Congratulations to Jamie McMickle, I'm sure we'd all like to pass our congratulations on, he has helped me with choosing my hardware choice so well done!!
BR Tony CCNP CCNA R&S MCSE JNCIA Sent from my iPhone on 3 On 2 May 2012, at 19:32, [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. Congrats to our new CCIE on the list! > (Edgar Mauricio Diaz Orellana) > 2. Re: iBgp vs eBgp path selection (Nick Bonifacio) > 3. Re: iBgp vs eBgp path selection (Bob McCouch) > 4. Re: iBgp vs eBgp path selection (Fulvio allegretti) > 5. Re: iBgp vs eBgp path selection (Bob McCouch) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Wed, 2 May 2012 14:01:43 -0400 > From: Edgar Mauricio Diaz Orellana <[email protected]> > To: [email protected] > Subject: [OSL | CCIE_RS] Congrats to our new CCIE on the list! > Message-ID: > <CAP_QRV7Q3cDd=nAMHF+6RjkDP=Lt0=9ovvopuwb1tae6buh...@mail.gmail.com> > Content-Type: text/plain; charset=ISO-8859-1 > > Congrats to our member Jay McMickle > > he pass their CCIE yesterday... so a big HURRAY to HIM and congrats > friend!!! > > > -- > > Edgar D?az Orellana > > > ------------------------------ > > Message: 2 > Date: Wed, 2 May 2012 11:10:31 -0700 (PDT) > From: Nick Bonifacio <[email protected]> > To: Christopher Lemish <[email protected]>, Jay McMickle > <[email protected]>, Bal Birdy <[email protected]> > Cc: "[email protected]" <[email protected]>, > Fulvio allegretti <[email protected]> > Subject: Re: [OSL | CCIE_RS] iBgp vs eBgp path selection > Message-ID: > <[email protected]> > Content-Type: text/plain; charset=iso-8859-1 > > Finally!? Thank you!!!! > > > > ________________________________ > From: Christopher Lemish <[email protected]> > To: Jay McMickle <[email protected]>; Bal Birdy <[email protected]> > Cc: "[email protected]" <[email protected]>; Fulvio > allegretti <[email protected]> > Sent: Wednesday, May 2, 2012 11:51 AM > Subject: Re: [OSL | CCIE_RS] iBgp vs eBgp path selection > > Thought I would add this one: > > > > We Love Oranges As Oranges Mean Pure Refreshment > > > > 1.? ? ? Weight > > 2.? ? ? Local Preference > > 3.? ? ? Originate > > 4.? ? ? AS > > 5.? ? ? Origin (IGP/EGP/i=incomplete) > > 6.? ? ? MED (lowest) > > 7.? ? ? Paths (External paths over Internal) > > 8.? ? ? Router ID > > > > Thank you, > > Chris > > > > > > > > > > > > -----Original Message----- > From: [email protected] > [mailto:[email protected]] On Behalf Of Jay McMickle > Sent: Tuesday, May 01, 2012 9:36 PM > To: Bal Birdy > Cc: [email protected]; Fulvio allegretti > Subject: Re: [OSL | CCIE_RS] iBgp vs eBgp path selection > > > > Great question! Here's the top 8 (it's all I can recall)- We Like Never See > Ladies Making Eggs Lately (sorry, it's the only way I could remember)- > > > > BGP pecking order: > > Weight > > Local-Pref > > Network statement or Aggregate > > Shortest AS Path > > Lowest Orig type (prefer eBGP) > > MED > > eBGP over iBGP > > Lowest IGP metric > > > > > > Regards, > > Jay McMickle- CCNP,CCSP,CCDP > > Sent from iJay > > > > On May 1, 2012, at 3:52 PM, Bal Birdy > <[email protected]<mailto:[email protected]>> wrote: > > > >> BGP Path decision process shows that weight is higher in the path > >> selection to the decision that says ebgp is preferred over ibgp. > >> > >> BGP is a tricky beast where the AD isn't chosen first, it's not a > >> traditional routing protocol more a path selection. Somebody correct > >> me if I'm wrong as I have my written exam soon and I'll have to go > >> back to the books !!!! > >> > >> B > >> > >> On Wed, May 2, 2012 at 7:11 AM, Fulvio allegretti > >> <[email protected]<mailto:[email protected]>>wrote: > >> > >>> > >>> Hi all, > >>> Doing lab 9 Volume 2 - Task 4.4, configure R6 such that if it learned > >>> the same route via eBGP, it would still prefer the same route it has > >>> from R2 (iBGP). For my little brain this was very clearly to do with > >>> distance, eBGP > >>> 20 - iBGP 200, change the distance for the eBGP peers the task refers > >>> to and job done. The solution suggests adjusting weight which has > >>> left me a bit confused, what do you think? I though that admin > >>> distance would be looked at before the path selection algorithm Using > >>> the same logic, why does step 7 of the algorithm uses eBGP and iBGP? > >>> Again, adming distance is different, so we shouldn't even start the > >>> path selection alogrithm. Unless the distance was changed manually I >>> suppose. > >>> Fulvio > >>> _______________________________________________ > >>> For more information regarding industry leading CCIE Lab training, > >>> please visit