From: Jeremy O'Dette (jeremyodette@hotmail.com)
Date: Tue Feb 14 2006 - 10:28:13 GMT-3
At a previous company I worked for we had ran into a few bugs in a
sup2/msfc2 environment where the msfc2s would crash but not all the way.
The symptom we had was two msfc2s that BOTH thought they were the active
speaker... not a good thing as it brought of the vlans they were routing to
a halt. As previously mentioned opening a TAC case would be a great idea.
At my current job I deployed SSO in our 6500s late last year and its worked
wonderfully... easy to configure and great failover times.
Jeremy O'Dette
CCIE #14973
jeremyodette@hotmail.com
>From: "Tim" <ccie2be@nyc.rr.com>
>Reply-To: "Tim" <ccie2be@nyc.rr.com>
>To: "'Mark Lasarko'" <mlasarko@co.ba.md.us>
>CC: "'Group Study'" <ccielab@groupstudy.com>
>Subject: RE: SRM vs HSRP
>Date: Mon, 13 Feb 2006 15:03:04 -0500
>
>Hey Mark,
>
>This 6500 has been running for several years and apparently there hadn't
>been a failover from the active HSRP router to the standby which is why it
>wasn't known there was a HSRP failover issue.
>
>So, as a workaround, SRM is being considered but I also agreed with the
>other reply about finding out the root cause of the HSRP problem prior to
>trying to work around it with another solution.
>
>I also agree that 2 chassis are better than one to provide a higher level
>of
>fault tolerance but for the moment and due to deadlines that's not really
>an
>option either.
>
>So, given the hardware we have and without upgrading it, I think the only
>options are DRM using HSRP or SRM. Would you agree?
>
>At this point, I wouldn't completely rule out a memory upgrade to support a
>newer version of CatOS and/or IOS but that's probably it as far as hardware
>upgrades goes.
>
>So, given these constraints, if we have the choice of using DRM with HSRP
>or
>SRM, which do you think is preferable?
>
>Thanks a million, Tim
>
>-----Original Message-----
>From: Mark Lasarko [mailto:mlasarko@co.ba.md.us]
>Sent: Monday, February 13, 2006 12:13 PM
>To: ccie2be@nyc.rr.com
>Subject: Re: SRM vs HSRP
>
>Greetings Tim,
>
>Wow, DRM - It's been a while :)
>My first question would be how long have these boxes been up
>
>There are a few modes of "internal redundancy" which can be deployed within
>a chassis: These include DRM, SSM, RPR, RPR+, SRM w/ SSO, and NSF w/ SSO
>
>All of these things operate between Sup's in the same chassis.
>The hardware and software you have to work with will clarify the options
>you
>have.
>
>HSRP was used with DRM to sync the Sup's back in the day...
>You kind of had to have it, along with (nearly) identical configurations on
>the Sups'. DRM w/ HSRP was "the original" mode of failover, and has been
>deprecated for the most part with the introduction of newer, stateful means
>(*SSO - stateful switchover)
>
>Though I would not make any concrete recommendations without knowing
>exactly
>what you had to work with, and where you were heading, I would stay clear
>of
>DRM, despite its potential performance benefits in older (initial)
>implementations and go with SRM. It's a simple config and with any luck
>your
>hardware and software roadmap will take you to something SSO-ish in the
>near
>future.
>
>Personally, I would keep the HSRP, VRRP, GLBP, etc. between devices, and
>not
>on the same chassis. I see a big part of these features as overcoming
>outages in physical links, intermediate switches, etc. so having them run
>within the same chassis, as you mention with HSRP is not exactly an
>apples-to-apples comparison.
>
>Also, pay close attention to things that may introduce additional time for
>recovery. I have seen configurations where core dumps may add significant
>additional time to failover, making what should have taken less than 5
>seconds turn into more than 5 minutes! My point - make time to test your
>work while implementing it (and I recommend turning off any core dumps
>unless TAC requests them)
>
>One more thing, if you happen to have Sup2's with 16MB bootflash, you'll
>want to get the 32MB bootflash now - you'll likely need it regardless of
>the
>redundancy option you choose.
>
>HTH,
>~M
>
>
> >>> "Tim" <ccie2be@nyc.rr.com> 02/13/06 10:10 AM >>>
>Hi Guys,
>
>
>
>I just learned about a 6500 feature called Single Router Mode (SRM). With
>this feature enabled on a 6500 with dual MSFC's, if one MSFC goes down the
>other takes over.
>
>
>
>http://www.cisco.com/univercd/cc/td/doc/product/lan/cat6000/sw_7_3/confg_gd/
>redund.htm#wp1071742
>
>
>
>If I have a choice between using this feature versus using HSRP which
>feature provides between fault-tolerance?
>
>
>
>Can anyone speak to the pro's and con's of using SRM vs HSRP?
>
>
>
>TIA, Tim
>
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