Routing – Networking & Security

BGP EVPN with VXLAN

22 Sep 20245 Jan 2025 by Farhan Patel, posted in Network Design, Routing, Software Defined Networking

Technical references: https://www.cisco.com/c/en/us/products/collateral/switches/nexus-9000-series-switches/guide-c07-734107.html About VXLAN: VXLAN is a network virtualization technology that allows for the extension of Layer 2 networks over a Layer 3 physical infrastructure. It helps overcome the limitations of traditional VLANs, especially in large data centers. VXLAN allows much better scalability as compared to traditional VLANs with the ability to provision many … Continue reading BGP EVPN with VXLAN

NSX-T VRF Gateway use-case and Traffic Flows

16 Jan 202416 Jan 2024 by Farhan Patel, posted in Network Design, Routing, Software Defined Networking, VMware NSX

Similar to routers with VRF lite feature, NSX Tier 0 Gateway supports VRF gateway feature which allows multiple VRF gateways to exist under the parent Tier 0 Gateway. Based on the VMware configmax portal, NSX version 4.1.2 supports up to 100 VRF gateways per edge node. VRF gateways in NSX save CPU, memory and storage … Continue reading NSX-T VRF Gateway use-case and Traffic Flows

Multiple VDS’ on host for Overlay on compute hosts

18 Feb 202319 Feb 2023 by Farhan Patel, posted in nsx-t, Routing

Multiple VDS' for Overlay on compute hosts This use case is also referenced in NSX-T Reference Design Guide which mentions that starting with NSX 3.1, a host can have virtual switches part of different overlay transport zones and the TEPs on each virtual switch can be on different VLAN/IP subnets (still, all the TEPs … Continue reading Multiple VDS’ on host for Overlay on compute hosts

NSX-T VRF Gateway

11 Jan 202125 Oct 2023 by Farhan Patel, posted in nsx-t, Routing

VRF Gateway feature in NSX-T is similar to VRF lite feature in physical networks in the following ways: Just like there is no need of another physical router for a separate routing instance using VRF lite feature, there is no need to deploy additional edges in case of NSX-T VRF gateways. This drastically reduces the … Continue reading NSX-T VRF Gateway

OSPF NSSA

30 Aug 201820 Dec 2018 by Farhan Patel, posted in Routing

In the topology above, routers R1 and R2 are the ABRs interfacing with backbone area 0 Area 1 in this topology has been configured as NSSA this time. My earlier topology referenced a Totally NSSA area. As mentioned earlier, NSSA configuration in OSPF allows redistribution to occur within the NSSA area. … Continue reading OSPF NSSA

Totally NSSA Area – OSPF

10 Jun 201820 Dec 2018 by Farhan Patel, posted in Routing

This blog will discuss the benefits derived by configuring OSPF area type as Totally NSSA OSPF Area type NSSA and Totally NSSA both allow redistribution within the NSSA area. Such redistribution creates Type 7 LSAs which are converted to Type 5 LSA by the ABR. Referencing the topology above, R1 or R2 which serve as … Continue reading Totally NSSA Area – OSPF

IP Routing Process

16 Jan 201720 Dec 2018 by Farhan Patel, posted in Routing

IP routing process is a fundamental concept in networks. Having a clear understanding of IP routing process helps network engineers troubleshoot complex network problems. A good hold of this concept also helps determine end to end traffic flow from any given source IP towards target IP. Below are key steps when traffic from source tries … Continue reading IP Routing Process

OSPF – Auto Cost Reference Bandwidth feature in Cisco IOS

4 Nov 201620 Dec 2018 by Farhan Patel, posted in Routing

In the case of OSPF, the OSPF metric – Cost is inversely proportional to interface bandwidth. Meaning, the higher bandwidth link on your device will have lower cost. But OSPF by default is unable to differentiate the cost properly for a device that has both TenG and Gig interfaces. The reason why OSPF is … Continue reading OSPF – Auto Cost Reference Bandwidth feature in Cisco IOS