Network Study Site

IS-IS Authentication

2022 Nov 30

IS-IS Authentication To add security to the IS-IS routing protocol, authentication can be configured between neighboring devices. IS-IS provides the option to authenticate Hello packets and Link State PDU (LSP) packets. This means, IS-IS neighborships are authenticated separately from route updates ...

Policy-Based Routing (PBR)

2022 Nov 24

Policy-Based Routing (PBR) Policy-based routing uses a route-map to determine the forwarding path of network traffic and as a result IP packets ignore the routing table. PBR is a method to enforce rules of path control through statically defined forwarding decisions on a router. Three main elements of PBR are configured ...

DHCP Utilization, EEM Script Mail

2022 Nov 22

DHCP Utilization, EEM Script Mail In this blog post utilization of a DHCP pool is tracked, and a warning message displayed based on a configured threshold value. Additionally, an EEM script monitors syslog messages for DHCP utilization warnings. The EEM script sends an email to an SMTP server, issuing a warning message that ...

DMVPN NHS, and NHS Cluster

2022 Nov 21

DMVPN NHS, and NHS Cluster In a DMVPN network the spoke routers are the Next-Hop Clients (NHC), and they register with the hub routers. The hub router is the Next-Hop Server (NHS). Redundant NHS can be grouped into clusters, and assigned a priority value to fine-tune the DMVPN registration process ...

DMVPN Redundancy

2022 Nov 20

DMVPN Redundancy Dynamic Multipoint Virtual Private Network (DMVPN) redundancy is when multiple hub and spoke routers are deployed in order to increase the availability and stability of a DMVPN network. This blog post explores the configuration of dual cloud DMVPN with dual hubs per cloud, using iBGP ...

Next-Generation mVPN

2022 Nov 15

Next-Generation mVPN

Next-Generation Multicast VPN (NG-mVPN) is a set of features that can be combined to transport independent multicast streams for different customers across a shared Layer-3 MPLS VPN architecture. In essence, NG-mVPN provides a framework to implement various improvements over the Classic Rosen Draft ...

DHCP Object Tracking

2022 Nov 9

DHCP default route object tracking A local router can receive two default routes on separate interfaces, and assign different administrative distances. As a result, one of the default routes is installed as the default gateway address. If the default gateway fails, then a failover happens to the secondary default route ...

Network Time Protocol (NTP)

2022 Nov 4

DHCP default route object tracking Network Time Protocol (NTP) is one of the oldest protocols on the internet and provides a mechanism of time synchronization for computers over UDP port 123. NTP provides time synchronization through a hierarchical system of public and private servers ...

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IS-IS Authentication

Policy-Based Routing (PBR)

DHCP Utilization, EEM Script Mail

DMVPN NHS, and NHS Cluster

DMVPN Redundancy

Next-Generation mVPN

DHCP Object Tracking

Network Time Protocol (NTP)