Posts Tagged ‘lag’

Beginner’s Guide to HPE 5000 Series Switches

October 14, 2017

I don’t closely track the popularity of my blog. If what I share helps people in their day to day job, it’s already good enough to me. But I do look at site statistics now and then just out of curiosity and it seems that network-related posts get a lot of popularity. A blog post I wrote a while ago on Dell N4000 switches has quickly got in top five over the last year.

So it seems that there is a demand for entry-level switch configuration guides. I’ve worked with a quite a few different switch brands over the years, so I thought I will build on the success of the Dell blog post and this time write about HPE FlexNetwork/FlexFabric 5000 switch series.

Operating Systems

HPE has several network switch product lines. I won’t even try to cover all of them in this post. But it’s important to know that there are a few different operating systems you can encounter, while working with HPE network switches. There is a familiar ProCurve product portfolio (now merged with Aruba), which is based on ProVision operating system.

HPE FlexNetwork/FlexFabric 5000 series, on the other hand, is based on Comware operating system. It has a different CLI command set and can be a complete surprise if you’ve worked only with ProCurve switches before. So this blog post will be particularly valuable for those who’re dealing with HPE 5000 for the first time.

The following guide has been tested on a pair of HPE FlexFabric 5700-series switches. Even though commands are mostly the same, on other switch series, like FlexNetwork 5800, there might be some minor differences.

Initial Configuration

When the switch is booted for the first time it will start automatic configuration by trying to obtain settings over DHCP, which you can interrupt by Ctrl+C to get straight to CLI.

You start in user view where you can run display commands to review switch settings. To start the configuration, change to system view:

> system-view

Let’s start by configuring remote access to the switch. There are two ways you can do that. You either use the out-of-band management port:

> interface M-GigabitEthernet 0/0/0
> ip address 10.10.10.10 255.255.255.0
> ip route-static 0.0.0.0 0.0.0.0 10.10.10.1

Or you can configure a VLAN interface IP address:

> interface vlan-interface 1
> ip address 10.10.10.10 255.255.255.0
> ip route-static 0.0.0.0 0.0.0.0 10.10.10.1

Then configure switch name, enable SSH, set passwords and you can start managing the switch over SSH:

> sysname switchname

> public-key local create rsa
> ssh server enable
> user-interface vty 0 15
> authentication-mode scheme
> protocol inbound ssh

> super password simple yourpassword
> local-user admin
> password simple yourpassword
> authorization-attribute user-role level-0
> service-type ssh

User “admin” will have an unprivileged role. You will need to run the following command and enter password once logged in, to elevate to network admin rights:

> super

Intelligent Resilient Framework

In small non-business-critical environments one standalone switch is usually sufficient. In larger environments switches are typically deployed in pairs for redundancy. To simplify management and to avoid network loops most switches support some sort of MLAG or stacking. IRF is HPE’s version of it.

Determine what ports you’re going to use for IRF. There are two QSFP+ ports on 5700-series dedicated for it. And then on on the first switch (master) run the following commands (it’s recommended to shut down the ports before you set them up as IRF):

> irf member 1 priority 32
> int range FortyGigE 1/0/41 to FortyGigE 1/0/42
> shutdown
> irf-port 1/1
> port group interface FortyGigE 1/0/41
> irf-port 1/2
> port group interface FortyGigE 1/0/42
> int range FortyGigE 1/0/41 to FortyGigE 1/0/42
> undo shut
> save
> irf-port-configuration active

On the second switch (slave) run the following commands to change the IRF ID to 2:

> irf member 1 renumber 2
> reboot

When the switch comes up, configure IRF ports:

> irf member 2 priority 30
> int range FortyGigE 2/0/41 to FortyGigE 2/0/42
> shutdown
> irf-port 2/1
> port group interface FortyGigE 2/0/41
> irf-port 2/2
> port group interface FortyGigE 2/0/42
> int range FortyGigE 2/0/41 to FortyGigE 2/0/42
> undo shut
> save
> irf-port-configuration active

Now you can connect the physical IRF ports. IRF is a ring topology, that means (in my case) port 1/0/41 should connect to 2/0/42 and port 1/0/42 should connect to 2/0/41.

