Virtual is only on the tshoot section which is completely virtualized, the config section is all physical with no plans to go virtual any time soon. Remember there's over 30 devices in the tshoot section!
Alef <[email protected]> wrote: Very informative Marko, Thanks! I do wonder why Cisco can't spare a few 3560's lying around and is going the virtual route. I guess scalability and automation of things. Alef On Jul 12, 2011, at 11:17 PM, [email protected] wrote: > Send CCIE_RS mailing list submissions to > [email protected] > > To subscribe or unsubscribe via the World Wide Web, visit > http://onlinestudylist.com/mailman/listinfo/ccie_rs > or, via email, send a message with subject or body 'help' to > [email protected] > > You can reach the person managing the list at > [email protected] > > When replying, please edit your Subject line so it is more specific > than "Re: Contents of CCIE_RS digest..." > > > Today's Topics: > > 1. CCIE Routing and Switching News and Updates (Marko Milivojevic) > 2. Re: loop in network? (marc abel) > 3. Re: loop in network? (Alef) > 4. allowing ospf in acl (Alef) > 5. Re: loop in network? (marc abel) > 6. Re: loop in network? (Alef) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Tue, 12 Jul 2011 14:15:50 -0700 > From: Marko Milivojevic <[email protected]> > To: OSL Routing and Switching <[email protected]>, GS CCIE > <[email protected]> > Subject: [OSL | CCIE_RS] CCIE Routing and Switching News and Updates > Message-ID: > <cagdym0zcysg6r+_vgoik5q76se5zws272fw--h+qofyujsv...@mail.gmail.com> > Content-Type: text/plain; charset=UTF-8 > > Hello everyone, > > Another Cisco Live SPAM - I apologize, but the information I'm about > to relay is probably of interest to most of you. > > I had the pleasure to attend the Techtorial on CCIE R&S presented by > Bruno van de Werve (CCIE R&S Program Manager) and Bruce Pinsky (Cisco > Distinguished Engineer). It as very informative, detailed and fun to > be there. I wrote some of the major observations and posted them on > IPexpert blog, on the link below. > > http://blog.ipexpert.com/2011/07/12/cisco-live-news-and-updates-ccie-routing-and-switching/ > > Happy studies! > > -- > Marko Milivojevic - CCIE #18427 > Senior Technical Instructor - IPexpert > > FREE CCIE training: http://bit.ly/vLecture > > Mailto: [email protected] > Telephone: +1.810.326.1444 > Web: http://www.ipexpert.com/ > > > ------------------------------ > > Message: 2 > Date: Tue, 12 Jul 2011 16:36:52 -0500 > From: marc abel <[email protected]> > To: Alef <[email protected]> > Cc: "[email protected] IE" <[email protected]> > Subject: Re: [OSL | CCIE_RS] loop in network? > Message-ID: > <CANYR4z=okqptpgq5emfrwnzxqgq9zpn3nn30gzcpsmmb4wb...@mail.gmail.com> > Content-Type: text/plain; charset=ISO-8859-1 > > Layer 2 loops are caused because switches by default flood traffic out > all ports, so any time you connect switches in a circular path a loop > would form if not for spanning-tree. > > In layer 3 this is not the case. Since you have to specifically tell > traffic where to route, making a circle does not make a loop. Routes > make loops by referring back to a host that thinks its path is back to > itself. So adding layer 3 interfaces is not the cause of the loops, > incorrect routes are. > > Take this example > > R1. > int g0/0 > ip address 10.10.10.1 255.255.255.0 > no shut > ! > ip route 6.6.6.6 255.255.255.255 10.10.10.2 > > R2. > int g0/0 > ip address 10.10.10.2 255.255.255.0 > no shut > ! > ip route 6.6.6.6 255.255.255.255 10.10.10.1 > > > Now try to traceroute to 6.6.6.6. R1 will send it to R2, R2 will send > it to R1, R1 will send to R2, repeat until the TTL expires. This is a > layer 3 loop. You will generally notice layer 3 loops by traffic not > reaching its destination(and proved by traceroute), or by routes