Heth at 05:04, 4 May 2009

2009-05-04T05:04:03Z

Heth: Redirecting to Gateway Load Balancing Protocol

2009-05-03T06:43:23Z

Redirecting to Gateway Load Balancing Protocol

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#Redirect [[Gateway Load Balancing Protocol]]

← Older revision		Revision as of 05:04, 4 May 2009
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−	~~#Redirect~~ [[Gateway Load Balancing ~~Protocol~~]]	+	= Purpose of GLBP =
		+
		+	:The purpose of GLBP is to ensure network connectivity in case of Router or access circuit failure. GLBP automatically Load balances the load from the IP traffic sources.
		+
		+	:Gateway Load Balancing Protocol (GLBP) is a Cisco proprietary protocol that attempts to overcome the limitations of existing redundant router protocols by adding basic load balancing functionality.
		+
		+	= Other high availability protocols =
		+	*HSRP [[Hot Standby Router Protocol]]
		+	*VRRP [[Virtual Router Redundancy Protocol]]
		+
		+	= GLBP functions =
		+	*Active virtual gateway (AVG): Members of a GLBP group elect one gateway to be the AVG for that group. Other group members provide backup for the AVG if the AVG becomes unavailable. The AVG assigns a virtual MAC address to each member of the group.
		+	*Active virtual forwarder (AVF): Each gateway assumes responsibility for forwarding packets sent to the virtual MAC address assigned to it by the AVG. These gateways are known as AVFs for their virtual MAC address.
		+	*Communication: GLBP members communicate with each other using hello messages sent every 3 seconds to the multicast address 224.0.0.102, User Datagram Protocol (UDP) port 3222.
		+
		+	= GLBP features =
		+	*Load sharing: Traffic from LAN clients can be shared by multiple routers.
		+	*Multiple virtual routers: Up to 1,024 virtual routers (GLBP groups) can be on each physical interface of a router, and there can be up to four virtual forwarders per group.
		+	*Preemption: You can preempt an AVG with a higher priority backup virtual gateway. Forwarder preemption works in a similar way, except that it uses weighting instead of priority and is enabled by default.
		+	*Efficient resource utilization: Any router in a group can serve as a backup, which eliminates the need for a dedicated backup router because all available routers can support network traffic.
		+	= How does GLBP work =
		+	{\|
		+	\|
		+	[[Image:GLBP1.png\|thumb\|500px\|float\|Picture 1: GLBP group with Router R1 as AVG and AVF and Router R2 and R3 as AVF]]
		+	\|valign="top"\|
		+	== GLBP Roles ==
		+	=== AVG - Active Virtual Gateway ===
		+	The Router with the highest priority is chosen as the AVG. The AVG has the responsebility of assigning MAC addresses to the AVF Routers.
		+	=== AVF - Active Virtual Forwarder ===
		+	The AVF Routers Route traffic from the connected clients. Each AVF is assigned its own MAC-Address. The MAC-Address is assigned from the AVG.
		+	=== Load Balancing ===
		+	When the clients broadcast [[ARP]] requests to get the MAC Address of the default gateway - 10.0.0.1 - the AVG responds with a MAC-Address of one of the AVF's. load balancing can be either
		+	* Round Robin: The AVG responds to ARP requests in sequence first AVF, second AVF, third AVF, first AVF.... (Default)
		+	* Host dependent: Specifies a load balancing method based on the MAC address of a host where the same forwarder is always used for a particular host while the number of GLBP group members remains unchanged.
		+	* Weighted: Specifies a load balancing method that is dependent on the weighting value advertised by the gateway.
		+
		+	=== Timers ===
		+	Default the hello time for GLBP is 3 seconds and holdtime is 10 seconds. In the example hello time is set to 0.25 second and holdtime is 0.7 second.
		+	\|}
		+
		+	{\|
		+	\|
		+	<pre>
		+	hostname R1
		+	!
		+	interface FastEthernet1/0
		+	ip address 10.0.0.11 255.0.0.0
		+	glbp 7 ip 10.0.0.1
		+	glbp 7 priority 130
		+	glbp 7 timers msec 200 msec 700
		+	</pre>
		+	\|
		+	<pre>
		+	hostname R2
		+	!
		+	interface FastEthernet1/0
		+	ip address 10.0.0.12 255.0.0.0
		+	glbp 7 ip 10.0.0.1
		+	glbp 7 priority 120
		+	glbp 7 timers msec 200 msec 700
		+	</pre>
		+	\|
		+	<pre>
		+	hostname R3
		+	!
		+	interface FastEthernet1/0
		+	ip address 10.0.0.13 255.0.0.0
		+	glbp 7 ip 10.0.0.1
		+	glbp 7 priority 110
		+	glbp 7 timers msec 200 msec 700
		+	</pre>
		+	\|}
		+
		+	[[Category:Cisco]][[Category:CCNP]][[Category:IOS]][[Category:Network]][[Category:CCNP3]][[Category:IOS]]

GLBP - Revision history

Heth at 05:04, 4 May 2009

Heth: Redirecting to Gateway Load Balancing Protocol