It's normal that many corporate entities want a redundant link nowadays certainly where I work, I agree is a waste of bandwidth depends on the SP contract though some only let you use active/standby with the given QoS contracts
in place of 2.use GLBP that way you ensure both are used links are used if you have redundant routers, that or consider multipath if using one router/ or PfR if using one or two routers with two exits. -- BR Tony Sent from my iPad > On 2 Jan 2014, at 18:10, "Ryanlk18 ." <[email protected]> wrote: > > If you only have 2 outbound connections to different ISPs, why do you need > to get the full routing table? I have 2 schools of thought on this one... > > 1. You could have 1 ISP as the primary and the second ISP as a backup. > This is a good option, but it means you have to spend money on a connection > that is rarely used. > > 2. You could do some route manipulation and send specific routes to each > ISP. For example you could send all your Odd routes to One and all your > Even routes to another. In order to ensure failover, you could use an > Advertise map with logic that will only advertise specific routes is the > link is operational, otherwise advertise all routes. > > If it were me, I would just use the second link as a backup or possibly if > you have a single system that is generating a large amount of traffic, > allow that traffic out over the second link. This way you can guarantee > certain applications bandwidth to the ISP. > > Sorry if this doesn't answer your question about the table size on a 2921, > but just thought I'd throw you my 2 cents. > > V/r, > > Ryan Krcelic > > > > On Thu, Jan 2, 2014 at 12:56 PM, 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 >> _______________________________________________ >> 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
