Skip to main content

RTP, Reliable Transport Protocol of EIGRP

RTP is a Cisco proprietry protocol, used in EIGRP to manage the communication of messages between EIGRP-Speaking Routers.Reliable Transport or Delivery of EIGRP packets meansAcknowledgement is required from the receiving Router and the packet should be delivered in order. Ordered delivery is ensured by including two sequence numbers in the packet. One sequence Number is assigned by the sending router for the packet order Number and that is incremented by one each time the sending Router sends a packet. Another Number is the Last Acknowledgement number received from destination or Neighbor Router.Why ordered delivery of EIGRP Packets is important?

Let me give you a simplest example to explain question. Suppose an EIGRP Router’s Link went down and up after some time. But the neighbor Router receives a message of Link-up first and then Link-Down after! What will happen? Out of order execution of packets, can result in corruption of the Routing Database.
Guaranteed delivery is accomplished by a Cisco Proprietary process called Reliable Multicast which uses the reserved class D address 224.0.0.10. Each neighbor receiving a reliable multicast pakcet must unicast an acknowledgment. If EIGP does not get a reply from a neighbor it Unicasts to that Number for sixteen (16) times, if still the Router does not get Reply then that Neighbor router is decalared as dead.

Some types of EIGRP packets are also sent unreliably, means NO Acknowledgement and Ordered-delivery is required for those packets.

Let’s see types of EIGRP Packets and whether they are delivered Reliably or Un-Reliably.
Types of EIGRP Pakcets that are delivered Reliably
  • Updates convey route information. Unlike RIP and IGRP updates, these packets are transmitted only when necessary, contain only necessary information, and are sent only to routers that require the information. When updates are required by a specific router, they are unicast. When updates are required by multiple routers, such as upon a metric or topology change, they are multicast. Updates always use reliable delivery.
  • Queries and Replies are used by the DUAL finite state machine to manage its diffusing computations. Queries can be multicast or unicast, and replies are always unicast. Both queries and replies use reliable delivery.
Types of EIGRP Packets that are delivered Un-reliably
  • Hellos are used by the neighbor discovery and recovery process. Hello packets are multicast and use unreliable delivery.
  • Acknowledgments (ACKs) are Hello packets with no data in them. ACKs are always unicast and use unreliable delivery.
Labels:

Comments

Post a Comment

Popular posts from this blog

How to check Gray-log current running version

If you planning to upgrade your graylog and want to see what your graylog current version is, here is how you can check it. Go to the Graylog Web Interface Click on System/Nodes Under System/Nodes --- Click on the N odes  Scroll down to the ' System ' Here you can see the current version of your graylog server
Post a Comment
Read more

How to import Putty Saved Connections to mRemoteNG

Just started using mRemoteNG and its being very cool to connect to different remote connection with different protocols e.g Window Remote Desktop, VNC to Linux, SSH, HTTP connection etc. from a single application. As new user I configured some remote desktop connection which was quite easy to figure out. But when I wanted to add SSH connections, it came in my mind to import all of the saved connections in the putty. But I couldn't figure it out how can it be done, though it was quite easy and here are the steps. Open your mRemoteNG Create a folder if you want segregation of multiple networks Create a new connection Enter the IP address of remote server under connection in Config pane Under the config pane, select protocol " SSH version 2 ".  Once you select protocol to SSH version 2 you are given option to import putty sessions, as shown in the snap below. In the above snap, I have imported CSR-AWS session from my saved sessions in Putty.
1 comment
Read more

Connection control operation failed for disk 'ide1:0'

I was getting this error while removing Operating System ISO image mounted on the Virtual Machine. What worked for me, is 1. Uncheck the "Connected and Connect at power on" from Device Status. 2. Then Change the Device type from " Datastore ISO File to Client Device " Radio Button 3. and press OK to save the changes. Note:- I was able to remove the mounted ISO only by directly logging to the ESXi at https://esxi-ip-address/ui where it asks "The guest operating system has locked the CD-ROM door and is probably using the CD-ROM, which can prevent the guest from recognizing media changes. If possible, eject the CD-ROM from inside the guest before disconnecting. Disconnect anyway and override the lock?" You need to select yes to eject the CD-ROM and then remove the ISO file successfully.
Post a Comment
Read more