Route Summarization

This chapter contains the following sections:

Route Summarization

Route summarization simplifies route tables by replacing many specific addresses with an single address. For example, 10.1.1.0/24, 10.1.2.0/24, and 10.1.3.0/24 can be replaced with 10.1.0.0/16. Route summarization policies enable routes to be shared efficiently among border leaf switches and their neighboring leaf switches. BGP, OSPF, or EIGRP route summarization policies are applied to a bridge domain or transit subnet. For OSPF, inter-area and external route summarization are supported. Summary routes are exported; they are not advertised within the fabric.

Guidelines and Limitations

A route summarization policy configured under an external EPG will result in the summarized prefix being advertised to all of the BGP peers that are connected to the same border leaf switch and in the same VRF. This includes BGP peers that belong to different L3Outs if the same border leaf switch and VRF condition is met.

If you do not want this behavior to take place and you want to limit which BGP peers receive the aggregate route, block the routes where applicable using outbound route-maps on the respective L3Outs.

Configuring Route Summarization for BGP, OSPF, and EIGRP Using the REST API

Procedure

Step 1

Configure BGP route summarization using the REST API as follows:

Example:

   
<fvTenant name="common">
           <fvCtx name="vrf1"/>
   <bgpRtSummPol name=“bgp_rt_summ” cntrl=‘as-set'/>
   <l3extOut name=“l3_ext_pol” >
             <l3extLNodeP name="bLeaf">
                <l3extRsNodeL3OutAtt tDn="topology/pod-1/node-101" rtrId=“20.10.1.1"/>
              <l3extLIfP name='portIf'>
              <l3extRsPathL3OutAtt tDn="topology/pod-1/paths-101/pathep-[eth1/31]" ifInstT=‘l3-port’ addr=“10.20.1.3/24/>
              </l3extLIfP>
           </l3extLNodeP>
         <bgpExtP />
           <l3extInstP name="InstP" >
         <l3extSubnet ip="10.0.0.0/8" scope=“export-rtctrl">
           <l3extRsSubnetToRtSumm tDn=“uni/tn-common/bgprtsum-bgp_rt_summ”/>
           <l3extRsSubnetToProfile tnRtctrlProfileName=“rtprof"/>
         </l3extSubnet>
       </l3extInstP>
       <l3extRsEctx tnFvCtxName=“vrf1”/>
   </l3extOut>
</fvTenant>

Step 2

Configure OSPF inter-area and external summarization using the following REST API:

Example:


<?xml version="1.0" encoding="utf-8"?>
<fvTenant name="t20">
  <!--Ospf Inter External route summarization Policy-->
  <ospfRtSummPol cost="unspecified" interAreaEnabled="no" name="ospfext"/>
  <!--Ospf Inter Area route summarization Policy-->
  <ospfRtSummPol cost="16777215" interAreaEnabled="yes" name="interArea"/>
  <fvCtx name="ctx0" pcEnfDir="ingress" pcEnfPref="enforced"/>
  <!-- L3OUT backbone Area-->
  <l3extOut enforceRtctrl="export" name="l3_1" ownerKey="" ownerTag="" targetDscp="unspecified">
    <l3extRsEctx tnFvCtxName="ctx0"/>
    <l3extLNodeP name="node-101">
      <l3extRsNodeL3OutAtt rtrId="20.1.3.2" rtrIdLoopBack="no" tDn="topology/pod-1/node-101"/>
      <l3extLIfP name="intf-1">
        <l3extRsPathL3OutAtt addr="20.1.5.2/24" encap="vlan-1001" ifInstT="sub-interface" tDn="topology/pod-1/paths-101/pathep-[eth1/33]"/>
      </l3extLIfP>
    </l3extLNodeP>
    <l3extInstP name="l3InstP1">
      <fvRsProv tnVzBrCPName="default"/>
      <!--Ospf External Area route summarization-->
      <l3extSubnet aggregate="" ip="193.0.0.0/8" name="" scope="export-rtctrl">
        <l3extRsSubnetToRtSumm tDn="uni/tn-t20/ospfrtsumm-ospfext"/>
      </l3extSubnet>
    </l3extInstP>
    <ospfExtP areaCost="1" areaCtrl="redistribute,summary" areaId="backbone" areaType="regular"/>
  </l3extOut>
  <!-- L3OUT Regular Area-->
  <l3extOut enforceRtctrl="export" name="l3_2">
    <l3extRsEctx tnFvCtxName="ctx0"/>
    <l3extLNodeP name="node-101">
      <l3extRsNodeL3OutAtt rtrId="20.1.3.2" rtrIdLoopBack="no" tDn="topology/pod-1/node-101"/>
      <l3extLIfP name="intf-2">
        <l3extRsPathL3OutAtt addr="20.1.2.2/24" encap="vlan-1014" ifInstT="sub-interface" tDn="topology/pod-1/paths-101/pathep-[eth1/11]"/>
      </l3extLIfP>
    </l3extLNodeP>
    <l3extInstP matchT="AtleastOne" name="l3InstP2">
      <fvRsCons tnVzBrCPName="default"/>
      <!--Ospf Inter Area route summarization-->
      <l3extSubnet aggregate="" ip="197.0.0.0/8" name="" scope="export-rtctrl">
        <l3extRsSubnetToRtSumm tDn="uni/tn-t20/ospfrtsumm-interArea"/>
      </l3extSubnet>
    </l3extInstP>
    <ospfExtP areaCost="1" areaCtrl="redistribute,summary" areaId="0.0.0.57" areaType="regular"/>
  </l3extOut>
</fvTenant>

Step 3

Configure EIGRP summarization using the following REST API:

Example:

   
<fvTenant name="exampleCorp"> 
  <l3extOut name="out1">
    <l3extInstP  name="eigrpSummInstp" >
      <l3extSubnet aggregate="" descr="" ip="197.0.0.0/8" name="" scope="export-rtctrl">
        <l3extRsSubnetToRtSumm/>
      </l3extSubnet>
    </l3extInstP>
  </l3extOut>
  <eigrpRtSummPol name="pol1" />

Note

 

There is no route summarization policy to be configured for EIGRP. The only configuration needed for enabling EIGRP summarization is the summary subnet under the InstP.

