Design question -- Best practices for interconnected 3560's on LAN

[corpengineer]

Hello there:

Can't seem to find any good documentation on this, so if somebody can direct me to solid documentation, that would be great.  We have one 3560X switch being used as a core switch, and (10) 3560 switches being used as 'access' switches.  We have 4 VLANs, 10 servers, IP phones, and a couple hundred users (also a point to point link to China).  We are not using any 10Gb ports, Gb uplinks, or SFP modules on the switches.  Just plugging the access switches into the core switch (Gb ethernet ports), servers on (1) 3560 switch, and users/phones/printers on the other (9) 3560 switches. 

My question is very basic -- how should the Gb ethernet ports on the core switch be setup (to interconnect the other 3560 switches), as well as the Gb ethernet ports on the access switches (connected back to the core 3560X)?                     

Thank you.

[Leo Laohoo]

With such small network, running a Layer 2 network with the 3560X performing the Layer 3 function is acceptable.

You can also do Layer 3 to all your switches.

[corpengineer]

Appreciate the feedback, thank you.

Then how would the configs look? 

If we did do all Layer 3, what does that get us (other than being able to set acl's on vlans)?

How would the configs look different if we did all layer 3?

Thank you.

[Leo Laohoo]

You break up each switch with different VLAN subnet.

You could use something like OSPF to route.

[corpengineer]

Does that help w/ speed or performance?  Just trying to understand the options, and why.

Thank you.

[Leo Laohoo]

Does that help w/ speed or performance?  Just trying to understand the options, and why.

Like I said in my first post.  With the size of your network, you can get away with running a Layer 2 network.  The fact that you are not running a flat Layer 2 (on VLAN for everyone) is, in my book, a good practice.

If you want to improve it, fine, you can run Layer 3 to all switches.  Will it improve?  Let's say you have three VLANs:  Data, voice and Others.  Each VLAN is the same number, 110, 120, 130.  But each VLAN is in each own subnet.    So you have each switch having the three VLANs but in a unique subnet.

Improvements?  You shrunk the size of your broadcast domain, from the entire network, into a single switch.

Speed?  Minimize broadcast to a single switch?  You basically made local traffic become local.  So useless broadcast traffic doesn't have to go all the way to your core switch. 

[corpengineer]

Thanks for the background, that's good information. 

Re the config's, are the settings correct for Gb ports interconnecting each switch?  I can ping the switch NWS-10 by IP, but not the can't servers connected to NSW-10.

Otherwise, can the configs be improved upon re performance or best practices?

Any other suggestions?

Also, where can I find good documentation re config examples?  The Cisco site is good, but if your scenario doesn't exactly match what they have online, it's not always relevant.

Thank you.

[corpengineer]

Here are the config's-

Switch number 10 3560 ,(Gb ethernet 0/24) is plugged into 3560X (Gb ethernet 0/9)

3560X :

