Forwarding address (FA) in OSPF LSAs

In scenarios where we have multiple ABRs converting/translating same network from Type7 to Type5 LSA, then OSPF database need to act on only one of them. The other must withdraw its LSA. This is one of many loop avoidance techniques adopted in OSPF. The RFC 2328 says “if two routers, both reachable from one another, … Continue reading Forwarding address (FA) in OSPF LSAs

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BGP deterministic MED and always compare MED options

The BGP MED (multiple exit discriminator) is an optional non-transitive attribute. That means this value is always carried along with BGP update and can be dropped if the BGP process doesn’t understand it. Let me first write about my understanding on both commands bgp deterministic-med command compares MED variable when choosing routes advertised by different peers … Continue reading BGP deterministic MED and always compare MED options

Default route (0.0.0.0/0) LSA Types in different OSPF areas

As we already know OSPF has different area types (normal, stub, totally stub, not-so-stubby/nssa and nssa totally stub) and the LSAs permitted inside them varies accordingly. In OSPF the default-route is treated differently. By default OSPF does not allow a default-route from any other domain to be advertised/redistributed into its domain. We need to configure … Continue reading Default route (0.0.0.0/0) LSA Types in different OSPF areas

VRRP vs Dell VLT Peer-routing

VLT (Virtual Link Trunking) is a Dell Networking proprietary protocol. This article describes the working functionality of VRRP and Peer-routing when implemented over VLT. For detail configuration I would suggest you to refer the Dell Networking Configuration guide for OS9 platforms. What is Dell Networking VLT (Virtual Link Trunking)? In simplified words, a VLT domain … Continue reading VRRP vs Dell VLT Peer-routing