Load balancing using GLBP

[M Talha]

Dear All,

I need to built a scenario where i am using two ISP's for redundancy for my internal network and at the same time wants to load balance in such a way that my first packet going outside the network (using NAT) goes from first ISP's public ip address and second packet going outside the network (using NAT) goes from second ISP's public ip address.

Need your help

Thank You

[paul driver]

Hello

I tried to lab this up - I managed to use a first hop protocol (hrsp) to a redundant HRSP & NAT configuration - however I have tried GLBP and at present not been successful in getting it to work-

Here is what I got with HRSP:

      --- R2
r1 -----        internet host 100.100.100.100
     ---- R3

R2
-----

interface FastEthernet0/0
Description Link to LAN
 ip address 10.1.123.252 255.255.255.0
 ip nat inside
 standby 123 ip 10.1.123.254
 standby 123 priority 115
 standby 123 preempt
 standby 123 name HRSP1
 standby 123 track FastEthernet0/1 50

interface FastEthernet0/1
Description Link to ISP1
 ip address 1.1.1.2 255.255.255.0
 ip nat outside
 standby 234 ip 1.1.1.254
 standby 234 priority 115
 standby 234 preempt
 standby 234 name HRSP2
 standby 234 track FastEthernet0/0 50

ip route 100.100.100.100 255.255.255.255 FastEthernet0/1 1.1.1.4
ip nat inside source static 10.1.123.251 1.1.1.1 redundancy HRSP1

R3
-----

interface FastEthernet0/0
Description Link to LAN
 ip address 10.1.123.253 255.255.255.0
 ip nat inside
 standby 123 ip 10.1.123.254
 standby 123 preempt
 standby 123 name HRSP1
 standby 123 track FastEthernet0/0

interface FastEthernet0/1
Description Link to ISP2
 ip address 1.1.1.3 255.255.255.0
 ip nat outside
 standby 234 ip 1.1.1.254
 standby 234 preempt
 standby 234 name HRSP2
 standby 234 track FastEthernet0/1 50

ip route 100.100.100.100 255.255.255.255 FastEthernet0/1 1.1.1.4
ip nat inside source static 10.1.123.251 1.1.1.1 redundancy HRSP1

R2#sh ip nat translations
Pro Inside global      Inside local       Outside local      Outside global
icmp 1.1.1.1:7         10.1.123.251:7     100.100.100.100:7  100.100.100.100:7
icmp 1.1.1.1:12        10.1.123.251:12    100.100.100.100:12 100.100.100.100:12
--- 1.1.1.1            10.1.123.251       ---                ---

R2#sh standby brief
 
Interface   Grp  Pri P State   Active          Standby         Virtual IP
Fa0/0       123  115 P Active  local           10.1.123.253    10.1.123.254
Fa0/1       234  115 P Active  local           1.1.1.3         1.1.1.254

R3#sh stan brief
                 
Interface   Grp  Pri P State   Active          Standby         Virtual IP
Fa0/0       123  100 P Standby 10.1.123.252    local           10.1.123.254
Fa0/1       234  100 P Standby 1.1.1.2         local           1.1.1.254

R3#sh ip nat translations
Pro Inside global      Inside local       Outside local      Outside global
--- 1.1.1.1            10.1.123.251       ---                --

R2
int fa0/1
shut

R2#sh standby brief
               
Interface   Grp  Pri P State   Active          Standby         Virtual IP
Fa0/0       123  65  P Standby 10.1.123.253    local           10.1.123.254
Fa0/1       234  115 P Init    unknown         unknown         1.1.1.254

R2#sh ip nat translations
Pro Inside global      Inside local       Outside local      Outside global
--- 1.1.1.1            10.1.123.251       ---                ---


3#sh stan brief
            
                     |
Interface   Grp  Pri P State   Active          Standby         Virtual IP
Fa0/0       123  100 P Active  local           10.1.123.252    10.1.123.254
Fa0/1       234  100 P Active  local           unknown         1.1.1.254

R3#sh ip nat translations
Pro Inside global      Inside local       Outside local      Outside global
icmp 1.1.1.1:7         10.1.123.251:7     100.100.100.100:7  100.100.100.100:7
icmp 1.1.1.1:12        10.1.123.251:12    100.100.100.100:12 100.100.100.100:12
--- 1.1.1.1            10.1.123.251       ---                ---
 

res

Paul

[Joseph W. Doherty]

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Posting

If I understand your question correctly, if you have equal cost routes, to same destination, via both ISP links, and if CEF is enabled, CEF packet-by-packet load balancing might do the trick.  However, splitting packets from a single flow, is generally a very bad idea.

Better would be to round robin egress flows across both your ISPs.  Best would be to use something like OER/PfR to dynamically load balance egress flows across both you ISPs.