version 12.2
no service pad
service timestamps debug datetime msec
service timestamps log datetime msec
service password-encryption
!
hostname NSW-01
!
boot-start-marker
boot-end-marker
!
enable secret 5   *****************
enable password 7 **************
!
!
no aaa new-model
clock timezone PST -8
clock summer-time PDT recurring
system mtu routing 1500
ip routing
!
!
no ip domain-lookup
!
!
license boot level ipservices
spanning-tree mode pvst
spanning-tree extend system-id
!
!
!
!
vlan internal allocation policy ascending
!
lldp run
!
!
!
interface FastEthernet0
no ip address
no ip route-cache cef
no ip route-cache
no ip mroute-cache
shutdown
!
interface GigabitEthernet0/1
description : Cisco 5510 inside
switchport access vlan 10
switchport mode access
spanning-tree portfast
!
interface GigabitEthernet0/2
switchport access vlan 100
switchport mode access
spanning-tree portfast
!
interface GigabitEthernet0/3
description : Shanghai office p2p Gi0/1
no switchport
ip address x.y.129.1 255.255.255.0
ntp broadcast
!
interface GigabitEthernet0/4
switchport trunk encapsulation dot1q
switchport trunk native vlan 100
switchport trunk allowed vlan 1,100,200
switchport mode trunk
switchport nonegotiate
switchport voice vlan 200
spanning-tree portfast
!
interface GigabitEthernet0/5
switchport trunk encapsulation dot1q
switchport trunk native vlan 100
switchport trunk allowed vlan 1,100,200
switchport mode trunk
switchport nonegotiate
switchport voice vlan 200
spanning-tree portfast
!
interface GigabitEthernet0/6
switchport trunk encapsulation dot1q
switchport trunk native vlan 100
switchport trunk allowed vlan 1,100,200
switchport mode trunk
switchport nonegotiate
switchport voice vlan 200
spanning-tree portfast
!
interface GigabitEthernet0/7
switchport trunk encapsulation dot1q
switchport trunk native vlan 100
switchport trunk allowed vlan 1,100,200
switchport mode trunk
switchport nonegotiate
switchport voice vlan 200
spanning-tree portfast
!
interface GigabitEthernet0/8
description : NSW-11 Gi0/1
switchport trunk encapsulation dot1q
switchport trunk native vlan 2
switchport trunk allowed vlan 1,2,10,100,200
switchport mode trunk
switchport nonegotiate
switchport voice vlan 200
spanning-tree portfast
!
interface GigabitEthernet0/9
description : NSW-10 Gi/01
switchport trunk encapsulation dot1q
switchport trunk native vlan 2
switchport trunk allowed vlan 1,2,10,100,200
switchport mode trunk
switchport nonegotiate
!
interface GigabitEthernet0/10
description : NSW-09 Gi0/1
switchport trunk encapsulation dot1q
switchport trunk native vlan 2
switchport trunk allowed vlan 1,2,10,100,200
switchport mode trunk
switchport nonegotiate
!
interface GigabitEthernet0/11
description : Shortel Switch
switchport access vlan 200
switchport mode access
spanning-tree portfast
!
interface GigabitEthernet0/12
description : NSW-08 Gi0/1
switchport trunk encapsulation dot1q
switchport trunk native vlan 2
switchport trunk allowed vlan 1,2,10,100,200
switchport mode trunk
switchport nonegotiate
!
interface GigabitEthernet0/13
description : Shortel Switch
switchport access vlan 200
switchport mode access
spanning-tree portfast
!
interface GigabitEthernet0/14
description : Shortel Switch
switchport access vlan 200
switchport mode access
spanning-tree portfast
!
interface GigabitEthernet0/15
description : Shortel Switch
switchport access vlan 200
switchport mode access
spanning-tree portfast
!
interface GigabitEthernet0/16
description : Shortel Switch
switchport access vlan 200
switchport mode access
spanning-tree portfast
!
interface GigabitEthernet0/17
description : Shortel Switch
switchport access vlan 200
switchport mode access
spanning-tree portfast
!
interface GigabitEthernet0/18
description : Shortel Switch
switchport access vlan 200
switchport mode access
spanning-tree portfast
!
interface GigabitEthernet0/19
description : NSW-05 Gi0/1
switchport trunk encapsulation dot1q
switchport trunk native vlan 2
switchport trunk allowed vlan 1,2,10,100,200
switchport mode trunk
!
interface GigabitEthernet0/20
description : NSW-06 Gi0/1
switchport trunk encapsulation dot1q
switchport trunk native vlan 2
switchport trunk allowed vlan 1,2,10,100,200
switchport mode trunk
!
interface GigabitEthernet0/21
description : NSW-07 Gi0/1
switchport trunk encapsulation dot1q
switchport trunk native vlan 2
switchport trunk allowed vlan 1,2,10,100,200
switchport mode trunk
!
interface GigabitEthernet0/22
description : NSW-04 Gi0/1
switchport trunk encapsulation dot1q
switchport trunk native vlan 2
switchport trunk allowed vlan 1,2,10,100,200
switchport mode trunk
!
interface GigabitEthernet0/23
description : NSW-03 Gi0/1
switchport trunk encapsulation dot1q
switchport trunk native vlan 2
switchport trunk allowed vlan 1,2,10,100,200
switchport mode trunk
!
interface GigabitEthernet0/24
description : NSW-02 Gi0/1
switchport trunk encapsulation dot1q
switchport trunk native vlan 2
switchport trunk allowed vlan 1,2,10,100,200
switchport mode trunk
!
interface GigabitEthernet0/25
!
interface GigabitEthernet0/26
!
interface GigabitEthernet0/27
!
interface GigabitEthernet0/28
!
interface GigabitEthernet0/29
!
interface GigabitEthernet0/30
!
interface GigabitEthernet0/31
!
interface GigabitEthernet0/32
!
interface GigabitEthernet0/33
!
interface GigabitEthernet0/34
!
interface GigabitEthernet0/35
!
interface GigabitEthernet0/36
!
interface GigabitEthernet0/37
!
interface GigabitEthernet0/38
!
interface GigabitEthernet0/39
!
interface GigabitEthernet0/40
!
interface GigabitEthernet0/41
!
interface GigabitEthernet0/42
!
interface GigabitEthernet0/43
!
interface GigabitEthernet0/44
!
interface GigabitEthernet0/45
!
interface GigabitEthernet0/46
!
interface GigabitEthernet0/47
!
interface GigabitEthernet0/48
!
interface GigabitEthernet1/1
!
interface GigabitEthernet1/2
!
interface GigabitEthernet1/3
!
interface GigabitEthernet1/4
!
interface TenGigabitEthernet1/1
!
interface TenGigabitEthernet1/2
!
interface Vlan1
no ip address
shutdown
!
interface Vlan2
description : Management vlan
ip address x.y.252.1 255.255.255.0
!
interface Vlan10
description : Cisco ASA5510 connection
ip address x.y.253.2 255.255.255.0
!
interface Vlan100
description : Data VLAN
ip address x.y.1.1 255.255.255.0
!
interface Vlan200
description : Voice VLAN
ip address x.y.254.1 255.255.255.0
ip helper-address x.y.1.81
!
router ospf 1
log-adjacency-changes
redistribute connected subnets
redistribute static subnets
network x.y.1.0 0.0.0.255 area 0
network x.y.252.0 0.0.0.255 area 0
network x.y.253.0 0.0.0.255 area 0
network x.y.254.0 0.0.0.255 area 0
!
ip classless
ip route x.y.130.0 255.255.255.0 x.y.129.2 200
ip route x.y.131.0 255.255.255.0 x.y.129.2 200
ip route x.y.132.0 255.255.255.0 x.y.129.2 200
ip route x.y.251.0 255.255.255.0 x.y.129.2 200
ip route 192.168.0.0 255.255.255.0 x.y.1.15
!
ip http server
ip http secure-server
!
ip sla enable reaction-alerts
!
!
!
line con 0
line vty 0 4
password 7 *************
login
transport input telnet
transport output telnet
line vty 5 15
password 7 *************
login local
!
ntp clock-period 36026342
ntp source Vlan10
ntp server x.y.1.81 prefer
end

