Couple of questions

[igor_bakman]

Hi all,

I came across a couple of issues I cannot figure out:

1. I have in my environment some switches that do not have the ablity to run "SHOW FLOGI DATABASE". The switches are from the 91XX family. However, I can see the attached WWNs (on every port) if I dig in the Cisco-fabric-manager. So what command in the CLI will deliver me the attached WWNs?
2. Port-Channels: what are the benefits of configuring port-channels? why should I configure 2 ports that are trunking as one port-channel and what are the reasons of not doing so?

Best regards,

Igor.

[dynamoxxx]

Igor Bakman wrote:
Hi all,
I came across a couple of issues I cannot figure out:
I have in my environment some switches that do not have the ablity to run "SHOW FLOGI DATABASE". The switches are from the 91XX family. However, I can see the attached WWNs (on every port) if I dig in the Cisco-fabric-manager. So what command in the CLI will deliver me the attached WWNs?

what models/code are those ? Are they running in npv mode ?

About PortChannels

A PortChannel has the following functionality:

•Provides a point-to-point connection over ISL (E ports) or EISL (TE ports). Multiple links can be combined into a PortChannel.

•Increases the aggregate bandwidth on an ISL by distributing traffic among all functional links in the channel.

•Load  balances across multiple links and maintains optimum bandwidth  utilization. Load balancing is based on the source ID, destination ID,  and exchange ID (OX ID).

•Provides  high availability on an ISL. If one link fails, traffic previously  carried on this link is switched to the remaining links. If a link goes  down in a PortChannel, the upper protocol is not aware of it. To the  upper protocol, the link is still there, although the bandwidth is  diminished. The routing tables are not affected by link failure.  PortChannels may contain up to 16 physical links and may span multiple  modules for added high availability.

[igor_bakman]

Thanks for the answer.

I still do not understand.

lets say I have two switches, between them I have two connections. I define those two connections as trunk.

Why should I define those two connections as port-channel rather than leave them as a plane trunk?

Best Regards,

Igor.    

[santkumd528]

consider trunk=port channel. why you should use portChannel/trunk is explaind by the 4 funcationality listed above. Check if any of those scenarios are applicable to you

[dynamoxxx]

if you have two switches connected together with ISL, MDS will do a pretty good job load-balancing the links but let me give you an example where having a trunk is beneficial:

let's say i have storage array 1 connected to switch 1 and storage array 2 connected to switch 2. You started replication between the two and they are chugging alone just fine, internally it will only use one or the other ISL. So now if that ISL breaks you will experience disruption in replication as it will need to failover to the other ISL link. If you had those two ports in a port-channel then failure of link 1 would not disrupt replication because port-channel is a logical "container" and member failure would not be noticed by services running on top of it (replication in our case)

[igor_bakman]

Thanks a lot, you've been a great help

One last point to clarify:

Consider two switches, SW1 and SW2.

They are connected by 4 ports - fc1/1, fc1/2, fc2/1, fc2/2.

fc1/1 and fc1/2 are trunking.

fc2/1 and fc2/2 are also trunking but defined as port-channel.

Is this configuration valid?

What are considerations of using the first connection type and the second one?

Is there even a difference between the two types?

Best regards,

Igor.   

[vsathiam]

For details on PC, PC+trunking .. Check (

http://www.cisco.com/en/US/docs/switches/datacenter/mds9000/sw/5_2/configuration/guides/int/nx-os/pc.html#wp1072522 )

Configurtion is valid.

[santkumd528]

can you post

#show port-channel summary

#show port-channel database

[igor_bakman]

The scenario is a bit different than I described.

#show topology

FC Topology for VSAN 1 :

--------------------------------------------------------------------------------

       Interface  Peer Domain Peer Interface     Peer IP Address

--------------------------------------------------------------------------------

            fc1/5 0xdc(220)            fc1/1  172.19.170.235

            fc2/5 0xdc(220)            fc1/2  172.19.170.235

   port-channel 2  0x30(48)   port-channel 2  172.16.254.191

#show port-channel databse

port-channel 2

    Administrative channel mode is on

    Operational channel mode is on

    Last membership update succeeded

    First operational port is fc3/2

    2 ports in total, 2 ports up

    Ports:   fc4/2    [up] 

             fc3/2    [up] *

It is a switch configuration by one of my clients, I wonder for the reason or perpuse for connecting one switch by two trunked ports, and one switch by two port-channeled ports.

[dynamoxxx]

Igor Bakman wrote:
Thanks a lot, you've been a great help 
One last point to clarify:
Consider two switches, SW1 and SW2. 
They are connected by 4 ports - fc1/1, fc1/2, fc2/1, fc2/2.
fc1/1 and fc1/2 are trunking.
fc2/1 and fc2/2 are also trunking but defined as port-channel.
Is this configuration valid?
What are considerations of using the first connection type and the second one?
Is there even a difference between the two types?
Best regards,
Igor.    

the question is why ?