being > repeatedly installed and removed from the routing table (debug ip > routing). > > Layer 2 loops will generally either keep looping the traffic around so > much that you lose access to the device and the whole damn network > crashes, or if you are lucky you might not have it so bad and you will > see a message in the logs that says something like host x.x.x.x is > flapping between interface..... > > -Marc > > > > > On Tue, Jul 12, 2011 at 3:37 PM, Alef <[email protected]> wrote: >> No no redistribution. I tried to keep it as simple as possible. >> Ok let me try my hand at some ascii art. >> >> But before i do that, is there some inherent stupid thing about putting vlan >> interfaces in all the vlans on all the switches ( i have dot1q trunks in x >> between all 4 switches). I can imagine in my network it would create a loop. >> Just a hunch if i follow the paths. Would i not automatically introduce L3 >> loops by doing that. I think ipexpert topology is setup similar ? >> >> ok scratch that, i uploaded a small jpg >> http://tinypic.com/r/fkqfqr/7 >> >> All switches loopbacks are reachable by at least 3 paths (2 trough the FR >> cloud, and 1 other) >> >> R2# >> O ? ? ? 11.11.11.11 [110/66] via 100.100.100.6, 01:01:51, Serial1/1.256 >> ? ? ? ? ? ? ? ? ? ?[110/66] via 100.100.100.5, 01:01:51, Serial1/1.256 >> ? ? ? ? ? ? ? ? ? ?[110/66] via 100.100.24.4, 00:00:43, Serial1/0.24 >> ? ? 44.0.0.0/32 is subnetted, 1 subnets >> O ? ? ? 44.44.44.44 [110/66] via 100.100.100.6, 01:01:51, Serial1/1.256 >> ? ? ? ? ? ? ? ? ? ?[110/66] via 100.100.100.5, 01:01:51, Serial1/1.256 >> ? ? ? ? ? ? ? ? ? ?[110/66] via 100.100.24.4, 00:00:43, Serial1/0.24 >> >> On a probably unrelated side note, anyone ever got : >> %OSPF-4-ERRRCV: Received invalid packet: Bad Checksum from 100.100.14.1, >> Vlan14 >> >> Cisco website says change the port or cable, which i did, and cable, well >> considering it's a dynamips sim i did ?that as best as i could :-) >> >> Can't get the message to go away though. >> >> On Jul 12, 2011, at 5:24 PM, Di Bias, Steve wrote: >> >>> >>> What makes you think you have any kind of loop? What are the symptoms? Are >>> you redistributing anywhere? >>> >>> -----Original Message----- >>> From: [email protected] >>> [mailto:[email protected]] On Behalf Of Alef >>> Sent: Tuesday, July 12, 2011 8:27 AM >>> To: [email protected] IE >>> Subject: [OSL | CCIE_RS] loop in network? >>> >>> All, >>> >>> So i have this network, and i am thinking i have a loop. I'm just not sure >>> where or how. >>> And i think it started happening after i created vlan interfaces in all >>> vlans on all switches. So Cat1 is having vlan14,vlan567 and vlan69 >>> interfaces and all the other switches in similar. >>> >>> They are NM16ESW cards, but IEEE stp is running so a Layer2 loop should be >>> out of the question. Could i still have a routing loop? >>> I am running OSPF in one giant area 0. >>> >>> How would i go about solving it? I can't use split horizon as OSPF doesn't >>> use that. Should i artificially set routes such that they get a lower >>> metric and manipulate things like that? >>> >>> I attached a small picture to clarify (this is taken from the Security lab >>> Day4 VoD btw). >>> Mind you, it might be something different entirely although i don't think >>> so. >>> >>> But it's probably going to be something very stupid. And yes, i probably >>> don't understand switching very well yet :-) >>> >>> Alef >>> >>> >>> UHS Confidentiality Notice: ?This e-mail message, including any >>> attachments, is for the sole use of the intended recipient (s) and may >>> contain confidential and privileged information. ?Any unauthorized review, >>> use, disclosure or distribution of this information is prohibited. ?If this >>> was sent to you in error, please notify the sender by reply e-mail