Ethernet Switches & Routers

Reply
Occasional Contributor
Posts: 15
Registered: ‎02-21-2011

Unstable Routing through Stack

Hello All!

I have a stack of six FCX648 with L3 software 7.2.02a. It happens that routing between particular IP hosts fails during some random hours and then continues to work OK.

For example, the stack has 2 VLANs, say VLAN4 and VLAN6 with router-interfaces ve4 and ve6, which have addresses 192.168.4.254/24 and 192.168.6.254/24 respectively. A physical host in VLAN4 has address 192.168.4.1/24 with gateway 192.168.4.254. There is a virtual Hyper-V machine on that physical host that has address 192.168.4.2/24 with gateway 192.168.4.254. There is a host in VLAN6 that has address 192.168.6.1/24 with gateway 192.168.6.254. At some moment we saw that:

1) ping from host 192.168.6.1 to 192.168.4.2 failed;

2) ping from host 192.168.6.1 to 192.168.4.1 was successful;

3) pings from the stack to 192.168.4.1, 192.168.4.2, 192.168.6.1 were successful.

In some hours after that, all those pings were successful again.

In some days after that, there were the same problem between other hosts.

How can I prevent such cases?

Thank you if you answer.

Contributor
Posts: 61
Registered: ‎12-08-2009

Re: Unstable Routing through Stack

it seems this issue is related to your virtual switch on your host machine.
I dont think fcx  fails while doing inter-vlan routing.
Does your host machine tag vlans?
What is your interface configuration?

you can also check this article:
http://social.technet.microsoft.com/wiki/contents/articles/151.aspx

Occasional Contributor
Posts: 15
Registered: ‎02-21-2011

Re: Unstable Routing through Stack

Dear serhat.kahraman,

Thank you for your response. My host machine 192.168.4.1 does not tag VLANs. The corresponding ports on the switch for host 192.168.4.1 are untagged, belong to VLAN4, and have no other non-default configuration. The connection type in Hyper-V is external. It is connacted to a team of two adapters. The type of the team is "Adapter Fault Tolerance". Do you know some sources, which discribe some similar instability porblems with Microsoft Virtual Switch?

Contributor
Posts: 61
Registered: ‎12-08-2009

Re: Unstable Routing through Stack

if you have NIC teaming on your host,  you should configure static (or dynamic if your host supports) LAG on the switch.
you can find information  about this topic on the configuration guide;;
http://www.brocade.com/forms/getFile?p=documents/product_manuals/B_FastIron/FastIron_07300_ConfigGuide.pdf

hope this helps,

Serhat

Occasional Contributor
Posts: 15
Registered: ‎02-21-2011

Re: Unstable Routing through Stack

Dear serhat.kahraman,

Thank you for your response. Do I understand right that LAG balances traffic? If this is true, then we can have another problem. This is because Adapter Fault Tolerance does not balance traffic. It just sets one adapter to pass traffic (Active) and sets another adapter not to pass traffic (Standby). If the switch balances traffic between them, then we'll lose traffic going to the Standby adapter.

Thank you anyway.

Contributor
Posts: 61
Registered: ‎12-08-2009

Re: Unstable Routing through Stack

Yes you are right but if you did not configure LACP of static LAG it does not load balance traffic .
thanks,
Serhat

Occasional Contributor
Posts: 15
Registered: ‎02-21-2011

Re: Unstable Routing through Stack

Dear Serhat,

What commands would you recommend for my two ports that are connected to host 192.168.4.1?

Contributor
Posts: 61
Registered: ‎12-08-2009

Re: Unstable Routing through Stack

I suggest you to connect only one port (active one).
and if you dont see any problem then it means the issue is from your virtual switch.
if you want to use both ports it is better to configure nic teaming and LACP /static lag on your FCX stack.
by this way you can have both redundancy and high bandwidth.

Thanks,

Serhat

Frequent Contributor
Posts: 98
Registered: ‎07-12-2011

Re: Unstable Routing through Stack

You might try to upgrade to 7202e to see if it helps, we ran into this with 7202a, clearing the mac table for that mac or the arp table for that address would fix the issue temporarily.

Defect ID:

DEFECT000357433

Technical Severity:

High

Summary:

Layer 3 traffic sometimes does not get forwarded on an FCX stack.

Symptom:

IP Traffic is not forwarded on an FCX stack’s member units.

Workaround:

Clearing the MAC or ARP tables temporarily resolves the problem.

Probability:

Low

Feature:

FCX Layer 3 Forwarding - IPV4

Function:

Data Forwarding (IPV4)

Reported In Release:

FI 07.2.02

Service Request ID:

601967

Occasional Contributor
Posts: 15
Registered: ‎02-21-2011

Re: Unstable Routing through Stack

Dear John,

Thank you for your response. What if we upgrade to 7300 or 7300a? What is better with respect to solution of our problem and overall stability?

Thank you again.

Join the Community

Get quick and easy access to valuable resource designed to help you manage your Brocade Network.