Second switch will automatically reboot and if all is configured correctly, you should see both switches join the IRF fabric. Member switch 1 has the highest priority of 32 and becomes the master:

> display irf

Firmware Upgrade

Firmware upgrade is the next logical step after you set up IRF. The latest firmware revision for the switches can be download from HPE web-site. Keep in mind you will need a HPE passport account, with a valid service agreement (SAID) added to it.

You will also need a TFTP server to upgrade the firmware. There are a few of them out there, but the most commonly used is probably Tftpd64.

When you get the TFTP server up and running and copy the firmware file to it, perform an upgrade:

> tftp 10.10.10.20 get 5700-CMW710-R2432P03.ipe
> boot-loader file flash:/5700-CMW710-R2432P03.ipe slot 1 main
> boot-loader file flash:/5700-CMW710-R2432P03.ipe slot 2 main
> irf auto-update enable
> reboot

Confirm firmware has been updated:

> display version

VLANs, Aggregation Groups and Tagging

In Comware the term “aggregation group” is used to describe what is a “port channel” in Cisco world. Trunk/access ports are also called tagged/untagged ports throughout the documentation.

In this section we will discuss a few common port configuration scenarios:

  • Untagged ports, which can be your iSCSI storage array ports
  • Tagged ports, such as your VMware host uplinks
  • Aggregation groups, typically used for LAGs to upstream switches

First of all create all VLANs and give them descriptions:

> vlan 10
> description iSCSI
> vlan 20
> description Server
> vlan 30
> description Dev and test

Then specify untagged ports:

> vlan 10
> port te 1/0/1
> port te 2/0/1

To configure tagged ports and allow certain VLANs (ports will be added to the VLANs automatically):

> int te 1/0/2
> description ESX01 vmnic0
> port link-type trunk
> port trunk permit vlan 20 30
> int te 2/0/2
> description ESX02 vmnic0
> port link-type trunk
> port trunk permit vlan 20 30

And to create an LACP aggregation group:

> interface bridge-aggregation 1
> description Trunk to upstream switch
> link-aggregation mode dynamic
> port link-type trunk
> port trunk permit vlan 20 30

> interface te 1/0/3
> port link-aggregation group 1
> interface te 2/0/3
> port link-aggregation group 1

Common Commands

Other useful commands that don’t fall under any specific category, but handy to know.

Display switch configuration:

> display current-configuration

Save switch configuration:

> save

Shut down a port:

> int te 1/0/27
> shutdown

Undo a command:

> undo shutdown

Conclusion

Whether you are a network engineer new to the Comware operating system or a VMware administrator looking for a quick cheat sheet for FlexNetwork/FlexFabric switches, I hope this guide has helped you get the job done.

If this blog post gets the same amount of popularity, maybe it will turn into another series. But for now – over and out.

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Dell Force10 Part 2: VLT Basics

July 10, 2016

dell-force10Last time I made a blog post on initial configuration of Force10 switches, which you can find here. There I talked about firmware upgrade and basic features, such as STP and Flow Control. In this blog post I would like to touch on such a key feature of Force10 switches as Virtual Link Trunking (VLT).

VLT is Force10’s implementation of Multi-Chassis Link Aggregation Group (MLAG), which is similar to Virtual Port Channels (vPC) on Cisco Nexus switches. The goal of VLT is to let you establish one aggregated link to two physical network switches in a loop-free topology. As opposed to two standalone switches, where this is not possible.

You could say that switch stacking gives you similar capabilities and you would  be right. The issue with stacked switches, though, is that they act as a single switch not only from the data plane point of view, but also from the control plane point of view. The implication of this is that if you need to upgrade a switch stack, you have to reboot both switches at the same time, which brings down your network. If you have an iSCSI or NFS storage array connected to the stack, this may cause trouble, especially in enterprise environments.

With VLT you also have one data plane, but individual control planes. As a result, each switch can be managed and upgraded separately without full network downtime.