and >>> destroy all copies of the original message. >> >> _______________________________________________ >> For more information regarding industry leading CCIE Lab training, please >> visit www.ipexpert.com >> >> Are you a CCNP or CCIE and looking for a job? Check out >> www.PlatinumPlacement.com >> > > > ------------------------------ > > Message: 3 > Date: Tue, 12 Jul 2011 22:49:08 +0100 > From: Alef <[email protected]> > To: marc abel <[email protected]> > Cc: "[email protected] IE" <[email protected]> > Subject: Re: [OSL | CCIE_RS] loop in network? > Message-ID: <[email protected]> > Content-Type: text/plain; charset=us-ascii > > Thanks Marc. > > This was the problem: > R6#sh class-map type inspect > Class Map type inspect match-any corporate-to-private-class (id 1) > Match protocol telnet > Match protocol ssh > Match protocol ftp > > Once i added icmp all was well. I didn't actually expect the route to go over > that for some reason, nor do i understand why it had r6 in it's path with > equal distance, as there is at least one more l3 switch in between compared > to R5. Same for R4. Does it not see the "switches" as a hop or something ? > O 33.33.33.33 [110/66] via 100.100.100.6, 00:13:27, Serial1/1.256 > [110/66] via 100.100.100.5, 00:13:27, Serial1/1.256 > [110/66] via 100.100.24.4, 00:07:08, Serial1/0.24 > > This is what i get for fiddling with labs designed for a different purpose > and then trying to add more functionality (or get more out of it) ;-) > > > On Jul 12, 2011, at 10:36 PM, marc abel wrote: > >> Layer 2 loops are caused because switches by default flood traffic out >> all ports, so any time you connect switches in a circular path a loop >> would form if not for spanning-tree. >> >> In layer 3 this is not the case. Since you have to specifically tell >> traffic where to route, making a circle does not make a loop. Routes >> make loops by referring back to a host that thinks its path is back to >> itself. So adding layer 3 interfaces is not the cause of the loops, >> incorrect routes are. >> >> Take this example >> >> R1. >> int g0/0 >> ip address 10.10.10.1 255.255.255.0 >> no shut >> ! >> ip route 6.6.6.6 255.255.255.255 10.10.10.2 >> >> R2. >> int g0/0 >> ip address 10.10.10.2 255.255.255.0 >> no shut >> ! >> ip route 6.6.6.6 255.255.255.255 10.10.10.1 >> >> >> Now try to traceroute to 6.6.6.6. R1 will send it to R2, R2 will send >> it to R1, R1 will send to R2, repeat until the TTL expires. This is a >> layer 3 loop. You will generally notice layer 3 loops by traffic not >> reaching its destination(and proved by traceroute), or by routes being >> repeatedly installed and removed from the routing table (debug ip >> routing). >> >> Layer 2 loops will generally either keep looping the traffic around so >> much that you lose access to the device and the whole damn network >> crashes, or if you are lucky you might not have it so bad and you will >> see a message in the logs that says something like host x.x.x.x is >> flapping between interface..... >> >> -Marc >> >> >> >> >> On Tue, Jul 12, 2011 at 3:37 PM, Alef <[email protected]> wrote: >>> No no redistribution. I tried to keep it as simple as possible. >>> Ok let me try my hand at some ascii art. >>> >>> But before i do that, is there some inherent stupid thing about putting >>> vlan interfaces in all the vlans on all the switches ( i have dot1q trunks >>> in x between all 4 switches). I can imagine in my network it would create a >>> loop. Just a hunch if i follow the paths. Would i not automatically >>> introduce L3 loops by doing that. I think ipexpert topology is setup >>> similar ? >>> >>> ok scratch that, i uploaded a small jpg >>> http://tinypic.com/r/fkqfqr/7 >>> >>> All switches loopbacks are reachable by at least 3 paths (2 trough the FR >>> cloud, and 1 other) >>> >>> R2# >>> O 