On Tue, Jun 10, 2014 at 11:36 AM, Blake Hudson <bl...@ispn.net> wrote:
> > joel jaeggli wrote the following on 6/10/2014 1:10 PM: > > On 6/10/14, 10:39 AM, Blake Hudson wrote: >> >>> Łukasz Bromirski wrote the following on 6/10/2014 12:15 PM: >>> >>>> Hi Blake, >>>> >>>> On 10 Jun 2014, at 19:04, Blake Hudson <bl...@ispn.net> wrote: >>>> >>>> In this case, does the 512k limit of the 6500/7600 refer to the RIB >>>>> or the FIB? And does it even matter since the BGP prefix table can >>>>> automatically be reduced to ~300k routes? >>>>> >>>> Te 512k limit refers to FIB in the B/C (base) versions of 6500/7600 >>>> Supervisors and DFCs (for line cards). BXL/CXL versions have FIB for >>>> 1M IPv4 prefixes. >>>> >>>> You can find more information here: >>>> >>>> http://www.cisco.com/c/en/us/support/docs/switches/ >>>> catalyst-6500-series-switches/117712-problemsolution-cat6500-00.html >>>> >>>> >>>> And yes, you’re right - no matter how many neighbors you have, the FIB >>>> will only contain best paths, so it will be closer to 500k entries in >>>> total rather than N times number of neighbours. >>>> >>>> Please correct me if I'm wrong, but if the BGP table contains ~500k >>> prefixes, which are then summarized into ~300k routes (RIB), >>> >> Unlikely, just because prefixes could be cidr aggregated doesn't mean >> they are. the more specifics exist for a reason, in the case of >> deaggrates with no covering anouncement, well not much you're doing with >> those. >> >> your rib should be the sum of all received routes that you did not filter. >> > On the couple Cisco platforms I have available with full tables, Cisco > summarizes BGP by default. Since this thread is talking about Cisco gear, I > think it's more topical than results from BIRD. > > One example from a non-transit AS: > ASR#sh ip route sum > IP routing table name is default (0x0) > > IP routing table maximum-paths is 32 > Route Source Networks Subnets Replicates Overhead Memory > (bytes) > connected 0 10 0 600 1800 > static 1 2 0 180 540 > application 0 0 0 0 0 > bgp xxxxx 164817 330796 0 29736780 89210340 > External: 495613 Internal: 0 Local: 0 > internal 5799 20123680 > Total 170617 330808 0 29737560 109336360 > > I'm not sure you're reading that correctly. 164817+330796 = 495613 That is, the BGP routing table size is the union of the "Networks" and the "Subnets"; it's not magically doing any summarization for you. Matt