topic Re: GLBP not working between two switches in Routing and SD-WAN

GLBP not working between two switches

vitumbiko nkhwazi — Thu, 28 Oct 2021 20:31:43 GMT

Hello guys.

I have connected two switches directly to each other over a trunk link on Ethernet0/0, i have then created VLAN 200 in both switches and configured Interface VLAN 100 with an IP address and GLBP group IP address, the configuring is a minimimal GLBP configuration, the problem is that the GLBP is not communicating over the trunk link, each switch is selecting itself as active and does not see the other switch, what could be the problem, see configuration and output below:

Switch 2:

interface Ethernet0/0
switchport trunk encapsulation dot1q
switchport mode trunk
duplex auto

CORE-SWITCH-02#sh run int vlan 200
interface Vlan200
ip address 192.168.200.3 255.255.255.0
glbp 200 ip 192.168.200.1

Switch 1:

interface Ethernet0/0
switchport trunk encapsulation dot1q
switchport mode trunk
duplex auto

CORE-SWITCH-01#sh run int vlan 200
interface Vlan200
ip address 192.168.200.2 255.255.255.0
glbp 200 ip 192.168.200.1

CORE-SWITCH-02#sh int trunk

Port Mode Encapsulation Status Native vlan
Et0/0 on 802.1q trunking 1
Et0/1 on 802.1q trunking 1
Et0/3 desirable n-isl trunking 1

Port Vlans allowed on trunk
Et0/0 1-4094
Et0/1 1-4094
Et0/3 1-4094

Port Vlans allowed and active in management domain
Et0/0 1,100,110,200
Et0/1 1,100,110,200
Et0/3 1,100,110,200

Port Vlans in spanning tree forwarding state and not pruned
Et0/0 1,100,110,200
Et0/1 1,100,110,200
Et0/3 1,100,110,200

CORE-SWITCH-02#sh glbp brief
Interface Grp Fwd Pri State Address Active router Standby router
Vl200 200 - 100 Active 192.168.200.1 local unknown
Vl200 200 1 - Active 0007.b400.c801 local -

Re: GLBP not working between two switches

Georg Pauwen — Fri, 29 Oct 2021 07:17:04 GMT

Hello,

do you have 'ip routing' enabled on both switches ? If possible, post the full running configs of both switches...

Re: GLBP not working between two switches

balaji.bandi — Thu, 28 Oct 2021 21:19:10 GMT

i suggest to add on the primary :

glbp 200 priority 110
glbp 200 preempt

also check on both the switch do you have vlan 200 created : post below output

show vlan

show span vlan 200

shw ip interface brief

show glbp 200

Re: GLBP not working between two switches

vitumbiko nkhwazi — Fri, 29 Oct 2021 09:11:54 GMT

@Georg Pauwen yes, "ip routing" is enabled on both switches

Re: GLBP not working between two switches

vitumbiko nkhwazi — Fri, 29 Oct 2021 09:24:36 GMT

@balaji.bandi i have added the priority and preempt commands on primary, but not seeing each other yet.

below are the command output

Switch 1:

CORE-SWITCH-01#sh vlan

VLAN Name Status Ports
---- -------------------------------- --------- -------------------------------
1 default active Et0/2, Et1/0, Et1/1, Et1/2
Et1/3, Et2/0, Et2/1, Et2/2
Et2/3, Et3/0, Et3/1, Et3/2
Et3/3
100 ASA-01 active
110 ASA-02 active
200 USERS active
1002 fddi-default act/unsup
1003 token-ring-default act/unsup
1004 fddinet-default act/unsup
1005 trnet-default act/unsup

VLAN Type SAID MTU Parent RingNo BridgeNo Stp BrdgMode Trans1 Trans2
---- ----- ---------- ----- ------ ------ -------- ---- -------- ------ ------
1 enet 100001 1500 - - - - - 0 0
100 enet 100100 1500 - - - - - 0 0
110 enet 100110 1500 - - - - - 0 0
200 enet 100200 1500 - - - - - 0 0
1002 fddi 101002 1500 - - - - - 0 0
1003 tr 101003 1500 - - - - - 0 0
1004 fdnet 101004 1500 - - - ieee - 0 0
1005 trnet 101005 1500 - - - ibm - 0 0