www.ipexpert.com<http://www.ipexpert.com> > >>> > >>> Are you a CCNP or CCIE and looking for a job? Check out > >>> www.PlatinumPlacement.com<http://www.PlatinumPlacement.com> > >>> > >>> http://onlinestudylist.com/mailman/listinfo/ccie_rs > >>> > >> _______________________________________________ > >> For more information regarding industry leading CCIE Lab training, > >> please visit www.ipexpert.com<http://www.ipexpert.com> > >> > >> Are you a CCNP or CCIE and looking for a job? Check out > >> www.PlatinumPlacement.com<http://www.PlatinumPlacement.com> > >> > >> http://onlinestudylist.com/mailman/listinfo/ccie_rs > > _______________________________________________ > > For more information regarding industry leading CCIE Lab training, please > visit www.ipexpert.com<http://www.ipexpert.com> > > > > Are you a CCNP or CCIE and looking for a job? Check out > www.PlatinumPlacement.com<http://www.PlatinumPlacement.com> > > > > http://onlinestudylist.com/mailman/listinfo/ccie_rs > _______________________________________________ > 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 > > http://onlinestudylist.com/mailman/listinfo/ccie_rs > > ------------------------------ > > Message: 3 > Date: Wed, 2 May 2012 14:16:17 -0400 > From: Bob McCouch <[email protected]> > To: Fulvio allegretti <[email protected]> > Cc: [email protected] > Subject: Re: [OSL | CCIE_RS] iBgp vs eBgp path selection > Message-ID: > <CAJFuDdZ68BxtYABvmgs6NWgrQ5Ovx22OkY_biiZuUc7qC=u...@mail.gmail.com> > Content-Type: text/plain; charset=ISO-8859-1 > > Hi Fulvio, > > Think of it the other direction. All the protocols converge internally and > use their internal algorithms to select its own best path to "offer" to the > IP routing table. Among all routes offered to the IP routing table, the > "best" one is then selected based on the AD of the protocol. > > In your example below, if the prefix is known via EIGRP, EBGP and IBGP, > EIGRP will offer a route for the IP routing table at an AD of 90. BGP will > go through it's process and if every other value is the same, eventually > the external path will be chosen over the internal one, which will then be > offered to the IP routing table. > > At that point, the IP routing selection process will pick the BGP route > (which happens to be an EBGP route in this case, with an AD of 20) over the > EIGRP route. > > If the route was only known via an IBGP path, it would be offered to the IP > routing table with an AD of 200, and then EIGRP would win instead (and BGP > would record a "RIB failure" for the route because it wasn't selected). > > Make sense? > > > > On Wed, May 2, 2012 at 6:43 AM, Fulvio allegretti > <[email protected]>wrote: > >> Thank Bob, >> >> OK that makes sense. I am familiar with BGP Best Path selection algorithm, >> but I thought it wouldn't even start the algorithm as AD are different, >> hence my second part of the question. But, as you say, admin >> distance is only taken into account to choose which routing protocol to use >> in the first place, then its down to the protocol algorithm. So, if we had >> a prefix known by igp, ebgp and ibgp and assuming default admin distance, >> the ebgp admin distance would make BGP the best routing protocol, but the >> path selection alogorithm could select the ibgp path due to a different >> parameter, local pref for example. How interesting. Thanks again Bob >> >> ------------------------------ >> From: [email protected] >> Date: Tue, 1 May 2012 21:27:45 -0400 >> Subject: Re: [OSL | CCIE_RS] iBgp vs eBgp path selection >> To: [email protected] >> >> >> Hi Fulvio, >> >> This matter took me a long time to really understand. Administrative >> distance is used only to select the best route among multiple protocols for >> installation into the routing table. Each protocol has it's own selection >> algorithm to identify the candidate route it is offering for selection by >> the IP routing table, at which point AD is used to select the best overall >> route. >> >> In other words, Admin Distance cannot be used to select a specific route >> *within* a protocol, only among all protocols that have the route. >> >> For example, EIGRP will always select Internal routes over External >> routes. Even if you set the AD for external routes to 1, if the best route >> to a destination prefix is learned as an EIGRP internal route, that one >> will be installed with the AD of 90. AD doesn't matter when selecting >> *which* EIGRP route will be used, only when selecting EIGRP vs. another >> protocol. >> >> Likewise, OSPF will always select O, the O IA, then E1/N1, then