11.11.11.11 [110/66] via 100.100.100.6, 01:01:51, Serial1/1.256 >>> [110/66] via 100.100.100.5, 01:01:51, Serial1/1.256 >>> [110/66] via 100.100.24.4, 00:00:43, Serial1/0.24 >>> 44.0.0.0/32 is subnetted, 1 subnets >>> O 44.44.44.44 [110/66] via 100.100.100.6, 01:01:51, Serial1/1.256 >>> [110/66] via 100.100.100.5, 01:01:51, Serial1/1.256 >>> [110/66] via 100.100.24.4, 00:00:43, Serial1/0.24 >>> >>> On a probably unrelated side note, anyone ever got : >>> %OSPF-4-ERRRCV: Received invalid packet: Bad Checksum from 100.100.14.1, >>> Vlan14 >>> >>> Cisco website says change the port or cable, which i did, and cable, well >>> considering it's a dynamips sim i did that as best as i could :-) >>> >>> Can't get the message to go away though. >>> >>> On Jul 12, 2011, at 5:24 PM, Di Bias, Steve wrote: >>> >>>> >>>> What makes you think you have any kind of loop? What are the symptoms? Are >>>> you redistributing anywhere? >>>> >>>> -----Original Message----- >>>> From: [email protected] >>>> [mailto:[email protected]] On Behalf Of Alef >>>> Sent: Tuesday, July 12, 2011 8:27 AM >>>> To: [email protected] IE >>>> Subject: [OSL | CCIE_RS] loop in network? >>>> >>>> All, >>>> >>>> So i have this network, and i am thinking i have a loop. I'm just not sure >>>> where or how. >>>> And i think it started happening after i created vlan interfaces in all >>>> vlans on all switches. So Cat1 is having vlan14,vlan567 and vlan69 >>>> interfaces and all the other switches in similar. >>>> >>>> They are NM16ESW cards, but IEEE stp is running so a Layer2 loop should be >>>> out of the question. Could i still have a routing loop? >>>> I am running OSPF in one giant area 0. >>>> >>>> How would i go about solving it? I can't use split horizon as OSPF doesn't >>>> use that. Should i artificially set routes such that they get a lower >>>> metric and manipulate things like that? >>>> >>>> I attached a small picture to clarify (this is taken from the Security lab >>>> Day4 VoD btw). >>>> Mind you, it might be something different entirely although i don't think >>>> so. >>>> >>>> But it's probably going to be something very stupid. And yes, i probably >>>> don't understand switching very well yet :-) >>>> >>>> Alef >>>> >>>> >>>> UHS Confidentiality Notice: This e-mail message, including any >>>> attachments, is for the sole use of the intended recipient (s) and may >>>> contain confidential and privileged information. Any unauthorized review, >>>> use, disclosure or distribution of this information is prohibited. If >>>> this was sent to you in error, please notify the sender by reply e-mail >>>> and destroy all copies of the original message. >>> >>> _______________________________________________ >>> For more information regarding industry leading CCIE Lab training, please >>> visit www.ipexpert.com >>> >>> Are you a CCNP or CCIE and looking for a job? Check out >>> www.PlatinumPlacement.com >>> > > > > ------------------------------ > > Message: 4 > Date: Tue, 12 Jul 2011 22:59:15 +0100 > From: Alef <[email protected]> > To: "[email protected] IE" <[email protected]> > Subject: [OSL | CCIE_RS] allowing ospf in acl > Message-ID: <[email protected]> > Content-Type: text/plain; charset=us-ascii > > When you have say r1 and r2 > and you want to only allow ospf in > > would applying this on R1 fa0/0 (assuming this is the connecting interface to > R2) inbound be sufficient? > Extended IP access list 101 > 10 permit ospf any any (4826 matches) > > it seems it is. Do we not need to allow ospf going out as well? In my lab R1 > has acl 102 outbound defined and there is nothing there about ospf. > > Regards, > Alef > > ------------------------------ > > Message: 5 > Date: Tue, 12 Jul 2011 17:05:26 -0500 > From: marc abel <[email protected]> > To: Alef <[email protected]> > Cc: "[email protected] IE" <[email protected]> > Subject: Re: [OSL | CCIE_RS] loop in network? > Message-ID: > <canyr4zkd5eofepvaly1-pyoit8sdfhs+3hifaysrq2umpcs...