question in understanding vrrp protocol

[Dr.X]

hi ,

ive read that vrrp used as redudancy protocol .

and about config i know that we  can configure virtual ip so that clients should put it as thier default gateway .

but

ive read a sentense about vrrp and need explanation for it

i read that :

""vrrp can use the real ip of router as the gateway address """

im not understanding this ...

im just confused becuase as i know , we can use the virtual ip of vrrp group as gateway , not the ip of the router or MLS as gateway for clients .

any clarification ?

regards

[Peter Paluch · Accepted solution]

Hello,

""vrrp can use the real ip of router as the gateway address """
im not understanding this ...

This means that one of the routers in the router group can have its IP address identical to the the virtual IP (vIP) of the entire router group. This basically allows you to save one IP address because in HSRP or GLBP, all IP addresses of real routers have to be unique and distinct from the vIP of the standby group.

So the configuration would be, basically:

! Router1:
interface FastEthernet0/0
 ip address 10.0.1.1 255.255.255.0
 vrrp 1 ip 10.0.1.1
! Router2:
interface FastEthernet0/0
 ip address 10.0.1.2 255.255.255.0
 vrrp 1 ip 10.0.1.1
! Router3:
interface FastEthernet0/0
 ip address 10.0.1.3 255.255.255.0
 vrrp 1 ip 10.0.1.1

You would still point your clients towards the vIP as their default gateway, that is, 10.0.1.1 here. It would work just nicely because the 10.0.1.1 is either handled by the router whose own IP address is 10.0.1.1, or if that router is disconnected, some other router will assume the vIP of 10.0.1.1 just like in HSRP.

In VRRP, the router whose own IP address is equal to the vIP is called the address owner, and it will always be the Master of the group (meaning it will always handle packets destined for 10.0.1.1, regardless of its configured priority). This is done by this router automatically announcing the VRRP priority of 255 (notice that you can not configure this priority manually - the highest priority you can configure is 254).

Best regards,

Peter

[Dr.X]

what a nice explanation ,

thanks very very very much

best regards