We're OT on an OT thread, but I'll throw in my 2 cents as the dissenting opinion here. I think full tables with just two ISP connections is quite reasonable and I do it regularly with my customers. Most prefer optimal routing and having more bandwidth in the nominal state with the understanding that they could have performance degradation in the event one ISP link fails. Depends on the customer's situation, I suppose, but generally for a monthly-fee resource like Internet access, my customers hate the idea of getting no use out of the backup link and would prefer to get value from that additional resource when it's operational. You just have to monitor overall usage and make sure you don't get *way* out of whack like averaging 90 Mb/s with 2 50 Mb/s feeds.
Any half-decent modern router (1900 and up) will easily swallow and process 2 full tables with minimal CPU impact and just a small RAM upgrade (which are finally priced at a tolerable level). I have a pair of 1941's at a customer's colo in NYC eating full tables from two ISPs and sure, CPU spikes to 100% for a few seconds if a BGP peer actually bounces, but processing the normal ongoing table churn barely impacts the CPU, if at all. And with 1GB of RAM, there is no problem on the memory side either. Saying it is "too much work" for a router was accurate in the 2500/2600 era. IMO it is not a concern now. Ryan J., do be aware that any time you have two BGP connected ISP links, you may experience asymmetric routing where a request could come in your Verizon link and the best path to return may still be out your other ISP link. The only way to *guarantee* you don't have the potential for symmetric routing would actually be something like setting LP on your preferred outbound connection and using BGP conditional advertisement to only even originate your prefix out the backup ISP if the primary ISP goes away. You *may* be able to force your backup ISP to deprefer your advertisement to them using community values to tamp down the local preference on their side, but not all ISPs support that or respect it in all cases. I'll get off my soapbox and shut up now :-) Bob McCouch CCIE #38296 HerdingPackets.net On Thu, Jan 2, 2014 at 2:14 PM, Ryanlk18 . <[email protected]> wrote: > Hi Ryan, > > > I get what you are trying to do, but from an efficiency standpoint, unless > you have an application that has problems with microseconds of delay from > routing inside the ISP cloud, or you have documented delays from traffic > having to traverse the ISP, I would not really worry about that problem. > Pulling down the entire Routing table from 2 different ISPs is a big task > and not something that is typically done from a non-ISP. > > Your ISPs should be efficient enough to route packets to each other with a > very very small amount of delay. Especially if you are connecting to 2 > different ISPs that are in the same vacinity(city). If you were connecting > to an ISP in the US and a different ISP in Europe or Asia, and you had a > lot of people that were connecting from those different locations, then > maybe I could see doing that, but the amount of processing that will have > to take place on your router holding the entire internet routing table will > only increase the amount of delay required to route the packet. > > Active/Standby is the best route in my opinion simply because when you > start sending traffic over different links into different ISP clouds, it > can make it difficult to troubleshoot if there is a problem, unless you are > doing something like odd even or something that is easily recognizable. > > V/r, > > Ryan Krcelic > > > > On Thu, Jan 2, 2014 at 2:00 PM, Ryan Jensen <[email protected]> wrote: > > > Thanks for the feedback everyone. > > To answer Ryan's question about WHY is that I was thinking about this: > > With my dual connections now, they're Active/Standby, but I was thinking > if > > a member accessing one of our web apps has the same ISP as we do, we > could > > route more directly. I.E. Member accesses app and they're on Verizon, > > request could come in Verizon connection and be routed back out that > > connection even though our default route was pointing out the other ISP. > > Unless I'm mistaken, wouldn't I need full tables to do this? > > I have no qualms with Active/Standby, but would just prefer to route > > optimally if possible. Does this make sense or am I off-base here? I'm > not > > too familiar with how other people would implement this. > > These routers don't implement any other services other than routing with > > very course edge-filtering and Netflow. They just sit outside the > firewalls > > and peer with ISP. There's no QoS, NAT, IPS, Multicast, etc ,etc. > > > > > > On Thu, Jan 2, 2014 at 1:39 PM, Tony Singh <[email protected]> > wrote: > > > > > > > > I had an alarm on an ASR1002 in one of our sites in Australia can't > > recall > > > but it was a known bug, something like punt_linux on the NMS screen > when > > I > > > contacted TAC just acknowledged it, free memory was sufficient enough > > though > > > > > > The memory architecture on these beasts is complex and depends on > models > > > and the line cards installed as you have RP's per line card then the > > memory > > > is shared and protected in case one process fails which means the whole > > > router does not die as what were used to in regular routers.. > > > > > > -- > > > BR > > > > > > Tony > > > > > > Sent from my iPad > > > > > > > On 2 Jan 2014, at 18:03, marc abel <[email protected]> wrote: > > > > > > > > Slightly OT, but has anyone had any memory issues with ASR 1K's? I've > > run > > > > into memory issues on two different one taking two full BGP feeds. > One > > > > would think that these size