Primary Secondary Type Ports
------- --------- ----------------- ------------------------------------------

CORE-SWITCH-01#sh span vlan 200

VLAN0200
Spanning tree enabled protocol ieee
Root ID Priority 32968
Address aabb.cc00.0100
Cost 100
Port 1 (Ethernet0/0)
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority 32968 (priority 32768 sys-id-ext 200)
Address aabb.cc00.0200
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300 sec

Interface Role Sts Cost Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
Et0/0 Root FWD 100 128.1 Shr
Et0/1 Desg FWD 100 128.2 Shr
Et0/3 Desg FWD 100 128.4 Shr

CORE-SWITCH-01#sh ip int brief
Interface IP-Address OK? Method Status Protocol
Ethernet0/0 unassigned YES unset up up
Ethernet0/1 unassigned YES unset up up
Ethernet0/2 unassigned YES unset up up
Ethernet0/3 unassigned YES unset up up
Ethernet1/0 unassigned YES unset up up
Ethernet1/1 unassigned YES unset up up
Ethernet1/2 unassigned YES unset up up
Ethernet1/3 unassigned YES unset up up
Ethernet2/0 unassigned YES unset up up
Ethernet2/1 unassigned YES unset up up
Ethernet2/2 unassigned YES unset up up
Ethernet2/3 unassigned YES unset up up
Ethernet3/0 unassigned YES unset up up
Ethernet3/1 unassigned YES unset up up
Ethernet3/2 unassigned YES unset up up
Ethernet3/3 unassigned YES unset up up
Vlan1 unassigned YES unset up up
Vlan100 10.2.2.108 YES manual up up
Vlan110 10.2.2.116 YES manual up up
Vlan200 192.168.200.2 YES manual up up

CORE-SWITCH-01#sh glbp

Vlan200 - Group 1002
State is Active
1 state change, last state change 00:39:19
Virtual IP address is 192.168.200.1
Hello time 3 sec, hold time 10 sec
Next hello sent in 1.792 secs
Redirect time 600 sec, forwarder timeout 14400 sec
Preemption enabled, min delay 0 sec
Active is local
Standby is unknown
Priority 200 (configured)
Weighting 100 (default 100), thresholds: lower 1, upper 100
Load balancing: round-robin
Group members:
aabb.cc80.0200 (192.168.200.2) local
There is 1 forwarder (1 active)
Forwarder 1
State is Active
1 state change, last state change 00:39:08
MAC address is 0007.b403.ea01 (default)
Owner ID is aabb.cc80.0200
Redirection enabled
Preemption enabled, min delay 30 sec
Active is local, weighting 100

Switch 2

CORE-SWITCH-02#sh vlan

Primary Secondary Type Ports
------- --------- ----------------- ------------------------------------------

CORE-SWITCH-02#sh span vlan 200

VLAN0200
Spanning tree enabled protocol ieee
Root ID Priority 32968
Address aabb.cc00.0100
This bridge is the root
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority 32968 (priority 32768 sys-id-ext 200)
Address aabb.cc00.0100
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300 sec

Interface Role Sts Cost Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
Et0/0 Desg FWD 100 128.1 Shr
Et0/1 Desg FWD 100 128.2 Shr
Et0/3 Desg FWD 100 128.4 Shr

CORE-SWITCH-02#sh ip int brief
Interface IP-Address OK? Method Status Protocol
Ethernet0/0 unassigned YES unset up up
Ethernet0/1 unassigned YES unset up up
Ethernet0/2 unassigned YES unset up up
Ethernet0/3 unassigned YES unset up up
Ethernet1/0 unassigned YES unset up up
Ethernet1/1 unassigned YES unset up up
Ethernet1/2 unassigned YES unset up up
Ethernet1/3 unassigned YES unset up up
Ethernet2/0 unassigned YES unset up up
Ethernet2/1 unassigned YES unset up up
Ethernet2/2 unassigned YES unset up up
Ethernet2/3 unassigned YES unset up up
Ethernet3/0 unassigned YES unset up up
Ethernet3/1 unassigned YES unset up up
Ethernet3/2 unassigned YES unset up up
Ethernet3/3 unassigned YES unset up up
Vlan1 unassigned YES unset up up
Vlan100 10.2.2.109 YES NVRAM up up
Vlan110 10.2.2.117 YES NVRAM up up
Vlan200 192.168.200.3 YES NVRAM up up

