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Merge branch '1-bgp-section'
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66f0fbe645
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@ -36,6 +36,7 @@
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\newacronym{dwdm}{DWDM}{}
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\newacronym{eap}{EAP}{Extensible Authentication Protocol}
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\newacronym{eapol}{EAPoL}{Extensible Authentication Protocol over Local Area Network}
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\newacronym{ebgp}{eBGP}{Externel Border Gateway Protocol}
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\newacronym{ecn}{ECN}{Explicit Congestion Notification}
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\newacronym{eff}{EFF}{Electronic Frontier Foundation}
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\newacronym{eigrp}{EIGRP}{Enhanced Interior Gateway Routing Protocol}
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@ -62,11 +63,13 @@
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\newacronym{https}{HTTPS}{Hyper Text Transfer Protocol Secure}
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\newacronym{iab}{IAB}{Internet Architecture Board}
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\newacronym{iana}{IANA}{Internet Assigned Numbers Authority}
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\newacronym{ibgp}{iBGP}{Internal Border Gateway Protocol}
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\newacronym{icann}{ICANN}{Internet Corporation for Assigned Names and Numbers}
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\newacronym{icmp}{ICMP}{Internet Control Message Protocoll}
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\newacronym{icmp6}{ICMPv6}{Internet Control Message Protocol version 6}
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\newacronym{ieee}{IEEE}{Institute of Electrical and Electronics Engineers}
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\newacronym{ietf}{IETF}{Internet Engineering Task Force}
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\newacronym{igp}{IGP}{Interior Gateway Protocol}
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\newacronym{igrp}{IGRP}{Interior Gateway Routing Protocol}
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\newacronym{imap}{IMAP}{Internet Message Access Protocol}
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\newacronym{ios}{IOS}{Internetwork Operating System}
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@ -131,6 +134,7 @@
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\newacronym{ros}{ROS}{MikroTik RouterOS}
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\newacronym{rpr}{RPR}{Route Processor Redundancy}
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\newacronym{rpr+}{RPR+}{Route Processor Redundancy Plus}
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\newacronym{rr}{RR}{Route Reflector}
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\newacronym{rspan}{RSPAN}{Remote Switch Port Analyser}
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\newacronym{rstp}{RSTP}{Rapid Spanning Tree Protocol}
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\newacronym{rpvst}{RPVST}{Per Vlan Rapid Spanning Tree}
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@ -160,6 +164,7 @@
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\newacronym{tlv}{TLV}{Type, Length, Value}
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\newacronym{toc}{ToC}{Table of Contents}
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\newacronym{tosdr}{ToS;DR}{Terms of Service; Didn't Read}
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\newacronym{ttl}{TTL}{Time-to-live}
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\newacronym{udld}{UDLD}{Unidirectional Link Detection}
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\newacronym{udp}{UDP}{User Datagram Protocol}
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\newacronym{ula}{ULA}{Unique Local Address}
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@ -7,6 +7,9 @@
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\section{EIGRP}
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\section{RIP}
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\section{Static}
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\newpage
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\section{BGP}
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\wikicommons{BGP_FSM}
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@ -14,38 +17,93 @@
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The protocol of the internet used since 1994.\cite{wiki:Border_Gateway_Protocol}
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Currently based upon \rfc{4271} with updates following in \rfc{6286} \rfc{6608}, \rfc{6793}, \rfc{7606}, \rfc{7607}, \rfc{7705}.
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\subsection{Properties}
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\begin{itemize}
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\item \itemhead{Properties}
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\begin{itemize}
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\item Uses tcp/179 as \gls{dst} port
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\item Sends keep-alive message every 1 minute
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\item Keep-alive message is 19 byte
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\end{itemize}
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\item \itemhead{Route exchange}
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\begin{itemize}
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\item \itemhead{Route-maps mechanism}
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\begin{itemize}
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\item Routes can be aggregated between \Glspl{as}.