NSW-01#

3560 config:

version 12.2

no service pad

service timestamps debug datetime msec

service timestamps log datetime msec

no service password-encryption

!

hostname NSW-10

!

boot-start-marker

boot-end-marker

!

enable secret 5    ***************

enable password 7 **************

!

no aaa new-model

clock timezone PST -8

clock summer-time PDT recurring

system mtu routing 1500

ip subnet-zero

!

!

!

!

!

!

!

!

spanning-tree mode pvst

spanning-tree extend system-id

!

vlan internal allocation policy ascending

!

!

!

interface GigabitEthernet0/1

switchport trunk encapsulation dot1q

switchport trunk native vlan 2

switchport trunk allowed vlan 1,2,10,100,200

switchport mode trunk

power inline never

!

interface GigabitEthernet0/2

switchport trunk encapsulation dot1q

switchport trunk native vlan 100

switchport trunk allowed vlan 1,100,200

switchport mode trunk

switchport nonegotiate

switchport voice vlan 200

spanning-tree portfast

!

interface GigabitEthernet0/3

switchport trunk encapsulation dot1q

switchport trunk native vlan 100

switchport trunk allowed vlan 1,100,200

switchport mode trunk

switchport nonegotiate

switchport voice vlan 200

spanning-tree portfast

!

interface GigabitEthernet0/4

switchport trunk encapsulation dot1q

switchport trunk native vlan 100

switchport trunk allowed vlan 1,100,200

switchport mode trunk

switchport nonegotiate

switchport voice vlan 200

spanning-tree portfast

!

interface GigabitEthernet0/5

switchport trunk encapsulation dot1q

switchport trunk native vlan 100

switchport trunk allowed vlan 1,100,200

switchport mode trunk

switchport nonegotiate

switchport voice vlan 200

spanning-tree portfast

!

