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Questions tagged [route-summarization]

For questions about route summarization, a method for collapsing multiple routes into a single route which covers all the collapsed routes.

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26 votes
7 answers
11k views

Does CIDR really "do away" with IP address classes?

I am still struggling to understand to what extent CIDR really renders IP address classes obsolete. Here's what I understood so far: It's ridiculously inefficient (and impossible, too) to assign ...
user avatar
10 votes
3 answers
4k views

3 subnets, 2 OSPF areas - Will This Work?

Will any issues occur if I have a topology involving 3 subnets and two OSPF areas where one subnet is in AREA 0 and the other two subnets are both in AREA 1? For example: [area 1, subnet 1]---[ABR #...
THE DOCTOR's user avatar
10 votes
2 answers
946 views

ipv6 Aggregatable global unicast addresses

Studying IPv6 addressing I haven't understood IPv6 aggregable global unicast addresses, I mean on RFC 4291 there is a generic scheme: | n bits | m bits | 128-n-m bits ...
abc's user avatar
  • 203
9 votes
2 answers
2k views

Why do summary routes get a low Administrative Distance?

Why do summary routes get a lower AD than other routing protocols? For example: The AD of EIGRP is 90, whereas the AD of a summary route is 5.
Abiral's user avatar
  • 489
5 votes
2 answers
2k views

Summarized route not being shared in EIGRP

Working through a lab for CCNP prep. Task is simple - create 4 loopback addresses on R3 - all 172.16.X.0/24 addresses, and share the routes to neighboring routers so that they appear as /22's instead....
A L's user avatar
  • 3,310
4 votes
1 answer
200 views

BGP | Advertise a summary prefix out to customer location

I don't know what I should be using for this or how I should go about it. In my lab where I am testing out the BGP configs that I've learned I want my ISP topology to have a summary prefix for the ...
Isaac Bill's user avatar
4 votes
1 answer
857 views

incorrect subnet mask for route summarization

I am learning about route summarization and how it represent different subnets with a single address and single subnet mask, for example, if i have two subnets, 10.1.1.0 10.1.2.0 The summarized ...
Riley Willow's user avatar
3 votes
2 answers
798 views

Why I Can't Summarize (aggregate) These Subnets in BGP router?

In a BGP routing context, giving these networks address: 192.168.0.0 /28 192.168.0.32 /28 For me, the summary address will be : 192.168.0.0 /26 But someone tells me that this is impossible because ...
Dimareal's user avatar
  • 133
2 votes
1 answer
364 views

Summarization on received Routes - BGP

We need to do Summarization on received Routes (as we are receiving 20K+ routes )to reduce load, saving memory, bandwidth, and CPU Cycle. Please suggest some quick and accurate methods to do. I m ...
engineerbaz's user avatar
2 votes
1 answer
1k views

Difference in VLSM and FLSM in Rute Summarisation

Is there any specific advantage that VLSM or FLSM has over the other when it comes to route summarization? I was of the opinion that neither had an advantage over the other when it came to route ...
Danis Fermi's user avatar
1 vote
2 answers
354 views

Summary address any technique? [duplicate]

I was answering some Summary Address questions, and one problem is this. 192.168.1.0 through 192.168.120.0. do I really need to one by one 1 to 120 convert them to binary and to find where is the ...
Scape Goat's user avatar
1 vote
3 answers
2k views

Summarize subnet from 4 ip addresses

I am trying to figure out how to summarize the subnet for ip route. I am following this information here... http://www.pearsonitcertification.com/articles/article.aspx?p=2169746&seqNum=7 It ...
Jack Hammer's user avatar
1 vote
1 answer
98 views

Cisco numeric EIGRP routing IP summarizing and routing

I have 2 routers connected via Serial 0/0/0 both running EIGRP with an ASN of 65000, and i want to advertise and summarize the interfaces, being just my loopbacks, and set the loopbacks as passive. ...
Edwin Martin's user avatar
1 vote
1 answer
63 views

EIGRP manual summarization prevent dual query

In EIGRP, manual summarization will prevent/ limit dual query. Is it true ? How can we limit the dual query by introducing manual summary ?
Sajith S.K's user avatar
1 vote
1 answer
223 views

Multicast summarization

I was wondering, does it make any sense to summarize(supernet) multicast IPv4 addresses ? Can anyone please explain why yes, or no ?
Emin Galić's user avatar
1 vote
3 answers
2k views

OSPF LSA type 3

This is what I know about LSA types from what I've learnt. LSA type 1 is circulated inside an area and doesn't get to other areas. LSA type 3 is sent from one area(From backbone to non-backbone and ...
RRHS's user avatar
  • 405
0 votes
1 answer
205 views

Doesn't OSPF Have Auto Summarization?

I asked AI if there is a command in OSPF for auto summarization like RIP and EIGRP. Here is the answer: "No, OSPF does not have a command like RIP and EIGRP that enables or disables automatic ...
Shadi's user avatar
  • 285
0 votes
1 answer
229 views

What's the point of aggregate routes when the default preference is reject?

studying for my JNCIS-SP and finally digging into the minutiae. I'm trying to grasp the default behavior of aggregate/summary routes. Why are these a reject? Maybe I'm just using them wrong, but here'...
scotho3's user avatar
0 votes
0 answers
24 views

Route summarization first IP address in block [duplicate]

I am not understanding how to determine the first network address or "first IP address of block" per Cisco Press documentation when summarizing routes/subnets. I am clear on how to get the ...
humbleStrength's user avatar
0 votes
0 answers
90 views

The Atomic Aggregate Attribute in BGP

I am trying to understand how the Atomic Aggregate attribute works in BGP. So if my understanding is correct, once we configure route summarization, the path attributes of those routes that we've ...
Mitrixsen's user avatar
  • 803
0 votes
0 answers
30 views

Conflicting opinions for route aggregation [duplicate]

I am a student and I came accross this question: An ABR in OSPF has in its range networks 10.0.8.9/24 to 10.0.21.0/24. how can it summarise the networks? not necessarily in one prefix. What we ve ...
riverwastaken's user avatar