What's the purpose of EIGRP topology base?

[hfakoor222]

Doing some labs and the configs are going:

router eigrp xxxxxx
address-family ipv4 unicast autonomous-system 150
topology base
exit-af-topology
network 192.11.11.11 0.0.0.0

abd so i wonder what's the poing of the topology base command, if anyone can help me.

Thank you.

[Flavio Miranda · Accepted solution]

Hi @hfakoor222 

 I believe this link can give you a pretty good idea. 

https://www.cisco.com/c/en/us/support/docs/ip/enhanced-interior-gateway-routing-protocol-eigrp/200156-Configure-EIGRP-Named-Mode.html

If seems when we use named EIGRP, we unlock some possibilities:

"...

The traditional way to configure EIGRP requires various parameters to be configured under the interface and EIGRP configuration mode. In order to configure EIGRP IPV4 and IPv6, it is required to configure separate EIGRP instances. Traditional EIGRP does not support Virtual Routing and Forwarding (VRF) in IPv6 EIGRP implementations.

With Named mode EIGRP, everything is configured at a single place under the EIGRP configuration and there are no restrictions as mentioned previously..."

 And then, inside named you ca have:

Address-family Interface Configuration Mode

Address-family Topology Configuration Mode

  Topology Configuration Mode provides several configuration options which operate on the EIGRP topology table. Things like redistribution, distance, offset list, variance and so on can be configured under this mode. You can enter this mode from the address-family configuration mode.

R1(config-router-af)#topology base
R1(config-router-af-topology)#?
Address Family Topology configuration commands:
  auto-summary         Enable automatic network number summarization
  default              Set a command to its defaults
  default-information  Control distribution of default information
  default-metric       Set metric of redistributed routes
  distance             Define an administrative distance
  distribute-list      Filter entries in eigrp updates
  eigrp                EIGRP specific commands
  exit-af-topology     Exit from Address Family Topology configuration
  maximum-paths        Forward packets over multiple paths
  metric               Modify metrics and parameters for advertisement
  no                   Negate a command or set its defaults
  offset-list          Add or subtract offset from EIGRP metrics
  redistribute         Redistribute IPv4 routes from another routing proto
  summary-metric       Specify summary to apply metric/filtering
  timers               Adjust topology specific timers
  traffic-share        How to compute traffic share over alternate paths
  variance             Control load balancing variance

[hfakoor222]

Thanks, I don't think I'm going to read the link, your explanation explained a lot, I'm going to keep doing these labs and learning from that.

[MHM Cisco World]

If you compare ospf with eigrp you will see 

In ospf you can direct config vrf by

Ip router ospf 100 vrf A 

But eigrp you can not' eigrp in this point is similar to bgp you need address family under bgp to config vrf.

Hence the eigrp use address family for multi vrf under same eigrp name.

For topology base' th eigrp have it topolgy (databased) so we need topology baes under address family.