Load balancing / redundancy on 6509 VSS

[Zeeeee]

Hi Guys,

Before I configure both my chassis to VSS, i need assistance to understand better.

I have 1 ISP downstream to both chassis. Once VSS are configured, is there any way to do load balancing to the ISP?

Thanks.

[Mark Malone]

what way is the ISP device physically connected back to the network

if your VSS is using pos which I say it will be to the other switches you can load balance traffic downstream through the port-channel to the  , we use
port-channel load-balance src-dst-port it works well for vss but you have multiple optuiond

(config)#port-channel load-balance ?
  dst-ip                      Dst IP Addr
  dst-mac                     Dst Mac Addr
  dst-mixed-ip-port           Dst IP Addr and TCP/UDP Port
  dst-port                    Dst TCP/UDP Port
  mpls                        Load Balancing for MPLS packets
  src-dst-ip                  Src XOR Dst IP Addr
  src-dst-mac                 Src XOR Dst Mac Addr
  src-dst-mixed-ip-port       Src XOR Dst IP Addr and TCP/UDP Port
  src-dst-port                Src XOR Dst TCP/UDP Port
  src-ip                      Src IP Addr
  src-mac                     Src Mac Addr
  src-mixed-ip-port           Src IP Addr and TCP/UDP Port
  src-port                    Src TCP/UDP Port
  vlan-dst-ip                 Vlan, Dst IP Addr
  vlan-dst-mixed-ip-port      Vlan, Dst IP Addr and TCP/UDP Port
  vlan-src-dst-ip             Vlan, Src XOR Dst IP Addr
  vlan-src-dst-mixed-ip-port  Vlan, Src XOR Dst IP Addr and TCP/UDP Port
  vlan-src-ip                 Vlan, Src IP Addr
  vlan-src-mixed-ip-port      Vlan, Src IP Addr and TCP/UDP Port

http://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst6500/ios/12-2SY/configuration/guide/sy_swcg/etherchannel.html#pgfId-1020804

[Zeeeee]

Hi Mark,

From the ISP, it will be connected to 1 of the linecards in both the two chassis.

From the chassis going downstream to other switches, yes i am using port channels and load balancing should be ok like you have mentioned.

But from the two chassis upstream to ISP, is there any way for me to load balance?

[Mark Malone]

Hi what's the connection to the ISP device going to be from the VSS routed or layer 2 , is it just static or whats going to be in place , then you can decide on specifc types of load balancing , you can do LB with defaults , statics and BGP at layer 3

[Menelaos Sazos]

Hello, Aizat!

What Mark says is not 100% correct. For the VSS, the main rule is always "local forwarding".

That means in case you're landing both links from the ISP with LACP and you have like one static default route to the ISP in the config, all the traffic to the Internet received from the Access switch to the 1st 6509 is always sent from it's uplink to the ISP, disregarding any Etherchannel hashes. Same for traffic, received by the 2nd 6509.

In case you're landing an ISP as two separate routed links, one per chassis, and have two static default routes, exact the same forwarding rule applies - each chassis will use local forwarding to the ISP via local link unless the routes are of the equal cost. If one is with lower metric, the whole VSS would prefer it and utilize the VSL to push the traffic between the chassis.

[Joseph W. Doherty]

Another way to described what Menelaos has already explained, VSS tries to avoid using the VSL between the VSS pair.

Everything else being equal, to load balance out of a VSS pair you need to load balance into the VSS pair.

[Zeeeee]

Hi Menelaos,

ISP is only providing a static route, no lacp. Can i do this then:

I will place an Access switch in between ISP and VSS. From the Access switch to VSS, i will do a MEC. This way, VSS will load balance my uplink to the Access switch.

Thanks!