Configuring Route Summarization for BGP, OSPF, and EIGRP Using the NX-OS Style CLI

Procedure

Step 1

Configure BGP route summarization using the NX-OS CLI as follows:

  1. Enable BGP as follows:

    Example:

    
apic1(config)# pod 1
apic1(config-pod)# bgp fabric
apic1(config-pod-bgp)# asn 10
apic1(config-pod)# exit
apic1(config)# leaf 101
apic1(config-leaf)# router bgp 10

  2. Configure the summary route as follows:

    Example:

       
apic1(config-bgp)# vrf member tenant common vrf vrf1
apic1(config-leaf-bgp-vrf)# aggregate-address 10.0.0.0/8

Step 2

Configure OSPF external summarization using the NX-OS CLI as follows:

Example:


apic1(config-leaf)# router ospf default
apic1(config-leaf-ospf)# vrf member tenant common vrf vrf1
apic1(config-leaf-ospf-vrf)# summary-address 10.0.0.0/8

Step 3

Configure OSPF inter-area summarization using the NX-OS CLI as follows: 


apic1(config-leaf)# router ospf default
apic1(config-leaf-ospf)# vrf member tenant common vrf vrf1
apic1(config-leaf-ospf-vrf)# area 0.0.0.2 range 10.0.0.0/8 cost 20

Step 4

Configure EIGRP summarization using the NX-OS CLI as follows:

Example:

   
apic1(config)# leaf 101
apic1(config-leaf)# interface ethernet 1/31 (Or interface vlan <vlan-id>)
apic1(config-leaf-if)# ip summary-address eigrp default 10.0.0.0/8

Note

 

There is no route summarization policy to be configured for EIGRP. The only configuration needed for enabling EIGRP summarization is the summary subnet under the InstP.

Configuring Route Summarization for BGP, OSPF, and EIGRP Using the GUI

Before you begin

For each of the following configurations, you have already created an L3 Out. For the L3 Out, you can create external routed networks, subnets, and route summarization polices.

Procedure

Step 1

Configure BGP route summarization using the GUI as follows:

  1. On the menu bar, choose Tenants > common

  2. In the Navigation pane, expand Networking.> External Routed Networks .

  3. Right-click on External Routed Networks, then select Create Routed Outside.

    The Create Routed Outside dialog box appears.

  4. In the work pane, check the check box next to BGP.

  5. Enter a name in the Name field, then click NEXT.

    The External EPG Networks dialog box appears.

  6. In the work pane, click the + sign.

    The Define an External Network dialog box appears.

  7. Enter a name in the Name field, then click the + sign above Route Summarization Policy.

    The Create Subnet dialog box appears.

  8. In the Specify the Subnet dialog box, you can associate a route summarization policy to the subnet as follows:

Example:

  • Enter an IP address in the IP Address field.

  • Check the check box next to Export Route Control Subnet.

  • Check the check box next to External Subnets for the External EPG.

  • From the BGP Route Summarization Policy drop-down menu, select either default for an existing (default) policy or Create BGP route summarization policy to create a new policy.

  • If you selected Create BGP route summarization policy, the Create BGP Route Summarization Policy dialog box appears. Enter a name for it in the Name field, check the Control State check box for Generate AS-SET information, click SUBMIT, click OK, click OK, click FINISH.

Step 2

Configure OSPF inter-area and external summarization using GUI as follows:

  1. On the menu bar, choose Tenants > common

  2. In the Navigation pane, expand Networking > External Routed Networks > Networks

  3. In the work pane, click the + sign above Route Summarization Policy.

    The Create Subnet dialog box appears.

  4. In the Specify the Subnet dialog box, you can associate a route summarization policy to the subnet as follows:

Example:

  • Enter an IP address in the IP Address field.

  • Check the check box next to Export Route Control Subnet.

  • Check the check box next to External Subnets for the External EPG.

  • From the OSPF Route Summarization Policy drop-down menu, choose either default for an existing (default) policy or Create OSPF route summarization policy to create a new policy.

  • If you chose Create OSPF route summarization policy, the Create OSPF Route Summarization Policy dialog box appears. Enter a name for it in the Name field, check the check box next to Inter-Area Enabled, enter a value next to Cost, click SUBMIT.

Step 3

Configure EIGRP summarization using the GUI as follows:

  1. On the menu bar, choose Tenants > common

  2. In the Navigation pane, expand Networking.> External Routed Networks.

  3. Right-click on External Routed Networks, choose Create Routed Outside.

    The Create Routed Outside dialog box appears.

  4. In the work pane, check the check box next to EIGRP.

  5. Enter a name in the Name field, click NEXT.

    The External EPG Networks dialog box appears.

  6. In the work pane, click the + sign.

    The Define an External Network dialog box appears.

  7. Enter a name in the Name field, then click the + sign above Route Summarization Policy.

    The Create Subnet dialog box appears.

  8. In the Specify the Subnet dialog box, you can associate a route summarization policy to the subnet as follows:

Example:

  • Enter an IP address in the IP Address field.

  • Check the check box next to Export Route Control Subnet.

  • Check the check box next to External Subnets for the External EPG.

  • Check the check box next to EIGRP Route Summarization, click OK, click OK, click FINISH.