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What is "proto=89" in this IP packet debug output?
workfrom925
Member Posts: 196
in CCNA & CCENT
What is "proto=89" in this IP packet debug output?
IP: s=172.16.22.1 (FastEthernet0/0), d=224.0.0.5, len 72, rcvd 0, proto=89
IP: s=172.16.22.1 (FastEthernet0/0), d=224.0.0.5, len 72, rcvd 0, proto=89
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networker050184
Mod Posts: 11,962 Mod
An expert is a man who has made all the mistakes which can be made. -
Optionsworkfrom925
Member Posts: 196
Thanks for that.
Not relating to my question, but I don't find a protocol number for RIP in your linked page. Is it that RIP just don't need a protocol number? -
Optionsnetworker050184
Mod Posts: 11,962 Mod
RIP uses UDP so the packet will have a protocol number of 17.An expert is a man who has made all the mistakes which can be made.
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OptionsFrankGuthrie
Member Posts: 245
Are we not getting thing mixed?
All routing protocols use a Protocol number to tell the receiving device what kind of data can be found in the packet received. UDP is the transport method used, like EIGRP uses RTP (Layer 4). What OSPF uses, still not clear to me. RIP also uses Layer 4 transport protocol (UDP) -
Optionsnetworker050184
Mod Posts: 11,962 Mod
The IP protocol number indicates what the protocol will be at the next layer. OSPF does not use a transport protocol so the IP protocol number indicates OSPF. RIP uses UDP so the protocol filed indicates a UDP header coming up next. This field's naming is a little easier to understand in IPv6 as it is called 'next header'.An expert is a man who has made all the mistakes which can be made.
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OptionsFrankGuthrie
Member Posts: 245
networker050184 wrote: »The IP protocol number indicates what the protocol will be at the next layer. OSPF does not use a transport protocol so the IP protocol number indicates OSPF. RIP uses UDP so the protocol filed indicates a UDP header coming up next. This field's naming is a little easier to understand in IPv6 as it is called 'next header'.
Another lesson learned today. Thank you sir. -
Optionstheodoxa
Member Posts: 1,340 ■■■■□□□□□□
d=224.0.0.5
It would also be useful to know the common Multicast addresses.
Multicast address - Wikipedia, the free encyclopedia
224.0.0.5 All OSPF Routers
224.0.0.6 All OSPF Designated Routers
224.0.0.9 All RIPv2 Routers
224.0.0.10 All EIGRP Routers
As for the protocol numbers, they are a number assigned by IP to identify the Transport Layer Protocol to hand the segment (IP Packet with the IP Header Removed) off to. OSPF (89) and EIGRP (8
both handle the Transport Layer duties. EIGRP uses its own Transport Layer Protocol called RTP (Reliable Transport Protocol). RIP uses UDP, which means IP would hand off the segment to UDP. Once it reaches Layer 7 (Application Layer), it is handed off to RIP. BGP uses TCP and would follow the same process as RIP, except handing the segment off to TCP instead of UDP.
Layer 7
Layer 4
Layer 3
Layer 2
Layer 1
EIGRP
RTP - 88
IPv4, IPv6, IPX, or AppleTalk
Various
Various
OSPF
??? - 89
IPv4, IPv6, ???
Various
Various
RIP
UDP - 17
IPv4, IPv6, ???
Various
Various
BGP
TCP - 06
IPv4, IPv6, ???
Various
Various
R&S: CCENT → CCNA → CCNP → CCIE [ ]
Security: CCNA [ ]
Virtualization: VCA-DCV [ ] -
Optionsnetworker050184
Mod Posts: 11,962 Mod
EIGRP uses its own Transport Layer Protocol called RTP (Reliable Transport Protocol).
RTP is not a transport layer protocol. It is basically just sequence numbers in the EIGRP packets.An expert is a man who has made all the mistakes which can be made. -
OptionsFrankGuthrie
Member Posts: 245
Notice the ??? with OSPF at Layer 4. If the IP protocol tell to which next layer protocol the /datapacket needs to be given, what is the Layer 4 protocol for OSPF ???
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Optionsnetworker050184
Mod Posts: 11,962 Mod
Nothing. You have to remember the OSI is nothing but a model. Not everything fits perfectly into the little world of OSI.An expert is a man who has made all the mistakes which can be made.