VLT Terminology

Virtual Link Trunking uses the following set of terms:

  • VLT peer – one of the two switches participating in VLT (you can have a maximum of two switches in a VLT domain)
  • VLT interconnect (VLTi) – interconnect link between the two switches to synchronize the MAC address tables and other VLT-related data
  • VLT backup link – heartbeat link to send keep alive messages between the two switches, it’s also used to identify switch state if VLTi link fails
  • VLT – this is the name of the feature – Virtual Link Trunking, as well as a VLT link aggregation group – Virtual Link Trunk. We will call aggregated link a VLT LAG to avoid ambiguity.
  • VLT domain – grouping of all of the above

VLT Topology

This’s what a sample VLT domain looks like. S4048-ON switches have six 40Gb QSFP+ ports, two of which we use for a VLT interconnect. It’s recommended to use a static LAG for VLTi.

basic_vlt

Two 1Gb links are used for VLT backup. You can use switch out-of-band management ports for this. Four 10Gb links form a VLT LAG to the upstream core switch.

Use Cases

So where is this actually helpful? Vast majority of today’s environments are virtualized and do not require LAGs. vSphere already uses teaming on vSwitch uplinks for traffic distribution across all network ports by default. There are some use cases in VMware environments, where you can create a LAG to a vSphere Distributed Switch for faster link failure convergence or improved packet switching. Unless you have a really large vSphere environment this is generally not required, but you may use this option later on if required. Read Chris Wahl’s blog post here for more info.

Where VLT is really helpful is in building a loop-free network topology in your datacenter. See, all your vSphere hosts are connected to both Force10 switches for redundancy. Since traffic comes to either of the switches depending on which uplink is being picked on a ESXi host, you have to make sure that VMs on switch 1 are able to communicate to VMs on switch 2. If all you had in your environment were two Force10 switches, you would establish a LAG between the two and be done with it. But if your network topology is a bit larger than this and you have at least a single additional core switch/router in your environment you’d be faced with the following dilemma. How can you ensure efficient traffic switching in your network without creating loops?

stp_loop

You can no longer create a LAG between the two Force10 switches, as it will create a loop. Your only option is to keep switches connected only to the core and not to each other. And by doing that you will cause all traffic from VMs on switch 1 destined to VMs on switch 2 and vise versa to traverse the core.

east_west_traffic

And that’s where VLT comes into play. All east-west traffic between servers is contained within the VLT domain and doesn’t need to traverse the core. As shown above, if we didn’t use VLT, traffic from one switch to another would have to go from switch 1 to core and then back from core to switch 2. In a VLT domain traffic between the switches goes directly form switch 1 to switch 2 using VLTi.

Conclusion

That’s a brief introduction to VLT theory. In the next few posts we will look at how exactly VLT is configured and map theory to practice.

NetApp SnapMirror Optimization

May 31, 2013

gzipSnapMirroring to disaster recovery site requires huge amount of data to be transferred over the WAN link. In some cases replication can significantly lag from the defined schedule. There are two ways to reduce the amount of traffic and speed up replication: deduplication and compression.

If you apply deduplication to the replicated volumes, you simply reduce the amount of data you need to be transferred. You can read how to enable deduplication in my previous post.

Compression is a less known feature of SnapMirror. What it does is compression of the data being transferred on the source and decompression on the destination. Data inside the volume is left intact.

To enable SnapMirror compression you first need to make sure, that all your connections in snapmirror.conf file have names, like:

connection_name=multi(src_system,dst_system)

Then use ‘compression=enable’ configuration option to enable it for particular SnapMirror:

connection_name:src_vol dst_system:dst_vol compression=enable 0 2 * *

To check the compression ration after the transfer has been finished run:

> snapmirror status -l

And look at ‘Compression Ratio’ line:

Source: fas1:src
Destination: fas2:dest
Status: Transferring
Progress: 24 KB
Compression Ratio: 3.5 : 1

The one drawback of compression is an increased CPU load. Monitor your CPU load and if it’s too high, use compression selectively.