E2/N2. >> Can't be changed (as far as I know). But then whichever route is selected >> will be installed in the IP routing table with a (default) AD of 110. >> >> For BGP, consult this: >> http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080094431.shtml >> >> See Step 7. BGP External routes will always be chosen over Internal, all >> other values in steps 1-6 being equal. Unlike most other protocols, BGP has >> knobs that can be used to tune route selection before getting to Step 7. >> That's where weight, local preference, etc. come in. >> >> It took me a long time to wrap my brain around this. AD has nothing to do >> with intra-protocol route selection. >> >> Hope this helps, >> Bob >> >> >> >> On Tue, May 1, 2012 at 5:11 PM, Fulvio allegretti <[email protected] >>> wrote: >> >> >> Hi all, >> Doing lab 9 Volume 2 - Task 4.4, configure R6 such that if it learned the >> same route via eBGP, it would still prefer the same route it has from R2 >> (iBGP). For my little brain this was very clearly to do with distance, eBGP >> 20 - iBGP 200, change the distance for the eBGP peers the task refers to >> and job done. The solution suggests adjusting weight which has left me a >> bit confused, what do you think? I though that admin distance would be >> looked at before the path selection algorithm >> Using the same logic, why does step 7 of the algorithm uses eBGP and iBGP? >> Again, adming distance is different, so we shouldn't even start the path >> selection alogrithm. Unless the distance was changed manually I suppose. >> Fulvio >> _______________________________________________ >> 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 <http://www.platinumplacement.com/> >> >> http://onlinestudylist.com/mailman/listinfo/ccie_rs >> >> >> > > > ------------------------------ > > Message: 4 > Date: Wed, 2 May 2012 18:27:24 +0000 > From: Fulvio allegretti <[email protected]> > To: <[email protected]> > Cc: [email protected] > Subject: Re: [OSL | CCIE_RS] iBgp vs eBgp path selection > Message-ID: <[email protected]> > Content-Type: text/plain; charset="iso-8859-1" > > > Ok, I see, so if through the internal alogrithm iBGP wins, because of local > pref for example, then the iBGP will be offered to the IP routing table and > the EIGRP would be selected in your example. Great stuff. Thanks > > > > From: [email protected] > Date: Wed, 2 May 2012 14:16:17 -0400 > Subject: Re: [OSL | CCIE_RS] iBgp vs eBgp path selection > To: [email protected] > CC: [email protected] > > Hi Fulvio, > > > Think of it the other direction. All the protocols converge internally and > use their internal algorithms to select its own best path to "offer" to the > IP routing table. Among all routes offered to the IP routing table, the > "best" one is then selected based on the AD of the protocol. > > > In your example below, if the prefix is known via EIGRP, EBGP and IBGP, EIGRP > will offer a route for the IP routing table at an AD of 90. BGP will go > through it's process and if every other value is the same, eventually the > external path will be chosen over the internal one, which will then be > offered to the IP routing table. > > > At that point, the IP routing selection process will pick the BGP route > (which happens to be an EBGP route in this case, with an AD of 20) over the > EIGRP route. > > > If the route was only known via an IBGP path, it would be offered to the IP > routing table with an AD of 200, and then EIGRP would win instead (and BGP > would record a "RIB failure" for the route because it wasn't selected). > > > Make sense? > > > > > > On Wed, May 2, 2012 at 6:43 AM, Fulvio allegretti <[email protected]> > wrote: > > > > Thank Bob, > > OK that makes sense. I am familiar with BGP Best Path selection algorithm, > but I thought it wouldn't even start the algorithm as AD are different, hence > my second part of the question. But, as you say, admin distance is only taken > into account to choose which routing protocol to use in the first place, then > its down to the protocol algorithm. So, if we had a prefix known by igp, ebgp > and ibgp and assuming default admin distance, the ebgp admin distance would > make BGP the best routing protocol, but the path selection alogorithm could > select the ibgp path due to a different parameter, local pref for example. > How interesting. Thanks again Bob > > > > > > > > From: [email protected] > Date: Tue, 1 May 2012 21:27:45 -0400 > Subject: Re: [OSL | CCIE_RS] iBgp vs eBgp path selection > To: [email protected] > > > > Hi Fulvio, > > > This matter took me a long time to really understand. Administrative