This topic is to discuss the following lesson:
You write the best articles of how to configure these things.
Well written, good job René!
Still how the computers uses both gateways in their configuration if we load balance between two groups?
For example, if you have 100 computers then you configure 50 of them to use 192.168.1.3 and the other 50 to use 192.168.1.4.
I’m using for the lab Cisco Switches 3550 and 3750 as layer 3 switches, and those doesn’t seem to support VRRP or GLBP, what model are you using for this lab and the glbp lab, thank you and by the way, thank you for your last reply.
The 3550 only supports HSRP while the 3750 supports HSRP + GLBP. I just checked my 3750 and this is the IOS image I am using:
Funny thing is, I have a 3560 that runs the same IOS version but it only supports HSRP:
Probably best to use some routers or GNS3 to test this.
I cant understand two things:
- why HSRP has 16 groups? not 255?
- in your table we see that VRRP doesnt support authentication, but you configured it…?
Good question and there’s a long answer…
Originally on the 3550 and some of the 6500 supervisors only 16 HSRP groups were allowed but this limitation applied only to a single interface. You could use the same group number on different interfaces without any issues. On newer platforms this 16 limit doesn’t apply anymore…the 3750 supports 32 groups I think and my 2800 router supports 255.
About authentication…originally the RFC 2338 standard described authentication but it was removed in RFC 3678 since it wasn’t secure. Not sure which RFC the Cisco implementation is based on but they probably added authentication to VRRP themselves.
Hope this helps!
Tnx, for answers,
BTW question from another field, have you something new materials for CCNP v2 ?
And maybe you know if I have ROUTE v1 , can I pass SWITCH v2 and TSHOOT v2?
Because in different resources I found different answers…
You can mix the V1 and V2 exams, here’s a link where they explain this:
The answer is in the “Old vs New Exams” topic.
I’m currently updating the lessons pages to add some of the new material. SWITCH now has a stackwise and VSS lesson, ROUTE has DMVPN. Some of the topics I still have to add are SDM templates and EVN.
Well written. Any way we can track the object in VRRP ? Can you give an example
For sure, it could be something as simple as this:
R1(config)#track 1 interface FastEthernet 0/0 line-protocol R1(config)#interface FastEthernet 0/0 R1(config-if)#vrrp 1 track 1 decrement 50
or you can configure IP SLA and combine it with tracking like I did here:
I think above configuration can be applied to all SVI for supporting multiple Vlans .
Is it correct? Is there any limitation ?
That’s right, you can enable this on routed interfaces or SVI interfaces.
I want lessons about VRRP version3
I will add this to my list.
Thank you for this lecture.
However I’m still having hard time understanding how load-balancing for different vlans has to be configured.
Let’s say we have Routers instead of Switches A and B in the lecture topology and computers are in different vlans. How do you provide routing between them and load balancing with stateful failover?!?
The short answer to your question is that you will need a separate VRRP instance for each vlan that you want to have a highly available gateway.
I have attached a new topology to discuss this. In it, you will see that Computers A and B are in different VLANs (A and B). Switch A and Switch B are both connected to the access-layer Switch C. Note: These connections must be configured as trunks, let’s say the modern 802.1Q standard with both VLAN A and VLAN B allowed. Additionally, it would be a good idea to have Switch A and Switch B directly connected to each other (in the real world this is done with Etherchannel), and that connection must also be a trunk that allows all VLANs between them.
At this point, you are ready to configure Switch A and Switch B. Each will need an SVI (switched virtual interface) for both VLAN A and VLAN B. You would treat these SVIs just like regular interfaces–just think of them as the Switch’s presence in the VLAN in question. Here’s a sample of getting the config going for Switch A:
SwitchA(config)#interface vlan A SwitchA(config-if)#ip address 192.168.1.252 255.255.255.0 SwitchA(config-if)#vrrp 1 ip 192.168.1.254 SwitchA(config-if)#vrrp 1 priority 105 SwitchA(config-if)#interface vlan B SwitchA(config-if)#ip address 192.168.1.252 255.255.255.0 SwitchA(config-if)#vrrp 2 ip 192.168.2.254
Now Switch B:
SwitchB(config)#interface vlan A SwitchB(config-if)#ip address 192.168.1.253 255.255.255.0 SwitchB(config-if)#vrrp 1 ip 192.168.1.254 SwitchB(config-if)#interface vlan B SwitchB(config-if)#ip address 192.168.1.253 255.255.255.0 SwitchB(config-if)#vrrp 2 ip 192.168.2.254 SwitchB(config-if)#vrrp 2 priority 105
Notice above, that Switch B will have priority for being the virtual gateway of VLAN B, and likewise, Switch A has priority for VLAN A. This way, you can load balance which Switch will handle the traffic on a per-VLAN basis.
You might have to provide more details, but at first glance, this won’t work well. My suggestion would be, if you are using Cisco Routers or Switches, to use GLBP instead of VRRP since it has the ability to do what you are asking easily. If you insist on using VRRP, you will have a problem with DHCP. From your example, I assume you are trying to balance the gateways on the same subnet. In DHCP (at least the Windows version), although you can define multiple gateways, this won’t result in load-balancing. Instead, the additional gateways will only be used if the primary is unavailable.
Again, it sounds like Gateway Load-Balancing Protocol is what you should use. By the way, there is a lesson on GLBP here.
I have confusion between interface tracking & object tracking.As you have mentioned VRRP only supports object tracking,does IP SLA mean object tracking?