08-18-2008 01:41 PM - edited 03-03-2019 11:11 PM
Hi, I just want to clarify GLBP config on one of our VLAN after our main WAN link went down. We used 2 6506s as our core:
Primary:
Vlan20 - Group 20
State is Active
2 state changes, last state change 29w2d
Virtual IP address is 10.80.104.1
Hello time 3 sec, hold time 10 sec
Next hello sent in 0.096 secs
Redirect time 600 sec, forwarder time-out 14400 sec
Preemption enabled, min delay 0 sec
Active is local
Standby is 10.80.104.3, priority 254 (expires in 7.580 sec)
Priority 255 (configured)
Weighting 90, low (configured 110), thresholds: lower 95, upper 105
Track object 20 state Down decrement 20
Load balancing: weighted
There are 2 forwarders (0 active)
Forwarder 1
State is Listen
680 state changes, last state change 00:25:44
MAC address is 0007.b400.1401 (default)
Owner ID is 0015.2ce0.d800
Redirection enabled
Preemption enabled, min delay 30 sec
Active is 10.80.104.3 (secondary), weighting 110 (expires in 7.580 sec)
Arp replies sent: 16973696
Forwarder 2
State is Listen
14 state changes, last state change 5d17h
MAC address is 0007.b400.1402 (learnt)
Owner ID is 0015.2ce0.dc00
Redirection enabled, 599.932 sec remaining (maximum 600 sec)
Time to live: 14399.932 sec (maximum 14400 sec)
Preemption enabled, min delay 30 sec
Active is 10.80.104.3 (primary), weighting 110 (expires in 9.932 sec)
Arp replies sent: 16975045
_____________________________________
Secondary:
Vlan20 - Group 20
State is Standby
5 state changes, last state change 29w2d
Virtual IP address is 10.80.104.1
Hello time 3 sec, hold time 10 sec
Next hello sent in 2.948 secs
Redirect time 600 sec, forwarder time-out 14400 sec
Preemption enabled, min delay 0 sec
Active is 10.80.104.2, priority 255 (expires in 9.464 sec)
Standby is local
Priority 254 (configured)
Weighting 110 (configured 110), thresholds: lower 95, upper 105
Track object 20 state Up decrement 20
Load balancing: weighted
There are 2 forwarders (2 active)
Forwarder 1
State is Active
1 state change, last state change 00:25:50
MAC address is 0007.b400.1401 (learnt)
Owner ID is 0015.2ce0.d800
Time to live: 12849.216 sec (maximum 14400 sec)
Preemption enabled, min delay 30 sec
Active is local, weighting 110
Forwarder 2
State is Active
15 state changes, last state change 5d17h
MAC address is 0007.b400.1402 (default)
Owner ID is 0015.2ce0.dc00
Preemption enabled, min delay 30 sec
Active is local, weighting 110
Questions:
1. Why are there 2 forwarders? Two devices configured for GLBP?
2. What is the difference between the MAC address and Owner ID?
3. Why is it on the primary vlan group 20 is active? Should it be in a standby state because that's the device where the link failed?
4. Does GLBP use 0007.b400.14xx pool of MAC addresses to be assigned to AVFs?
5. Why there is no indicator/status which state that it's the AVG?
Solved! Go to Solution.
08-19-2008 04:31 AM
Hello John,
review GLBP
http://www.cisco.com/en/US/docs/ios/ipapp/configuration/guide/ipapp_glbp.html
1) GLBP L=load-balancing so there is the concept of multiple forwarders within a single group is the reason for this protocol existance.
2) GLBP Virtual MAC Address Assignment
A GLBP group allows up to four virtual MAC addresses per group. The AVG is responsible for assigning the virtual MAC addresses to each member of the group. Other group members request a virtual MAC address after they discover the AVG through hello messages. Gateways are assigned the next MAC address in sequence. A virtual forwarder that is assigned a virtual MAC address by the AVG is known as a primary virtual forwarder. Other members of the GLBP group learn the virtual MAC addresses from hello messages. A virtual forwarder that has learned the virtual MAC address is referred to as a secondary virtual forwarder.
3) because in GLBP there are two dimensions: priority and weighting and tracking has reduced the weighting value:
Priority 255 (configured)
Weighting 90, low (configured 110), thresholds: lower 95, upper 105
Track object 20 state Down decrement 20
4)
yes up to 4 for a group:
0007.b400.0101 for group 1
The function of the AVG is that it assigns a virtual MAC address to each member of the GLBP group. Each gateway assumes responsibility for forwarding packets sent to the virtual MAC address assigned to it by the AVG. These gateways are known as active virtual forwarders (AVFs) for their virtual MAC address
5) AVG state is given by Active / Standby
but traffic is forwarded by forwarders.
Hope to help
Giuseppe
08-19-2008 04:31 AM
Hello John,
review GLBP
http://www.cisco.com/en/US/docs/ios/ipapp/configuration/guide/ipapp_glbp.html
1) GLBP L=load-balancing so there is the concept of multiple forwarders within a single group is the reason for this protocol existance.
2) GLBP Virtual MAC Address Assignment
A GLBP group allows up to four virtual MAC addresses per group. The AVG is responsible for assigning the virtual MAC addresses to each member of the group. Other group members request a virtual MAC address after they discover the AVG through hello messages. Gateways are assigned the next MAC address in sequence. A virtual forwarder that is assigned a virtual MAC address by the AVG is known as a primary virtual forwarder. Other members of the GLBP group learn the virtual MAC addresses from hello messages. A virtual forwarder that has learned the virtual MAC address is referred to as a secondary virtual forwarder.
3) because in GLBP there are two dimensions: priority and weighting and tracking has reduced the weighting value:
Priority 255 (configured)
Weighting 90, low (configured 110), thresholds: lower 95, upper 105
Track object 20 state Down decrement 20
4)
yes up to 4 for a group:
0007.b400.0101 for group 1
The function of the AVG is that it assigns a virtual MAC address to each member of the GLBP group. Each gateway assumes responsibility for forwarding packets sent to the virtual MAC address assigned to it by the AVG. These gateways are known as active virtual forwarders (AVFs) for their virtual MAC address
5) AVG state is given by Active / Standby
but traffic is forwarded by forwarders.
Hope to help
Giuseppe
08-24-2008 12:28 PM
i'm enlightened now. thanks!
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