interface GigabitEthernet0/6

switchport trunk encapsulation dot1q

switchport trunk native vlan 100

switchport trunk allowed vlan 1,100,200

switchport mode trunk

switchport nonegotiate

switchport voice vlan 200

spanning-tree portfast

!

interface GigabitEthernet0/7

switchport trunk encapsulation dot1q

switchport trunk native vlan 100

switchport trunk allowed vlan 1,100,200

switchport mode trunk

switchport nonegotiate

switchport voice vlan 200

spanning-tree portfast

!

interface GigabitEthernet0/8

switchport trunk encapsulation dot1q

switchport trunk native vlan 100

switchport trunk allowed vlan 1,100,200

switchport mode trunk

switchport nonegotiate

switchport voice vlan 200

spanning-tree portfast

!

interface GigabitEthernet0/9

switchport trunk encapsulation dot1q

switchport trunk native vlan 100

switchport trunk allowed vlan 1,100,200

switchport mode trunk

switchport nonegotiate

switchport voice vlan 200

spanning-tree portfast

!

interface GigabitEthernet0/10

switchport trunk encapsulation dot1q

switchport trunk native vlan 100

switchport trunk allowed vlan 1,100,200

switchport mode trunk

switchport nonegotiate

switchport voice vlan 200

spanning-tree portfast

!

interface GigabitEthernet0/11

switchport trunk encapsulation dot1q

switchport trunk native vlan 100

switchport trunk allowed vlan 1,100,200

switchport mode trunk

switchport nonegotiate

switchport voice vlan 200

spanning-tree portfast

!

interface GigabitEthernet0/12

switchport trunk encapsulation dot1q

switchport trunk native vlan 100

switchport trunk allowed vlan 1,100,200

switchport mode trunk

switchport nonegotiate

switchport voice vlan 200

spanning-tree portfast

!

interface GigabitEthernet0/13

switchport trunk encapsulation dot1q

switchport trunk native vlan 100

switchport trunk allowed vlan 1,100,200

switchport mode trunk

switchport nonegotiate

switchport voice vlan 200

spanning-tree portfast

!

interface GigabitEthernet0/14

switchport trunk encapsulation dot1q

switchport trunk native vlan 100

switchport trunk allowed vlan 1,100,200

switchport mode trunk

switchport nonegotiate

switchport voice vlan 200

spanning-tree portfast

!

interface GigabitEthernet0/15

switchport trunk encapsulation dot1q

switchport trunk native vlan 100

switchport trunk allowed vlan 1,100,200

switchport mode trunk

switchport nonegotiate

switchport voice vlan 200

spanning-tree portfast

!

interface GigabitEthernet0/16

switchport trunk encapsulation dot1q

switchport trunk native vlan 100

switchport trunk allowed vlan 1,100,200

switchport mode trunk

switchport nonegotiate

switchport voice vlan 200

spanning-tree portfast

!

interface GigabitEthernet0/17

switchport trunk encapsulation dot1q

switchport trunk native vlan 100

switchport trunk allowed vlan 1,100,200

switchport mode trunk

switchport nonegotiate

switchport voice vlan 200

spanning-tree portfast

!

interface GigabitEthernet0/18

switchport trunk encapsulation dot1q

switchport trunk native vlan 100

switchport trunk allowed vlan 1,100,200

switchport mode trunk

switchport nonegotiate

switchport voice vlan 200

spanning-tree portfast

!

interface GigabitEthernet0/19

switchport trunk encapsulation dot1q

switchport trunk native vlan 100

switchport trunk allowed vlan 1,100,200

switchport mode trunk

switchport nonegotiate

switchport voice vlan 200

spanning-tree portfast

!

interface GigabitEthernet0/20

switchport trunk encapsulation dot1q

switchport trunk native vlan 100

switchport trunk allowed vlan 1,100,200

switchport mode trunk

switchport nonegotiate

switchport voice vlan 200

spanning-tree portfast

!

interface GigabitEthernet0/21

switchport trunk encapsulation dot1q

switchport trunk native vlan 100

switchport trunk allowed vlan 1,100,200

switchport mode trunk

switchport nonegotiate

switchport voice vlan 200

spanning-tree portfast

!

