Understanding EIGRP #3

prepared by SURAJ (imeansuraj@gmail.com)
Within the EIGRP packet header:
  1. Version field - is 4-bit field used to indicate the protocol version of the originating EIGRP router process. The version has not changed since its release.
  2. OPCode - is a 4-bit field that specifies the EIGRP message type, 1 = Update, 3 = Query, 4 = Reply, 5 = Hello, 6 = IPX SA, 10 = SIA Query, 11 = SIA Reply.
  3. Checksum – is a 24-bit field that is used to run a sanity check on the EIGRP packet itself. This field is based on the entire EIGRP packet and not including the IP header.
  4. Flags – is a 32-bit field that is used to indicate either an INIT (when set (0×00000001)) for a new EIGRP neighbour or for the Conditional Receive (CR) (second bit (0×00000002)), used in the proprietary Reliable Multicasting algorithm, for EIGRP Reliable Transport Protocol. (RTP)
  5. Sequence – is a 32-bit field that contains sequence number used by RTP. This is used to ensure orderly delivery of reliable packets.
  6. Acknowledgment – is a 32-bit field that contains the sequence number last heard from the neighbour to which the packet is being sent. A Hello packet with a nonzero ACK field will be treated as an ACK packet rather than as a Hello. Note that an ACK field will only be nonzero if the packet itself is a unicast because an acknowledgment are never multicast.
  7. Autonomous System Number – is a 32-bit field that identifies the number of the EIGRP domain.
  8. Type/Length/Value (TLV) – is a 32-bit triplet field that is used to carry route entries, as well as provide EIGRP DUAL information.
Note:
  • EIGRP does not build peer relationships over secondary addresses. All EIGRP traffic is sourced from the primary address of the interface.
  • When configuring EIGRP over a multi-access Frame Relay network (point-to-multipoint, and so on), configure the broadcast keyword in the frame-relay map statements.
  • There are no limitations on the number of neighbours that EIGRP can support.
Some of the many advantages of EIGRP are:
  • very low usage of network resources during normal operation; only hello packets are transmitted on a stable network
  • when a change occurs, only routing table changes are propagated, not the entire routing table; this reduces the load the routing protocol itself places on the network
  • rapid convergence times for changes in the network topology (in some situations convergence can be almost instantaneous)
Difference between EIGRP and OSPF:



(notes compiled and collected from various sources)

Comments

Post a Comment

Popular posts from this blog

Vadodara- The Pride of Gujarat

Image
     Economy:   Major industries include petrochemicals, engineering, chemicals, pharmaceuticals, plastics, IT and foreign exchange.    Out of the 4 major PSUs of Gujarat, 3 are in Vadodara, GSFC, Gujarat Refinery and ONGC.   Has the highest share of well-established large scale industries in Gujarat, some of the popular names are as follows- TBEA  ABB, Collabera, IOC, TBEA (Chinese), SunPharma, Alembic Pharmacy (oldest pharma firm), Sarabai Chemicals, Jyoti Laboratories, GM manufacturing plant(US), Reliance Industries, Apollo, Schneider (French), Siemens (German), Alstom (French), Bombardier (Canadian), L&T, GIPCL, Mahindra etc.    Due to the good presence of these major firms who hire on national basis, a large number of well-educated crowd have settled in Vadodara from outside Gujarat making it the most cosmopolitan of all the cities in the state. Hence the general public has a more sophisticated taste than ...
View Full Article »

In Her Paradise

Image
The universe was created with a thought and the thought came from a feeling, the feeling of love, so they say. A sense of protectiveness and insecurity naturally engulfs you with this powerful word. I too felt strong until I held Jia for the first time, and her soft tiny fingers curled into my palm. Jia was born when I was going through one of the toughest times in academics and there was a fear of losing it all. She was born to my elder sister on 15 th  of December, 2012, just a day after my birthday. She yawned as beautifully as anyone could yawn and stared at everyone with her raised eyebrows, trying to figure the small world around her. She immediately started crying. Months went by and I took care of her in every possible way until the day, when she was about to leave for Hyderabad. I knew I had to make the most of it, I knew I was not going to see much of her for a very long time. I had a whole bunch of things planned for her, after I returned ...
View Full Article »

Glass Half Full

Image
What I disclose here is something that I have hardly shared before. It is about the time when I was 16, which wasn't as sweet to me as it is normally called. I had just separated from the girl I loved and I didn't know how to start preparing for my 10 th grade boards which was due in few months. But this one day out of nowhere my mom called me and said, “See, there’s huge discounts on the package tour to Goa ”. Few days later we had packed off ourselves to leave for the gorgeous destination. While in the train I was still lost in the medley of emotional thoughts about my love. This was probably the first time that I had experienced anything like this. The feeling of staring and feeling the utmost beauty of slipping oneself into the fantasy zone where only we existed was a world I never wanted to come out of. Songs started making more sense than before and the pathetic cries of my friends about their own love life suddenly felt not so pathetic anymore. Whi...
View Full Article »