WAAS 574 - Inline Card speed

[CSCO12021643]

Hello,

We installed a WAAS 574 (IOS 5.0.3) inline between a switch and a router.

It's a Giga switch and Fast router.

What does Cisco advice to do in this situation ??

We set all the ports (Switch, WAAS inlinegroup, Router) to 100M Full to avoid speed difference between LAN and WAN side of the WAAS. It results on traffic disruption ...

We set back all the ports to Auto/Auto, everything came back to normal. We have now a 1G connection on the LAN side and 100M on the WAN side.

Can't the WAAS be a traffic bottle neck in this situation ??!!

The Cisco 574 Hardware Installation Guide however says :

Speed and duplex settings are port specific so that two inline ports can negotiate different speeds independently.

Any advice ??

Thanks

Ismael

[Nicolas Fournier]

Hi Ismael,

The only issue I see with having one side of the Inline interface as Gig and the other side as FE is what would happen if the WAE goes into hardware bypass.

There are some requirements in terms of cabling when you want to use FE on both sides of the inline interface:

http://www.cisco.com/en/US/docs/app_ntwk_services/waas/wae/module/inline/installation/guide/17880fru.html#wp39995

Could it be the reason you are unable to pass traffic when you hardcode both sides to 100 Full?

Regards,

Nicolas

[CSCO12021643]

Hi Nicolas,

Thanks for the quick answer.

We did exactly this type of cabling when we tried to use FE on both sides :

- straight-through between switch and WAE

- crossover between WAE and router

Traffic loss appeared however.

I am not sure how the WAE behave in a hardware bypass situation when one of its port had negotiated Giga and the other Fast ...

In this case, as the WAE is "down", does the switch port directly negotiates with the router port to end up doing 100M ??!!

Any idea ?

Best regards,

Ismaël

[Nicolas Fournier]

Hi Ismael,

When the WAE goes down, it goes into hardware bypass so it should be as if the cables on both sides of the connection were patched together and if there is a setting negotiation, it would take place directly between the router and the switch.

Regards,

Nicolas

[CSCO12021643]

It means that in a WAE hardware issue situation, the Giga switch and the Fast router should negotiate 100M connection speed.

So, no problem right ?!

Regards,

Ismael

[Nicolas Fournier]

Hi Ismael,

You should see the same behavior as it the router and switch were directly connected through a cross cable.

Regards,

Nicolas

[CSCO12021643]

In conclusion, I can set up my equipements in the following manner without any problem :

- WAE in Auto/Auto

- Giga switch port in Auto

- Fast router port in Auto

Normal state :

- switch to WAE LAN : Giga connection (straight-through wire)

- WAE WAN to router : Fast connection (crossover wire)

Bypass state :

- switch to router : Fast connection

Is that correct ?

No bottle-neck issues in the normal state as it's Giga on one side and Fast on the other ?

Thanks for the help.

Regards,

Ismael

[Nicolas Fournier]

Hi Ismael,

Looks correct to me.

For the bottle-neck, for sure you are not going to be able to pass more then what the FE interface allows but the flow control mechanisms of the layer above should make sure you don't oversubscribe the router interface too much.

Regards,

Nicolas

[CSCO12021643]

Allrights thanks a lot !!!

So hardcoded ports configuration should never be used I guess.

Kind regards,

Ismael