interface GigabitEthernet0/22

switchport trunk encapsulation dot1q

switchport trunk native vlan 100

switchport trunk allowed vlan 1,100,200

switchport mode trunk

switchport nonegotiate

switchport voice vlan 200

spanning-tree portfast

!

interface GigabitEthernet0/23

switchport trunk encapsulation dot1q

switchport trunk native vlan 100

switchport trunk allowed vlan 1,100,200

switchport mode trunk

switchport nonegotiate

switchport voice vlan 200

spanning-tree portfast

!

interface GigabitEthernet0/24

switchport trunk encapsulation dot1q

switchport trunk native vlan 100

switchport trunk allowed vlan 1,100,200

switchport mode trunk

switchport nonegotiate

switchport voice vlan 200

spanning-tree portfast

!

interface GigabitEthernet0/25

!

interface GigabitEthernet0/26

!

interface GigabitEthernet0/27

!

interface GigabitEthernet0/28

!

interface Vlan1

no ip address

shutdown

!

interface Vlan2

ip address x.y.252.10 255.255.255.0

!

ip default-gateway x.y.252.1

ip classless

ip http server

!

!

control-plane

!

!

line con 0

line vty 0 4

password 7 **************

login local

transport input all

transport output all

line vty 5 15

password 7 *************

login

!