@mail.gmail.com> > Content-Type: text/plain; charset=ISO-8859-1 > > You can see they all have an equal cost [110/66] of 66. Looking at > your diagram I see > > R2-R4-Cat1-Cat2-Cat2 loopback > R2-R5-Cat3-Cat2-Cat2 loopback > R2-R6-Cat4-Cat2-Cat2 loopback > > Extra fiddling is one of the best ways to learn this stuff. > > On Tue, Jul 12, 2011 at 4:49 PM, Alef <[email protected]> wrote: >> Thanks Marc. >> >> This was the problem: >> R6#sh class-map type inspect >> ?Class Map type inspect match-any corporate-to-private-class (id 1) >> ? Match protocol telnet >> ? Match protocol ssh >> ? Match protocol ftp >> >> Once i added icmp all was well. I didn't actually expect the route to go >> over that for some reason, nor do i understand why it had r6 in it's path >> with equal distance, as there is at least one more l3 switch in between >> compared to R5. Same for R4. Does it not see the "switches" as a hop or >> something ? >> O ? ? ? 33.33.33.33 [110/66] via 100.100.100.6, 00:13:27, Serial1/1.256 >> ? ? ? ? ? ? ? ? ? ?[110/66] via 100.100.100.5, 00:13:27, Serial1/1.256 >> ? ? ? ? ? ? ? ? ? ?[110/66] via 100.100.24.4, 00:07:08, Serial1/0.24 >> >> This is what i get for fiddling with labs designed for a different purpose >> and then trying to add more functionality (or get more out of it) ;-) >> >> >> On Jul 12, 2011, at 10:36 PM, marc abel wrote: >> >>> Layer 2 loops are caused because switches by default flood traffic out >>> all ports, so any time you connect switches in a circular path a loop >>> would form if not for spanning-tree. >>> >>> In layer 3 this is not the case. Since you have to specifically tell >>> traffic where to route, making a circle does not make a loop. Routes >>> make loops by referring back to a host that thinks its path is back to >>> itself. So adding layer 3 interfaces is not the cause of the loops, >>> incorrect routes are. >>> >>> Take this example >>> >>> R1. >>> int g0/0 >>> ip address 10.10.10.1 255.255.255.0 >>> no shut >>> ! >>> ip route ?6.6.6.6 255.255.255.255 10.10.10.2 >>> >>> R2. >>> int g0/0 >>> ip address 10.10.10.2 255.255.255.0 >>> no shut >>> ! >>> ip route ?6.6.6.6 255.255.255.255 10.10.10.1 >>> >>> >>> Now try to traceroute to 6.6.6.6. R1 will send it to R2, R2 will send >>> it to R1, R1 will send to R2, repeat until the TTL expires. This is a >>> layer 3 loop. You will generally notice layer 3 loops by traffic not >>> reaching its destination(and proved by traceroute), or by routes being >>> repeatedly installed and removed from the routing table (debug ip >>> routing). >>> >>> Layer 2 loops will generally either keep looping the traffic around so >>> much that you lose access to the device and the whole damn network >>> crashes, or if you are lucky you might not have it so bad and you will >>> see a message in the logs that says something like host x.x.x.x is >>> flapping between interface..... >>> >>> -Marc >>> >>> >>> >>> >>> On Tue, Jul 12, 2011 at 3:37 PM, Alef <[email protected]> wrote: >>>> No no redistribution. I tried to keep it as simple as possible. >>>> Ok let me try my hand at some ascii art. >>>> >>>> But before i do that, is there some inherent stupid thing about putting >>>> vlan interfaces in all the vlans on all the switches ( i have dot1q trunks >>>> in x between all 4 switches). I can imagine in my network it would create >>>> a loop. Just a hunch if i follow the paths. Would i not automatically >>>> introduce L3 loops by doing that. I think ipexpert topology is setup >>>> similar ? >>>> >>>> ok scratch that, i uploaded a small jpg >>>> http://tinypic.com/r/fkqfqr/7 >>>> >>>> All switches loopbacks are reachable by at least 3 paths (2 trough the FR >>>> cloud, and 1 other) >>>> >>>> R2# >>>> O ? ? ? 