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\item Properties can be changed on the fly by mathing
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\item Keep-alive message is 19 byte long
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\end{itemize}
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Be ware if sessions are terminated immediately upon trying to establish connection. Try debugging following points.
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\begin{itemize}
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\item tcp/179 is not open,
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\item random port 1023> is not open,
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\item incorrect peer-ip,
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\item incorrect peer-as.
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\end{itemize}
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\subsection{Route exchange}
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Exchanging routes between routers is a reliant and tolerant manner is \glspl{bgp} 1-advantage over \gls{ospf}/\gls{isis}/\gls{rip}/\gls{eigrp}.
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The sheer tuning and control mechanisms \gls{bgp} can offer is simply astounding. Route-maps is the key and access-lists just one option.
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\subsubsection[Route-maps]{Route-maps mechanism}
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Route-maps is used to target a select set of routes and either modify/add/remove attributes attached to the select route-set.
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\begin{itemize}
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\item Routes can be aggregated between \glspl{as}.
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\item Properties can be changed on the fly by matching
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\begin{enumerate}[label={\alph*)}]
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\item \Gls{bgp} communities,
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\item \Gls{ip} prefix,
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\item \Gls{bgp} as-path,
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\end{enumerate}
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\end{itemize}
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\item
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\end{itemize}
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\item \itemhead{States}
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\begin{enumerate}
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\item Idle: \Gls{bgp} while initializing refuses all incoming connections. Will initiate \Gls{tcp} connection to peer.
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\item Connect: Waits for \Gls{tcp} connection. If \Gls{tcp} is established goes to state OpenSent. If \Gls{tcp} is \textit{un}successful ConnectRetry timer is started and then goes to Active state.
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\end{itemize}
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An simple example of using route-maps is
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\begin{cisco}
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ip prefix-list 1 permit 172.16.0.0/16
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ip prefix-list 2 permit 192.168.1.0/24
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!
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route-map RED permit 10
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match ip address prefix-list 1
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set ip next hop 10.1.1.1
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continue 20 ! Continues to apply rules normally only
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! applied to prefix-list 2. To apply to
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! prefix-list 1, too.
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! Any attributes set in '20' will
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! override any set during '10'.
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route-map RED permit 20
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match ip address prefix-list 2
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set ip next hop 10.2.2.2 ! Last rule overrides previous rules from
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! previous '10' rule-set.
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\end{cisco}
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When rules from a rule-set is chained together as shown above. The last rule will override all previous set values regarding the attribute being applied. In this case \texttt{next-hop} from 'permit 10' is overridden in 'permit 20'.
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\subsection[States]{BGP States}
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The states is the way \gls{bgp} handles peer/neighbor connection establishing. The \underline{playbook} so to speak.
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\begin{enumerate}
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\item Idle: \gls{bgp} while initializing refuses all incoming connections. Will initiate \gls{tcp} connection to peer.
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\item Connect: Waits for \gls{tcp} connection. If \gls{tcp} is established goes to state OpenSent. If \gls{tcp} is \textit{un}successful ConnectRetry timer is started and then goes to Active state.
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\item Active: When ConnectRetry counter reaches 0 goes to state Connect.
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\item OpenSent: Sends \gls{msg} to remote node. Waits for reply \gls{msg} before going to OpenConfirm.
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\item OpenConfirm: Nodes exchange keepalive \glspl{msg} and goes to Established state if successful.
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\item Established: Nodes can now exchange KeepAlive, Updates, and Notification \glspl{msg}.
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\end{enumerate}
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\end{itemize}
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\end{enumerate}
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\subsection[iBGP]{Internal Border Gateway Protocol}
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\gls{ibgp} is running \gls{bgp} within the same \gls{as} between routers. Much like running a general \gls{igrp} in the network.
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Tradition one has to be fearful of creating \textit{routing loops} in the network. \glspl{bgp} mechanism for this is using either \begin{mylist} \item Full Mesh, or \item \glspl{rr} \end{mylist}.
