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Community Member

GLBP Virtual Address not found

hi,

Scenario:

Dual Cat 6500 chassis connected via trunk. All the vlans on MSFC have SVI configured with glbp as below

Switch 1

interface Vlan8

ip address 1.1.1.1 255.255.255.0

glbp 10 ip 1.1.1.10

glbp 10 priority 10

glbp 10 preempt

Switch 2

interface Vlan8

ip address 1.1.1.2 255.255.255.0

glbp 10 ip 1.1.1.10

After every 3 - 5 minutes I lose connectivity to the gateway and outside from the host on 1.1.1.x network. I checked the arp table on the host and noticed that mac keeps changing for the AVG i.e. 1.1.1.10. Is it right ? I can also see the message in the log i.e. GLBP: API ARP active virutal address 1.1.1.10 not found. And it only appears on Switch2 and not Switch1.

Please assist.

7 REPLIES
Hall of Fame Super Silver

Re: GLBP Virtual Address not found

Hello New,

be aware that like for HSRP the default priority is 100

so in your case Switch2 should be the owner of the AVG.

But only Sw1:vlan8 has GLBP preemption enabled

try

Sw1

int vlan8

glbp 10 priority 110

sw2

int vlan8

glbp 10 preempt

see

http://www.cisco.com/en/US/docs/ios/ipapp/configuration/guide/ipapp_glbp_ps6922_TSD_Products_Configuration_Guide_Chapter.html#wp1054570

Hope to help

Giuseppe

Community Member

Re: GLBP Virtual Address not found

hi,

I have changed the config as per your suggestion but it is still the same.

Please suggest.

Thanks

Hall of Fame Super Silver

Re: GLBP Virtual Address not found

Hello New,

the two switches are stand alone not part of same VSS ? This from another thread.

I suppose they are standalone.

Two possible suggestions:

a) using debug commands related to GLBP to see if there is something strange

b) using for a test an HSRP group on the same vlans 8: just to see if the problem appears only with GLBP or also with HSRP.

the 3 to 5 minutes appear similar to CAM aging time so another test could be that of increasing aging time in vlan 8 to see if this changes the frequency of the issue

Hope to help

Giuseppe

Community Member

Re: GLBP Virtual Address not found

How do I set the aging time on Cat 6500 for a vlan.

Secondly, I do see the 'glbp group client-cache' command on the switch.

The software version is: 12.2(17r)SX5

Community Member

Re: GLBP Virtual Address not found

The topology in short is:

- Two Cat 6500 chassis (with GLBP for e.g. VLAN8)

- VLAN8 is also shared with FWSM on the outside interface (without GLBP). However, standby IP is defined on the FWSM outside.

Is the above correct design i.e. FWSM without GLBP shared with a VLAN configured with GLBP.

Hall of Fame Super Silver

Re: GLBP Virtual Address not found

Hello New,

your design looks like correct only that if FWSM is on the path it can filter GLBP packets.

I mean if there is a L2 trunk between the two chassis that carries vlan 8 the FWSM(s) cannot be an issue

Hope to help

Giuseppe

Hall of Fame Super Silver

Re: GLBP Virtual Address not found

Hello New,

use

(config)#mac-address-table aging-time vlan 8

mac-address-table aging-time ?

<0-0> Enter 0 to disable aging

<5-1000000> Aging time in seconds

Hope to help

Giuseppe

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