distance > is used only to select the best route among multiple protocols for > installation into the routing table. Each protocol has it's own selection > algorithm to identify the candidate route it is offering for selection by the > IP routing table, at which point AD is used to select the best overall route. > > > In other words, Admin Distance cannot be used to select a specific route > *within* a protocol, only among all protocols that have the route. > > > For example, EIGRP will always select Internal routes over External routes. > Even if you set the AD for external routes to 1, if the best route to a > destination prefix is learned as an EIGRP internal route, that one will be > installed with the AD of 90. AD doesn't matter when selecting *which* EIGRP > route will be used, only when selecting EIGRP vs. another protocol. > > > Likewise, OSPF will always select O, the O IA, then E1/N1, then E2/N2. Can't > be changed (as far as I know). But then whichever route is selected will be > installed in the IP routing table with a (default) AD of 110. > > > For BGP, consult this: > http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080094431.shtml > > > See Step 7. BGP External routes will always be chosen over Internal, all > other values in steps 1-6 being equal. Unlike most other protocols, BGP has > knobs that can be used to tune route selection before getting to Step 7. > That's where weight, local preference, etc. come in. > > > It took me a long time to wrap my brain around this. AD has nothing to do > with intra-protocol route selection. > > > Hope this helps, > Bob > > > > > > > On Tue, May 1, 2012 at 5:11 PM, Fulvio allegretti <[email protected]> > wrote: > > > Hi all, > Doing lab 9 Volume 2 - Task 4.4, configure R6 such that if it learned the > same route via eBGP, it would still prefer the same route it has from R2 > (iBGP). For my little brain this was very clearly to do with distance, eBGP > 20 - iBGP 200, change the distance for the eBGP peers the task refers to and > job done. The solution suggests adjusting weight which has left me a bit > confused, what do you think? I though that admin distance would be looked at > before the path selection algorithm > Using the same logic, why does step 7 of the algorithm uses eBGP and iBGP? > Again, adming distance is different, so we shouldn't even start the path > selection alogrithm. Unless the distance was changed manually I suppose. > Fulvio > _______________________________________________ > 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 > > http://onlinestudylist.com/mailman/listinfo/ccie_rs > > > > > ------------------------------ > > Message: 5 > Date: Wed, 2 May 2012 14:31:53 -0400 > From: Bob McCouch <[email protected]> > To: Fulvio allegretti <[email protected]> > Cc: [email protected] > Subject: Re: [OSL | CCIE_RS] iBgp vs eBgp path selection > Message-ID: > <CAJFuDdaCZj6n6K=h_nkidmatxmwrtpyoscd59vjzq-n3rbw...@mail.gmail.com> > Content-Type: text/plain; charset=ISO-8859-1 > > You got it! If the IBGP route is forced via weight, local preference, > origin code manipulation, etc., it would become the best BGP path to the > target, but still lose out to the EIGRP route for insertion into the IP > routing table. > > And remember, AD *only* comes in to play if multiple protocols are offering > the exact same prefix for insertion into the IP routing table. For routes > with different destination prefix lengths, the most specific prefix will > always win, every time, no exceptions. (OK, unless you override that with > PBR/PfR!) > > > On Wed, May 2, 2012 at 2:27 PM, Fulvio allegretti > <[email protected]>wrote: > >> Ok, I see, so if through the internal alogrithm iBGP wins, because of >> local pref for example, then the iBGP will be offered to the IP routing >> table and the EIGRP would be selected in your example. Great stuff. Thanks >> ------------------------------ >> From: [email protected] >> Date: Wed, 2 May 2012 14:16:17 -0400 >> >> Subject: Re: [OSL | CCIE_RS] iBgp vs eBgp path selection >> To: [email protected] >> CC: [email protected] >> >> >> Hi Fulvio, >> >> Think of it the other direction. All the protocols converge internally and >> use their internal algorithms to select its own best path to "offer" to the >> IP routing table. Among all routes offered to the IP routing table, the >> "best" one is then selected based on the AD of the protocol. >> >> In your example below, if the prefix is known via EIGRP, EBGP and IBGP, >> EIGRP will offer a route for the IP routing table at an AD of 90. BGP will >> go through it's process