Re: configure NTP between 6509 and 4948 switches

Wassim Aouadi · ‎11-15-2011

Hi,

our 6509 is configured as NTP master. Our 4948 is configured as NTP client.

on each of these switches we have configured a management VRF.

The problem is that 4948 can not synchronize its clock with NTP master. Both switches are directly connected.

show cdp neighbor on 4948 switch:

6K5 Fas 1 138 R S I WS-C6509- Gig 2/2/43

interface config on 6509:

interface GigabitEthernet2/2/43

description *** Mgmt Switch Externe 1 ***

switchport

switchport access vlan 1900

switchport mode access

wrr-queue cos-map 1 1 1

wrr-queue cos-map 2 1 0

wrr-queue cos-map 3 1 4

wrr-queue cos-map 3 2 2

wrr-queue cos-map 3 3 3

wrr-queue cos-map 3 4 6

wrr-queue cos-map 3 5 7

udld port

spanning-tree portfast edge

spanning-tree bpduguard enable

end

interface config on 4948:

interface FastEthernet1

description ********** Interface Mgmt **********

ip vrf forwarding mgmtVrf

ip address 10.100.254.32 255.255.255.0

speed auto

duplex auto

end

I activated the following debugs on both switches:

- debug ntp packet

- debug ntp event

debug on 4948:

Nov 15 08:42:16.640: NTP: xmit packet to 10.100.254.1:

Nov 15 08:42:16.640: leap 3, mode 3, version 3, stratum 0, ppoll 64

Nov 15 08:42:16.640: rtdel 0000 (0.000), rtdsp 10001 (1000.015), refid 00000000 (0.0.0.0)

Nov 15 08:42:16.640: ref 00000000.00000000 (01:00:00.000 CET Mon Jan 1 1900)

Nov 15 08:42:16.640: org 00000000.00000000 (01:00:00.000 CET Mon Jan 1 1900)

Nov 15 08:42:16.640: rec 00000000.00000000 (01:00:00.000 CET Mon Jan 1 1900)

Nov 15 08:42:16.640: xmt D26CA468.A40C1B76 (09:42:16.640 CET Tue Nov 15 2011)

debugs on 6509 do not show any packets received or sent to 4948.

any help would be appreciated

Marvin Rhoads · ‎11-15-2011

It sounds like you might be mixing up your Layer 2 (VLAN) and Layer 3 (SVIs and routed interfaces) a bit. Your 6509 interface is a non-routed port. Is the Mgmt VRF you mentioned available over VLAN 1900? e.g., you would need something like:

interface vlan 1900

ip vrf forwarding mgmt

...in your config.

Otherwise the default routing table (RIB) on the 6509 will be servicing layer 3 requests on Vlan 1900.

Hope this helps.

Wassim Aouadi · ‎11-18-2011

on 6509, here's the config of interface vlan 1900:

6K5#sh run int vlan 1900

Building configuration...

Current configuration : 127 bytes

!

interface Vlan1900

ip vrf forwarding VRF_Mgmt

ip address 10.100.254.1 255.255.255.0

no ip redirects

no ip proxy-arp

end

on the 4948, there is no interface vlan1900.

for other devices, NTP packets are sent and exchanged on vlan1900. But there's trouble only with this 4948, which now I think it's due to the presence of VRF.

Update: problem solved:

On the 4948, I replaced "ntp server 10.100.254.1" with "ntp server vrf mgmtVrf 10.100.254.1" and added "ntp source Fa1" to specify the interface that issues NTP packets

Thanks for the guidance

Message was edited by: Wassim Aouadi