11.11.11.11 [110/66] via 100.100.100.6, 01:01:51, Serial1/1.256 >>>> ? ? ? ? ? ? ? ? ? ?[110/66] via 100.100.100.5, 01:01:51, Serial1/1.256 >>>> ? ? ? ? ? ? ? ? ? ?[110/66] via 100.100.24.4, 00:00:43, Serial1/0.24 >>>> ? ? 44.0.0.0/32 is subnetted, 1 subnets >>>> O ? ? ? 44.44.44.44 [110/66] via 100.100.100.6, 01:01:51, Serial1/1.256 >>>> ? ? ? ? ? ? ? ? ? ?[110/66] via 100.100.100.5, 01:01:51, Serial1/1.256 >>>> ? ? ? ? ? ? ? ? ? ?[110/66] via 100.100.24.4, 00:00:43, Serial1/0.24 >>>> >>>> On a probably unrelated side note, anyone ever got : >>>> %OSPF-4-ERRRCV: Received invalid packet: Bad Checksum from 100.100.14.1, >>>> Vlan14 >>>> >>>> Cisco website says change the port or cable, which i did, and cable, well >>>> considering it's a dynamips sim i did ?that as best as i could :-) >>>> >>>> Can't get the message to go away though. >>>> >>>> On Jul 12, 2011, at 5:24 PM, Di Bias, Steve wrote: >>>> >>>>> >>>>> What makes you think you have any kind of loop? What are the symptoms? >>>>> Are you redistributing anywhere? >>>>> >>>>> -----Original Message----- >>>>> From: [email protected] >>>>> [mailto:[email protected]] On Behalf Of Alef >>>>> Sent: Tuesday, July 12, 2011 8:27 AM >>>>> To: [email protected] IE >>>>> Subject: [OSL | CCIE_RS] loop in network? >>>>> >>>>> All, >>>>> >>>>> So i have this network, and i am thinking i have a loop. I'm just not >>>>> sure where or how. >>>>> And i think it started happening after i created vlan interfaces in all >>>>> vlans on all switches. So Cat1 is having vlan14,vlan567 and vlan69 >>>>> interfaces and all the other switches in similar. >>>>> >>>>> They are NM16ESW cards, but IEEE stp is running so a Layer2 loop should >>>>> be out of the question. Could i still have a routing loop? >>>>> I am running OSPF in one giant area 0. >>>>> >>>>> How would i go about solving it? I can't use split horizon as OSPF >>>>> doesn't use that. Should i artificially set routes such that they get a >>>>> lower metric and manipulate things like that? >>>>> >>>>> I attached a small picture to clarify (this is taken from the Security >>>>> lab Day4 VoD btw). >>>>> Mind you, it might be something different entirely although i don't think >>>>> so. >>>>> >>>>> But it's probably going to be something very stupid. And yes, i probably >>>>> don't understand switching very well yet :-) >>>>> >>>>> Alef >>>>> >>>>> >>>>> UHS Confidentiality Notice: ?This e-mail message, including any >>>>> attachments, is for the sole use of the intended recipient (s) and may >>>>> contain confidential and privileged information. ?Any unauthorized >>>>> review, use, disclosure or distribution of this information is >>>>> prohibited. ?If this was sent to you in error, please notify the sender >>>>> by reply e-mail and destroy all copies of the original message. >>>> >>>> _______________________________________________ >>>> For more information regarding industry leading CCIE Lab training, please >>>> visit www.ipexpert.com >>>> >>>> Are you a CCNP or CCIE and looking for a job? Check out >>>> www.PlatinumPlacement.com >>>> >> >> > > > ------------------------------ > > Message: 6 > Date: Tue, 12 Jul 2011 23:19:00 +0100 > From: Alef <[email protected]> > To: marc abel <[email protected]> > Cc: "[email protected] IE" <[email protected]> > Subject: Re: [OSL | CCIE_RS] loop in network? > Message-ID: <[email protected]> > Content-Type: text/plain; charset=us-ascii > > Hey Marc, > To emphasise, this is for the 33.33.33.33 loopback, or Cat3 loopback route. > > I see: > R2-R5-Cat3 > R2-R6-Cat4-Cat3 > R2-R4-Cat1-Cat3 > > Why would i go through Cat2 ? So in my count it should prefer the route > through R5? > On Jul 12, 2011, at 11:05 PM, marc abel wrote: > >> You can see they all have an equal cost [110/66] of 