routers should be able to handle 2 full > > feeds > > > > as that seems like exactly what they are designed for. > > > > > > > > > > > > On Thu, Jan 2, 2014 at 11:56 AM, Edgar Mauricio Diaz Orellana < > > > > [email protected]> wrote: > > > > > > > >> Greetings Ryan. > > > >> > > > >> there is a memory sizing table on the BGP Design and Implementation > > > Book, > > > >> As my mind recalls, as much memory as you can take on your router is > > > >> better, but my worries are the CPU to handle all the BGP Table. > > > >> > > > >> did your ISP put limit on the prefixes lenght push to your peer ?, > did > > > you > > > >> think put the prefix limit on your side ? > > > >> > > > >> a good reading on that is "ISP Essentials" and the "BGP Design and > > > >> Implementation" both from CiscoPress > > > >> > > > >> Best Regards. > > > >> > > > >> > > > >>> On Thu, Jan 2, 2014 at 1:12 PM, marc abel <[email protected]> > > wrote: > > > >>> > > > >>> You do not need BGP soft-reconfiguration as of IOS 12.0 so that > > should > > > >>> save > > > >>> you some memory. > > > >>> > > > >>> > > > >>> > > > > > > http://www.cisco.com/en/US/products/ps6599/products_data_sheet09186a0080087b3a.html > > > >>> > > > >>> Previously, in order to perform a soft reset for inbound routing > > table > > > >>> updates, the neighbor soft-reconfiguration command directed the > Cisco > > > IOS > > > >>> software in the local BGP router to store all received (inbound) > > > routing > > > >>> policy updates without modification. This method is > memory-intensive > > > and > > > >>> not recommended unless absolutely necessary. (Outbound updates have > > > never > > > >>> required the extra memory and are not affected by this feature.) > > > >>> > > > >>> With this software release, the BGP Soft Reset Enhancement feature > > > >>> provides > > > >>> automatic support for dynamic soft reset of inbound BGP routing > table > > > >>> updates that is not dependent upon stored routing table update > > > >>> information. > > > >>> The new method requires no preconfiguration (as with the neighbor > > > >>> soft-reconfiguration command) and requires much less memory than > the > > > >>> previous soft reset method for inbound routing table updates. > > > >>> > > > >>> > > > >>>> On Thu, Jan 2, 2014 at 9:51 AM, Ryan Jensen <[email protected]> > > wrote: > > > >>>> > > > >>>> Morning! > > > >>>> I have an OT question... > > > >>>> I have two 40mbps internet connections from the same ISP today, > each > > > one > > > >>>> runs into a 2921 router. I receive a default route via eBGP with > ISP > > > and > > > >>>> the two routers peer via iBGP with each other. I'm going to be > > > dropping > > > >>> one > > > >>>> internet connection soon and picking up a second ISP, same > > bandwidth. > > > >>> We're > > > >>>> just doing this to diversify. > > > >>>> Question is: Would the 2921s have enough resources to accept full > > > >>> internet > > > >>>> tables from each ISP? > > > >>>> The way I look at it, each router would store the BGP table from > the > > > >>> ISP, > > > >>>> and also store the table from its iBGP peer... with > > > soft-reconfiguration > > > >>>> enabled, It then stores a second copy of each peer's updates. > > > Basically > > > >>>> requiring the router to store the entire internet BGP table 4 > > times... > > > >>> Am I > > > >>>> looking at this correctly? > > > >>>> > > > >>>> I know my current ISP has an option for them to advertise their > > > >>> originated > > > >>>> routes (core routes) and a default, so that would significantly > > > decrease > > > >>>> the update size from that peer, but I don't know if my incoming > ISP > > > has > > > >>>> that option. > > > >>>> > > > >>>> Routers are default hardware spec, 1g RAM, 256mb Flash > > > >>>> IOS 15.2(4)M3 > > > >>>> > > > >>>> Thoughts?? > > > >>>> _______________________________________________ > > > >>>> Free CCIE R&S, Collaboration, Data Center, Wireless & Security > > Videos > > > :: > > > >>>> > > > >>>> iPexpert on YouTube: www.youtube.com/ipexpertinc > > > >>> > > > >>> > > > >>> > > > >>> -- > > > >>> Marc Abel > > > >>> CCIE #35470 > > > >>> (Routing and Switching) > > > >>> _______________________________________________ > > > >>> Free CCIE R&S, Collaboration, Data Center, Wireless & Security > Videos > > > :: > > > >>> > > > >>> iPexpert on YouTube: www.youtube.com/ipexpertinc > > > >> > > > >> > > > >> > > > >> -- > > > >> > > > >> Edgar Díaz Orellana > > > >> CCENT/CCNA/CCDA/CCNA Security, CCNP, CCNP Security en progreso. > > > >> Kaspersky Administrator / Technical Specialist > > > >> Microsoft Certified Professional. > > > >> Celular : 09-91283087 / 09-94118996 > > > >> skype: eorellan1969 > > > > > > > > > > > > -- > > > > Marc Abel > > > > CCIE #35470 > > > > (Routing and Switching) > > > > _______________________________________________ > > > > Free CCIE R&S, Collaboration, Data Center, Wireless & Security Videos > > :: > > > > > > > > iPexpert on YouTube: www.youtube.com/ipexpertinc > > > _______________________________________________ > > > Free CCIE R&S, Collaboration, Data Center, Wireless & Security Videos > :: > > > > > > iPexpert on YouTube: www.youtube.com/ipexpertinc > > > > > _______________________________________________ > > Free CCIE R&S, Collaboration, Data Center, Wireless & Security Videos :: > > > > iPexpert on YouTube: www.youtube.com/ipexpertinc > > > _______________________________________________ > Free CCIE R&S, Collaboration, Data Center, Wireless & Security Videos :: > > iPexpert on YouTube: www.youtube.com/ipexpertinc > _______________________________________________ Free CCIE R&S, Collaboration, Data Center, Wireless & Security Videos :: iPexpert on YouTube: www.youtube.com/ipexpertinc
