1.. .... = Don't fragment: Set
        ..0. .... = More fragments: Not set
    Fragment offset: 0
    Time to live: 128
    Protocol: UDP (17)
    Header checksum: 0x0000 [incorrect, should be 0xb7ba]
        [Good: False]
        [Bad: True]
            [Expert Info (Error/Checksum): Bad checksum]
                [Message: Bad checksum]
                [Severity level: Error]
                [Group: Checksum]
    Source: 10.100.0.16 (10.100.0.16)
    Destination: 10.100.8.2 (10.100.8.2)
User Datagram Protocol, Src Port: bootps (67), Dst Port: bootps (67)
    Source port: bootps (67)
    Destination port: bootps (67)
    Length: 310
    Checksum: 0x1e21 [validation disabled]
        [Good Checksum: False]
        [Bad Checksum: False]
Bootstrap Protocol
    Message type: Boot Reply (2)
    Hardware type: Ethernet
    Hardware address length: 6
    Hops: 0
    Transaction ID: 0xa6dd94f1
    Seconds elapsed: 0
    Bootp flags: 0x0000 (Unicast)
        0... .... .... .... = Broadcast flag: Unicast
        .000 0000 0000 0000 = Reserved flags: 0x0000
    Client IP address: 0.0.0.0 (0.0.0.0)
    Your (client) IP address: 10.100.1.123 (10.100.1.123)
    Next server IP address: 10.100.0.16 (10.100.0.16)
    Relay agent IP address: 10.100.8.2 (10.100.8.2)
    Client MAC address: Dell_51:39:c6 (00:15:c5:51:39:c6)
    Client hardware address padding: 00000000000000000000
    Server host name not given
    Boot file name not given
    Magic cookie: DHCP
    Option: (t=53,l=1) DHCP Message Type = DHCP Offer
        Option: (53) DHCP Message Type
        Length: 1
        Value: 02
    Option: (t=1,l=4) Subnet Mask = 255.255.248.0
        Option: (1) Subnet Mask
        Length: 4
        Value: fffff800
    Option: (t=58,l=4) Renewal Time Value = 12 hours
        Option: (58) Renewal Time Value
        Length: 4
        Value: 0000a8c0
    Option: (t=59,l=4) Rebinding Time Value = 21 hours
        Option: (59) Rebinding Time Value
        Length: 4
        Value: 00012750
    Option: (t=51,l=4) IP Address Lease Time = 1 day
        Option: (51) IP Address Lease Time
        Length: 4
        Value: 00015180
    Option: (t=54,l=4) DHCP Server Identifier = 10.100.0.16
        Option: (54) DHCP Server Identifier
        Length: 4
        Value: 0a640010
    Option: (t=15,l=10) Domain Name = "encsd.net"
        Option: (15) Domain Name
        Length: 10
        Value: 656e6373642e6e657400
    Option: (t=3,l=4) Router = 10.100.0.4
        Option: (3) Router
        Length: 4
        Value: 0a640004
    Option: (t=6,l=8) Domain Name Server
        Option: (6) Domain Name Server
        Length: 8
        Value: 0a64000f0a640010
        IP Address: 10.100.0.15
        IP Address: 10.100.0.16
    End Option

[hugh.lancaster]

Thank you very much!!!!

I created a new scope and bingo. It works! Now I am a little confused. For VLAN1, do I need to remove superscope and create just a scope?

[acampbell]

Hugh,

Superscopes were used a while back when we had to enter more than 1 IP subnet on a single

ethernet segment. In Cisco these were like adding IP address xxxxxx secondary.

Nowadays with multiple vlans we don not use the superscopes

I subnet per vlan etc.

If you had the scope for vlan 5 under the same superscope as vlan 1

then the DHCP server will not allocate the adresses correctly you might get DHCP NAKS all over the place.

To delete the super scope just right click delete.

It will only delete the superscope NOT the scopes it umbrellas.

HTH

Alex

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