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Problems by running \textit{Full Mesh} is the formula of \[ iBGPsessions = n*(n-1)/2 \] \note{where $ n $ is the number \gls{ibgp} speakers} which results in scaling problems as \gls{ibgp} speakers are added to the \gls{as}.
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\textit{\glspl{rr}} solves this problem by peering with all \gls{ibgp} speakers in the \gls{as}. All \gls{ibgp} speakers are then clients of the \glspl{rr}. This in turn helps maintainability by also advertising routes learnt from \gls{ibgp} clients to clients. Classic filtering/mathing route-maps/prefix-filters can be used to \textit{not} advertise all routes select group of clients from the \glspl{rr}.
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\subsection[eBGP]{External Border Gateway Protocol}
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\gls{ebgp} connections is inherently different from \gls{ibgp} connections. Some assumptions are made such as
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\begin{enumerate}
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\item a \gls{ttl} of 1 is the default\footnote{Multi-hop \gls{ebgp} can thou be configured and therefore increase the max-\gls{ttl} value},
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\item distance is set to 20 compared to 200 for \gls{ibgp} routes,
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\item Next hop does \textit{not} change for \gls{ebgp} routes advertised to \gls{ibgp} neighbours \textit{by-default}\footnote{Often times it is necessary to tell a router to set itself as the next-hop before advertising to \gls{ibgp} neighbours}.
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\end{enumerate}
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@ -132,6 +132,11 @@ License: \texttt{\href{https://creativecommons.org/licenses/by-sa/3.0/}{CC BY-SA
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\newcommand{\rfc}[1]{RFC #1\footnote{\href{https://tools.ietf.org/html/rfc#1}{tools.ietf.org/html/rfc#1}}}
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% Usage: \note{<text>} or \nb{<text>}
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\newcommand{\note}[1]{{\color{Mahogany!20!black}{\small(#1)}}}
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\newcommand{\nb}[1]{\note{#1}}
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% Usage:
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% https://tex.stackexchange.com/a/75349
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\newcommand{\plaintextinput}[1]{\lstinputlisting[language={},style=plaintxt]{code/#1.txt}}
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@ -2,7 +2,7 @@
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author = "Hector Camba Lainez",
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title = "Cap4 implementing vtp",
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year = "2010",
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url = {https://www.slideshare.net/lucky0679/cap4-implementing-vtp},
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url = {\url{https://www.slideshare.net/lucky0679/cap4-implementing-vtp}},
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note = "[Online; accessed 22-May-2017]"
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}
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@ -31,3 +31,12 @@
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year = {2010},
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note = {(Accessed on 07/23/2017)}
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}
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@misc{ Differen15:online,
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author = {\url{http://www.differencebetween.com/author/root/}{Andrew}},
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title = "Difference Between EBGP and IBGP",
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howpublished = {\url{http://www.differencebetween.com/difference-between-ebgp-and-vs-ibgp/}},
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month = "September",
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year = "2011",
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note = "[Online; accessed on 24-June-2017]"
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}
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@ -191,7 +191,7 @@
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\geometry{a4paper,margin=1.5cm}
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\setlength{\columnsep}{1.5cm} %space between columns
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\setlength{\headheight}{15pt}
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\setlength{\footnotesep}{0.5cm} %space between footnotes:
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\setlength{\footnotesep}{1mm} %space between footnotes:
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\setlength{\skip\footins}{2cm} %space between the text body and the footnotes
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\setlist[itemize,1]{leftmargin=\dimexpr 26pt-.2cm}
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\setlist[itemize,2]{leftmargin=\dimexpr 26pt-.3cm}
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@ -273,3 +273,8 @@
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\renewcommand{\footnote}[1]{%
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\renewcommand\footnotesize\scriptsize % here there is scriptsize in footnotes (example)
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\origfootnote{#1}}
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% https://tex.stackexchange.com/a/146312
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\newlist{mylist}{enumerate*}{1}
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\setlist[mylist]{label={\alph*)},font={\color{red!25!black}\bfseries}}
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