Re: HSRP Priority

shah.chintan · ‎07-30-2006

Hi,

I'm using two MLS 6509. I have configured two FE at each MLS with same stanby 1 (HSRP Group) but with diff HSRP IP address/ subnet

Can any body tell me , HSRP priority is per interface or per MLS?

Rgds

Chintan

abhishek_nandavat · ‎07-30-2006

Hi,

Howcome have you configured two different IPs. The Virtual IP has to be same on both the interfaces else your HSRP is never going to work!

The physical IP should be different, whereas the virtual IP needs to be same!!!

Refer the following link for configuring HSRP on 6509:

http://www.cisco.com/en/US/products/hw/switches/ps700/products_command_reference_chapter09186a00800eb24d.html#xtocid2393513

Hope this helps.

Regards,

AbhisheK

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jackyoung · ‎07-30-2006

The HSRP priority is per interface / VLAN.

shah.chintan · ‎07-31-2006

Hi Abhishek,

Set up is like this :

MLS-1 - gig 4/8 and MLS-2 gi5/8 HSRP group 1 (standby 1)and same HSRP virtual ip address.

Now, I want gig4/9 on MLS-1 and gig4/9 on MLS-2 both on with HSRP gropu 1 only (standby 1) with diff HSRP ip address ( as here diff subnet). So, will it work ?as HSRP priority for group is per interface.

Please suggest.

Rgds

Chintan

abhishek_nandavat · ‎07-31-2006

Hi,

I dont think there should be any problem with that. If you define same HSRP group for multiple interfaces, then they will be sharing the same virtual MAC address, other than that nothing is similar.There is no reason why it shouldnt work.

Can you please elaborate as in why you want the same group number to be configured on the two different subnets??? What exactly are you trying to do?

shah.chintan · ‎07-31-2006

Hi,

Here we will have more around 15 FE/GE for what we need to HSRP for each Interface and Each interface will be different subnet and why we are going with same HSRP group id is Sup2 doesnt support more than 16 group id.

you mean to say same Virtual MAC-Address for all interface HSRP address even i have diff HSRP ip add on diff interface . Can you pleae clarify.

Rgds

Chintan

abhishek_nandavat · ‎07-31-2006

Hi,

I know Sup2 doesnt support more than 16 groups, that is because of some hardware design limitation. But even then I think 16 groups should suffice isnt it???

They will share the same virtual MAC address when they have been configured with the same HSRP group id.

Refer the following link:

http://cisco.com/en/US/products/hw/switches/ps700/products_qanda_item09186a008011c6bb.shtml#q5

Hope this helps.

Regards,

AbhisheK

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shah.chintan · ‎07-31-2006

Hi,

I have gone through this link before. But it is not per interface it is per MLS and i may need more than 16 HSRP group here in this case thats reason i asked.

Can you let me know if i use same HSRP Group it will be same Vriual MAC address but will it create any Harm and Security issue ? and How ARP will happen ?

Rgds

Chintan

shah.chintan · ‎07-31-2006

Hi,

I Found below FAQ from cisco.

What is the implication of the use of the same HSRP group ID on multiple interfaces?

A. When you define the same HSRP group ID on multiple interfaces, they all share the same HSRP virtual MAC address. In most modern LAN switches, there are no issues because they maintain a per-VLAN MAC address table. However, if your network contains any third party switches which maintain a system-wide MAC address table regardless of VLAN, you may experience problems.

Now, I have setup like this

FE/GE configured with ip address on MLS no VLAN but at L2 diff interface will be seperated via VLAN.

Will it work with out any issue with same HSRP Group at all interface.

Please suggest and reply.

Rgds

Chintan

abhishek_nandavat · ‎07-31-2006

Hi,

Configuring multiple interfaces with same HSRP group id shouldnt be of any harm. But as mentioned in the FAQ, there can be issues if you have any switches other than cisco, then there might be a problem.

Now if your interfaces having the same group id are members of different VLANs then there should not be any issue at all, but if they are member of the same VLAN then you might experience some problem. You might get errors saying the same MAC address was discovered at different interfaces.

Can't you configure interfaces with same group id in different VLANs??

Hope this helps.

Regards,

AbhisheK

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shah.chintan · ‎08-01-2006

Hi,

If i configure interface with same group id in different vlan. then VLAN tagging start from MLS.

Another thing is there will be l2 between MLS FE/GE and L2 siwtch and i have to run STP on this for Loop avoidance.

so for above two reason i'm planning to go with FE/Ge layer 3 configuraion....

Can you please suggest if i configure VLAN what are things need to be taken care apart from this.

abhishek_nandavat · ‎08-01-2006

Hi,

I can't think of anything specifically. If you can tell what exactly are you trying to achieve, maybe then I can think of things to take care about.

Regards,

AbhisheK

Wilson Samuel · ‎08-01-2006

Hi Chintan,

The answer is very simple, its always PER Interface i.e. if you have 10 different interfaces comprising of VLAN Interface or FE or GE interface you could define 10 groups on both the switches.

One more thing, contrary to the normal system, here greater the number of priority you set, higher the priority the interface gets.

I guess it should have solved by this time.

Kindly Rate, if it helps.

Regards,

Wilson Samuel