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alex 08-08-2012 10:01 PM

sh glbp [brief]
 
Hi there,

is there anyone who can explain the output of the command in the subject?
I don't know why it looks not consistent across the memebers
partecipating in the GLBP group.

Especially the state column: listen, active and STANDBY.

I understand somehow that active refers to the IP address that is active
in the router where the command is performed and listen means that such
router is listening to that neighbour but I cannot understand why on the
standby router I do have the label standby for what is actually the AVG,

Also I don't know why in a router that is not neither the AVG nor the
standby VG I canno differentiate who's the active and who's the standby
VG.

If you have dealt with GLBP or if you would share your ideas on it with
me it will be appreciated a lot.

Thanks!

Alex

Martin Gallagher 08-09-2012 09:27 AM

Re: sh glbp [brief]
 
Hi Alex

>
> is there anyone who can explain the output of the command in the subject?
> I don't know why it looks not consistent across the memebers
> partecipating in the GLBP group.
>
> Especially the state column: listen, active and STANDBY.
>


I used to have to worry about this. Perhaps you can post the output you are
looking at so we all can see.

Rgds,
Martin

alex 08-09-2012 09:06 PM

Re: sh glbp [brief]
 
Martin Gallagher wrote:

> Hi Alex
>
>>
>> is there anyone who can explain the output of the command in the subject?
>> I don't know why it looks not consistent across the memebers
>> partecipating in the GLBP group.
>>
>> Especially the state column: listen, active and STANDBY.
>>

>
> I used to have to worry about this. Perhaps you can post the output you are
> looking at so we all can see.


Unfortunately my dynamips crashed but I can refer to this link

http://cciethebeginning.wordpress.co...cing-protocol/

from where I picked the following (sorry is not formatted with courier
character):

R2#sh glbp brief
Interface Grp Fwd Pri State Address Active router Standby route
Fa1/0 10 – 100 Standby 10.20.20.1 10.20.20.3 local
Fa1/0 10 1 7 Listen 0007.b400.0a01 10.20.20.3 -
Fa1/0 10 2 7 Active 0007.b400.0a02 local -
Fa1/0 10 3 7 Listen 0007.b400.0a03 10.20.20.4 -

Anyway I gave myself an explanation and the conclusion I came to is that
the first line is completely not linked to the remaining ones, meaning
the way you read it is different from how you read the rest of the
output.

This way from the 2nd onwards the output is more coherent.

I don't know if you had the same difficulty in reading this output but
please share your thoughts.

Thanks,

Alex

Martin Gallagher 08-10-2012 09:31 AM

Re: sh glbp [brief]
 
Hello Alex,

>
> R2#sh glbp brief
> Interface Grp Fwd Pri State Address Active router Standby route
> Fa1/0 10 – 100 Standby 10.20.20.1 10.20.20.3 local
> Fa1/0 10 1 7 Listen 0007.b400.0a01 10.20.20.3 -
> Fa1/0 10 2 7 Active 0007.b400.0a02 local -
> Fa1/0 10 3 7 Listen 0007.b400.0a03 10.20.20.4 -
>
> Anyway I gave myself an explanation and the conclusion I came to is that
> the first line is completely not linked to the remaining ones, meaning
> the way you read it is different from how you read the rest of the
> output.
>


Yes. There are two diffrent roles in GLBP, Virtual Gateway (VG) and Virtual
Forwarder (VF).

VG is like in HSRP and the first line descibes the VG information:

This router is the Standby router.
The Virtual IP addres is 10.20.20.1
The Active router is 10.20.20.3

In HSRP only one router forwards traffic. In GLBP you can have up 4
forwarders and lines 2-4 in the output describe the Virtual forwarders:

There are three forwarders.
10.20.20.3 using MAC address 0007.b400.0a01
10.20.20.4 using MAC address 0007.b400.0a03
This router using MAC address 0007.b400.0a02

REF:
====
GLBP - Gateway Load Balancing Protocol
http://www.cisco.com/en/US/docs/ios/...e/ft_glbp.html

--
Rgds,
Martin


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