66. Looking at >> your diagram I see >> >> R2-R4-Cat1-Cat2-Cat2 loopback >> R2-R5-Cat3-Cat2-Cat2 loopback >> R2-R6-Cat4-Cat2-Cat2 loopback >> >> Extra fiddling is one of the best ways to learn this stuff. >> >> On Tue, Jul 12, 2011 at 4:49 PM, Alef <[email protected]> wrote: >>> Thanks Marc. >>> >>> This was the problem: >>> R6#sh class-map type inspect >>> Class Map type inspect match-any corporate-to-private-class (id 1) >>> Match protocol telnet >>> Match protocol ssh >>> Match protocol ftp >>> >>> Once i added icmp all was well. I didn't actually expect the route to go >>> over that for some reason, nor do i understand why it had r6 in it's path >>> with equal distance, as there is at least one more l3 switch in between >>> compared to R5. Same for R4. Does it not see the "switches" as a hop or >>> something ? >>> O 33.33.33.33 [110/66] via 100.100.100.6, 00:13:27, Serial1/1.256 >>> [110/66] via 100.100.100.5, 00:13:27, Serial1/1.256 >>> [110/66] via 100.100.24.4, 00:07:08, Serial1/0.24 >>> >>> This is what i get for fiddling with labs designed for a different purpose >>> and then trying to add more functionality (or get more out of it) ;-) >>> >>> >>> On Jul 12, 2011, at 10:36 PM, marc abel wrote: >>> >>>> Layer 2 loops are caused because switches by default flood traffic out >>>> all ports, so any time you connect switches in a circular path a loop >>>> would form if not for spanning-tree. >>>> >>>> In layer 3 this is not the case. Since you have to specifically tell >>>> traffic where to route, making a circle does not make a loop. Routes >>>> make loops by referring back to a host that thinks its path is back to >>>> itself. So adding layer 3 interfaces is not the cause of the loops, >>>> incorrect routes are. >>>> >>>> Take this example >>>> >>>> R1. >>>> int g0/0 >>>> ip address 10.10.10.1 255.255.255.0 >>>> no shut >>>> ! >>>> ip route 6.6.6.6 255.255.255.255 10.10.10.2 >>>> >>>> R2. >>>> int g0/0 >>>> ip address 10.10.10.2 255.255.255.0 >>>> no shut >>>> ! >>>> ip route 6.6.6.6 255.255.255.255 10.10.10.1 >>>> >>>> >>>> Now try to traceroute to 6.6.6.6. R1 will send it to R2, R2 will send >>>> it to R1, R1 will send to R2, repeat until the TTL expires. This is a >>>> layer 3 loop. You will generally notice layer 3 loops by traffic not >>>> reaching its destination(and proved by traceroute), or by routes being >>>> repeatedly installed and removed from the routing table (debug ip >>>> routing). >>>> >>>> Layer 2 loops will generally either keep looping the traffic around so >>>> much that you lose access to the device and the whole damn network >>>> crashes, or if you are lucky you might not have it so bad and you will >>>> see a message in the logs that says something like host x.x.x.x is >>>> flapping between interface..... >>>> >>>> -Marc >>>> >>>> >>>> >>>> >>>> On Tue, Jul 12, 2011 at 3:37 PM, Alef <[email protected]> wrote: >>>>> No no redistribution. I tried to keep it as simple as possible. >>>>> Ok let me try my hand at some ascii art. >>>>> >>>>> But before i do that, is there some inherent stupid thing about putting >>>>> vlan interfaces in all the vlans on all the switches ( i have dot1q >>>>> trunks in x between all 4 switches). I can imagine in my network it would >>>>> create a loop. Just a hunch if i follow the paths. Would i not >>>>> automatically introduce L3 loops by doing that. I think ipexpert topology >>>>> is setup similar ? >>>>> >>>>> ok scratch that, i uploaded a small jpg >>>>> http://tinypic.com/r/fkqfqr/7 >>>>> >>>>> All switches loopbacks are reachable by at least 3 paths (2 trough the FR >>>>> cloud, and 1 other) >>>>> >>>>> R2# >>>>> O 11.11.11.11 [110/66] via 100.100.100.6, 01:01:51, Serial1/1.256 >>>>> [110/66] via 100.100.100.5, 01:01:51, Serial1/1.256 >>>>> [110/66] via 100.100.24.4, 00:00:43, Serial1/0.24 >>>>> 