Re: BGP Local Pref and MED/Metric - Route Maps Inbound/Outbound
Just wanted to commend Brian on an excellent explanation. Whenever you start studying BGP (and advanced interior routing), and things start getting confused, it's a good idea always to stop and think: am I dealing with TRAFFIC flow or ROUTING UPDATE flow? On Sat, 9 Dec 2000, Jennifer Mellone wrote: BGP Local Pref is used to control outbound traffic. MED/Metric is used to control inbound traffic. Why is it that you do an inbound route map (vs outbound) when setting local pref and an outbound route map (vs. inbound) when setting MED? It seems opposite. ok...here we go: to get OUT of a router you follow one of the routes in the routing table. These routes come IN to the router from say a peer or upstream. So you need to modify them as they come IN so that they are changed before they are added to the routing/bgp table. Inbound routes effect outbound traffic. for traffic to get IN to your router, its going to follow one of the routes that came OUT of your router. Your router announces its routes to its BGP peers. On their way out you can modify these routes, such as setting med etc. Outbound routes effect inbound traffic. For local pref: 1. route comes from our peer into your router 2. your router can set the local pref of this route coming into your router 3. your router adds this route to its bgp/routing tables now your router will use this route for outbound traffic. For MED: 1. a route is in your router 2. you announce this route to a BGP peer 3. on its way out to the peer, you can modify the metric (MED) 4. The route is added to the peers routing/bgp tables 5. the peer may use this route to get traffic into you Brian - Jennifer Mellone _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] --- Brian Feeny, CCNP+ATM, CCDP [EMAIL PROTECTED] Network Administrator ShreveNet Inc. (ASN 11881) _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
BGP Local Pref and MED/Metric - Route Maps Inbound/Outbound
BGP Local Pref is used to control outbound traffic. MED/Metric is used to control inbound traffic. Why is it that you do an inbound route map (vs outbound) when setting local pref and an outbound route map (vs. inbound) when setting MED? It seems opposite. - Jennifer Mellone _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: BGP Local Pref and MED/Metric - Route Maps Inbound/Outbound
Because you aren't controlling the traffic, you are controlling the prefixes that you are recieving or announcing. andy On Sat, 9 Dec 2000, Jennifer Mellone wrote: BGP Local Pref is used to control outbound traffic. MED/Metric is used to control inbound traffic. Why is it that you do an inbound route map (vs outbound) when setting local pref and an outbound route map (vs. inbound) when setting MED? It seems opposite. - Jennifer Mellone _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: BGP Local Pref and MED/Metric - Route Maps Inbound/Outbound
On Sat, 9 Dec 2000, Jennifer Mellone wrote: BGP Local Pref is used to control outbound traffic. MED/Metric is used to control inbound traffic. Why is it that you do an inbound route map (vs outbound) when setting local pref and an outbound route map (vs. inbound) when setting MED? It seems opposite. ok...here we go: to get OUT of a router you follow one of the routes in the routing table. These routes come IN to the router from say a peer or upstream. So you need to modify them as they come IN so that they are changed before they are added to the routing/bgp table. Inbound routes effect outbound traffic. for traffic to get IN to your router, its going to follow one of the routes that came OUT of your router. Your router announces its routes to its BGP peers. On their way out you can modify these routes, such as setting med etc. Outbound routes effect inbound traffic. For local pref: 1. route comes from our peer into your router 2. your router can set the local pref of this route coming into your router 3. your router adds this route to its bgp/routing tables now your router will use this route for outbound traffic. For MED: 1. a route is in your router 2. you announce this route to a BGP peer 3. on its way out to the peer, you can modify the metric (MED) 4. The route is added to the peers routing/bgp tables 5. the peer may use this route to get traffic into you Brian - Jennifer Mellone _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] --- Brian Feeny, CCNP+ATM, CCDP [EMAIL PROTECTED] Network Administrator ShreveNet Inc. (ASN 11881) _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