CORE-SWITCH-02#sh glbp

Vlan200 - Group 1002
State is Active
1 state change, last state change 00:37:20
Virtual IP address is 192.168.200.1
Hello time 3 sec, hold time 10 sec
Next hello sent in 2.688 secs
Redirect time 600 sec, forwarder timeout 14400 sec
Preemption disabled
Active is local
Standby is unknown
Priority 100 (default)
Weighting 100 (default 100), thresholds: lower 1, upper 100
Load balancing: round-robin
Group members:
aabb.cc80.0100 (192.168.200.3) local
There is 1 forwarder (1 active)
Forwarder 1
State is Active
1 state change, last state change 00:37:09
MAC address is 0007.b403.ea01 (default)
Owner ID is aabb.cc80.0100
Redirection enabled
Preemption enabled, min delay 30 sec
Active is local, weighting 100

Re: GLBP not working between two switches

Georg Pauwen — Fri, 29 Oct 2021 10:36:58 GMT

Hello,

can both switches ping each other's IP address ?

Re: GLBP not working between two switches

Giuseppe Larosa — Fri, 29 Oct 2021 13:47:37 GMT

Hello @vitumbiko nkhwazi ,

as we can see on the output

of show spanning-tree vlan 200

Switch02 is the root bridge for VLAN 200 and Switch01 has as root port eth0/0

Please note if these are two Nexus you need in global config:

feature glbp

Hope to help

Giuseppe

Re: GLBP not working between two switches

balaji.bandi — Sun, 31 Oct 2021 15:42:51 GMT

What is the devices here, what IOS code running, Can you shutdown the vlan interface 200 and bring up.

Just did a quick testing based on your config here is my results (i used 300 vlan instead of 200)

Re: GLBP not working between two switches

paul driver — Sun, 31 Oct 2021 22:04:30 GMT

Hello

Basicaly you dont have L3 connectivity between sw1-sw2!

Is the physical connectivity correct, Have you created vlans for vlan 200 on both swithes, is the SVi up on both siwthes?

Re: GLBP not working between two switches

vitumbiko nkhwazi — Mon, 01 Nov 2021 12:22:26 GMT

@Giuseppe Larosa they are not Nexus switches, they are Cisco IOU L2 switches running in GNS3, version 15.1

Re: GLBP not working between two switches

vitumbiko nkhwazi — Mon, 01 Nov 2021 12:25:22 GMT

@balaji.bandi these are Cisco IOU L2 switches running in GNS3, version 15.1, shutting down the interfaces and bringing them back up does not resolve the issue.

Re: GLBP not working between two switches

vitumbiko nkhwazi — Mon, 01 Nov 2021 12:29:29 GMT

@paul driver i have confirmed L3 connectivity, SVI's are up on both ends, see ping from SW1 to SW2 below

CORE-SWITCH-01#sh ip int brief | in Vlan200
Vlan200 192.168.200.2 YES NVRAM up up
CORE-SWITCH-01#
CORE-SWITCH-01#ping 192.168.200.3
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.200.3, timeout is 2 seconds:
.!!!!
Success rate is 80 percent (4/5), round-trip min/avg/max = 1/3/9 ms

Re: GLBP not working between two switches

balaji.bandi — Mon, 01 Nov 2021 17:33:39 GMT

Try different version latest one 15.2 onwards, i tried on PNET lan sale IOL works as expected.

Re: GLBP not working between two switches

Georg Pauwen — Mon, 01 Nov 2021 17:41:13 GMT

Hello,

post the output of:

show ip route

from both switches.

Re: GLBP not working between two switches

Jon Marshall — Mon, 01 Nov 2021 20:25:39 GMT

Can you try disabling IGMP snooping on the switches ie. "no igmp snooping".

I have seen it in the past where HSRP etc. does not work until you do that.

Jon