ntp clock-period 36028821

ntp server x.y.252.1

end version 12.2
no service pad
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname NSW-10
!
boot-start-marker
boot-end-marker
!
enable secret 5    ***************
enable password 7 **************
!
no aaa new-model
clock timezone PST -8
clock summer-time PDT recurring
system mtu routing 1500
ip subnet-zero
!
!
!
!
!
!
!
!
spanning-tree mode pvst
spanning-tree extend system-id
!
vlan internal allocation policy ascending
!
!
!
interface GigabitEthernet0/1
switchport trunk encapsulation dot1q
switchport trunk native vlan 2
switchport trunk allowed vlan 1,2,10,100,200
switchport mode trunk
power inline never
!
interface GigabitEthernet0/2
switchport trunk encapsulation dot1q
switchport trunk native vlan 100
switchport trunk allowed vlan 1,100,200
switchport mode trunk
switchport nonegotiate
switchport voice vlan 200
spanning-tree portfast
!
interface GigabitEthernet0/3
switchport trunk encapsulation dot1q
switchport trunk native vlan 100
switchport trunk allowed vlan 1,100,200
switchport mode trunk
switchport nonegotiate
switchport voice vlan 200
spanning-tree portfast
!
interface GigabitEthernet0/4
switchport trunk encapsulation dot1q
switchport trunk native vlan 100
switchport trunk allowed vlan 1,100,200
switchport mode trunk
switchport nonegotiate
switchport voice vlan 200
spanning-tree portfast
!
interface GigabitEthernet0/5
switchport trunk encapsulation dot1q
switchport trunk native vlan 100
switchport trunk allowed vlan 1,100,200
switchport mode trunk
switchport nonegotiate
switchport voice vlan 200
spanning-tree portfast
!
interface GigabitEthernet0/6
switchport trunk encapsulation dot1q
switchport trunk native vlan 100
switchport trunk allowed vlan 1,100,200
switchport mode trunk
switchport nonegotiate
switchport voice vlan 200
spanning-tree portfast
!
interface GigabitEthernet0/7
switchport trunk encapsulation dot1q
switchport trunk native vlan 100
switchport trunk allowed vlan 1,100,200
switchport mode trunk
switchport nonegotiate
switchport voice vlan 200
spanning-tree portfast
!
interface GigabitEthernet0/8
switchport trunk encapsulation dot1q
switchport trunk native vlan 100
switchport trunk allowed vlan 1,100,200
switchport mode trunk
switchport nonegotiate
switchport voice vlan 200
spanning-tree portfast
!
interface GigabitEthernet0/9
switchport trunk encapsulation dot1q
switchport trunk native vlan 100
switchport trunk allowed vlan 1,100,200
switchport mode trunk
switchport nonegotiate
switchport voice vlan 200
spanning-tree portfast
!
interface GigabitEthernet0/10
switchport trunk encapsulation dot1q
switchport trunk native vlan 100
switchport trunk allowed vlan 1,100,200
switchport mode trunk
switchport nonegotiate
switchport voice vlan 200
spanning-tree portfast
!
interface GigabitEthernet0/11
switchport trunk encapsulation dot1q
switchport trunk native vlan 100
switchport trunk allowed vlan 1,100,200
switchport mode trunk
switchport nonegotiate
switchport voice vlan 200
spanning-tree portfast
!
interface GigabitEthernet0/12
switchport trunk encapsulation dot1q
switchport trunk native vlan 100
switchport trunk allowed vlan 1,100,200
switchport mode trunk
switchport nonegotiate
switchport voice vlan 200
spanning-tree portfast
!
interface GigabitEthernet0/13
switchport trunk encapsulation dot1q
switchport trunk native vlan 100
switchport trunk allowed vlan 1,100,200
switchport mode trunk
switchport nonegotiate
switchport voice vlan 200
spanning-tree portfast
!
interface GigabitEthernet0/14
switchport trunk encapsulation dot1q
switchport trunk native vlan 100
switchport trunk allowed vlan 1,100,200
switchport mode trunk
switchport nonegotiate
switchport voice vlan 200
spanning-tree portfast
!
interface GigabitEthernet0/15
switchport trunk encapsulation dot1q
switchport trunk native vlan 100
switchport trunk allowed vlan 1,100,200
switchport mode trunk
switchport nonegotiate
switchport voice vlan 200
spanning-tree portfast
!
interface GigabitEthernet0/16
switchport trunk encapsulation dot1q
switchport trunk native vlan 100
switchport trunk allowed vlan 1,100,200
switchport mode trunk
switchport nonegotiate
switchport voice vlan 200
spanning-tree portfast
!
interface GigabitEthernet0/17
switchport trunk encapsulation dot1q
switchport trunk native vlan 100
switchport trunk allowed vlan 1,100,200
switchport mode trunk
switchport nonegotiate
switchport voice vlan 200
spanning-tree portfast
!
interface GigabitEthernet0/18
switchport trunk encapsulation dot1q
switchport trunk native vlan 100
switchport trunk allowed vlan 1,100,200
switchport mode trunk
switchport nonegotiate
switchport voice vlan 200
spanning-tree portfast
!
interface GigabitEthernet0/19
switchport trunk encapsulation dot1q
switchport trunk native vlan 100
switchport trunk allowed vlan 1,100,200
switchport mode trunk
switchport nonegotiate
switchport voice vlan 200
spanning-tree portfast
!
interface GigabitEthernet0/20
switchport trunk encapsulation dot1q
switchport trunk native vlan 100
switchport trunk allowed vlan 1,100,200
switchport mode trunk
switchport nonegotiate
switchport voice vlan 200
spanning-tree portfast
!
interface GigabitEthernet0/21
switchport trunk encapsulation dot1q
switchport trunk native vlan 100
switchport trunk allowed vlan 1,100,200
switchport mode trunk
switchport nonegotiate
switchport voice vlan 200
spanning-tree portfast
!
interface GigabitEthernet0/22
switchport trunk encapsulation dot1q
switchport trunk native vlan 100
switchport trunk allowed vlan 1,100,200
switchport mode trunk
switchport nonegotiate
switchport voice vlan 200
spanning-tree portfast
!
interface GigabitEthernet0/23
switchport trunk encapsulation dot1q
switchport trunk native vlan 100
switchport trunk allowed vlan 1,100,200
switchport mode trunk
switchport nonegotiate
switchport voice vlan 200
spanning-tree portfast
!
interface GigabitEthernet0/24
switchport trunk encapsulation dot1q
switchport trunk native vlan 100
switchport trunk allowed vlan 1,100,200
switchport mode trunk
switchport nonegotiate
switchport voice vlan 200
spanning-tree portfast
!
interface GigabitEthernet0/25
!
interface GigabitEthernet0/26
!
interface GigabitEthernet0/27
!
interface GigabitEthernet0/28
!
interface Vlan1
no ip address
shutdown
!
interface Vlan2
ip address x.y.252.10 255.255.255.0
!
ip default-gateway x.y.252.1
ip classless
ip http server
!
!
control-plane
!
!
line con 0
line vty 0 4
password 7 **************
login local
transport input all
transport output all
line vty 5 15
password 7 *************
login
!
ntp clock-period 36028821
ntp server x.y.252.1
end