The Long and Winding Road wrote: > > ""Jenny McLeod"" wrote in message > news:200210280429.EAA24675@;groupstudy.com... > > The Long and Winding Road wrote: > > [snipped] > > > > area 0 range 172.16.1.0 255.255.255.0 area not working on > ABR > > > either > > > > > > > > > > CL: well, area 0 range is an illegal command. you may be > able > > > to enter it, > > > but it does nothing. the area range command is design to > > > summarize non > > > backbone routes into the backbone. if you think aout it, > there > > > is probably > > > not a real good reaso for backbone routes to be summarized > > > > > > > > JMcL: Since when?? > > I use the area 0 range blah blah command (without the "area" > at the end, > if > > that was supposed to be part of the command above), and it > certainly > doesn't > > do nothing. As far as I've seen, it works in exactly the > same way as area > > anything else range blah blah. > > > All right, Miss Smarty Pants. I don't know what IOS versions > you use / have > been using, but I have been through this song and dance with > OSPF area 0 > summarization, or lack thereof for a while now. I have yet to > see it work. > > Seriously, Jen, you know I respect your wisdom and value your > advice. I am > absolutely certain that I have never successfuly summarized > area 0 routes > over a couple of years of lab rat living. The following is from > my current > study pod, and the IOS version is 12.1.5T10. > > First, router 1 configurations. There are a number of > loopbacks,containing > the route addresses in question. > JMcL: Are any of the relevant routes being redistributed from RIP, or are the relevant bits pure OSPF?
> router ospf 123 > log-adjacency-changes > area 0 range 100.100.0.0 255.255.240.0 > redistribute rip subnets route-map rip2ospf > network 99.99.99.1 0.0.0.0 area 51 > network 100.100.0.1 0.0.0.0 area 0 > network 100.100.1.1 0.0.0.0 area 0 > network 100.100.2.1 0.0.0.0 area 0 > network 100.100.3.1 0.0.0.0 area 0 > network 100.100.4.1 0.0.0.0 area 0 > network 100.100.5.1 0.0.0.0 area 0 > network 100.100.6.1 0.0.0.0 area 0 > network 100.100.7.1 0.0.0.0 area 0 > network 160.160.255.0 0.0.0.255 area 0 > > note the summary in the R1 routing table: > > Gateway of last resort is not set > > 100.0.0.0/8 is variably subnetted, 9 subnets, 2 masks > O 100.100.0.0/20 is a summary, 00:11:57, Null0 > > now observe router 2's table: > > 100.0.0.0/24 is subnetted, 8 subnets JMcL: Interesting line above. You sure that's what it said? > O 100.100.0.0 [110/26] via 160.160.255.1, 00:12:53, > TokenRing0 > O 100.100.1.0 [110/26] via 160.160.255.1, 00:12:53, > TokenRing0 > O 100.100.2.0 [110/26] via 160.160.255.1, 00:12:53, > TokenRing0 > O 100.100.3.0 [110/26] via 160.160.255.1, 00:12:53, > TokenRing0 > O 100.100.4.0 [110/26] via 160.160.255.1, 00:12:53, > TokenRing0 > O 100.100.5.0 [110/26] via 160.160.255.1, 00:12:53, > TokenRing0 > O 100.100.6.0 [110/26] via 160.160.255.1, 00:12:54, > TokenRing0 > O 100.100.7.0 [110/26] via 160.160.255.1, 00:12:54, > TokenRing0 > 99.0.0.0/32 is subnetted, 1 subnets > > This has remained constant through several reconfigurations and > several ospf > process resets. > JMcL: I'm not quite clear on your setup. Pick me up if I go wrong here. R1 and R2 are connected by 160.160.255.0/24, yes? 160.160.255.0/24 is in area 0, yes? So R2 is also in area 0, yes? So why are you expecting that the backbone routes will have been summarised? You haven't left the backbone yet - you haven't crossed an area boundary (referring to the quote below). What happens if you connect R1 and R2 by a non-backbone link? > It also remain true even if on R1 I use a more generic network > 100.100.0.0 > 0.0.255.255 area 0 command. > > So........ > > I stand by my statement that even though you may be able to > enter the > commands, the fact is that you cannot summarize area 0 routes > on a cisco > router, at least not that I've been able to figure out.. My > position is > further supported by the Cisco documentation, which states "The > area range > command is used only with area border routers (ABRs). It is > used to > consolidate or summarize routes for an area. The result is that > a single > summary route is advertised to other areas by the ABR. Routing > information > is condensed at area boundaries." > Sorry - how does this say that you can't summarise in either direction? I don't see how it backs up your position. > http://www.cisco.com/univercd/cc/td/doc/product/software/ios121/121cgcr/ip_r > /iprprt2/1rdospf.htm#xtocid4 > watch the wrap > > Of course, I am ready to learn something new, if you've got a > trick I have > yet to learn. > > > > > Why not summarise backbone routes for the same reasons as > summarising > > non-backbone routes - reduce routing tables, database sizes, > route change > > propagations etc? > > In regards to the wisdom of summarizing backbone routes in an > OSPF network, > while I was pondering your response, I went through a few > ideas, and I see > where it "might" be advantageous.. I still believe that > generally speaking, > one would want all backbone routes to be visible throughout the > backbone to > allow for uninterrupted routing should one or more backbone > routers fail. > This assuming a redundant backbone design. > > I can't located specifics in the RFC, but I "suspect" that Mr. > Moy is of > similar mind. > > JMcL: Obviously this would depend on network design - I'm certainly not arguing that summarising backbone routes would be advantageous (or even non-harmful) in all cases. > with all respects > > Chuck > -- And you know I respect your opinions too, Chuck. But with all the respect in the world, I still reckon you're wrong on this one, because just last week I had to deal with a problem caused because I'd forgotten to put some area 0 range statements on an ABR. I have used area 0 range statements on IOS 11.2, and 12.1, at least. And probably 10.3 - can't remember when we started summarising. Excerpt of config on ABR... area 0 range 1.4.0.0 255.255.0.0 area 0 range 1.5.0.0 255.255.0.0 area 0 range 1.6.0.0 255.255.0.0 area 4.1.0.0 range 4.0.0.0 255.128.0.0 network 1.0.0.0 0.255.255.255 area 0 excerpt of routes from ABR... O 1.5.0.0/16 is a summary, 00:32:13, Null0 C 1.4.1.0/24 is directly connected, Serial1/0.1 C 1.4.0.1/32 is directly connected, Loopback0 O 1.6.0.2/32 [110/2006] via 1.4.1.1, 00:32:13, Serial1/0.1 O 1.5.1.0/24 [110/2000] via 1.4.1.1, 00:32:30, Serial1/0.1 O 1.5.0.1/32 [110/2001] via 1.4.1.1, 00:32:30, Serial1/0.1 O 1.4.0.0/16 is a summary, 00:32:30, Null0 O 1.6.1.0/24 [110/2000] via 1.4.1.1, 00:32:30, Serial1/0.1 O 1.6.0.1/32 [110/2001] via 1.4.1.1, 00:32:30, Serial1/0.1 O 1.5.0.2/32 [110/2006] via 1.4.1.1, 00:32:31, Serial1/0.1 O 1.6.0.0/16 is a summary, 00:32:31, Null0 O 1.4.0.2/32 [110/6] via 1.4.100.2, 00:32:31, Ethernet0/0/0 excerpt of routes from a (non-ABR) router in area 4.1.0.0... 1.0.0.0/8 is variably subnetted, 66 subnets, 4 masks O IA 1.5.0.0/16 [110/2520] via 4.100.1.1, 07:50:41, Serial0.1 O IA 1.4.0.0/16 [110/521] via 4.100.1.1, 07:50:41, Serial0.1 O IA 1.6.0.0/16 [110/2520] via 4.100.1.1, 07:50:41, Serial0.1 No subnets of the above summaries show up on the 4.1.0.0 router. JMcL > > > > > > > JMcL > > Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=56433&t=56136 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
