Couple of questions

igor_bakman · ‎04-10-2013

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?
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 · ‎04-10-2013

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.

@dynamoxxx

igor_bakman · ‎04-10-2013

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 · ‎04-10-2013

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 · ‎04-10-2013

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)

@dynamoxxx

igor_bakman · ‎04-10-2013

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 · ‎04-11-2013

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 · ‎04-11-2013

can you post

#show port-channel summary

#show port-channel database

igor_bakman · ‎04-14-2013

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 · ‎04-11-2013

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 ?

@dynamoxxx