44.0.0.0/32 is subnetted, 1 subnets >>>>> O 44.44.44.44 [110/66] via 100.100.100.6, 01:01:51, Serial1/1.256 >>>>> [110/66] via 100.100.100.5, 01:01:51, Serial1/1.256 >>>>> [110/66] via 100.100.24.4, 00:00:43, Serial1/0.24 >>>>> >>>>> On a probably unrelated side note, anyone ever got : >>>>> %OSPF-4-ERRRCV: Received invalid packet: Bad Checksum from 100.100.14.1, >>>>> Vlan14 >>>>> >>>>> Cisco website says change the port or cable, which i did, and cable, well >>>>> considering it's a dynamips sim i did that as best as i could :-) >>>>> >>>>> Can't get the message to go away though. >>>>> >>>>> On Jul 12, 2011, at 5:24 PM, Di Bias, Steve wrote: >>>>> >>>>>> >>>>>> What makes you think you have any kind of loop? What are the symptoms? >>>>>> Are you redistributing anywhere? >>>>>> >>>>>> -----Original Message----- >>>>>> From: [email protected] >>>>>> [mailto:[email protected]] On Behalf Of Alef >>>>>> Sent: Tuesday, July 12, 2011 8:27 AM >>>>>> To: [email protected] IE >>>>>> Subject: [OSL | CCIE_RS] loop in network? >>>>>> >>>>>> All, >>>>>> >>>>>> So i have this network, and i am thinking i have a loop. I'm just not >>>>>> sure where or how. >>>>>> And i think it started happening after i created vlan interfaces in all >>>>>> vlans on all switches. So Cat1 is having vlan14,vlan567 and vlan69 >>>>>> interfaces and all the other switches in similar. >>>>>> >>>>>> They are NM16ESW cards, but IEEE stp is running so a Layer2 loop should >>>>>> be out of the question. Could i still have a routing loop? >>>>>> I am running OSPF in one giant area 0. >>>>>> >>>>>> How would i go about solving it? I can't use split horizon as OSPF >>>>>> doesn't use that. Should i artificially set routes such that they get a >>>>>> lower metric and manipulate things like that? >>>>>> >>>>>> I attached a small picture to clarify (this is taken from the Security >>>>>> lab Day4 VoD btw). >>>>>> Mind you, it might be something different entirely although i don't >>>>>> think so. >>>>>> >>>>>> But it's probably going to be something very stupid. And yes, i probably >>>>>> don't understand switching very well yet :-) >>>>>> >>>>>> Alef >>>>>> >>>>>> >>>>>> UHS Confidentiality Notice: This e-mail message, including any >>>>>> attachments, is for the sole use of the intended recipient (s) and may >>>>>> contain confidential and privileged information. Any unauthorized >>>>>> review, use, disclosure or distribution of this information is >>>>>> prohibited. If this was sent to you in error, please notify the sender >>>>>> by reply e-mail and destroy all copies of the original message. >>>>> >>>>> _______________________________________________ >>>>> For more information regarding industry leading CCIE Lab training, please >>>>> visit www.ipexpert.com >>>>> >>>>> Are you a CCNP or CCIE and looking for a job? Check out >>>>> www.PlatinumPlacement.com >>>>> >>> >>> > > > > End of CCIE_RS Digest, Vol 66, Issue 26 > *************************************** _______________________________________________ For more information regarding industry leading CCIE Lab training, please visit www.ipexpert.com Are you a CCNP or CCIE and looking for a job? Check out www.PlatinumPlacement.com UHS Confidentiality Notice: This e-mail message, including any attachments, is for the sole use of the intended recipient (s) and may contain confidential and privileged information. Any unauthorized review, use, disclosure or distribution of this information is prohibited. If this was sent to you in error, please notify the sender by reply e-mail and destroy all copies of the original message. _______________________________________________ For more information regarding industry leading CCIE Lab training, please visit www.ipexpert.com Are you a CCNP or CCIE and looking for a job? Check out www.PlatinumPlacement.com
