Hi Guys, sorry for jumping into the middle of this one but I'm curious about this.
So if there's an indirect link failure, do all non-portfast links have to go through LIS and LRN again? Kind regards Neil -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of marc abel Sent: 10 March 2011 02:15 To: [email protected] Cc: [email protected] Subject: Re: [OSL | CCIE_RS] Rapid Spanning Tree convergence times Jay thank you for that, it cleared a misconception I had. I thought portfast only affected the port in question when it came online, as when you plugged it in. I didn't realize that it would impact an indirect re-convergence. I tested it and it worked just like you said, I drop one packet. I am doing both ether-channel and HSRP on the uplinks. I'm thinking more about what happens if I lose one of my redundant core switches. Also my IDF's are setup as a ring or stacked topology because I don't have enough fiber to uplink each switch. So in a situation where I lose the middle switch in a stack I would be relying on spanning-tree re-converging. One other thing I am still unclear about is that the max-age still shows 20 seconds, in the output. Isn't it supposed to be 3 x hello? Bah, I probably just need to re-watch the STP videos. Cat1#show span VLAN0001 Spanning tree enabled protocol rstp Root ID Priority 24577 Address 5475.d029.7080 This bridge is the root Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec Bridge ID Priority 24577 (priority 24576 sys-id-ext 1) Address 5475.d029.7080 Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec Aging Time 300 On Wed, Mar 9, 2011 at 7:50 PM, [email protected] <[email protected]> wrote: > Well if yor timers are that bad for VOIP you can always use hsrp if > you don't want to use the etherchannel option. You can tune hsrp down > to milliseconds if you wanted to. Of course your distribution switches > need to support an enhanced IOS image > > Sent from my Verizon Wireless Phone > > ----- Reply message ----- > From: "Jay Taylor" <[email protected]> > Date: Wed, Mar 9, 2011 7:57 pm > Subject: [OSL | CCIE_RS] Rapid Spanning Tree convergence times > To: "marc abel" <[email protected]> > Cc: <[email protected]> > > > Enable portfast on the host ports and you'll see a much quicker transition. > Just labbed this up and with portfast enabled I lost a single ping > during the failover. Without it enabled I lost 12. > > For the VoIP question - in production I'd recommend building with > Etherchannels just so STP never needs to converge. > > > On Wed, Mar 9, 2011 at 5:41 PM, marc abel <[email protected]> wrote: > >> I have 4 switches connected in a loop. >> >> Cat1-------------Cat2 >> | | >> | | >> Cat3----------Cat4 >> >> >> Cat 1 is the root, Cat 2 is the secondary root. All the switches are >> set to RPVSTP and I have confirmed that show spanning-tree shows RSTP >> as the protocol. Cat 4 shows it's interface to cat3 as it's root port >> and the interface to Cat3 as the Alternate. I have not tuned any >> timers. >> >> What should be the convergence time in this situation? >> >> If I run a ping from a host attached to Cat4 to a host attached to >> Cat1 and then I shut the Cat1-Cat3 interface (on the Cat1 side) it >> takes about 32 seconds before pings pick back up. I thought RSTP was >> supposed to converge in about 6 seconds? >> >> Another question, what is the fastest recovery time we can tune down >> to from RSTP? How do others tune this for VOIP? I know that I can get >> sub second convergence from OSPF but not all my switches have an >> appropriate image to run ospf. >> >> >> Thanks in advance. >> >> Marc >> _______________________________________________ >> For more information regarding industry leading CCIE Lab training, >> please visit www.ipexpert.com >> > _______________________________________________ > For more information regarding industry leading CCIE Lab training, > please visit www.ipexpert.com > > > > _______________________________________________ For more information regarding industry leading CCIE Lab training, please visit www.ipexpert.com _______________________________________________ For more information regarding industry leading CCIE Lab training, please visit www.ipexpert.com