and if every other value is the same, eventually >> the external path will be chosen over the internal one, which will then be >> offered to the IP routing table. >> >> At that point, the IP routing selection process will pick the BGP route >> (which happens to be an EBGP route in this case, with an AD of 20) over the >> EIGRP route. >> >> If the route was only known via an IBGP path, it would be offered to the >> IP routing table with an AD of 200, and then EIGRP would win instead (and >> BGP would record a "RIB failure" for the route because it wasn't selected). >> >> Make sense? >> >> >> >> On Wed, May 2, 2012 at 6:43 AM, Fulvio allegretti <[email protected] >>> wrote: >> >> Thank Bob, >> >> OK that makes sense. I am familiar with BGP Best Path selection algorithm, >> but I thought it wouldn't even start the algorithm as AD are different, >> hence my second part of the question. But, as you say, admin >> distance is only taken into account to choose which routing protocol to use >> in the first place, then its down to the protocol algorithm. So, if we had >> a prefix known by igp, ebgp and ibgp and assuming default admin distance, >> the ebgp admin distance would make BGP the best routing protocol, but the >> path selection alogorithm could select the ibgp path due to a different >> parameter, local pref for example. How interesting. Thanks again Bob >> >> ------------------------------ >> From: [email protected] >> Date: Tue, 1 May 2012 21:27:45 -0400 >> Subject: Re: [OSL | CCIE_RS] iBgp vs eBgp path selection >> To: [email protected] >> >> >> Hi Fulvio, >> >> This matter took me a long time to really understand. Administrative >> distance is used only to select the best route among multiple protocols for >> installation into the routing table. Each protocol has it's own selection >> algorithm to identify the candidate route it is offering for selection by >> the IP routing table, at which point AD is used to select the best overall >> route. >> >> In other words, Admin Distance cannot be used to select a specific route >> *within* a protocol, only among all protocols that have the route. >> >> For example, EIGRP will always select Internal routes over External >> routes. Even if you set the AD for external routes to 1, if the best route >> to a destination prefix is learned as an EIGRP internal route, that one >> will be installed with the AD of 90. AD doesn't matter when selecting >> *which* EIGRP route will be used, only when selecting EIGRP vs. another >> protocol. >> >> Likewise, OSPF will always select O, the O IA, then E1/N1, then E2/N2. >> Can't be changed (as far as I know). But then whichever route is selected >> will be installed in the IP routing table with a (default) AD of 110. >> >> For BGP, consult this: >> http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080094431.shtml >> >> See Step 7. BGP External routes will always be chosen over Internal, all >> other values in steps 1-6 being equal. Unlike most other protocols, BGP has >> knobs that can be used to tune route selection before getting to Step 7. >> That's where weight, local preference, etc. come in. >> >> It took me a long time to wrap my brain around this. AD has nothing to do >> with intra-protocol route selection. >> >> Hope this helps, >> Bob >> >> >> >> On Tue, May 1, 2012 at 5:11 PM, Fulvio allegretti <[email protected] >>> wrote: >> >> >> Hi all, >> Doing lab 9 Volume 2 - Task 4.4, configure R6 such that if it learned the >> same route via eBGP, it would still prefer the same route it has from R2 >> (iBGP). For my little brain this was very clearly to do with distance, eBGP >> 20 - iBGP 200, change the distance for the eBGP peers the task refers to >> and job done. The solution suggests adjusting weight which has left me a >> bit confused, what do you think? I though that admin distance would be >> looked at before the path selection algorithm >> Using the same logic, why does step 7 of the algorithm uses eBGP and iBGP? >> Again, adming distance is different, so we shouldn't even start the path >> selection alogrithm. Unless the distance was changed manually I suppose. >> Fulvio >> _______________________________________________ >> 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 <http://www.platinumplacement.com/> >> >> http://onlinestudylist.com/mailman/listinfo/ccie_rs >> >> >> >> > > > End of CCIE_RS Digest, Vol 76, Issue 4 > ************************************** _______________________________________________ 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 http://onlinestudylist.com/mailman/listinfo/ccie_rs
