Route summarization

bornwithbornwith Member Posts: 21 ■■□□□□□□□□
I am trying to summarize two networks and create a static route.

The networks are

172.16.3.0 /24 and 172.16.4.0/24

i summarized them as 172.16.3.0/23.

But it when I try to create the static route I get an error.

iP route 172.16.3.0 255.255.254.0 201.10.4.9

i get an Inconsistent address and mask error.

I can create individual routes for each of the /24 network without a problem.

I am using PT 7.2

TIA

Comments

  • OfWolfAndManOfWolfAndMan Member Posts: 923 ■■■■□□□□□□
    That's because your subnetting is off. Remember that each byte starts at 0, not 1. Therefore, using a 255.255.254.0 mask, your subnet ranges would look like this:
    -172.16.0.0/23
    -172.16.2.0/23

    Its best to use two /24s in this situation. You could use a /21, but not recommended in real life. Here's what the configs should look like:
    -Option 1: create two separate routes:
    ip route 172.16.3.0 255.255.255.0 201.10.4.9
    ip route 172.16.4.0 255.255.255.0 201.10.4.9
    -Option 2: create aggregate address and catch unavailable prefixes at next hop with bit bucket:
    ip route 172.16.0.0 255.255.248.0 201.10.4.9
    (At the next hop router, 201.10.4.9)
    ip route 172.16.0.0 255.255.248.0 null0

    hope that helped.
    :study:Reading: Lab Books, Ansible Documentation, Python Cookbook 2018 Goals: More Ansible/Python work for Automation, IPSpace Automation Course [X], Build Jenkins Framework for Network Automation []
  • bornwithbornwith Member Posts: 21 ■■□□□□□□□□
    That's because your subnetting is off. Remember that each byte starts at 0, not 1. Therefore, using a 255.255.254.0 mask, your subnet ranges would look like this:
    -172.16.0.0/23
    -172.16.2.0/23

    Its best to use two /24s in this situation. You could use a /21, but not recommended in real life. Here's what the configs should look like:
    -Option 1: create two separate routes:
    ip route 172.16.3.0 255.255.255.0 201.10.4.9
    ip route 172.16.4.0 255.255.255.0 201.10.4.9
    -Option 2: create aggregate address and catch unavailable prefixes at next hop with bit bucket:
    ip route 172.16.0.0 255.255.248.0 201.10.4.9
    (At the next hop router, 201.10.4.9)
    ip route 172.16.0.0 255.255.248.0 null0

    hope that helped.

    thank you for your time

    yeah it showed me I had a flawed understanding of how subnetting works ��
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